Novel dihydropteroate synthase gene mutation in Pneumocystis jirovecii among HIV-infected patients in India: Putative association with drug resistance and mortality

Abstract Objectives Pneumocystis pneumonia (PCP) remains a debilitating cause of death among HIV-infected patients. Trimethoprim-sulfamethoxazole (TMP-SMX) combinations are the most effective anti- Pneumocystis treatment and prophylaxis. Long term usage of this combination has raised alarms about emergence of resistant organisms. Present study was carried out to investigate dihydropteroate synthase ( DHPS ) mutations and their clinical consequences in HIV-infected patients with PCP. Methods Seventy-six clinically suspected cases of pneumocystis pneumonia among HIV-seropositive adult patients from March 2014 to March 2017 were included. Clinical samples (BALF/Sputa) were investigated for the detection of P. jirovecii using both microscopy and polymerase chain reaction (PCR) assay. DHPS genotyping and mutational analyses were carried out and the data obtained were correlated with clinical characteristics. Results Among all enrolled HIV-positive adult patients, only 17 (22.3%) were positive for P. jirovecii . DHPS gene sequencing showed novel nucleotide substitution at position 288 (Val96Ile) in three patients (n = 3/12;25%). Patients infected with this mutant P. jirovecii genotype (Val96Ile) had severe episodes of PCP, did not respond to TMP-SMX and had fatal outcome ( P =  0.005). All these three patients had CD4+ T-cell count less than 100 cells/ul and two of them also had co-infections. Conclusions Present study suggests that emergence of mutant P. jirovecii genotype are probably associated with drug resistance and mortality. Our data also suggest that DHPS mutational analyses should be performed in HIV-seropositive patients to avoid treatment failure and death due to PCP. However, role of underlying disease severity and comorbidities cannot be underestimated.