Sensitivity patterns, serotypes of cryptococcusneoformans and diagnostic value of india ink in patients with cryptococcal meningitis at Kenyatta National Hospital.

Abstract

Background: Cryptococcal meningitis caused by the environmental encapsulated fungus Cryptococcus neoformans, is an important and often fatal infection whose incidence has multiplied severally after the advent of HIV. Correct diagnosis and appropriate treatment is required to reduce the high mortality rates associated with it. Objective: To determine the culture yield and the sensitivity of India ink as a diagnostic tool; To determine the sensitivity patterns of Cryptococcus neoformans to amphotericin B, fluconazole, miconazole and 5 flucytosine;and to determine the prevalent serotype of Cryptococcus neoformans at Kenyatta National Hospital. Study design: Cross-sectional study. • Setting: In-patient medical wards, Kenyatta National Hospital, Nairobi, Kenya. Study population: All patients admitted to medical wards of Kenyatta National Hospital with clinical diagnosis of meningo-encephalitis . Study method: Patients with meningo-encephalitis were subjected to a lumbar puncture after excluding contra-indications. CRAG test was done on the CSF obtained. Positive CSF samples were subjected to India ink stain. The CSF was cultured and sensitivity patterns to amphotericin B, fluconazole, miconazole and 5 flucytosine were determined. Sero-typing of the isolates was carried out. The HIV status of the cases was determined. Data entry and analysis: Data was entered into a computer database then analysed using SPSS version 12. Descriptive statistics were used for both continuous and cateqorical data. Inferential statistics were used to determine associations. The p value of <0.05 was considered significant. Results: Three hundred and seven CSF specimens were obtained during a 3 month period. Sixty one tested positive for CRAG (19.8%).Three specimens grew other fungi (T.mucoides-2 andT.Beigelii-1) on further microbiological analysis. Fifty eight specimens were thus analysed. India ink was found to be positive in 33 CSF samples (56.9%); culture positive samples were 39 (67.2%). Three isolates (7.7%) had MICs of >2I-Jg/ml for amphotericin B and were thus resistant. Twenty eight isolates (71.8%) were susceptible to fluconazole having MICs of <4I-Jg/ml; 8 patients (20.5%) had MICs of between 8 and 161-Jg/mland were categorized as intermediate resistant; 3 (7.7%) were highly resistant having MICs of >16I-Jg/ml. Miconazole susceptible isolates were 37(94.9%) having MICs of <1.0I-Jg/ml; only 2 isolates had MICs >1I-Jg/ml signifying resistance. 5- Flucytosine susceptible isolates were 19 (48.7%) having MICs <4I-Jg/ml;13 (33.3%) patients had MICs of between 8 and 161-Jg/ml and were in the intermediate resistant group whereas 7 patients (17.9%) fell in the highly resistant category with MICs of >32I-Jg/ml. Fifty. seven had underlying HIV and cryptococcus meningitis was the AIDS defining illness in 65.5% of them. One patient repeatedly tested negative for ELISA but this was not confirmed by a PCR. All 39 isolates cultured were sero-type A (Cryptococcus Neoformans var grubit). Conclusion: India ink that is currently being used widely as the sole diagnostic test for cryptococcal meningitis has a very low sensitivity thus misses a number of cases leading to misdiagnosis and inappropriate treatment decisions. The sensitivity patterns though concerning especially to Amphotericin B show that the isolates are still susceptible to the tested anti-fungals invitro.