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 ~  Abstract
 ~ Introduction
 ~ Cytadherence
 ~  Cytotoxicity and...
 ~  Community-Acquir...
 ~  Pathogenesis of ...
 ~  Drug Resistance:...
 ~ Conclusion
 ~  References
 ~  Article Figures

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REVIEW ARTICLE
Year : 2016  |  Volume : 34  |  Issue : 1  |  Page : 7-16
 

Pathogenesis of Mycoplasma pneumoniae: An update


Department of Microbiology, AIIMS, New Delhi, India

Date of Submission30-Sep-2014
Date of Acceptance08-Sep-2015
Date of Web Publication15-Jan-2016

Correspondence Address:
R Chaudhry
Department of Microbiology, AIIMS, New Delhi
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0255-0857.174112

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 ~ Abstract 

Genus Mycoplasma, belonging to the class Mollicutes, encompasses unique lifeforms comprising of a small genome of 8,00,000 base pairs and the inability to produce a cell wall under any circumstances. Mycoplasma pneumoniae is the most common pathogenic species infecting humans. It is an atypical respiratory bacteria causing community acquired pneumonia (CAP) in children and adults of all ages. Although atypical pneumonia caused by M. pneumoniae can be managed in outpatient settings, complications affecting multiple organ systems can lead to hospitalization in vulnerable population. M. pneumoniae infection has also been associated with chronic lung disease and bronchial asthma. With the advent of molecular methods of diagnosis and genetic, immunological and ultrastructural assays that study infectious disease pathogenesis at subcellular level, newer virulence factors of M. pneumoniae have been recognized by researchers. Structure of the attachment organelle of the organism, that mediates the crucial initial step of cytadherence to respiratory tract epithelium through complex interaction between different adhesins and accessory adhesion proteins, has been decoded. Several subsequent virulence mechanisms like intracellular localization, direct cytotoxicity and activation of the inflammatory cascade through toll-like receptors (TLRs) leading to inflammatory cytokine mediated tissue injury, have also been demonstrated to play an essential role in pathogenesis. The most significant update in the knowledge of pathogenesis has been the discovery of Community-Acquired Respiratory Distress Syndrome toxin (CARDS toxin) of M. pneumoniae and its ability of adenosine diphosphate (ADP) ribosylation and inflammosome activation, thus initiating airway inflammation. Advances have also been made in terms of the different pathways behind the genesis of extrapulmonary complications. This article aims to comprehensively review the recent advances in the knowledge of pathogenesis of this organism, that had remained elusive during the era of serological diagnosis. Elucidation of virulence mechanisms of M. pneumoniae will help researchers to design effective vaccine candidates and newer therapeutic targets against this agent.


Keywords: Epidemiology, Mycoplasma pneumoniae, pathogenesis


How to cite this article:
Chaudhry R, Ghosh A, Chandolia A. Pathogenesis of Mycoplasma pneumoniae: An update. Indian J Med Microbiol 2016;34:7-16

How to cite this URL:
Chaudhry R, Ghosh A, Chandolia A. Pathogenesis of Mycoplasma pneumoniae: An update. Indian J Med Microbiol [serial online] 2016 [cited 2019 Jul 24];34:7-16. Available from: http://www.ijmm.org/text.asp?2016/34/1/7/174112



 ~ Introduction Top


Community-acquired pneumonia (CAP) continues to be a significant cause of mortality and morbidity worldwide, particularly in the elderly population and under five children.[1],[2] The mortality rate of CAP can rise to 10% in hospital ward admitted patients and can exceed 30% in Intensive Care Unit patients requiring mechanical ventilation and prolonged hospitalisation.[3] Of all aetiological agents of CAP, atypical respiratory bacteria viz., Mycoplasma pneumoniae, Chlamydia pneumoniae and Legionella spp. are increasingly being recognised as emerging pathogens.[4] Studies have demonstrated that the atypical bacteria rank as the third or fourth leading organisms causing CAP, being present in about 22–40% of all CAP patients, often as co-pathogens with other bacteria.[5],[6],[7] In a multi-centric study involving 12 medical centres across Asia, atypical respiratory bacteria were noted in more than 23% of CAP cases. M. pneumoniae was detected in approximately 12% of all CAP cases and was the most common atypical bacteria isolated.[8] In paediatric population, M. pneumoniae account for approximately 10–40% of all lower respiratory tract infections.[8],[9]

Infection with M. pneumoniae is mostly encountered in outpatient setting. However, it is a significant cause of hospitalisation also due to pneumonia, especially in elderly population and immunocompromised patients.[10] Manifestations of M. pneumoniae infection can range from self-limiting upper respiratory illness to severe pneumonia. Children <5 years of age usually suffer from mild upper respiratory symptoms while older children and adolescents develop bronchopneumonia, requiring hospitalisation.[11],[12]M. pneumonia e has been detected in higher proportions in respiratory samples of adults and children with asthmatic attacks or exacerbation, as compared to healthy controls.[13] High rates of carriage of M. pneumoniae in the airways of chronic stable asthmatics also point towards the association of M. pneumoniae with asthma.[14] In a study from our centre too, there was statistically significant association between M. pneumoniae infection and children with severe persistent asthma and acute exacerbation of asthma in previously diagnosed asthmatic children.[15] However, it is only in the recent studies, significant progress has been made in establishing the mechanism by which this organism can cause or exacerbate asthma, an issue that had remained debatable over the years.[16]

Mycoplasmas, which belong to the bacterial class Mollicutes, are cell-wall deficient smallest self-replicating organisms capable of cell free survival.[17] The genome of M. pneumoniae is small (approximately 816 kilo base-pairs) which accounts for its limited biosynthetic capabilities and slow replication rate.[18] Thus, a major obstacle in understanding the pathogenic role of this organism has been the lack of knowledge of its biological properties due to difficulties associated with cultivation of this organism.

Early researches that have counted the role of M. pneumoniae in the pathogenesis of different clinical entities depended only on serological assays which were less specific and could not provide a definite association with disease pathogenesis.[12] Since, IgM antibodies may not be present early in the course of infection, diagnosis based only on serology may not be accurate. In fact, seroprevalence of M. pneumoniae in adults with pneumoniae has been found to be highly variable ranging from 1.9% to over 30%.[19] Moreover, simultaneous detection of co-pathogens, which included respiratory viruses and other bacteria, often considered M. pneumoniae as an innocent bystander organism.[20],[21] Advances in molecular diagnosis such as nucleic-acid amplification tests (NAATs), sequencing and proteomic studies have helped us to gain knowledge about the pathogenesis of this organism that had remained elusive.[22],[23] In the past few years, potential pathogenic factors associated with this organism have been studied in details using molecular methods by researchers who had looked into different aspects of pathogenesis such as complex adherence mechanism of M. pneumoniae, the community-acquired respiratory distress syndrome toxin (CARDS toxin) that activate the inflammasomes and the genesis of extrapulmonary complications. The inflammatory pathways leading to tissue injury following M. pneumoniae infection have been elucidated using highly sensitive cytokine assays and mRNA expression systems. In this article, we try to comprehensively review the pathogenesis of M. pneumoniae highlighting the recent advances in terms of cytadherence, cytotoxic and inflammatory potential and the pathogenic role of CARDS toxin. We also discuss about the updates in molecular pathogenesis of extrapulmonary manifestations of M. pneumoniae infection.


