|Year : 2020 | Volume
| Issue : 2 | Page : 229-234
Cryptococcosis in non-human immunodeficiency virus-infected patients: A clinical dilemma and diagnostic enigma
Manisha Paul, Mohit Bhatia, Ranjana Rohilla, Udayakumar Sasirekha, Neelam Kaistha
Department of Microbiology, All India Institute of Medical Sciences, Rishikesh, Uttarakhand, India
|Date of Submission||06-Jun-2020|
|Date of Decision||12-Jul-2020|
|Date of Acceptance||27-Jul-2020|
|Date of Web Publication||29-Aug-2020|
Dr. Mohit Bhatia
Department of Microbiology, All India Institute of Medical Sciences, Rishikesh, Uttarakhand
Source of Support: None, Conflict of Interest: None
Cryptococcosis is a fungal disease with worldwide distribution and wide array of clinical manifestations, caused by encapsulated basidiomycetous yeasts called Cryptococcus spp. It has traditionally been considered an opportunistic infection known to occur in immunocompromised hosts, particularly those who are infected with human immunodeficiency virus. However, this infection has also been reported in phenotypically 'normal' or otherwise clinically non-immunocompromised patients. The seemingly mysterious nature of this potentially fatal illness has always kept clinicians and diagnosticians in a dilemma. This case series reiterates this perspective.
Keywords: Cryptococcosis, human immunodeficiency virus, non-immunocompromised
|How to cite this article:|
Paul M, Bhatia M, Rohilla R, Sasirekha U, Kaistha N. Cryptococcosis in non-human immunodeficiency virus-infected patients: A clinical dilemma and diagnostic enigma. Indian J Med Microbiol 2020;38:229-34
|How to cite this URL:|
Paul M, Bhatia M, Rohilla R, Sasirekha U, Kaistha N. Cryptococcosis in non-human immunodeficiency virus-infected patients: A clinical dilemma and diagnostic enigma. Indian J Med Microbiol [serial online] 2020 [cited 2020 Sep 26];38:229-34. Available from: http://www.ijmm.org/text.asp?2020/38/2/229/293903
| ~ Introduction|| |
Cryptococcosis is an acute, sub-acute and/or chronic fungal disease with worldwide distribution and wide array of clinical manifestations, caused by encapsulated basidiomycetous yeasts called Cryptococcus spp. Infection with Cryptococcus spp. primarily occurs by inhalation of the infectious propagules (poorly encapsulated yeast cells or basidiospores) from environmental reservoirs with deposition into pulmonary alveoli. Historically, the genus Cryptococcus was classified into 3 varieties, 5 serotypes (based on structural differences in the polysaccharide capsule) and 8 molecular subtypes. Based on the results of molecular studies, recently proposed taxonomic changes have divided the pathogenic cryptococcal species as follows: Cryptococcus neoformans var. grubii (serotype A; genotypes VNI-III); C. neoformans var. neoformans (serotype D; genotype VNIV) and five cryptic species namely, Cryptococcus gattii, Cryptococcus bacillisporus, Cryptococcus deuterogattii, Cryptococcus tetragattii, and Cryptococcus decagattii (serotypes B/C; genotypes VGI-IV). Human infection is commonly caused by C. neoformans and C. gattii.
Cryptococcosis has traditionally been considered an opportunistic infection known to occur in immunocompromised hosts, particularly those with defective cell mediated immunity. Some of the predisposing factors for this clinical condition include human immunodeficiency virus infection, hematologic malignancies, prolonged use of corticosteroids and/or other immunosuppressive drugs and solid organ transplantation. However, this infection has also been reported in phenotypically 'normal' or otherwise clinically non-immunocompromised patients.,
C. neoformans has a predilection for central nervous system, thereby resulting in meningoencephalitis. Although the involvement of other organs/organ systems has frequently been reported, these clinical entities have often been misdiagnosed as tuberculosis, malignancy, cutaneous vasculitis, etc.,, Furthermore, on several occasions, laboratory diagnosis of cryptococcosis has incidentally been established from samples other than cerebrospinal fluid (CSF).,,,,,
The seemingly mysterious nature of this potentially fatal illness has always kept clinicians and diagnosticians in a dilemma. Therefore, it is important to have a high index of suspicion for diagnosing cryptococcosis, even when the clinical manifestations are not suggestive of this infection. The series of cases presented herewith, reiterates this perspective.
