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Open Forum Infect Dis. 2015 Jun 3;2(3):ofv080. doi: 10.1093/ofid/ofv080. eCollection 2015 Sep.

Use of Oropharyngeal Washes to Diagnose and Genotype Pneumocystis jirovecii.

Author information

1
Division of Infectious Diseases ; Curriculum in Genetics and Molecular Biology , University of North Carolina School of Medicine ; Department of Epidemiology , Gillings School of Global Public Health, University of North Carolina , Chapel Hill.
2
Division of Infectious Diseases.
3
Division of Infectious Diseases ; Curriculum in Genetics and Molecular Biology , University of North Carolina School of Medicine.
4
Department of Epidemiology , Gillings School of Global Public Health, University of North Carolina , Chapel Hill ; Division of Infectious Diseases and International Health , Duke University Medical Center , Durham.
5
Department of Epidemiology , Gillings School of Global Public Health, University of North Carolina , Chapel Hill.
6
HIV/AIDS Division.
7
HIV/AIDS Division ; Division of Pulmonary and Critical Care Medicine , San Francisco General Hospital, University of California.

Abstract

Pneumocystis jirovecii is a symbiotic respiratory fungus that presents in 2 clinical forms: pneumonia in immunocompromised patients or colonization, defined by the presence of the organism without associated clinical symptoms. Currently, diagnosis requires invasive bronchoscopy, which may not be available in some settings and is inappropriate for detecting colonization in healthy individuals. Noninvasive diagnostic techniques and molecular strain typing tools that can be used on these samples are critical for conducting studies to better understand transmission. We evaluated 2 real-time polymerase chain reaction (PCR) assays targeting dihydropteroate synthase and the major surface glycoprotein for detection in 77 oropharyngeal washes (OPWs) from 43 symptomatic human immunodeficiency virus-infected patients who underwent bronchoscopy. We also evaluated the ability of a new microsatellite (MS) genotyping panel to strain type infections from these samples. Each PCR used individually provided a high sensitivity (>80%) for detection of pneumonia but a modest specificity (<70%). When used in combination, specificity was increased to 100% with a drop in sensitivity (74%). Concentration of organisms by PCR in the OPW tended to be lower in colonized individuals compared with those with pneumonia, but differences in concentration could not clearly define colonization in symptomatic individuals. Oropharyngeal wash samples were genotyped using 6 MSs with ≥4 alleles successfully genotyped in the majority of colonized patients and ≥5 alleles in patients with pneumonia. The MS profile was consistent over time within patients with serial OPWs analyzed. Microsatellite genotyping on noninvasive samples may aid in studying the molecular epidemiology of this pathogen without requiring invasive diagnostic techniques.

KEYWORDS:

microsatellite; molecular epidemiology; pneumocystis; real-time PCR

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