 ~ Cytadherence Top


The initial step of M. pneumoniae respiratory tract infection involves cytadherence of the organism to the ciliated columnar epithelium of the respiratory tract, which protects the organism from mucociliary clearance and local cytotoxic effects.[12] Cellular adherence to sialoglycoproteins and sulphated glycolipids is mediated by a specialised organelle, the structure of which has been delineated by electron microscopy. It consists of a central core composed of dense filaments and a tip-like structure composed of adhesins and accessory proteins.[24],[25] The major proteins, that have been experimentally proven directly involved in receptor binding, are the 170 kilodalton P1-adhesin and the P30-adhesin. High molecular weight protein-1 (HMW-1), HMW-2, HMW-3 and proteins A, B and C act as accessory proteins, interacting with P1 and P30 and assisting in cytadherence.[26],[27] A schematic representation of M. pneumoniae adherence organelle is provided in [Figure 1].
Figure 1: Mycoplasma pneumoniae cytadherence organelle with adherence proteins (Reproduced from Frontiers in Bioscience 2007; 12: 690-699 by R Chaudhry et al.)

Click here to view


P1-adhesin

The P1-adhesin is a transmembrane protein, concentrated primarily at the tip of the attachment organelle of M. pneumoniae. Mutant strains lacking P1-adhesin fail to adhere to animal cells and are avirulent.[28],[29]In vitro studies have demonstrated that P1-adhesin is also involved in gliding motility of the organism that may help in cell to cell transfer. Repeated gliding motility allows the organism to bind and release itself from the attaching surface which eventually increases the infective surface area. Anti-P1 monoclonal antibody had inhibitory effects on gliding motility and adherence to tracheal rings by M. pneumoniae.[30]

Studies by Kenri et al. and Su et al. have shown that there are variable regions on the P1-adhesin protein attributed to the repetitive sequences of this cytadhesin gene.[31],[32] According to Jacobs, the adherence mediating domains of P1-adhesin are highly conserved while the immunodominant epitopes are variable. Thus, antibodies which are predominantly against the immunodominant epitopes, fail to block the antigenically distinct cytadherent protein, allowing the organism to evade antibody response.[33] In a recent study from our centre, we have shown that immunodominant regions are actually distributed throughout the length of P1-protein. Only the amino and carboxy-terminals of P1-protein are surface exposed and antibodies directed to these regions blocked adherence of M. pneumoniae to Hep-2 cell line. Antibodies to the middle part failed to block cytadhesion.[34]

P30-adhesin

The other important protein involved in adherence of M. pneumoniae is the P30-adhesin. It is a transmembrane protein present in cluster at the attachment organelle tip. Additional function of P30 includes gliding motility and co-ordination of cell division with biogenesis of the attachment organelle.[35],[36]

Accessory adhesion proteins

Interactions of major adhesin proteins with the accessory proteins such as HMW-1, HMW-2, HMW-3 and protein-A, protein-B and protein-C help in establishing the complete attachment organelle structure. Mutations in genes encoding the accessory proteins lead to cytadherence defects.[36],[37] Two other proteins viz., P65 and P116 have recently been shown to be present at the distal end of the terminal organelle, which probably act by interacting with P1 and P30 adhesins thus assisting in attachment.[38],[39] However, further role of these accessory proteins in pathogenesis of M. pneumoniae needs to be studied for better understanding of interactions between host cells and the organism. The adhesion proteins may serve as potential targets for therapeutic and vaccine strategies against M. pneumoniae.

To summarise, the adhesins of M. pneumoniae through their complex interactions allow close association of the organism with host cells which is followed by cytotoxicity and inflammation. Intracellular localisation may occur in M. pneumoniae before it induces cytotoxicity. However, the extent of intracellular localisation is not known in vivo. The fusion of Mycoplasma cell membrane with the host cell enabling intracellular location may help in establishing latent or chronic states, avoiding immune response and impairing drug therapy.


 ~ Cytotoxicity and Inflammation Top


Free radical mediated cellular damage is one of the pathways by which M. pneumoniae affects respiratory epithelium. Oxidative stress as an important step in pathogenesis of M. pneumoniae results from the hydrogen peroxide and superoxide radicals generated by the organisms as well as by the host immune system.[40] Superoxide radicals also inhibit host cell catalase, thereby augmenting the effect of free radical damage.[41] Sun et al. in 2008 demonstrated that M. pneumoniae infection of A549 human lung carcinoma cell line led to generation of reactive oxygen species (ROS). Generation of ROS induced changes in proteomic profile of the cell line in terms of exposure of host oxidative stress response enzymes such as glucose-6-phosphate dehydrogenase, nicotinamide adenine dinucleotide (NAD) dehydrogenase and also caused DNA double-stranded breaks.[42] Similar role of ROS in mediating lung injury by M. pneumoniae has been demonstrated in mice. Mycoplasma infection in mice caused impairment of alveolar ion transport leading to decreased alveolar fluid clearance due to ROS-mediated damage to epithelial sodium channels.[43]

Pulmonary injury due to M. pneumoniae infection has also been attributed to the host inflammatory response. M. pneumoniae infection is characterised by peribronchiolar alveolar infiltration with neutrophils, lymphocytes and plasma cells.[44]In vitro studies in human lung epithelial carcinoma cells have shown increased levels of proinflammatory cytokines-like interleukin-8 (IL-8) and tumour necrosis factor α (TNF-α) in culture media and cellular expression of IL-1β mRNA. These cytokines act as potent chemoattractants for inflammatory cells. Increased levels of these proinflammatory cytokines result from the activation of pattern recognition receptors (PRRs) namely toll-like receptor-1 (TLR-1), TLR-2 and TLR-6 by M. pneumoniae membrane proteins.[45] Lipid-associated membrane protein or a dipalmitoylated lipoprotein of M. pneumoniae activates TLR-1, TLR-2 and TLR-6 leading to activation of monocytic nuclear factor-κβ (NF-κβ), a key regulator of proinflammatory cytokine release.[45],[46] In mice models it was demonstrated that a previous challenge with M. pneumoniae extracts actually upregulated TLR-2 expression in alveolar macrophages which resulted in a magnified inflammatory response to subsequent challenges by the same extract.[45]

Thus, a major pathway of M. pneumoniae pathogenesis is induction of inflammation via the TLR-mediated cytokine release and generation of free radicals. In addition an exaggerated innate immune response in M. pneumoniae infection can be due to a positive feedback effect of previous M. pneumoniae colonisation or asymptomatic infection. This recent update in the concept of immunopathogenesis of M. pneumoniae will help researchers to target potential molecules such as the membrane lipoproteins and other TLR ligands for modulating high levels of airway inflammation and prevent lung injury due to M. pneumoniae.


