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Open Access Research article

Detection of hydrogen peroxide-producing Lactobacillus species in the vagina: a comparison of culture and quantitative PCR among HIV-1 seropositive women

Jennifer E Balkus12*, Caroline Mitchell2, Kathy Agnew2, Congzhou Liu3, Tina Fiedler3, Susan E Cohn4, Amneris Luque5, Robert Coombs6, David N Fredricks3 and Jane Hitti2

Author Affiliations

1 Department of Epidemiology, University of Washington, Box 359909, 325 9th Avenue, Seattle, WA, 98104, USA

2 Department of Obstetrics and Gynecology, University of Washington, Seattle, USA

3 Vaccine Infectious Diseases Division, Fred Hutchinson Cancer Research Center, Seattle, USA

4 Division of Infectious Diseases, Department of Medicine, Northwestern University, Chicago, USA

5 Department of Medicine, University of Rochester, Rochester, USA

6 Departments of Laboratory Medicine and Medicine, University of Washington, Seattle, USA

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BMC Infectious Diseases 2012, 12:188  doi:10.1186/1471-2334-12-188

Published: 13 August 2012

Abstract

Background

The presence of hydrogen peroxide (H2O2) producing Lactobacillus in the vagina may play a role in controlling genital HIV-1 shedding. Sensitive molecular methods improve our ability to characterize the vaginal microbiota; however, they cannot characterize phenotype. We assessed the concordance of H2O2-producing Lactobacillus detected by culture with quantitative PCR (qPCR) detection of Lactobacillus species commonly assumed to be H2O2-producers.

Methods

Samples were collected as part of a prospective cohort study of HIV-1 seropositive US women. Cervicovaginal lavage specimens were tested for L. crispatus and L. jensenii using 16S rRNA gene qPCR assays. Vaginal swabs were cultured for Lactobacillus and tested for H2O2-production. We calculated a kappa statistic to assess concordance between culture and qPCR.

Results

Culture and qPCR results were available for 376 visits from 57 women. Lactobacilli were detected by culture at 308 (82%) visits, of which 233 of 308 (76%) produced H2O2. L. crispatus and/or L. jensenii were detected at 215 (57%) visits. Concordance between detection of L. crispatus and/or L. jensenii by qPCR and H2O2-producing Lactobacillus by culture was 75% (kappa = 0.45).

Conclusions

Among HIV-1 seropositive women, there was a moderate level of concordance between H2O2-producing Lactobacillus detected by culture and the presence of L. crispatus and/or L. jensenii by qPCR. However, one-quarter of samples with growth of H2O2-producing lactobacilli did not have L. crispatus or L. jensenii detected by qPCR. This discordance may be due to the presence of other H2O2-producing Lactobacillus species.

Keywords:
Lactobacillus; Lactobacillus crispatus; Lactobacillus jensenii; Bacterial vaginosis; Culture; Hydrogen peroxide; 16S rRNA gene