High Prevalence of Dihydropteroate Synthase Mutations in Pneumocystis jirovecii Isolated from Patients with Pneumocystis Pneumonia in South Africa

Abstract

Pneumocystis jirovecii pneumonia (PCP) is an important cause of morbidity and mortality in immunocompromised patients. Sulfa-containing drugs are used for the treatment and prophylaxis of PCP. Mutations in the P. jirovecii fas gene, which encodes dihydropteroate synthase (DHPS), are associated with prior exposure to sulfa drugs, and their appearance suggests the emergence of variants with reduced sulfa susceptibility. The present study examined the prevalence of DHPS mutations in P. jirovecii strains isolated from South African patients with PCP. P. jirovecii infection was investigated by immunofluorescence microscopy and quantitative real-time PCR with respiratory specimens from 712 patients (93% of whom were >15 years of age) with suspected PCP consecutively received for the detection of P. jirovecii over 1 year. PCR amplification and sequencing of the DHPS fas gene was attempted with DNA from the P. jirovecii-positive samples. P. jirovecii infection was confirmed by immunofluorescence microscopy in 168/712 (24%) of the patients. Carriage of the fungus was revealed by real-time PCR in 17% of the patients with negative microscopy results. The P. jirovecii fas gene was successfully amplified from specimens from 151 patients and sequenced. Mutations resulting in the Thr55Ala and/or Pro57Ser amino acid substitution were detected in P. jirovecii strains from 85/151 (56%) patients. The high frequency of PCP episodes with P. jirovecii harboring DHPS mutations in South Africa indicates that populations of this fungus are evolving under the considerable selective pressure exerted by sulfa-containing antibiotics. These results, similar to previous observations of sulfa drug resistance in bacterial populations, underscore the importance of the rational use of sulfa medications either prophylactically against PCP or for the treatment of other infections.

Microbiological findings in bronchoalveolar lavage fluid from lung transplant patients in Sweden

“…In Lund, additional PCR for herpes simplex virus (HSV) 1 and 2 was performed with an in‐house method. Presence of Pneumocystis jiroveci was analyzed with PCR or immunofluorescence of BALF. CMV in blood or plasma was determined with quantitative PCR.…”

Low Prevalence of Pneumocystis pneumonia (PCP) but High Prevalence of Pneumocystis dihydropteroate synthase (dhps) Gene Mutations in HIV-Infected Persons in Uganda

“…[14], [15] We investigated P. jirovecii among a cohort of HIV-infected patients admitted to Mulago Hospital, a national referral center in Kampala, Uganda. We assessed the prevalence both of PCP amongst patients with pneumonia and of P. jirovecii mutations associated with antifolate drug resistance.…”

Prevalence and Genotype Distribution of Pneumocystis jirovecii in Cuban Infants and Toddlers with Whooping Cough

“…jirovecii qPCR assay. The quantitative PCR (qPCR) developed by Dini et al (13), targeting the mtLSU rRNA gene, was used with minor modifications. A 77-bp amplicon was amplified with the primers LSU1 (5=-AAA TAA ATA ATC AGA CTA TGT GCG ATA AGG-3=) and LSU2 (5=-GGG AGC TTT AAT TAC TGT TCT GGG-3=) and detected with the hydrolysis probe LSUPN1, labeled with 6-carboxyfluorescein (6-FAM) and 6-carboxytetramethylrhodamine (TAMRA) (5=-AGA TAG TCS AAA GGG AAA C-3=; the underlined S, a modification to the hydrolysis probe, hybridizes with G or C [the original nucleotide here is C]) (TAG Copenhagen A/S, Copenhagen, Denmark).…”