 ~ Community-Acquired Respiratory Distress Syndrome Toxin Top


Community-acquired respiratory distress syndrome toxin: Background

Early studies in the 1970s and 1980s had tried to describe the pathology of M. pneumoniae infection using organ culture and cell culture systems.[47],[48] Infection of hamster tracheal culture was characterised by ciliostasis and cytoplasmic vacuolisation followed by aggregation of intracellular vacuoles leading to cytoplasmic distortion and cell damage.[48] Based on the cytotoxic effects of M. pneumoniae infection, researchers hypothesised that a Mycoplasma membrane associated toxic factor could be responsible for pathogenesis.[49] Toxic effects of free radical generation could only partially explain such effects of M. pneumoniae virulence.[40],[50] In 1975, Hu et al. demonstrated the inhibition of RNA and protein synthesis along with decreased uptake of metabolic substrates in M. pneumoniae infected host cells which could not be explained by cytadherence process of the organism and effects of generation of ROS. Hu et al. thus, suggested that the primary detrimental effect on the host cell was at the transcriptional or translational level. The fact that cytopathic effects of M. pneumoniae infection could only be reversed by early addition of erythromycin to the organ culture (within 24 h of infection) pointed to the conclusion that the organism required to synthesise a certain protein or toxin to mediate host cell injury.[48]

Subsequently, Kannan et al. in their attempt to characterise the virulence factors of M. pneumoniae observed calcium dependent, trypsin sensitive binding M. pneumoniae to human surfactant protein-A. Surfactant protein-A binding of M. pneumoniae was found to be a crucial factor in the colonisation of the respiratory tract by the organism.[51] This protein of M. pneumoniae, required for binding, was identified by affinity chromatography followed by purification and sequencing. The 68-kDa protein, which was different from adhesin, cytadherence-associated proteins or fibronectin binding proteins, was initially termed as MPN 372. It shared amino acid homology at the catalytic site with that of the S1 subunit of Bordetella pertussis toxin. The MPN 372 protein was found to catalyse adenosine diphosphate ribosylation (ADP-ribosylation), similar to Bordetella pertussis toxin S1 subunit, and possess vacuolating function in infected cells.[51] Using mammalian cell lines and baboon tracheal organ culture, Kannan and Baseman confirmed the virulent properties of the protein and gave it the name CARDS toxin.[52]

Recombinant CARDS toxin was synthesised by expression in  Escherichia More Details coli to overcome the problem of isolating the toxin in minute or insufficient quantities in the broth culture of inherently slow growing mycoplasmas.[53] Treatment of Chinese hamster ovary cells or HEp-2 cells with the recombinant toxin showed its ability to transfer ADP-ribosyl group from nicotinamide adenine diphosphate (NAD +) to amino acids of cellular protein. The ribosylating property of CARDS toxin resulted in alteration of the protein targets including enzymes of host cell metabolic pathways which lead to cellular toxicity. Cytopathic effects in the form of vacuolisation, cellular rounding and cellular distortion were also exhibited.[53] In organ culture of baboon tracheal rings, recombinant CARDS toxin caused loss of ciliary function of respiratory epithelium, intensive cytoplasmic vacuolisation, karyopyknosis and disruption of epithelial integrity.[54] These toxin-mediated progressive cytotoxic changes in tracheal rings were partly explanatory for the mechanism of pathogenesis of airway disease of M. pneumoniae which had remained elusive over the years.

CARDS toxin: Role in pathogenesis

Effect of the recombinant toxin on the respiratory tract has also been studied in mice and primate models. Intranasal inoculation in BALB/c mice induced airway mucous production with extensive peribronchiolar and perivascular inflammation. Along with transient neutrophilia followed by significant increase in eosinophils at day 7 of exposure in the broncho-alveolar lavage fluid (BALF).[55] Hardy et al. demonstrated that the early cytokine response in mice was predominantly proinflammatory which included IL-1, IL-6, IL-12 and TNF-α. In baboons toxin inoculation led to increase in chemokines such as regulated on activation, normal T cell expressed and secreted, IL-8, interferon-γ (IFN-γ) and granulocyte-colony stimulating factor in addition to proinflammatory cytokines, closely resembling human M. pneumoniae infection.[56] Significant increases in expression of TH2 cytokines viz., IL-4 and IL-13 and chemokines, chemokine (C-C motif) ligand-7 (CCL-7) and CCL-32, were also demonstrated using quantitative reverse transcriptase-polymerase chain reaction (PCR) of M. pneumoniae infected mice BALF by Medina et al.[57] Recombinant CARDS toxin exposure resulted in exaggerated TH2 inflammatory response in the respiratory tract of mice, previously sensitised with ovalbumin. Invasive pulmonary measurements in infected mice recorded increased airway resistance and decreased lung compliance due to increased airway reactivity.[57] Thus, in animal models CARDS toxin exposure induced a proinflammatory response in the respiratory tract.

Chemoattractant activities of CCL-17 and CCL-22 leading to lymphocyte and eosinophil recruitment and increased expression of IL-4 and IL-13, eosinophil mediated pulmonary inflammation and increased airway reactivity are determining factors in the pathogenesis of asthma in humans. A similar cytokine and cellular profile of the respiratory tract secretions are induced by CARDS toxin in mice as well as primates such as baboons. These findings point towards a role of this toxin in asthmatic exacerbation and further confirm the association between M. pneumonia infection and asthma.

Community-acquired respiratory distress syndrome toxin and inflammasome

A recent discovery about M. pneumoniae pathogenesis has been the elucidation of the pathway, by which CARDS toxin induces inflammation through regulation of inflammasome activity [Figure 2]. A component of the innate immune response system in mammals, the inflammasome comprises of a multiprotein complex present in the cell cytoplasm and acts by activation of the enzyme caspase-1 which in turn cleaves pro-IL-1β to active IL-1β.[58] The IL-1β is an inflammatory cytokine, which through activation of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) dependent pathways amplifies inflammatory responses against infectious agents.[59] However, over-activaion of inflammasomes after infection can cause tissue injury due to 'hyperinflammation'.[58],[60] Allergen induced inflammasome activation also leading to lung injury and lung remodelling, which has been implicated in the pathogenesis asthma and chronic obstructive pulmonary disease.[61]
Figure 2: Schematic representation of the pathway for M. pneumoniae CARDS toxin mediated inflammation

Click here to view


Nucleotide-binding oligomerization domain leucine-rich repeats containing receptors (NLRs) are intracellular PRRs, present in a wide variety of cells viz., lymphocytes, macrophages and dendritic cells. The NLRs act as sensors for pathogen associated molecular patterns (PAMPs). The most well-characterised NLR that is, NLRP-3, which is expressed in myeloid cells, complexes with inflammasome after being upregulated in response to PAMPs. This NLRP-3-inflammososme complex can activate caspase-1 which in turn leads to IL-1β release.[60] The CARDS toxin co-localizes with NLRP-3-inflammasome within mice bone-marrow derived macrophages in vitro and by its ADP-ribosylating property of NLRP-3 activates the inflammasome followed by release of IL-1β.[62],[63] The M. pneumoniae CARDS toxin has been shown to be internalised into mammalian cells via clathrin-mediated endocytosis.[64] Hence, following cellular entry CARDS toxin mediated activation of inflammasomes in alveolar macrophages can a potent mechanism of release of IL-1β, a pro-inflammatory cytokine, into the airways. In fact, higher levels of IL-1β has been detected in respiratory samples of symptomatic asthmatic patients compared to healthy controls.[65] Thus, CARDS toxin of M. pneumoniae by its ability to activate inflammasome can act as a trigger in initiating airway inflammation recapitulating the events the occurs in asthma However, the hypothesis of M. pneumoniae CARDS toxin being a causative agent or a triggering factor of asthma still remains to be tested in human models.


