title: Molecular evidence of interhuman transmission in an outbreak of Pneumocystis jirovecii pneumonia among renal transplant recipients.
abstract: Pneumocystis jirovecii pneumonia (PCP) remains an important cause of morbidity and mortality in immunocompromised individuals. The epidemiology and pathogenesis of this infection are poorly understood, and the exact mode of transmission remains unclear. Recent studies reported clusters of PCP among immunocompromised patients, raising the suspicion of interhuman transmission. An unexpected increase of the incidence of PCP cases in our nephrology outpatient clinic prompted us to conduct a detailed analysis. Genotyping of 7 available specimens obtained from renal transplant recipients was performed using multi-locus DNA sequence typing (MLST). Fragments of 4 variable regions of the P. jirovecii genome (ITS1, 26S, mt26S, beta-tubulin) were sequenced and compared with those of 4 independent control patients. MLST analysis revealed identical sequences of the 4 regions among all 7 renal allograft recipients with available samples, indicating an infection with the same P. jirovecii genotype. We observed that all but 1 of the 19 PCP-infected transplant recipients had at least 1 concomitant visit with another PCP-infected patient within a common waiting area. This study provides evidence that nosocomial transmission among immunocompromised patients may have occurred in our nephrology outpatient clinic. Our findings have epidemiological implications and suggest that prolonged chemoprophylaxis for PCP may be warranted in an era of more intense immunosuppression.
authors.affiliation: Division of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, Zurich, Switzerland.
authors.forename: S
authors.initials: S
authors.lastname: Gianella
authors.forename: L
authors.initials: L
authors.lastname: Haeberli
authors.forename: B
authors.initials: B
authors.lastname: Joos
authors.forename: B
authors.initials: B
authors.lastname: Ledergerber
authors.forename: R P
authors.initials: RP
authors.lastname: Wüthrich
authors.forename: R
authors.initials: R
authors.lastname: Weber
authors.forename: H
authors.initials: H
authors.lastname: Kuster
authors.forename: P M
authors.initials: PM
authors.lastname: Hauser
authors.forename: T
authors.initials: T
authors.lastname: Fehr
authors.forename: N J
authors.initials: NJ
authors.lastname: Mueller
mesh_terms: D000328:Adult; D000368:Aged; D003428:Cross Infection / Q000453:epidemiology / Q000382:microbiology / Q000635:transmission*; D004271:DNA, Fungal / Q000032:analysis / Q000235:genetics; D021903:DNA, Ribosomal Spacer / Q000032:analysis; D005260:Female; D006801:Humans; D016030:Kidney Transplantation / Q000009:adverse effects*; D008297:Male; D008875:Middle Aged; D016533:Mycological Typing Techniques; D045363:Pneumocystis carinii / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification; D011020:Pneumonia, Pneumocystis / Q000453:epidemiology / Q000382:microbiology / Q000635:transmission*; D012335:RNA, Ribosomal / Q000235:genetics; D017422:Sequence Analysis, DNA; D014404:Tubulin / Q000235:genetics; D055815:Young Adult
chemical_list: D004271:DNA, Fungal; D021903:DNA, Ribosomal Spacer; D012335:RNA, Ribosomal; C065096:RNA, ribosomal, 26S; D014404:Tubulin