| ~ Case Reports|| |
A 40-year-old female patient presented to the emergency department with chief complaint of altered sensorium for the past 2 days. On examination, two significant findings were obtained: (1) PaO2 = 58 mmHg and (2) bilateral consolidation in the lungs. X-ray chest, which was performed in the emergency department, revealed bilateral patchy consolidation suggestive of pneumonic consolidation. A presumptive diagnosis of Type 1 respiratory failure was made. The patient was transferred to High Dependency Unit and placed on bilevel positive airway pressure.
Laboratory findings of blood and urine samples collected from this patient revealed normocytic normochromic anaemia (haemoglobin: 7.2 g/dL), raised total white blood cell count (31.13 × 103/μL) with the presence of myelocytes, metamyelocytes and neutrophilic leukocytosis, consistently raised blood urea (>30 mg/dL), serum creatinine (>6 mg/dL), procalcitonin (0.50–1.99 ng/mL) levels and erythrocyte sedimentation rate respectively, and pyuria (>104 pus cells/ml of urine). Escherichia coli (>105 CFU/ml) sensitive to imipenem, meropenem, doripenem and nitrofurantoin, was isolated in culture. Aerobic blood culture was performed using BacT/ALERT three-dimensional (3D) microbial detection system (bioMerieux India Private Limited), which flagged as positive after 72 h of incubation. Variable sized, Gram-positive, spherical, and narrow-based budding yeast cells were observed in Gram stained smear prepared from the content of the positive blood culture bottle. Subcultures were performed from this bottle on blood and Sabouraud dextrose agar, respectively, which were incubated aerobically at 37°C. Tiny, white, non-haemolytic colonies were obtained on blood agar and creamy white colonies were obtained on Sabouraud dextrose agar [Figure 1], after overnight incubation. Gram stained smears of these colonies revealed Gram-positive, spherical, narrow-based budding yeast cells [Figure 2]. The colonies were also subjected to urease test, which turned out to be positive. MALDI-TOF MS (Bruker Daltonik GmbH, Germany) was used for final identification of these colonies, which turned out to be C. neoformans var grubii (confidence level: 2.2).
|Figure 2: Gram stained smear of growth obtained on Sabouraud dextrose agar showing Gram-positive, spherical, narrow-based budding yeast cells|
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Ultrasonogram of abdomen revealed Grade II renal parenchymal disease. Contrast-enhanced computed tomogram of thorax, abdomen and pelvis showed the presence of multiple expansile lytic skeletal lesions with associated soft-tissue component, lytic destruction of D7 vertebra suggestive of metastatic deposits, well-defined mixed density lesion with coarse calcifications along with a well-defined hyper-dense lesion showing no significant enhancement in the right breast parenchyma (confirmed as benign lesions by fine-needle aspiration cytology), mild bilateral pleural effusion with a consolidative patch in the right upper lobe and mosaic attenuation in bilateral upper lobes, respectively. NCCT KUB revealed multiple cystic lesions. 2D Echo revealed LVWF: 35%–40%, aortic regurgitation, and aortic root dilatation, respectively.
The patient was subjected to urgent haemodialysis. Two units of packed red blood cells were transfused. In lieu of irrelevant talking by the patient, a psychiatry opinion was also sought. On advice of medical oncology team, testing for tumour markers was performed which revealed raised CA-19-9 and normal CEA levels, respectively.
Treatment with levofloxacin, linezolid, nitro-glycerine and pantoprazole respectively was empirically started for this patient, before results of blood and urine culture were available. Result of her ANA profile by immunoblot method (EUROLINE ANA Profile 3 Plus DFS70 [IgG]) was negative. Bone marrow biopsy and lumbar puncture were also advised, but the patient was not willing to undergo further investigations and was discharged on request.