 ~ Pathogenesis of Extrapulmonary Manifestations Top


Respiratory infections with M. pneumoniae is often complicated in as many as 25% of cases by the involvement of various extrapulmonary systems such as nervous system, cardiovascular system, bones and joints, kidney, skin and mucosa. However, extrapulmonary manifestations can occur even in the absence of pneumonia.[66],[67] A retrospective study by Pönkä had shown that neurological complications, in absence of any respiratory symptoms, can occur in up to 18% of M. pneumoniae infected cases.[68] Pathogenic mechanisms of extrapulmonary complications have been partly elucidated and further studies are for complete understanding of these processes. Complications of central and peripheral nervous systems rank as the most common of all extrapulmonary complications and can occur in approximately 1–7% of serologically confirmed M. pneumoniae hospitalised for respiratory illnesses.[69],[70] Initial studies on central nervous system (CNS) complications were primarily based on serological diagnosis of M. pneumoniae infection and neural tissue damage was thought to be due to autoimmune mechanisms or due to other pathogens in presence of a false positive Mycoplasma serology.[66],[71] However, detection of Mycoplasma nucleic-acid by NAATs in neurological specimen has changed the perspective. M. pneumoniae associated neurological complications are now hypothesised to be caused by direct inflammatory injury due to cytokines induced by the organism, generation of antibodies cross-reactive with host tissue components and vascular occlusion due to vasculitis and/or thrombosis.[72] Interplay between these mechanisms lead to generation of neurological symptoms.

The most common form neurological complication is encephalitis, more common in children <10 years of age than in adults.[72] Up to 60% of paediatric encephalitis patients end up with neurological sequelae.[73] Other neurological manifestations include aseptic meningitis, meningoencephalitis, acute transverse myelitis, acute disseminating encephalomyelitis (ADEM), Guillain–Barré syndrome (GBS) and stroke.[74] As proposed by Narita, encephalitis due to M. pneumoniae can be classified into early-onset (onset of neurological symptoms within 7 days of onset of fever) and late-onset (onset of neurological symptoms at 8 days or after onset of fever) varieties.[75] Bitnun et al. and Socan et al. have also supported such a classification in their studies.[76],[77] It has been hypothesised that early-onset encephalitis is the result of cytokine mediated direct neural tissue injury while late-onset encephalitis is due to autoimmune mechanisms.[75]

M. pneumoniae was isolated from the autopsied brain specimen of a 30-year-old woman with encephalitis, as early as 1980. Isolation of this organism from lung, kidney and trachea of this patient was the evidence of dissemination of this organism.[66],[78] Subsequently, M. pneumoniae nucleic-acid was detected by PCR and nucleic-acid hybridisation from brain tissues of patients with early-onset encephalitis following pneumonia.[79] In a case series of patients with features of encephalitis, meningoencephalitis and ADEM, antibodies against M. pneumoniae were detected in 74% of cases in the cerebrospinal fluid (CSF) PCR.[80] Even M. pneumoniae antigen has been detected by immunohistochemistry in macrophages from perivascular infiltrates of cerebral hemispheres, medulla oblongata and spinal cord in patients positive for M. pneumoniae DNA in tracheobronchial secretions.[81] Since, M. pneumoniae positive serology or culture or PCR of respiratory tract samples cannot differentiate between colonisation and infection, demonstration of the organism by PCR or culture or antigen detection from CSF samples or detection of intrathecal antibodies have been the key factor behind the hypothesis of dissemination and direct tissue injury by the organism. In fact, other Mycoplasma species have the ability to infect brain tissue of animals such as Mycoplasma galliseptica in birds, Mycoplasma pulmonis in rodents and Mycoplasma hyopneumoniae in pigs.[12]

Dissemination to distant tissues is the earliest step in the pathogenesis of neurological complications due to M. pneumoniae. It has been shown that M. pneumoniae gets passively transferred through gaps between injured respiratory epithelial cells and probably reaches by circulating in blood in a cell-free form.[72],[82] Tissue injury is mediated by local production of cytokine by the interaction of M. pneumoniae glycolipid antigen and TLR-1, TLR-2 and TLR-6 of inflammatory cells leading to activation of cytokine cascade. The two major cytokine that have been found to be elevated intrathecally in early-onset encephalitis has been IL-6 and IL-8, of which IL-8 is a potent neutrophil chemoattractant. Neural tissue injury is probably due to inflammatory cell-mediated damage. In contrast to bacterial meningoencephalitis due to other organisms, elevated levels of IFN-γ and TNF-α were not observed. Another cytokine, IL-18 has been found to be elevated in CSF in patients with late-onset encephalitis due to M. pneumoniae.[75],[83]

Autoimmunity is the proposed mechanism of pathogenesis for M. pneumoniae associated late-onset encephalitis along with acute transverse myelitis, GBS, polyradiculopathies and optic neuritis. Both GM1 ganglioside and galactocerebroside epitopes have been detected on M. pneumoniae cell surface that cross-reacts with host myelin glycolipid moieties expressed in neuronal tissues. Cross-reacting antibodies are either intrathecally produced or cross the blood-brain barrier that become permeable during cytokine-mediated inflammation by direct effect of the organism.[84],[85]

Autoantibodies to lipid-associated neural antigens in patients with Mycoplasma induced CNS disease were first described by Biberfield in 1971.[86] Subsequently, anti-galactocerebroside and anti-GM1 ganglioside antibodies were demonstrated in CSF of patients with post M. pneumoniae CNS dysfunction. In these cases CNS manifestations were preceded by respiratory symptoms by 8 days or more which coincides with the generation of these antibodies.[87],[88] Approximately 5–15% GBS cases are associated with a preceding M. pneumoniae infection and (GBS) patients with evidence of recent M. pneumoniae infection have been shown to be more likely positive for anti-galactocerebroside and anti-GM1 ganglioside antibodies than other GBS patients.[89],[90],[91] The antigen-antibody complexes activates the complement cascade and formation of membrane-attack complex leading to demyelination. Since most of the GBS cases have been diagnosed by serological testing for M. pneumoniae following respiratory illness, establishing a definite causal relationship is difficult in absence of a positive culture or a PCR result.

Anti-galactocerebroside C and antiganglioside antibodies such as anti-GQ1B have also been detected in serum and CSF of patients with acute meningoencephalitis and Bickerstaff's brain-stem encephalitis following M. pneumoniae infection.[92] However, association of M. pneumoniae infection and pathogenesis of these disorders remains unclear and further studies are required. Role of these antibodies in CNS complications has been questioned in a study by Biberfeld et al. in which 80% of M. pneumoniae infected individuals without CNS manifestations had these circulating antibodies.[93] However, further evidence of molecular mimicry of M. pneumoniae has been provided by in vitro studies, where anti-P1-adhesion antibodies cross-reacted with intracellular enzymes viz., glyceralde-3-phosphate dehydrogenase and 2-phospho D-glycerate hydrolase in eukaryotic cell lines.[86]

The third mechanism for CNS manifestations has been proposed to be vascular occlusion. Vascular occlusion is caused by local vascular injury due to cytokines and chemokines due to M. pneumoniae infection.[72],[75] This form of ischaemic injury to CNS occurs in absence of thrombotic mechanism and is the main pathophysiology for bilateral striatal necrosis following M. pneumoniae infection. However, considering stroke in children and adults in whom M. pneumoniae DNA has been detected in CSF, the cause still remains to be elucidated.

M. pneumoniae infection has also been associated with dermatological complications in 1–5% cases, manifested by erythema multiforme and Mycoplasma induced rash and mucositis (MIRM), which includes mild erythematous maculo-papular rash, vesicular eruptions, toxic epidermal necrolysis and rarely Steven–Johnson syndrome.[94] Systematic corticosteroid therapy and/or intravenous immunoglobin may be required in some cases. Cause of MIRM has been attributed to the molecular mimicry between Mycoplasma P1-adhesin molecule and keratinocyte antigen leading to generation of cross-reacting antibodies, immune-complex formation and complement activation. Erythema multiforme following M. pneumoniae infection is hypothesised to be a type-IV hypersensitivity reaction or a cytotoxic damage through a Fas Ligand and granulysin mediated perforin-granzyme pathway.[95] Haematologic manifestations of M. pneumoniae infection include haemolytic anaemia due to autoimmune cold agglutinins and thrombotic thrombocytopenic purpura due to cross-reactive antibodies inactivating plasma von Willebrand factor-cleaving protease.[12],[96] For other systemic complications, additional studies are required to elucidate the pathological pathways.


