|Year : 2015 | Volume
| Issue : 4 | Page : 576-579
Rare yeasts causing fungemia in immunocompromised and haematology patients: Case series from Delhi
MR Capoor1, DK Gupta2, PK Verma3, HC Sachdeva3
1 Department of Microbiology, Vardhman Mahaveer Medical College and Safdarjung Hospital, New Delhi, India
2 Department of Haematology, Vardhman Mahaveer Medical College and Safdarjung Hospital, New Delhi, India
3 Department of Intensive Care, Vardhman Mahaveer Medical College and Safdarjung Hospital, New Delhi, India
|Date of Submission||28-May-2014|
|Date of Acceptance||19-May-2015|
|Date of Web Publication||16-Oct-2015|
M R Capoor
Department of Microbiology, Vardhman Mahaveer Medical College and Safdarjung Hospital, New Delhi
Source of Support: None, Conflict of Interest: None
Systemic fungal infection related to fluconazole-resistant yeasts are emerging in immunocompromised patients. In this case-series, we report eight cases of fungemia caused by Trichosporon spp. (2), Stephanoascus ceferrii (1), Kodamaea ohmeri (1), Pichia kutrawersi (2), Candida rugosa (1) and Candida lusitianae (1) in immunocompromised patients. All the yeasts except (Trichosporon asahii) were sequenced. As these rare species are inherently resistant to antifungal agents and they may lead to the development of nosocomial outbreaks, therefore, accurate identification followed by antifungal susceptibility testing is crucial for proper treatment and management.
Keywords: Antifungal susceptibility, fluconazole-resistant yeasts, immunocompromised patients, unusual yeasts
|How to cite this article:|
Capoor M R, Gupta D K, Verma P K, Sachdeva H C. Rare yeasts causing fungemia in immunocompromised and haematology patients: Case series from Delhi. Indian J Med Microbiol 2015;33:576-9
|How to cite this URL:|
Capoor M R, Gupta D K, Verma P K, Sachdeva H C. Rare yeasts causing fungemia in immunocompromised and haematology patients: Case series from Delhi. Indian J Med Microbiol [serial online] 2015 [cited 2020 Aug 12];33:576-9. Available from: http://www.ijmm.org/text.asp?2015/33/4/576/167320
| ~ Introduction|| |
Systemic fungal infection related to fluconazole-resistant yeasts are emerging in immunocompromised patients on fluconazole prophylaxis. These pathogenic yeasts include Trichosporon cutaneum, Blastoschizomyces capitatus, Geotrichum, Stephanoascus ciferrii, Kodamaea ohmeri, etc. The risk factors for the infection with these yeasts include haematologic malignancies, corticosteroid use, hemochromatosis, granulocyte function deficiencies, end-stage renal disease, etc. Their clinical presentation, course and dissemination usually are indistinguishable from candidemia.,
These infections (except Kodamaea spp.) are associated with extraordinarily high mortality rate and resistance or decreased susceptibility to amphotericin B, fluconazole, itraconazole and echinocandins. Furthermore, infection by these emergent pathogens require expedient diagnosis, antifungal therapy with triazoles (posaconazole, voriconazole and ravuconazole) and amphotericin B.
These yeasts were hitherto known as of low pathogenic potential but now being isolated from disseminated infections in immunocompromised patients.,, More than 90% of infections due to yeasts are attributed to only six spp.: Candida albicans, C. glabrata, C. parapsilosis, C. tropicalis, C. krusei and Cryptococcus neoformans. However, the documented species continue to increase and therefore it is essential for laboratories to provide their identification to species level and their pertinent antifungal susceptibility. Though worldwide there are reports of increasing isolation of unusual emerging yeasts. The data from India on clinical isolates of such emerging pathogens is scarce.,,,
In this case-series, we report eight cases of invasive fungemia caused by Trichosporon spp. (2), S. ciferrii (1), K. ohmeri (1), Pichia kutrawersi (2), C. rugosa (1) and C. lusitaniae (1) in immunocompromised patients. Seven out of eight yeasts were also sequenced.
| ~ Methods|| |
These atypical yeasts were isolated from blood samples of different patients during January 2009 to February 2011. Of a total of 184 cases of candidemia/fungemia, 8 patients showing atypical and uncommon yeasts in their blood samples were taken up for study. Clinico-epidemiological data included age, gender, risk factors, underlying conditions, treatment and outcome were collected.
