| [Download PDF]
|Year : 2013 | Volume
| Issue : 2 | Page : 211--213
Department of Microbiology, Bhopal Memorial Hospital and Research Centre, Karond Bhopal, Bhopal, India
Department of Microbiology, Bhopal Memorial Hospital and Research Centre, Karond Bhopal, Bhopal
|How to cite this article:|
Desikan P. Resaerch snippets.Indian J Med Microbiol 2013;31:211-213
|How to cite this URL:|
Desikan P. Resaerch snippets. Indian J Med Microbiol [serial online] 2013 [cited 2020 Nov 26 ];31:211-213
Available from: https://www.ijmm.org/text.asp?2013/31/2/211/115246
Since January 2013, six hepatitis A cases with travel history to Egypt during the incubation period (2-6 weeks after infection) were reported to the Norwegian Surveillance System for Communicable Diseases. Generally, only a single case of hepatitis A with travel history to Egypt is reported in Norway annually. Four of the six cases were genotyped and were found to be infected with the same genotype 1B hepatitis A virus (HAV) strain. On 15 April 2013, the Norwegian Institute of Public Health posted an urgent inquiry on the Epidemic Intelligence Information System (EPIS) platform about whether any other European countries had observed an increase in HAV with travel history to Egypt in the same period. Four countries (Denmark, Germany, Netherlands and Sweden) responded in positive ( http://www.eurosurveillance.org/ViewArticle.aspx?ArticleId = 20468 ). A study was conducted to assess hepatitis A vaccination coverage among adults aged 18-49 years, who were travelling to a country of high or intermediate endemicity. It concluded that, although travel to a country of high or intermediate hepatitis A endemicity was associated with higher likelihood of hepatitis A vaccination among adults aged 18-49 years, self-reported hepatitis A vaccination coverage was low among adult travellers to these areas (Vaccine. 2013 May 1;31 (19):2348-57. Epub 2013 Mar 21).
The enterovirus causing hand, foot and mouth disease (HFMD) is linked to a serious outbreak of meningitis on Sydney's northern beaches. The Northern Sydney Local Health District has confirmed a spike in cases of meningitis, encephalitis and transverse myelitis caused by this enterovirus ( http://www.heraldsun.com.au/news/national/northern-sydney-on-alert-over-virus/story-fndo317g-1226607174917 ). An investigation of an outbreak of HFMD in China found that human enterovirus 71 (EV71) was the main pathogen causing the outbreak there, while Coxsackievirus A16 (CoxA16) played only a subsidiary role (Virus Genes. 2013 Feb; 46 (1):1-9. Epub 2012 Oct 19).
The cholera epidemic in Haiti, which started in October 2010, caused more than 8000 deaths, according to the Ministry of Public Health and Population. It is believed that the source of the outbreak was a camp of soldiers of the United Nations Mission for the Stabilization of Haiti from Nepal. Of the 10 million inhabitants of Haiti, only 2% have access to drinking water. Most of the population lives in unsanitary conditions and uses exposed places like rivers for their needs ( http://www.plenglish.com/index.php?option = com_content and task = view and id = 1250211 and Itemid = 1 ). A study examined different formulations of Vibrio cholerae (Vc) O1 lipopolysaccharide (LPS, a T-independent antigen) conjugate because detoxified LPS is a central component of a LPS-based conjugate vaccine for cholera. The study found that pmLPS, which is detoxified by acid treatment, is a superior immunogen as compared with hydrazine-detoxified LPS (DetAcLPS) that has altered lipid A acyl chains (Pathogens Dis. 2013 Mar; 67 (2):136-58. Epub 2013 Feb 25).
The authorities in New Caledonia report that three people have been infected with chikungunya virus ( http://www.rnzi.com/pages/news.php?op = read and id = 75614 ). This has happened when health services there were currently stretched by a dengue outbreak, which, this season, has affected more than 8000 people and has killed three. The mosquito-borne chikungunya virus (CHIKV) causes severe disease in humans and represents a serious public health threat. A study describes for the first time the successful production of CHIKV virus-like particles (VLPs) in insect cells using recombinant baculoviruses. A single immunization with 1 μg of non-adjuvanted CHIKV VLPs induced high-titre neutralizing antibody responses and provided complete protection against viraemia and joint inflammation upon challenge with the Réunion Island CHIKV strain in an adult wild-type mouse model of CHIKV disease. CHIKV VLPs produced in insect cells using recombinant baculoviruses thus represents as a new, safe, non-replicating, and effective vaccine candidate against CHIKV infections (PLoSNegl Trop Dis. 2013 Mar; 7 (3):e2124. Epub 2013 Mar 14).