 ~ Drug Resistance: an Emerging Problem Top


Effective treatment includes macrolides, the antimicrobial of choice and tetracycyclines and fluoroquinolones. However, high rates of macrolide resistance have been reported from Asian countries such as China and Japan. More than 90% of Chinese and approximately 87% of Japanese isolates have been shown to be macrolide resistant.[97],[98] Macrolide resistance strains are also emerging from other parts of the world including USA and European countries such as Germany and France.[99],[100] Macrolide resistance in M. pnuemoniae has been attributed to nucleotide mutations in the 23S rRNA genes which have led to increased minimal inhibitory concentrations to erythromycin, azithromycin and clarithromycin. Although resistance to quinolones or tetracyclines among clinical isolates of M. pneumoniae has not been reported, considering the side effects of tetracycline therapy and fluoroquinolones not being recommended for use in children, an effective vaccine against M. pneumoniae is desirable. Developments of a successful vaccine will not only enable us to prevent the serious complications of M. pneumoniae infection but also act as a preventive strategy against outbreaks, particularly in closed community settings. Inactivated vaccines have been tested in clinical trials and the summarised efficacy was only 40% approximately against M. pneumoniae associated pneumonia.[101] Hence, further efforts for developing a more efficacious, yet safe, vaccine against M. pneumoniae should continue based on the recent advances in knowledge regarding the virulence properties of this organism.


 ~ Conclusion Top


Although majority of patients with M. pneumoniae infection can be treated in outpatient or ambulatory setting, severe infections in susceptible population may require hospitalisation. Moreover, extrapulmonary manifestations, particularly the neurological complications, can lead to poor outcome in infected patients.

Our knowledge regarding the pathogenesis of this organism has improved ever since the introduction of highly sensitive molecular assays. Newer cytadherence proteins have been discovered, immunological pathways leading to tissue injury have been elucidated and researchers have also characterised the novel CARDS toxin molecule. There have been significant advances in the knowledge of immunopathogenesis in terms of the role of TLRs and inflammasomes, which can be used as potential therapeutic targets in modulation of the disease process eg. inhibitors or antibodies against relevant peptides. However, most of the studies have been performed in cell lines or in animal models. Hence, the authors feel that for designing a vaccine which will produce high levels of protective immunity in susceptible population, larger studies regarding the pathogenesis at subcellular levels need to be undertaken in humans. Such studies will further improve our understanding about the disease process, particularly in terms of association of the organism with chronic lung diseases and debilitating extrapulmonary complications. A holistic approach of studying the molecular virulence properties of the organism will not only help in designing an effective vaccine but can also lead to development of newer therapeutic modalities and better diagnostic assays enabling us in comprehensive management of infections due to M. pneumoniae.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 
 ~ References Top

1.
Lozano R, Naghavi M, Foreman K, Lim S, Shibuya K, Aboyans V, et al. Global and regional mortality from 235 causes of death for 20 age groups in 1990 and 2010: A systematic analysis for the Global Burden of Disease Study 2010. Lancet 2012;380:2095-128.  Back to cited text no. 1
[PUBMED]    
2.
Nair H, Simões EA, Rudan I, Gessner BD, Azziz-Baumgartner E, Zhang JS, et al. Global and regional burden of hospital admissions for severe acute lower respiratory infections in young children in 2010: A systematic analysis. Lancet 2013;381:1380-90.  Back to cited text no. 2
    
3.
Nair GB, Niederman MS. Community-acquired pneumonia: An unfinished battle. Med Clin North Am 2011;95:1143-61.  Back to cited text no. 3
    
4.
File TM Jr, Tan JS, Plouffe JF. The role of atypical pathogens: Mycoplasma pneumoniae, Chlamydia pneumoniae, and Legionella pneumophila in respiratory infection. Infect Dis Clin North Am 1998;12:569-92.  Back to cited text no. 4
    
5.
Woodhead M. Community-acquired pneumonia guidelines – An international comparison: A view from Europe. Chest 1998;113:183S-7S.  Back to cited text no. 5
    
6.
Ruiz-González A, Falguera M, Nogués A, Rubio-Caballero M. Is Streptococcus pneumoniae the leading cause of pneumonia of unknown etiology? A microbiologic study of lung aspirates in consecutive patients with community-acquired pneumonia. Am J Med 1999;106:385-90.  Back to cited text no. 6
    
7.
Vergis EN, Yu VL. Macrolides are ideal for empiric therapy of community-acquired pneumonia in the immunocompetent host. Semin Respir Infect 1997;12:322-8.  Back to cited text no. 7
    
8.
Ngeow YF, Suwanjutha S, Chantarojanasriri T, Wang F, Saniel M, Alejandria M, et al. An Asian study on the prevalence of atypical respiratory pathogens in community - Acquired pneumonia. Int J Infect Dis 2005;9:144-53.  Back to cited text no. 8
    
9.
Meyer Sauteur PM, Jacobs BC, Spuesens EB, Jacobs E, Nadal D, Vink C, et al. Antibody responses to Mycoplasma pneumoniae: Role in pathogenesis and diagnosis of encephalitis? PLoS Pathog 2014;10:e1003983.  Back to cited text no. 9
    
10.
Marston BJ, Plouffe JF, File TM Jr, Hackman BA, Salstrom SJ, Lipman HB, et al. Incidence of community-acquired pneumonia requiring hospitalization. Results of a population-based active surveillance Study in Ohio. The Community-Based Pneumonia Incidence Study Group. Arch Intern Med 1997;157:1709-18.  Back to cited text no. 10
    
11.
Foy HM. Infections caused by Mycoplasma pneumoniae and possible carrier state in different populations of patients. Clin Infect Dis 1993;17:S37-46.  Back to cited text no. 11
    
12.
Waites KB, Talkington DF. Mycoplasma pneumoniae and its role as a human pathogen. Clin Microbiol Rev 2004;17:697-728.  Back to cited text no. 12
    
13.
Rollins DR, Good JT Jr, Martin RJ. The role of atypical infections and macrolide therapy in patients with asthma. J Allergy Clin Immunol Pract 2014;2:511-7.  Back to cited text no. 13
    
14.
Martin RJ, Kraft M, Chu HW, Berns EA, Cassell GH. A link between chronic asthma and chronic infection. J Allergy Clin Immunol 2001;107:595-601.  Back to cited text no. 14
    
15.
Varshney AK, Chaudhry R, Saharan S, Kabra SK, Dhawan B, Dar L, et al. Association of Mycoplasma pneumoniae and asthma among Indian children. FEMS Immunol Med Microbiol 2009;56:25-31.  Back to cited text no. 15
    
16.
Guilbert TW, Denlinger LC. Role of infection in the development and exacerbation of asthma. Expert Rev Respir Med 2010;4:71-83.  Back to cited text no. 16
    
17.
Wilson MH, Collier AM. Ultrastructural study of Mycoplasma pneumoniae in organ culture. J Bacteriol 1976;125:332-9.  Back to cited text no. 17
[PUBMED]    
18.
Himmelreich R, Hilbert H, Plagens H, Pirkl E, Li BC, Herrmann R. Complete sequence analysis of the genome of the bacterium Mycoplasma pneumoniae. Nucleic Acids Res 1996;24:4420-49.  Back to cited text no. 18
    
