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Open Access Highly Accessed Research article

Association between Lactobacillus species and bacterial vaginosis-related bacteria, and bacterial vaginosis scores in pregnant Japanese women

Renuka Tamrakar, Takashi Yamada*, Itsuko Furuta, Kazutoshi Cho, Mamoru Morikawa, Hideto Yamada, Noriaki Sakuragi and Hisanori Minakami

Author Affiliations

Department of Obstetrics and Gynecology, Hokkaido University Graduate School of Medicine, Kita-ku N14 W6, Sapporo, Japan, 060-8638

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BMC Infectious Diseases 2007, 7:128  doi:10.1186/1471-2334-7-128

Published: 7 November 2007

Abstract

Background

Bacterial vaginosis (BV), the etiology of which is still uncertain, increases the risk of preterm birth. Recent PCR-based studies suggested that BV is associated with complex vaginal bacterial communities, including many newly recognized bacterial species in non-pregnant women.

Methods

To examine whether these bacteria are also involved in BV in pregnant Japanese women, vaginal fluid samples were taken from 132 women, classified as normal (n = 98), intermediate (n = 21), or BV (n = 13) using the Nugent gram stain criteria, and studied. DNA extracted from these samples was analyzed for bacterial sequences of any Lactobacillus, four Lactobacillus species, and four BV-related bacteria by PCR with primers for 16S ribosomal DNA including a universal Lactobacillus primer, Lactobacillus species-specific primers for L. crispatus, L. jensenii, L. gasseri, and L. iners, and BV-related bacterium-specific primers for BVAB2, Megasphaera, Leptotrichia, and Eggerthella-like bacterium.

Results

The prevalences of L. crispatus, L. jensenii, and L. gasseri were significantly higher, while those of BVAB2, Megasphaera, Leptotrichia, and Eggerthella-like bacterium were significantly lower in the normal group than in the BV group. Unlike other Lactobacillus species, the prevalence of L. iners did not differ between the three groups and women with L. iners were significantly more likely to have BVAB2, Megasphaera, Leptotrichia, and Eggerthella-like bacterium. Linear regression analysis revealed associations of BVAB2 and Megasphaera with Nugent score, and multivariate regression analyses suggested a close relationship between Eggerthella-like bacterium and BV.

Conclusion

The BV-related bacteria, including BVAB2, Megasphaera, Leptotrichia, and Eggerthella-like bacterium, are common in the vagina of pregnant Japanese women with BV. The presence of L. iners may be correlated with vaginal colonization by these BV-related bacteria.