Three people have been infected with the same strain of Escherichia coli O157:H7 in Wisconsin, USA, and officials suspect that consumption of raw milk could be the cause ( http://www.dairyherd.com/dairy-news/Wis-raw-milk-suspected-in-E-coli-cases-204743251.html ). A commonly applied treatment of raw milk to reduce bacterial loads is the short-time application of heat at sub-pasteurization levels under continuous flow, generally referred to as thermization, because this method retains some of the beneficial properties of raw milk. Nine E. coli strains, including four Shiga toxin-producing E. coli (STEC) strains, were investigated for their reduction during a thermization treatment in raw milk using a pilot-plant pasteurizer to reflect typically applied commercial conditions. Six of the nine E. coli strains, including the four STEC strains, were similarly inactivated at 60, 62.5, and 65°C, whereas increased thermotolerance was observed for three E. coli strains. All strains were reduced to <2 log 10 at 60°C and 62.5°C within 25 s. At 65°C, six of the nine E. coli strains were reduced by at least 5 log 10 after 25s, whereas at 67.5°C, such a reduction was observed for eight strains. A much higher thermotolerance was found for E. coli strain FAM21805. For some E. coli strains, time-temperature combinations above 65°C were required to obtain a substantial reduction during a thermization treatment (J Dairy Sci. 2013 Mar 30. pii: S0022-0302 (13) 00243-9. [Epub ahead of print]).
The New Mexico Department of Health announced an outbreak of laboratory confirmed salmonellosis related to baby poultry in seven people. Four of the cases were in infants aged ≤13 months and two of them were hospitalized. The department has warned families to keep baby chicks or other baby birds out of their homes and to use caution so as to avoid salmonellosis ( http://myhighplains.com/fulltext?nxd_id = 366232 ). An investigation was carried out to determine the prevalence and antibiotic resistance of Salmonella serotypes at South Korean duck farms. A total of 7119 samples collected from 72 duck farms in five provinces were examined from 2011 to 2012. The overall prevalence of Salmonella serotypes was 43.4% (69/159) in duck flocks from 65.2% (47/72) of the duck farms. Eighty-five strains were isolated from 69 duck flocks. Three serotypes of Salmonella enterica were identified, such as S. typhimurium (39/85), S. enteritidis (44/85), and S. london (2/85). The prevalence of Salmonella infection decreased significantly in 3-week-old ducks as compared to that in 1-week-old ducks (P < 0.05). All isolates, except one, were resistant to at least one antimicrobial, and 27% of the isolates were resistant to 5-16 antimicrobials (Comp Immunol Microbiol Infect Dis. 2013 Apr 22. pii: S0147-9571 (13) 00020-9. [Epub ahead of print]).
On 26 April, 2013, Fujian province (China) reported its first H7N9 influenza case-the 9 th area of eastern China to be affected by the virus-as other provinces reported six more infections, raising the outbreak total to 119. In a pattern seen throughout the outbreak so far, most of the newly reported cases were in men, and many of the patients were elderly (http://www.cidrap.umn.edu/cidrap/content/influenza/h7n9/news/apr2613china2br.html). The first identified cases of avian influenza A (H7N9) virus infection in humans occurred in China during February and March 2013. A preliminary analysis of 82 persons with confirmed H7N9 virus infection found that the median age was 63 years (range 2-89), 73% were male, and 84% were urban residents. Of 77 persons with available data, 4 were poultry workers and 77% had a history of exposure to live animals, including chickens (76%). A total of 17 persons (21%) died after a median duration of illness of 11 days, 60 were critically ill, and 4 with clinically mild cases were discharged from the hospital; one paediatric patient was not admitted to the hospital. In two family clusters, human-to-human transmission of H7N9 virus could not be ruled out (N Engl J Med. 2013 Apr 24. [Epub ahead of print]).