A 7-year-old boy was admitted to paediatrics department with a history of low-grade intermittent fever associated with headache, nausea and vomiting for the past 1 month. This patient had previously been treated for tubercular meningitis and his present symptoms had developed a month after completion of anti-tubercular therapy. There was a significant family history in the form of death of his mother due to tuberculosis 6 years ago.
On examination, the patient was conscious, oriented and febrile. His blood pressure and heart rate were 100/60 mmHg and 64/min, respectively. Examination of central nervous system showed irritability and neck stiffness. Superficial and deep tendon reflexes were normal. No cranial nerve palsy was detected. Fundoscopic examination revealed papilledema along with multiple choroidal tubercles in retina. No other systemic abnormality was detected.
Contrast enhanced magnetic resonance imaging of brain revealed non-obstructive hydrocephalus with lateral ventriculitis, suggestive of tubercular meningitis. A presumptive diagnosis of recurrent tubercular meningitis was made and treatment with anti-tubercular drugs along with ceftriaxone 750 mg 12th hourly intravenously, dexamethasone 2.3 mg 6th hourly intravenously and glycerol syrup respectively, was started.
The patient was subjected to lumbar puncture and the grossly clear CSF sample thus obtained, was subjected to laboratory investigations which revealed increased total white blood cell count (250 cells/mm 3) with 80% monocytes and 20% polymorphonuclear cells, raised protein (232 mg/dL) and reduced glucose (31 mg/dL) respectively. No structures morphologically resembling Cryptococcus spp. were observed in India ink preparation. No growth was obtained in culture after 48 h of aerobic incubation. Cartridge-based nucleic acid amplification test (GeneXpert MTB/RIF, Cepheid, USA) was performed on both CSF and early morning gastric aspirate samples, respectively, which were negative for Mycobacterium tuberculosis.
Aerobic blood culture was performed using BacT/ALERT 3D microbial detection system (bioMerieux India Private Limited), which flagged as positive after 96 h of incubation. Variable sized, Gram-positive, spherical, narrow-based budding yeast cells were observed in Gram stained smear prepared from the content of the positive blood culture bottle. Sub-cultures were performed from this bottle on blood and Sabouraud dextrose agar respectively, which were incubated aerobically at 37°C. Tiny, white, non-haemolytic and creamy white colonies were obtained on blood and Sabouraud dextrose agar, respectively, after overnight incubation. Gram stained smears of these colonies revealed Gram-positive, spherical, narrow-based budding yeast cells. The colonies were also subjected to urease test, which turned out to be positive. MALDI-TOF MS (Bruker Daltonik GmbH, Germany) was used for final identification of these colonies, which turned out to be C. neoformans var grubii (confidence level: 2.1). In the light of these findings, the leftover CSF sample was inoculated in BacT/ALERT 3D culture bottle, which flagged as positive after 72 h of aerobic incubation. Sub-culture performed from this sample on blood and Sabouraud dextrose agar respectively revealed similar growth as above, which was identified as C. neoformans var grubii by MALDI-TOF MS (confidence level: 2.1).
The results of various other laboratory investigations such as complete blood counts, random blood glucose, kidney function and liver function tests, and urine routine and microscopic examination respectively were within normal limits. Viral markers such as anti-HIV antibodies, Hepatitis B surface antigen and anti-hepatitis C virus (HCV) antibodies were non-reactive.
Before the final blood and CSF culture reports could be conveyed to the treating paediatrician, the patient was discharged against medical advice and lost to follow-up.
A 54-year-old male patient presented to the medicine outpatient department with a history of cough with expectoration, chest and abdominal pain respectively of 1-month duration. He also had fever in the past 20 days and decreased urinary output with swelling in both lower limbs in the past 3 days. The patient was a known smoker with history of intake of anti-tubercular therapy 4 months back.
On examination, the patient was disoriented to time, place and person. He had pallor, icterus and bilateral pedal oedema. His pulse rate, blood pressure, respiratory rate and room air SpO2 were 113 bpm, 80/50 mmHg, 20/min and 98%, respectively. The patient had flapping tremors, bilateral basal crepitations and occasional rhonchi were heard on chest auscultation and his abdomen was distended with non-palpable tender liver.
