Comparison of API 50 CH Strips to Whole-Chromosomal DNA Probes for Identification of Lactobacillus Species

Abstract

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 ...

Inhibition of Neisseria gonorrhoeae Epithelial Cell Interactions by Vaginal Lactobacillus Species

“…L. jensenii and L. gasseri are two of the most prevalent Lactobacillus species recovered from the vaginal tract of healthy women (1,4,5,36) and were therefore chosen for this study. Previous research showed that L. jensenii ATCC 25258 and L. gasseri ATCC 33323 had the potential to kill or inhibit the growth of N. gonorrhoeae in vitro (27).…”

“…In this study, L. jensenii and L. gasseri strains were chosen because these species are two of the most prevalent species recovered from healthy women and because they had been previously studied for their effects on N. gonorrhoeae in the absence of epithelial cells (1,4,5,13,27,36). Each strain inhibited the adherence of N. gonorrhoeae to epithelial cells but adhered poorly to epithelial cells (average adherence frequency of ϳ1%).…”

Taxonomic and Strain-Specific Identification of the Probiotic Strain Lactobacillus rhamnosus 35 within the Lactobacillus casei Group

“…To date, however, the strain has been identified by carbohydrate fermentation profiling, which takes several days and has poor taxonomic resolution and reliability (12,41). In contrast, DNA-based techniques are useful tools for the accurate and reliable characterization of bacteria, since they are based on constant genetic properties of the strains (2,31). In addition, most give quicker results than culture-based techniques.…”

Labeling quality and molecular characterization studies of products containing Lactobacillus spp. strains.

“…The data were elaborated by bioMérieux software. 13 The two strains of L. acidophilus used in the product VIII (Table 1) were differentiated on the basis of bacterial morphology shapes, colonies morphology and biochemical profiles.…”