Vaginal microbiota in healthy pregnant women and prenatal screening of group B streptococci (GBS)

The microbiota of the lower female genital tract was evaluated from vaginal swabs obtained from 623 healthy pregnant women at gestation periods of 35-40 weeks. Isolated and identified microorganisms were expressed as percentages of total samples. As expected, lactobacilli made up the dominant vaginal microbiota (70%). Enterobacteriaceae, mainly Escherichia coli, Klebsiella spp. and Proteus, were present in 38% of the samples, which might reflect the possible contamination of vaginal tract with rectal microorganisms. Candida albicans was present in 10% of healthy pregnant woman assayed. Streptoccocci (Streptococcus sp. and Enterococcus faecalis with 3% and 4%, respectively) and other gram-positive cocci (Staphylococcus sp., 5%), along with other microorgansisms such as Gardnerella vaginalis (5%) and Pseudomonas aeruginosa (2%) may represent a potential infection risk. Streptococcus agalactiae (group B streptococci β-hemolytic, GBS) was detected in 7% of the samples. GBS infection is a leading cause of neonatal morbidity and mortality in the developed world. Furthermore, GBS was often co-isolated with C. albicans (54.5%) in the samples. A complete and detailed evaluation of the vaginal biota swab, with particular attention to the presence of potential pathogens such as GBS, is a preventive strategy that can provide useful information to obstetricians and gynecologist in managing the last days of pregnancy and delivery.