The results of various laboratory investigations revealed consistently raised total leucocyte count, total bilirubin, direct bilirubin, indirect bilirubin, serum glutamic pyruvic transaminase, serum glutamic oxaloacetic transaminase, alkaline phosphatase, prothrombin time, blood urea, serum creatinine and serum uric acid, respectively. Serum sample of this patient was reactive for anti-HCV antibodies by immunochromatographic card test (Tulip Diagnostics Pvt. Ltd., India).
X-ray chest revealed a heterogeneous opacity in the upper zone of the left lung with reticulonodular opacities in bilateral lung zones. Ultrasound abdomen was suggestive of grade II fatty liver changes with increased echogenicity without any focal lesion, bilateral grade I renal parenchymal disease with mild ascites.
During the course of hospital stay, the patient's condition rapidly deteriorated with constantly falling blood pressure. A provisional diagnosis of HCV related liver disease with hepatic encephalopathy, disseminated tuberculosis, and septic shock was made. Treatment with non-adrenaline and terlipressin, ceftriaxone, azithromycin, Vitamin K and rifaximin was started. However, his condition did not improve.
Aerobic blood culture was performed using BacT/ALERT 3D microbial detection system (bioMerieux India Private Limited), which flagged as positive after 24 h of incubation. Variable sized, Gram-positive, spherical, narrow-based budding yeast cells were observed in Gram stained smear prepared from the content of the positive blood culture bottle. Sub-cultures were performed from this bottle on blood and Sabouraud dextrose agar, respectively, which were incubated aerobically at 37°C. Creamy white mucoid colonies were obtained on these solid culture media after 48 h of incubation. Gram stained smears of these colonies revealed Gram-positive, spherical, narrow-based budding yeast cells. The colonies were also subjected to urease test, which turned out to be positive. MALDI-TOF MS (Bruker Daltonik GmbH, Germany) was used for final identification of these colonies, which turned out to be C. neoformans var grubii (confidence level: 2.0).
On receiving the aerobic blood culture report, treatment with anti-fungal drugs was advised by the treating physician. Owing to financial constraints, the patient's family members did not agree and decided to get the patient discharged against medical advice. However, the patient expired on the same day before any discharge-related formalities could be completed.
| ~ Discussion|| |
The plethora of clinical manifestations associated with cryptococcosis can be misleading for the treating physicians at times, with laboratory confirmation often being a matter of chance. Something similar had happened in all the three cases discussed here. The clinical presentation of these patients was not suggestive of cryptococcal infection as the primary underlying aetiology. Symptoms such as altered sensorium, headache, nausea and vomiting, as observed in these cases, can not only be encountered in meningoencephalitis but also other non-central nervous system-related conditions such as cardio-pulmonary derangements, liver and renal dysfunction. Moreover, the anti-HIV antibody status of two of these patients had been ascertained as non-reactive, thereby further reducing the likelihood of ruling in cryptococcosis as a differential diagnosis. Isolation of Cryptococcus spp. from blood samples of all the three patients was totally unexpected and left us all perplexed.
In human beings, alveolar macrophages are the first line of defence against Cryptococcus spp. followed by neutrophils and monocytes. The complement system also plays a vital role by enhancing the antibody mediated host response against this organism. The T&B lymphocytes, which produce various cytokines and specific antibodies, form the third line of defence. Infection with Cryptococcus spp. can occur whenever there is a breach in any of these defence mechanisms. Although cryptococcosis has traditionally been considered an acquired immune deficiency syndrome defining illness, this clinical entity can also be encountered in association with other underlying co-morbidities which are not primarily classified as immunodeficiency conditions. In all the three cases presented here, the patients had disseminated cryptococcosis in the setting of renal parenchymal disease with anaemia, tuberculosis and HCV infection with renal parenchymal disease respectively, in the first, second and third patient.
