Association of Atopobium vaginae, a recently described metronidazole resistant anaerobe, with bacterial vaginosis.

Michael J Ferris,Alicia Masztal,Paul L Fidel,J Dennis Fortenberry,Kenneth E Aldridge,David H Martin

doi:10.1186/1471-2334-4-5

Abstract

BackgroundBacterial vaginosis (BV) is a polymicrobial syndrome characterized by a change in vaginal flora away from predominantly Lactobacillus species. The cause of BV is unknown, but the condition has been implicated in diverse medical outcomes. The bacterium Atopobium vaginae has been recognized only recently. It is not readily identified by commercial diagnostic kits. Its clinical significance is unknown but it has recently been isolated from a tuboovarian abcess.MethodsNucleotide sequencing of PCR amplified 16S rRNA gene segments, that were separated into bands within lanes on polyacrylamide gels by denaturing gradient gel electrophoresis (DGGE), was used to examine bacterial vaginal flora in 46 patients clinically described as having normal (Lactobacillus spp. predominant; Nugent score ≤ 3) and abnormal flora (Nugent score ≥ 4). These women ranged in age from 14 to 48 and 82% were African American.ResultsThe DGGE banding patterns of normal and BV-positive patients were recognizably distinct. Those of normal patients contained 1 to 4 bands that were focused in the centre region of the gel lane, while those of BV positive patients contained bands that were not all focused in the center region of the gel lane. More detailed analysis of patterns revealed that bands identified as Atopobium vaginae were present in a majority (12/22) of BV positive patients, while corresponding bands were rare (2/24) in normal patients. (P < 0.001) Two A. vaginae isolates were cultivated from two patients whose DGGE analyses indicated the presence of this organism. Two A. vaginae 16S rRNA gene sequences were identified among the clinical isolates. The same two sequences were obtained from DGGE bands of the corresponding vaginal flora. The sequences differed by one nucleotide over the short (~300 bp) segment used for DGGE analysis and migrated to slightly different points in denaturing gradient gels. Both isolates were strict anaerobes and highly metronidazole resistant.ConclusionThe results suggest that A. vaginae may be an important component of the complex bacterial ecology that constitutes abnormal vaginal flora. This organism could play a role in treatment failure if further studies confirm it is consistently metronidozole resistant.

Highlights

Bacterial vaginosis (BV) is a polymicrobial syndrome characterized by a change in vaginal flora away from predominantly Lactobacillus species
denaturing gradient gel electrophoresis (DGGE) banding patterns of normal and BV positive samples Lavage samples were obtained from 24 patients with normal vaginal secretion Gram stains, from two patients with intermediate vaginal flora and from 20 with BV based on Nugent's score
When a patient's vaginal flora was normal by Nugent's score, their DGGE pattern was the normal type in 92% (22/24) of cases

Summary

Introduction

Bacterial vaginosis (BV) is a polymicrobial syndrome characterized by a change in vaginal flora away from predominantly Lactobacillus species. The bacterium Atopobium vaginae has been recognized only recently. It is not readily identified by commercial diagnostic kits. Bacterial vaginosis (BV) is a syndrome that appears to represent a disturbance of the vaginal ecosystem associated with a shift in the microflora [1,2]. While the cause of BV is not understood, some strong associations have been made between the syndrome and the presence of particular bacterial species, such as Gardnerella vaginalis and Prevotella sp. Molecular surveys of microbes in environmental samples have repeatedly shown that cultivated species do not represent the full complement of microbes in most habitats [16] and molecular analyses are commonly used to survey bacterial flora in mammalian systems [17,18]

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