All the samples blood, tracheal aspirate, urine and central venous catheter (CVC) were processed by standard protocols. The yeasts were identified by the germ tube test, characteristic morphology on cornmeal agar, urease test, carbon and nitrogen assimilation tests and ascospore production on malt extract agar. Clinical isolates from patients were also analysed using API 20C AUX yeast assimilation strips (bioMérieux, France).
Antifungal susceptibilities of the isolates to amphotericin B, fluconazole, itraconazole, voriconazole were determined using Clinical and Laboratory Standards Institute (CLSI) M-27 S3 microdilution method. The MICs were defined as the lowest drug concentrations that resulted in complete inhibition of growth.
Since, these are uncommon pathogenic yeasts; reconfirmation was performed at National Culture Collection for Pathogenic Fungi, Department of Medical Microbiology, Post Graduate Institute of Medical Education and Research (PGIMER), Chandigarh, India, by sequencing. The DNA of the isolates was amplified by polymerase chain reaction (Genei, Bengaluru, India) and sequenced using the BigDye Terminator Cycle (Applied Biosystems, Foster City, CA, USA). Sequences analysis of the 5.8 S rDNA was done on the genetic analyser 3130 (Applied Biosystems) by using universal primer ITSI and ITS4.
| ~ Result|| |
Clinico-epidemiological and antifungal susceptibility profile of the patients are shown in [Table 1]. Only two patients (case 6, 7) were treated successfully after therapy with voriconazole and amphotericin B. The isolates included: Trichosporon spp. (2), S. ciferrii (1), K. ohmeri (1), P. kutrawersi (2), C. rugosa (1) and C. lusitaniae (1).
|Table 1: Clinico-epidemiological and antifungal susceptibility profile of the patients|
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Seven out of eight yeasts were also sequenced. Trichosporon spp. in case 1 spp. was sequenced using ITSI and ITS2 primer. It proved to be T. japonicum (accession no.: AF444473), showing 99% homology with CB 58641 strain. The case-3 yeast was sequenced as K. ohmeri (accession no. FJ 21865) showing 99% maximum identification. The case-4 yeast proved to be S. ciferrii (accession no: AY493445) showing 98% homology. C. rugosa in case 5 was sequenced using ITSI and ITS2 primer. It proved to be C. rugosa. The case-5 yeast was sequenced as C. lusitaniae. The case-7 and case-8 yeasts proved to be Pichia kutrawersii.
| ~ Discussion|| |
The concerns regarding systemic infections caused by unusual fungi have grown as the population of immunocompromised patients has increased. Five patients (case 1, 2, 4, 5, 8) expired before the result of culture or sensitivity reached clinicians. Furthermore, in all the isolates the exact identification was done after at least 7 days of isolation, initial isolate as non-albicans Candida spp. followed by carbon and nitrogen assimilation test giving the tentative diagnosis at the species level. Subsequently, the isolates were sequenced and reconfirmed.
In this case series the T. japonicum and T. ashaii isolates were cultured from ICU patients on broad spectrum antimicrobials, CVC, ventilator and had prolonged ICU stay. The underlying conditions in these patients were ALL (1) and AML (1). Other risk factors documented are AIDS, extensive burns, intravascular catheters (biofilm formation), corticosteroids and cardiac surgery. Both these isolates were resistant to azoles but only T. asahii was resistant to amphotericin B. The incidence of Trichosporon infection in patients with leukaemia reported in the literature is 0.4% in a previous multicentre study. However, in India the data pertaining to the isolation of these unusual invasive yeasts is scarce.,,Trichosporon spp. are among the most common of the non-candida, non-cryptococcus yeasts isolated from clinical specimens throughout the world. The most common cause of trichosporonnosis world-wide is T. asahii followed by T. cutaneum, T. oviodes.
The pathogenesis and progression of trichosporonosis in ICU is similar to candidiasis., Unlike candidemia, the recommended guidelines of treatment for trichosporonosis are yet to be established because of the rarity of this infection. Furthermore, Trichosporon spp. are relatively resistant to antifungals including amphotericin B, fluconazole, itraconazole, flucytosine, caspofungin but are susceptible to newer triazoles , as were seen this case series. The overall treatment includes voriconazole, catheter removal and in the neutropenic patient administration of granulocyte-macrophage colony-stimulating factor.