19.
Hammerschlag MR. Mycoplasma pneumoniae infections. Curr Opin Infect Dis 2001;14:181-6.  Back to cited text no. 19
    
20.
Bitnun A, Richardson SE. Mycoplasma pneumoniae: Innocent bystander or a true cause of central nervous system disease? Curr Infect Dis Rep 2010;12:282-90.  Back to cited text no. 20
    
21.
Atkinson TP, Balish MF, Waites KB. Epidemiology, clinical manifestations, pathogenesis and laboratory detection of Mycoplasma pneumoniae infections. FEMS Microbiol Rev 2008;32:956-73.  Back to cited text no. 21
    
22.
Nilsson AC, Björkman P, Persson K. Polymerase chain reaction is superior to serology for the diagnosis of acute Mycoplasma pneumoniae infection and reveals a high rate of persistent infection. BMC Microbiol 2008;8:93.  Back to cited text no. 22
    
23.
Thurman KA, Walter ND, Schwartz SB, Mitchell SL, Dillon MT, Baughman AL, et al. Comparison of laboratory diagnostic procedures for detection of Mycoplasma pneumoniae in community outbreaks. Clin Infect Dis 2009;48:1244-9.  Back to cited text no. 23
    
24.
Krivan HC, Olson LD, Barile MF, Ginsburg V, Roberts DD. Adhesion of Mycoplasma pneumoniae to sulfated glycolipids and inhibition by dextran sulfate. J Biol Chem 1989;264:9283-8.  Back to cited text no. 24
    
25.
Roberts DD, Olson LD, Barile MF, Ginsburg V, Krivan HC. Sialic acid-dependent adhesion of Mycoplasma pneumoniae to purified glycoproteins. J Biol Chem 1989;264:9289-93.  Back to cited text no. 25
    
26.
Krause DC. Mycoplasma pneumoniae cytadherence: Unravelling the tie that binds. Mol Microbiol 1996;20:247-53.  Back to cited text no. 26
    
27.
Krause DC, Leith DK, Wilson RM, Baseman JB. Identification of Mycoplasma pneumoniae proteins associated with hemadsorption and virulence. Infect Immun 1982;35:809-17.  Back to cited text no. 27
[PUBMED]    
28.
Kahane I, Tucker S, Leith DK, Morrison-Plummer J, Baseman JB. Detection of the major adhesin P1 in triton shells of virulent Mycoplasma pneumoniae. Infect Immun 1985;50:944-6.  Back to cited text no. 28
[PUBMED]    
29.
Kahane I. In vitro studies on the mechanism of adherence and pathogenicity of mycoplasmas. Isr J Med Sci 1984;20:874-7.  Back to cited text no. 29
[PUBMED]    
30.
Seto S, Kenri T, Tomiyama T, Miyata M. Involvement of P1 adhesin in gliding motility of Mycoplasma pneumoniae as revealed by the inhibitory effects of antibody under optimized gliding conditions. J Bacteriol 2005;187:1875-7.  Back to cited text no. 30
    
31.
Kenri T, Taniguchi R, Sasaki Y, Okazaki N, Narita M, Izumikawa K, et al. Identification of a new variable sequence in the P1 cytadhesin gene of Mycoplasma pneumoniae: Evidence for the generation of antigenic variation by DNA recombination between repetitive sequences. Infect Immun 1999;67:4557-62.  Back to cited text no. 31
    
32.
Su CJ, Chavoya A, Dallo SF, Baseman JB. Sequence divergency of the cytadhesin gene of Mycoplasma pneumoniae. Infect Immun 1990;58:2669-74.  Back to cited text no. 32
    
33.
Jacobs E. Mycoplasma pneumoniae disease manifestations and epidemiology. In: Razin S, Herrman R, editors. Molecular Biology and Pathogenicity of Mycoplasmas. New York, N.Y: Kluwer Academic/Plenum Publishers; 2002. p. 519-30.  Back to cited text no. 33
    
34.
Chourasia BK, Chaudhry R, Malhotra P. Delineation of immunodominant and cytadherence segment(s) of Mycoplasma pneumoniae P1 gene. BMC Microbiol 2014;14:108.  Back to cited text no. 34
    
35.
Balish MF, Krause DC. Cytadherence and the cytoskeleton. In: Razin S, Hermann R, editors. Molecular Biology and Pathogenicity of Mycoplasmas. New York, NY: Kluwer Academic/Plenum Publishers; 2002. p. 491-518.  Back to cited text no. 35
    
36.
Chaudhry R, Varshney AK, Malhotra P. Adhesion proteins of Mycoplasma pneumoniae. Front Biosci 2007;12:690-9.  Back to cited text no. 36
    
37.
Waldo RH 3rd, Krause DC. Synthesis, stability, and function of cytadhesin P1 and accessory protein B/C complex of Mycoplasma pneumoniae. J Bacteriol 2006;188:569-75.  Back to cited text no. 37
    
38.
Hasselbring BM, Sheppard ES, Krause DC. P65 truncation impacts P30 dynamics during Mycoplasma pneumoniae gliding. J Bacteriol 2012;194:3000-7.  Back to cited text no. 38
    
39.
Drasbek M, Nielsen PK, Persson K, Birkelund S, Christiansen G. Immune response to Mycoplasma pneumoniae P1 and P116 in patients with atypical pneumonia analyzed by ELISA. BMC Microbiol 2004;4:7.  Back to cited text no. 39
    
40.
Tryon VV, Baseman JB. Pathogenic determinants and mechanisms. In: Maniloff J, editor. Mycoplasmas: Molecular Biology and Pathogenesis. Washington, D.C: American Society for Microbiology; 1992. p. 457-71.  Back to cited text no. 40
    
41.
Almagor M, Kahane I, Yatziv S. Role of superoxide anion in host cell injury induced by Mycoplasma pneumoniae infection. A study in normal and trisomy 21 cells. J Clin Invest 1984;73:842-7.  Back to cited text no. 41
[PUBMED]    
42.
Sun G, Xu X, Wang Y, Shen X, Chen Z, Yang J. Mycoplasma pneumoniae infection induces reactive oxygen species and DNA damage in A549 human lung carcinoma cells. Infect Immun 2008;76:4405-13.  Back to cited text no. 42
    
43.
Hickman-Davis JM, McNicholas-Bevensee C, Davis IC, Ma HP, Davis GC, Bosworth CA, et al. Reactive species mediate inhibition of alveolar type II sodium transport during Mycoplasma infection. Am J Respir Crit Care Med 2006;173:334-44.  Back to cited text no. 43
    
44.
Hardy RD, Jafri HS, Olsen K, Hatfield J, Iglehart J, Rogers BB, et al. Mycoplasma pneumoniae induces chronic respiratory infection, airway hyperreactivity, and pulmonary inflammation: A murine model of infection-associated chronic reactive airway disease. Infect Immun 2002;70:649-54.  Back to cited text no. 44
    
45.
Saraya T, Nakata K, Nakagaki K, Motoi N, Iihara K, Fujioka Y, et al. Identification of a mechanism for lung inflammation caused by Mycoplasma pneumoniae using a novel mouse model. Results Immunol 2011;1:76-87.  Back to cited text no. 45
    
