Abstract
Pneumocystis jirovecii dihydropteroate synthase (DHPS) gene mutations' (55th and 57th codon) association with prior sulfa prophylaxis failure has been reported from both developed and developing countries. We conducted a prospective study to determine the prevalence of P. jirovecii DHPS mutations from 2006 to 2009 on P. jirovecii isolates obtained from HIV-infected patients with a clinical diagnosis of Pneumocystis carinii pneumonia (PCP) admitted to our tertiary care reference health center in New Delhi, India. Detection of P. jirovecii cysts was performed by direct fluorescent antibody (DFA) staining and by Grocott's-Gomori methenamine silver staining (GMS). DNA detection was performed by polymerase chain reaction (PCR) using primers for the major surface glycoprotein (MSG) gene. P. jirovecii DHPS gene was amplified by nested PCR protocol and sequenced for detecting mutations at the 55th and 57th codons. Out of 147 HIV-positive patients with suspected Pneumocystis pneumonia (PCP), 16 (10.8%) PCP positive cases were detected. Of 16 cases, nine (56.2%) were positive by DFA staining, four (25%) were positive by Grocott's-Gomori methenamine silver staining, and all 16 were positive by MSG PCR. DHPS mutations at the 55th and 57th codons were observed in 6.2% of HIV patients studied, which was relatively low compared to reports from developed nations. Prevalence of Pneumocystis jirovecii DHPS mutations associated with cotrimoxazole treatment failure may be low in the Indian subpopulation of HIV-positive patients and warrants larger studies to elucidate the true picture of Pneumocystis jirovecii sulfa drug resistance in India.
Highlights
Pneumocystis jirovecii dihydropteroate synthase (DHPS) gene mutations’ (55th and 57th codon) association with prior sulfa prophylaxis failure has been reported from both developed and developing countries
Nine (56.2%) were positive by direct fluorescent antibody (DFA) staining, four (25%) were positive by Grocott’s-Gomori methenamine silver staining, and all 16 were positive by major surface glycoprotein (MSG) polymerase chain reaction (PCR)
DHPS mutations at the 55th and 57th codons were observed in 6.2% of human immunodeficiency virus (HIV) patients studied, which was relatively low compared to reports from developed nations
Summary
Pneumocystis jirovecii dihydropteroate synthase (DHPS) gene mutations’ (55th and 57th codon) association with prior sulfa prophylaxis failure has been reported from both developed and developing countries. We conducted a prospective study to determine the prevalence of P. jirovecii DHPS mutations from 2006 to 2009 on P. jirovecii isolates obtained from HIV-infected patients with a clinical diagnosis of Pneumocystis carinii pneumonia (PCP) admitted to our tertiary care reference health center in New Delhi, India. Numerous studies from developed countries have reported that mutations at codon 55 and codon 57 of the DHPS gene of P. jirovecii are associated with sulfa treatment and prophylaxis failure as these mutations are located in the highly conserved region of one of the active sites of the enzyme [6] and this correlates with point mutations that cause sulfa
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