Non-specific immunity plays a larger role than previously thought in protecting the host against mycobacterial infections. A study examined the role of heme catabolism by heme oxygenase-1 in conferring host resistance to mycobacterial infection. Hemeoxygenases (HO) catalyze the rate-limiting step of heme degradation. The cytoprotective action of the inducible HO-1 isoform, encoded by Hmox1 gene, is required for host protection against systemic infections. It was found that that up-regulation of HO-1 expression in macrophages was strictly required for protection against mycobacterial infection in mice. HO-1 deficient (Hmox1-/- ) mice were more susceptible to intravenous M. avium infection, failing to mount a protective granulomatous response and developing higher pathogen loads, as compared to infected wild-type (Hmox1+/+ ) controls. Furthermore, Hmox1-/- mice also developed higher pathogen loads and ultimately succumbed when challenged with a low-dose aerosol infection with M. tuberculosis. The protective effect of HO-1 was found to act independent of adaptive immunity, as revealed in M. avium infected Hmox1-/- vs. Hmox1+/+ SCID mice lacking mature B and T cells. It was concluded that HO-1 prevents the cytotoxic effect of heme, thus contributing to host resistance to mycobacterial infection (Infect Immun. 2013 Apr 29. [Epub ahead of print]).
A man died of Crimean-Congo hemorrhagic fever (CCHF) in the Black Sea province of Tokat (Turkey) on 27 th April 2013. He had been bitten by a tick while taking care of his animals in the fields on 17 th April 2013. He extracted the tick by himself and did not immediately seek professional attention. He was taken to Tokat State Hospital and later transferred to the Gaziosmanpasa University Research and Treatment Hospital, where his condition deteriorated ( http://www.worldbulletin.net/?aType = haber and ArticleID = 107692 ). Recently, in Sudan, a reverse transcription (RT) loop-mediated isothermal amplification (RT-LAMP) assay was developed and compared to nested RT-PCR for rapid detection of CCHF virus (CCHFV), targeting the small (S) RNA segment. A set of RT-LAMP primers, designed from a highly conserved region of the S segment of the viral genome, was employed to identify all the Sudanese CCHFV strains. The sensitivity studies indicated that the RT-LAMP detected 10 fg of CCHFV RNA as determined by a naked-eye turbidity read out, which is more appropriate to a resource-poor setting. This level of sensitivity was found to suffice for detecting most acute cases (J Virol Methods. 2013 Mar 28;190 (1-2):4-10).
Conventional wisdom holds that the best way to treat infection with antibiotics is to 'hit early and hit hard'. A favoured strategy is to deploy two antibiotics that produce a stronger effect in combination than when alone. But are such synergistic combinations necessarily optimal? A study combining mathematical modelling, evolution experiments, whole genome sequencing and genetic manipulation of a resistance mechanism demonstrated that deploying synergistic antibiotics can, in practice, be the worst strategy if bacterial clearance is not achieved after the first treatment phase. As treatment proceeds, it is only to be expected that the strength of antibiotic synergy will diminish as the frequency of drug-resistant bacteria increases. Drug-resistant bacteria replicate fastest when their drug-susceptible competitors are eliminated by overly aggressive treatment. In the experiment, synergy exerted such strong selection for resistance that an antagonism consistently emerged by day 1 and the initially most aggressive treatment produced the greatest bacterial load, much greater than when just one drug were given. Whole genome sequencing revealed that such rapid evolution was the result of the amplification of a genomic region containing four drug-resistance mechanisms, including the acrAB efflux operon. When this operon was deleted in genetically manipulated mutants and the evolution experiment repeated, antagonism failed to emerge in 5 days and antibiotic synergy was maintained for longer. It was, therefore, concluded that, unless super-inhibitory doses are achieved and maintained until the pathogen is successfully cleared, synergistic antibiotics can have the opposite effect to that intended by helping to increase pathogen load where and when the drugs are found at sub-inhibitory concentrations (PLoS Biol. 2013 Apr; 11 (4):e1001540. Epub 2013 Apr 23).