Lactobacillus acidophilus has been reported to be the predominant vaginal species. Vaginal lactobacilli isolated from 215 sexually active women were identified using whole-chromosomal DNA probes to 20 American Type Culture Collection Lactobacillus strains. Most women were colonized by L. crispatus (32%), followed by L. jensenii (23%), a previously undescribed species designated L. 1086V (15%), L. gasseri (5%), L. fermentum (0.3%), L. oris (0.3%), L. reuteri (0.3%), L. ruminis (0.3%), and L. vaginalis (0.3%). H2O2 was produced by 95% of L. crispatus and 94% of L. jensenii isolates, compared with only 9% of L. 1086V. Colonization by L. crispatus or L. jensenii was positively associated with being white (P<.001), age >/=20 years (P=.05), barrier contraceptive usage (P=.008), and lower frequency of bacterial vaginosis (P<.001) and gonorrhea (P=.03). L. crispatus and L. jensenii, not L. acidophilus, are the most common species of vaginal lactobacilli.

Lactobacilli colonizing the rectum may be a reservoir for vaginal lactobacilli. In a cross-sectional study of 531 females, vaginal and rectal colonization by lactobacilli were assessed by culture methods. A subset of isolates was identified to the species level by use of whole-chromosomal DNA probes. Lactobacillus crispatus (16%), L. jensenii (10%), and L. gasseri (10%) were the prevalent lactobacilli colonizing the rectums of 290 females. Only 13 (9%) of 147 females colonized by L. crispatus or L. jensenii vaginally and/or rectally had bacterial vaginosis (BV), compared with 12 (44%) of 27 females colonized by other H(2)O(2)-producing lactobacilli (P < .001). Cocolonization of the vagina and rectum by H(2)O(2)-producing lactobacilli was associated with the lowest prevalence of BV (5%), whereas females colonized only vaginally, only rectally, or at neither site had a successively increased risk of BV (P < .001). Lactobacillus species in the rectum may contribute to the maintenance of vaginal microflora.

To identify factors that predict sustained colonization by vaginal lactobacilli, microbiologic, behavioral, and demographic data were obtained from 101 nonpregnant women at baseline and at 4 and 8 months. A total of 272 isolates of lactobacilli were identified to the species level by use of whole chromosomal DNA homology to type strains. The predominant lactobacilli were the species Lactobacillus crispatus (38%) and L. jensenii (41%). Of 57 women initially colonized by H(2)O(2)-producing L. crispatus or L. jensenii, 23 (40%) remained colonized over 8 months, compared with 1 (5%) of 21 women colonized by other H(2)O(2)-producing species or by H(2)O(2)-negative strains (P=.01). Frequency of sexual intercourse (> or =1 sex act per week) was associated with loss of colonization with H(2)O(2)-producing lactobacilli (P=.018), as was antibiotic use (P< or =.0001). Other behavioral and demographic characteristics did not predict sustained colonization. The production of H(2)O(2) is closely linked with species and is a predictor for sustained long-term colonization of the vagina.

These data suggest that the factors that predict failure to become colonized by probiotic lactobacilli include exposure to semen, vaginal intercourse, and the presence of lactobacilli of the same species at enrollment.

The prevalence of bacterial vaginosis among lesbians is high. We assessed whether unique Lactobacillus strains were shared by female sex partners. Cultures of vaginal and rectal specimens for detection of Lactobacillus organisms were performed for women who reported having had sex with women. Lactobacilli were identified on the basis of DNA homology and were typed and fingerprinted by repetitive element sequence– based polymerase chain reaction (rep-PCR). Of 237 women, Lactobacillus crispatus was detected in 98% and Lactobacillus gasseri in 21%. Detection of L. gasseri was associated with recent receptive digital-vaginal sex (P = .04) and increased bacterial vaginosis risk (odds ratio, 4.2; 95% confidence interval, 1.4– 13.4). Of 31 couples monogamous for >3 months, rep-PCR fingerprints were identical in both members in 23 (77%).

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The API 50 CH identification system was evaluated for the identification of 97 strains of commensal lactobacilli. This system agreed with the species-level identifications for none of the 7 reference strains and only 4 of 90 vaginal isolates identified using whole-chromosomal DNA probes.Lactobacillus species maintain a healthy vaginal ecosystem and are associated with decreased acquisition of bacterial vaginosis (10), human immunodeficiency virus (13), and gonorrhea (13). There are over 50 species recognized in the genus Lactobacillus (7), and several of these species have been proposed as probiotics (4,14). In some instances, Lactobacillus strains found in food or probiotics have caused peritonitis (12) or endocarditis (9). Correct species identification of lactobacilli is essential to guide appropriate antibiotic therapy (12). Correct identification of lactobacilli is also relevant to studies of epidemiology (2, 3) and innate immunity (1).Phenotypic tests have been used as the primary methods for classifying Lactobacillus species. Klein et al. have reported that none of the commercial kits can be recommended and that some species of lactobacilli are incorrectly identified as Lactobacillus acidophilus (12). Using phenotypic techniques, L. acidophilus has been reported to be the most frequently isolated Lactobacillus species recovered from the vagina (1, 6, 16). However, using genotypic methods, studies done in the United States (2), Japan (18), and Europe (8,19) L. iners, L. gasseri, and L. vaginalis are the most common species of lactobacilli found in the vagina. This suggests that the phenotypic methods most commonly used for the identification of Lactobacillus species have poor concordance with genomics-based tests.Some investigators have relied on API 50 CH carbohydrate fermentation strips (bioMérieux, Inc., Marcy l'Etoile, France) to identify vaginal strains of Lactobacillus to the species level (1,15). In this study, we evaluate the use of API 50 CH carbohydrate fermentation strips for the identification of five common commensal Lactobacillus species isolates.Lactobacillus isolates (n ϭ 97) stored at Ϫ80°C in litmus milk (Becton Dickinson Microbiology Systems, Cockeysville, MD) were tested for species identification using the API 50 CH carbohydrate fermentation strips. Seven of these were reference strains: L. crispatus ATCC 33197 and ATCC 202225 (also known as CTV-05), L. jensenii ATCC 25258, L. gasseri ATCC 9857 and ATCC 4963, L. iners CCUG 28746, and L. vaginalis ATCC 49540. The remaining 90 isolates were recovered from vaginal specimens and identified to the species level using whole-chromosomal DNA probes (3). These included isolates of L. crispatus (n ϭ 16), L. jensenii (n ϭ 18), L. gasseri (n ϭ 18), L. iners (n ϭ 19), and L. vaginalis (n ϭ 19). These isolates were obtained from women in Seattle (n ϭ 26), Pittsburgh (n ϭ 28), and Uganda (n ϭ 36) from 1995 to 2002.Each isolate was inoculated onto a Columbia agar with 5% sheep blood (BA) (PML Microbiologicals, Portland, OR) plate, incubated at 37°C ...

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