46.
Shimizu T, Kida Y, Kuwano K. A dipalmitoylated lipoprotein from Mycoplasma pneumoniae activates NF-kappa B through TLR1, TLR2, and TLR6. J Immunol 2005;175:4641-6.  Back to cited text no. 46
    
47.
Clyde WA Jr. Models of Mycoplasma pneumoniae infection. J Infect Dis 1973;129:S69-71.  Back to cited text no. 47
    
48.
Hu PC, Collier AM, Baseman JB. Alterations in the metabolism of hamster tracheas in organ culture after infection by virulent Mycoplasma pneumoniae. Infect Immun 1975;11:704-10.  Back to cited text no. 48
[PUBMED]    
49.
Gabridge MG, Johnson CK, Cameron AM. Cytotoxicity of Mycoplasma pneumoniae membranes. Infect Immun 1974;10:1127-34.  Back to cited text no. 49
    
50.
Cohen G, Somerson NL. Mycoplasma pneumoniae: Hydrogen peroxide secretion and its possible role in virulence. Ann N Y Acad Sci 1967;143:85-7.  Back to cited text no. 50
[PUBMED]    
51.
Kannan TR, Provenzano D, Wright JR, Baseman JB. Identification and characterization of human surfactant protein A binding protein of Mycoplasma pneumoniae. Infect Immun 2005;73:2828-34.  Back to cited text no. 51
    
52.
Kannan TR, Baseman JB. ADP-ribosylating and vacuolating cytotoxin of Mycoplasma pneumoniae represents unique virulence determinant among bacterial pathogens. Proc Natl Acad Sci U S A 2006;103:6724-9.  Back to cited text no. 52
    
53.
Kannan TR, Musatovova O, Balasubramanian S, Cagle M, Jordan JL, Krunkosky TM, et al. Mycoplasma pneumoniae Community acquired respiratory distress syndrome toxin expression reveals growth phase and infection-dependent regulation. Mol Microbiol 2010;76:1127-41.  Back to cited text no. 53
    
54.
Techasaensiri C, Tagliabue C, Cagle M, Iranpour P, Katz K, Kannan TR, et al. Variation in colonization, ADP-ribosylating and vacuolating cytotoxin, and pulmonary disease severity among Mycoplasma pneumoniae strains. Am J Respir Crit Care Med 2010;182:797-804.  Back to cited text no. 54
    
55.
Kannan TR, Coalson JJ, Cagle M, Musatovova O, Hardy RD, Baseman JB. Synthesis and distribution of CARDS toxin during Mycoplasma pneumoniae infection in a murine model. J Infect Dis 2011;204:1596-604.  Back to cited text no. 55
    
56.
Hardy RD, Coalson JJ, Peters J, Chaparro A, Techasaensiri C, Cantwell AM, et al. Analysis of pulmonary inflammation and function in the mouse and baboon after exposure to Mycoplasma pneumoniae CARDS toxin. PLoS One 2009;4:e7562.  Back to cited text no. 56
    
57.
Medina JL, Coalson JJ, Brooks EG, Le Saux CJ, Winter VT, Chaparro A, et al. Mycoplasma pneumoniae CARDS toxin exacerbates ovalbumin-induced asthma-like inflammation in BALB/c mice. PLoS One 2014;9:e102613.  Back to cited text no. 57
    
58.
Latz E, Xiao TS, Stutz A. Activation and regulation of the inflammasomes. Nat Rev Immunol 2013;13:397-411.  Back to cited text no. 58
    
59.
Gabay C, Lamacchia C, Palmer G. IL-1 pathways in inflammation and human diseases. Nat Rev Rheumatol 2010;6:232-41.  Back to cited text no. 59
    
60.
Baroja-Mazo A, Martín-Sánchez F, Gomez AI, Martínez CM, Amores-Iniesta J, Compan V, et al. The NLRP3 inflammasome is released as a particulate danger signal that amplifies the inflammatory response. Nat Immunol 2014;15:738-48.  Back to cited text no. 60
    
61.
Besnard AG, Togbe D, Couillin I, Tan Z, Zheng SG, Erard F, et al. Inflammasome-IL-1-Th17 response in allergic lung inflammation. J Mol Cell Biol 2012;4:3-10.  Back to cited text no. 61
    
62.
Segovia JA Jr, Bose S, Somarajan SR, Chang TH, Kannan TR, Baseman JB. Mycoplasma pneumoniae CARDS toxin regulates NLRP3 inflammosome activation. J Allergy Clin Immunol 2015;135:S153.  Back to cited text no. 62
    
63.
Bose S, Segovia JA, Somarajan SR, Chang TH, Kannan TR, Baseman JB. ADP-ribosylation of NLRP3 by Mycoplasma pneumoniae CARDS toxin regulates inflammasome activity. MBio 2014;5:e02186-14.  Back to cited text no. 63
    
64.
Krishnan M, Kannan TR, Baseman JB. Mycoplasma pneumoniae CARDS toxin is internalized via clathrin-mediated endocytosis. PLoS One 2013;8:e62706.  Back to cited text no. 64
    
65.
Barnes PJ. The cytokine network in asthma and chronic obstructive pulmonary disease. J Clin Invest 2008;118:3546-56.  Back to cited text no. 65
    
66.
Talkington DF, Waites KB, Schwartz SB, Besser RE. Emerging from obscurity: Understanding pulmonary and extrapulmonary syndromes, pathogenesis, and epidemiology of human Mycoplasma pneumoniae infections. In:Scheld WM, Craig WA, Hughes JM, editors. Emerging Infections. Vol. 5. Washington, D.C: American Society for Microbiology; 2001. p. 57-84.  Back to cited text no. 66
    
67.
Murray HW, Masur H, Senterfit LB, Roberts RB. The protean manifestations of Mycoplasma pneumoniae infection in adults. Am J Med 1975;58:229-42.  Back to cited text no. 67
[PUBMED]    
68.
Pönkä A. The occurrence and clinical picture of serologically verified Mycoplasma pneumoniae infections with emphasis on central nervous system, cardiac and joint manifestations. Ann Clin Res 1979;11:1-60.  Back to cited text no. 68
    
69.
Koskiniemi M. CNS manifestations associated with Mycoplasma pneumoniae infections: Summary of cases at the University of Helsinki and review. Clin Infect Dis 1993;17:S52-7.  Back to cited text no. 69
    
70.
Mok JY, Inglis JM, Simpson H. Mycoplasma pneumoniae infection. A retrospective review of 103 hospitalised children. Acta Paediatr Scand 1979;68:833-9.  Back to cited text no. 70
[PUBMED]    
71.
Kleemola M, Käyhty H. Increase in titers of antibodies to Mycoplasma pneumoniae in patients with purulent meningitis. J Infect Dis 1982;146:284-8.  Back to cited text no. 71
    
72.
Narita M. Pathogenesis of neurologic manifestations of Mycoplasma pneumoniae infection. Pediatr Neurol 2009;41:159-66.  Back to cited text no. 72
    
73.
Bitnun A, Ford-Jones E, Blaser S, Richardson S. Mycoplasma pneumoniae ecephalitis. Semin Pediatr Infect Dis 2003;14:96-107.  Back to cited text no. 73
    
74.
Behan PO, Feldman RG, Segerra JM, Draper IT. Neurological aspects of mycoplasmal infection. Acta Neurol Scand 1986;74:314-22.  Back to cited text no. 74
[PUBMED]    
75.
Narita M. Pathogenesis of extrapulmonary manifestations of Mycoplasma pneumoniae infection with special reference to pneumonia. J Infect Chemother 2010;16:162-9.  Back to cited text no. 75
    