Two of our patients had renal disease and amongst these one of them was also suffering from HCV infection. The immune dysfunction associated with renal diseases is multifactorial and can be explained as follows: (a) Uraemia is associated with immunosuppression due to the impact of the uremic milieu and a variety of associated disorders exerted on immunocompetent cells; (b) Protein-energy wasting, which is a common complication of renal disease, has been found to be related to lymphocytopenia and impaired T lymphocyte function. Patients with liver disease have an increased predisposition to infections, such as cryptococcosis. The immune derangements observed in liver diseases could be attributed to impaired cell-mediated immunity, phagocytic dysfunction, decreased antibody and immunoglobulin concentration, and complement deficiency. HCV has a high propensity to persist and cause chronic hepatitis C and cirrhosis. HCV proteins interact with several pathways in the host's immune system and cause the following: (a) disruption of pathogen-associated pattern recognition pathways; (B) interference with cellular immunoregulation through CD81 binding and (c) subversion of the activities of NK (natural killer) cells and T-lymphocytes (both CD4 + and CD8+). In a study conducted by El-Serag et al., it was observed that patients suffering from HCV infection had a significantly higher prevalence of cryptococcal infections, compared to controls (0.4% vs. 0.1%).
Two of our patients had received anti-tubercular therapy and were HIV negative. Some of their clinical and radiological findings were also suggestive of tuberculosis. However, the results of laboratory tests revealed cryptococcosis instead. Although concurrent infections with Cryptococcus spp. and Mycobacterium tuberculosis have been reported in HIV-infected patients, cases of co-infection in non-HIV-infected patients are very rare. In these patients, it is likely that the presence of one disseminated infection creates or reflects an immunosuppressed state sufficient to allow for dissemination of another. Another non-HIV immune modulatory condition is iron deficiency anaemia, which was observed in the first patient. Iron has an essential role to play due to its growth promoting and differentiation inducing properties of immune cells, and its interference with cell mediated immune effector pathways and cytokines activities. Therefore, its deficiency can render a person susceptible to infections.
The presence of Cryptococcus spp. in blood indicates poor prognosis. The diagnosis of disseminated cryptococcosis is established on the basis of positive cultures from any two organ sites (e.g., skin, central nervous system, peritoneum and synovial fluid) or positive blood cultures., CSF samples could not be obtained from two of our patients. In one patient, CSF sample was initially reported as sterile after 48 h of aerobic incubation using conventional culture techniques. However, on recovering Cryptococcus spp. in blood culture using automated microbial growth detection system, his CSF sample was re-inoculated and incubated in BacT/ALERT-3D. This turned out to be a fruitful exercise for the laboratory team as we succeeded in isolating Cryptococcus spp. from CSF sample as well. Literature suggests that blood culture is an important adjunct to CSF culture for the isolation of Cryptococcus spp., On some occasions, the diagnosis of cryptococcal meningoencephalitis is made only after Cryptococcus spp. is recovered from another body site. This is especially true in case of AIDS patients who have a much higher likelihood of having extra neural disease, which is contrary to what we observed as two of our patients were HIV negative. Cryptococcus spp. can be isolated from blood in early stage of infection, as these are known to cause fungaemia before crossing the blood brain barrier. The probable reason for blood culture positive and initial CSF culture negative for Cryptococcus spp. in one patient could be due to amount of specimen submitted for microbiological processing. In general, not more than 2-3 mL of CSF sample would be available for culture when compared to blood sample which is approximately 8-10 mL. Moreover, with the increasing use of automated microbial growth detection systems in clinical microbiology laboratories, the likelihood of diagnosing infections in blood and sterile body fluids has grown exponentially. The use of highly enriched liquid culture media and fluorescence based microbial growth detection, makes automated systems like BacT/ALERT-3 D superior to conventional culture methods. Approximately 95% of cryptococcal infections are caused by C. neoformans var grubii. Similar findings were observed in our patients also.
| ~ Conclusion|| |
We would like to highlight the fact that the diagnosis of cryptococcosis seems to be a daunting task especially in non-HIV infected, apparently immunocompetent individuals. Routine laboratory investigations like aerobic blood culture can clinch the aetiological diagnosis on several occasions and guide the clinicians in starting timely and appropriate treatment. Automated microbial growth detection system is a valuable addition to the ever-expanding armamentarium of clinical microbiologists in their war against infectious diseases.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
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Conflicts of interest
There are no conflicts of interest.
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