Pichia (Kodamaea) ohmerii, a teleomorphic form of Candida guilliermondii var. membranifaciens is environmental yeast and was until now considered a contaminant but now it has emerged as a significant pathogen. First documented a case of K. ohmeri fungemia was reported in 1998.K. ohmeri is now implicated in fungemia, endocarditis, cellulitis, wound infection, catheter infection, peritonitis, phlebitis, urinary tract infection in immunocompromised patients. It has been isolated from tracheal aspirate, wound, CVC. The pre-existing condition documented for infection are implants (CVC, dialysis catheter, pacemaker), cancer with chemotherapy with or without neutropenia, immunosuppression, prematurity, intravenous drug abuse, diabetes, prolonged hospitalisation and abdominal surgery.,,,, In this case series, ALL on chemotherapy with neutropenia were the risk factor. The isolate was susceptible to amphotericin B, voriconazole and showed decreased susceptibility to fluconazole and itraconazole. These findings are in concurrence with results of the previous study. In contrast to Pichia anomola, only one nosocomial outbreak due to P. ohmeri has been described. The isolate from the patient was identified as K. ohmeri, showing 100% homology with K. ohmeri using ITS1 and ITS2 sequences. This was also observed by a prior study.
In this case series, S. ciferrii were isolated from blood of an AML patient. S. ciferrii has previously been isolated from blood, wound swab, aural discharge and nail sample. Principal sites of infection reported are in ear infections, patients with AML, immunodeficiency patients, superficial and deep mycosis.,,, Although this species has a strong tendency to become resistant especially in patients on fluconazole prophylaxis. However, in our case series the isolate was resistant to amphotericin B but susceptible to fluconazole and itraconazole despite being on fluconazole prophylaxis. Therefore, in vitro susceptibility testing is mandatory for the selection of an appropriate antimycotic drug. Although commercial kits are designed to identify common yeasts, but they fail to characterise these less frequent ones. Molecular methods using ITS1 and ITS2 are an effective tool, as the strain in this case series was characterised using ITS1 and ITS2 region.
The teleomorphic genus Pichia is ascomycetous yeast found in plants, fruits, soil and organic material. Human infections are usually sporadic, but outbreaks have been reported from India and elsewhere. The two species associated with human infection are P. anomola and P. (Kodomaea) ohmeri. Isolation of P. kutrawersii (which is telemorph of C. krusei) in two cases of fungemia in AIDS cases on fluconazole prophylaxis in this study calls for a reappraisal of the risk factors involved in this infection. Amphotericin B with or without flucytosine remains the drug of choice. Fluconazole, itraconazole have moderate activity as were seen in this case-series.
Until recently, C. rugosa was isolated as a single case report or occasional outbreaks as the risk factors such as CVCs, surgical interventions and use of broad-spectrum antibiotics. However, the emergence of this species as a major (20%) cause of candidemia in a major trauma centre in Delhi is a matter of grave concern. This was probably attributed to its isolation from milk of mastitic cows, thereby leading to intestinal colonisation as speculated by an editorial from United Kingdom. In this study, the C. rugosa isolate was resistant to fluconazole and itraconazole, but susceptible to voriconazole, amphotericin B. Similar results were obtained in the prior Indian study.
In this case series, C. lusitaniae were isolated from a case of Hodgkins lymphoma. It was resistant to amphotericin B, fluconazole and itraconazole. Most infections with C. lusitaniae have been in patients with hematologic malignancies with neutropenia and stem cell transplant. The polyene resistance is attributed to defect in ergosterol biosynthesis. It has been documented that few C. lusitaniae, even though originally susceptible to amphotericin B, might be less amenable to amphoterecin B therapy.
ITS region is an essential and effective tool for differentiating the rare species most frequently misdiagnosed, bearing in mind that reliable sequence databases should be used. Given the inability of phenotypic methods to distinguish some of these rare species, it is possible that molecular methods may ultimately become the primary means of identification of clinically important rare yeasts. As their mistaken identify could imply inappropriate treatment and clinical management.
| ~ Conclusions|| |
In laboratories where molecular tests like sequencing are not available, antifungal susceptibility should be provided to clinician and the rare yeast isolates characterised by phenotypic methods be submitted to references laboratories as a cost effective alternative measures, as was followed in this case-series. As these rare species are inherently resistant to antifungal agents and they may lead to the development of nosocomial outbreaks, therefore, accurate identification followed by antifungal susceptibility testing is crucial for proper treatment and management.
| ~ Acknowledgements|| |
The authors acknowledge Dr. Arunaloke Chakrabarti, Prof. and Head, Dr. M.R. Shivaprakash, Addl. Prof., National Culture Collection for Pathogenic Fungi, Department of Medical Microbiology, PGIMER, Chandigarh, India, for reconfirming the isolates by sequencing.
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