76.
Bitnun A, Ford-Jones EL, Petric M, MacGregor D, Heurter H, Nelson S, et al. Acute childhood encephalitis and Mycoplasma pneumoniae. Clin Infect Dis 2001;32:1674-84.  Back to cited text no. 76
    
77.
Socan M, Ravnik I, Bencina D, Dovc P, Zakotnik B, Jazbec J. Neurological symptoms in patients whose cerebrospinal fluid is culture- and/or polymerase chain reaction-positive for Mycoplasma pneumoniae. Clin Infect Dis 2001;32:E31-5.  Back to cited text no. 77
    
78.
Talkington DF. Mycoplasma and Ureaplasma in central nervous system disorders. In: Scheld M, Whitley R, Marra, C, editors. Infections of the Central Nervous System. Philadelphia, USA: In Press, Lippincott, Williams and Wilkins; 2004.  Back to cited text no. 78
    
79.
Narita M, Itakura O, Matsuzono Y, Togashi T. Analysis of mycoplasmal central nervous system involvement by polymerase chain reaction. Pediatr Infect Dis J 1995;14:236-7.  Back to cited text no. 79
    
80.
Bencina D, Dovc P, Mueller-Premru M, Avsic-Zupanc T, Socan M, Beovic B, et al. Intrathecal synthesis of specific antibodies in patients with invasion of the central nervous system by Mycoplasma pneumoniae. Eur J Clin Microbiol Infect Dis 2000;19:521-30.  Back to cited text no. 80
    
81.
Stamm B, Moschopulos M, Hungerbuehler H, Guarner J, Genrich GL, Zaki SR. Neuroinvasion by Mycoplasma pneumoniae in acute disseminated encephalomyelitis. Emerg Infect Dis 2008;14:641-3.  Back to cited text no. 81
    
82.
Ogata S, Kitamoto O. Clinical complications of Mycoplasma pneumoniae disease - Central nervous system. Nihon Kyobu Shikkan Gakkai Zasshi 1982;20:1084-9.  Back to cited text no. 82
    
83.
Bruch LA, Jefferson RJ, Pike MG, Gould SJ, Squier W. Mycoplasma pneumoniae infection, meningoencephalitis, and hemophagocytosis. Pediatr Neurol 2001;25:67-70.  Back to cited text no. 83
    
84.
Christie LJ, Honarmand S, Yagi S, Ruiz S, Glaser CA. Anti-galactocerebroside testing in Mycoplasma pneumoniae-associated encephalitis. J Neuroimmunol 2007;189:129-31.  Back to cited text no. 84
    
85.
Jacobs E, Bartl A, Oberle K, Schiltz E. Molecular mimicry by Mycoplasma pneumoniae to evade the induction of adherence inhibiting antibodies. J Med Microbiol 1995;43:422-9.  Back to cited text no. 85
    
86.
Biberfeld G. Antibodies to brain and other tissues in cases of Mycoplasma pneumoniae infection. Clin Exp Immunol 1971;8:319-33.  Back to cited text no. 86
[PUBMED]    
87.
Kumada S, Kusaka H, Okaniwa M, Kobayashi O, Kusunoki S. Encephalomyelitis subsequent to Mycoplasma infection with elevated serum anti-Gal C antibody. Pediatr Neurol 1997;16:241-4.  Back to cited text no. 87
    
88.
Komatsu H, Kuroki S, Shimizu Y, Takada H, Takeuchi Y. Mycoplasma pneumoniae meningoencephalitis and cerebellitis with antiganglioside antibodies. Pediatr Neurol 1998;18:160-4.  Back to cited text no. 88
    
89.
Sinha S, Prasad KN, Jain D, Pandey CM, Jha S, Pradhan S. Preceding infections and anti-ganglioside antibodies in patients with Guillain-Barré syndrome: A single centre prospective case-control study. Clin Microbiol Infect 2007;13:334-7.  Back to cited text no. 89
    
90.
Kusunoki S, Shiina M, Kanazawa I. Anti-Gal-C antibodies in GBS subsequent to Mycoplasma infection: Evidence of molecular mimicry. Neurology 2001;57:736-8.  Back to cited text no. 90
    
91.
Sharma MB, Chaudhry R, Tabassum I, Ahmed NH, Sahu JK, Dhawan B, et al. The presence of Mycoplasma pneumoniae infection and GM1 ganglioside antibodies in Guillain-Barré syndrome. J Inf Dev Ctries 2011;5:459-464.  Back to cited text no. 91
    
92.
Kikuchi M, Tagawa Y, Iwamoto H, Hoshino H, Yuki N. Bickerstaff's brainstem encephalitis associated with IgG anti-GQ1b antibody sub- sequent to Mycoplasma pneumoniae infection: Favorable response to immunoadsorption therapy. J Child Neurol 1997;12:403-5.  Back to cited text no. 92
    
93.
Biberfeld G, Johnsson T, Jonsson J. Studies on Mycoplasma pneumoniae infection in Sweden. Acta Pathol Microbiol Scand 1965;63:469-75.  Back to cited text no. 93
[PUBMED]    
94.
Canavan TN, Mathes EF, Frieden I, Shinkai K. Mycoplasma pneumoniae-induced rash and mucositis as a syndrome distinct from Stevens-Johnson syndrome and erythema multiforme: A systematic review. J Am Acad Dermatol 2015;72:239-45.  Back to cited text no. 94
    
95.
Schalock PC, Dinulos JG, Pace N, Schwarzenberger K, Wenger JK. Erythema multiforme due to Mycoplasma pneumoniae infection in two children. Pediatr Dermatol 2006;23:546-55.  Back to cited text no. 95
    
96.
Bar Meir E, Amital H, Levy Y, Kneller A, Bar-Dayan Y, Shoenfeld Y. Mycoplasma pneumonia - Induced thrombotic thrombocytopenic purpura. Acta Haematol 2000;103:112-5.  Back to cited text no. 96
    
97.
Bradley JS, Byington CL, Shah SS, Alverson B, Carter ER, Harrison C, et al. The management of community-acquired pneumonia in infants and children older than 3 months of age: Clinical practice guidelines by the pediatric infectious diseases society and the infectious diseases society of America. Clin Infect Dis 2011;53:617-30.  Back to cited text no. 97
    
98.
Okada T, Morozumi M, Tajima T, Hasegawa M, Sakata H, Ohnari S, et al. Rapid effectiveness of minocycline or doxycycline against macrolide-resistant Mycoplasma pneumoniae infection in a 2011 outbreak among Japanese children. Clin Infect Dis 2012;55:1642-9.  Back to cited text no. 98
    
99.
Eshaghi A, Memari N, Tang P, Olsha R, Farrell DJ, Low DE, et al. Macrolide-resistant Mycoplasma pneumoniae in humans, Ontario, Canada, 2010-2011. Emerg Infect Dis 2013;19:1525-7.  Back to cited text no. 99
    
100.
Peuchant O, Ménard A, Renaudin H, Morozumi M, Ubukata K, Bébéar CM, et al. Increased macrolide resistance of Mycoplasma pneumoniae in France directly detected in clinical specimens by real-time PCR and melting curve analysis. J Antimicrob Chemother 2009;64:52-8.  Back to cited text no. 100
    
101.
Linchevski I, Klement E, Nir-Paz R. Mycoplasma pneumoniae vaccine protective efficacy and adverse reactions: Systematic review and meta-analysis. Vaccine 2009;27:2437-46.  Back to cited text no. 101
    


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