Genotyping of Streptococcus agalactiae(group B streptococci) isolated from vaginal and rectal swabs of women at 35-37 weeks of pregnancy

Abstract

BackgroundGroup B streptococci (GBS), or Streptococcus agalactiae, are the leading bacterial cause of meningitis and bacterial sepsis in newborns. Here we compared different culture media for GBS detection and we compared the occurrence of different genotypes and serotypes of GBS isolates from the vagina and rectum.MethodsStreptococcus agalactiae was cultured separately from both rectum and vagina, for a total of 150 pregnant women, i) directly onto Columbia CNA agar, or indirectly onto ii) Granada agar resp. iii) Columbia CNA agar, after overnight incubation in Lim broth.ResultsThirty six women (24%) were colonized by GBS. Of these, 19 harbored GBS in both rectum and vagina, 9 only in the vagina and 8 exclusively in the rectum. The combination of Lim broth and subculture on Granada agar was the only culture method that detected all GBS positive women. Using RAPD-analysis, a total of 66 genotypes could be established among the 118 isolates from 32 women for which fingerprinting was carried out. Up to 4 different genotypes in total (rectal + vaginal) were found for 4 women, one woman carried 3 different genotypes vaginally and 14 women carried two 2 different genotypes vaginally. Only two subjects were found to carry strains with the same genotype, although the serotype of both of these strains was different.Eighteen of the 19 subjects with GBS at both sites had at least one vaginal and one rectal isolate with the same genotype.We report the presence of two to four different genotypes in 22 (61%) of the 36 GBS positive women and the presence of identical genotypes in both sites for all women but one.ConclusionThe combination of Lim broth and subculture on Granada medium provide high sensitivity for GBS detection from vaginal and rectal swabs from pregnant women. We established a higher genotypic diversity per individual than other studies, with up to four different genotypes among a maximum of 6 isolates per individual picked. Still, 18 of the 19 women with GBS from both rectum and vagina had at least one isolate from each sampling site with the same genotype.

Nasal carriage of methicillin resistant Staphylococcus aureus among health care workers at Al Shifa hospital in Gaza Strip

“…DNA was extracted from cultured isolates by alkaline lysis as previously described [15]. Briefly, one bacterial colony was suspended in 20 μl of lysis buffer (0.25% sodium dodecyl sulfate, 0.05 N NaOH) and heated at 95 °C for 15 min.…”

Strong Correspondence of the Vaginal and Rectal Load of Group B Streptococci in Pregnant Women

“…Rectovaginal swabs have been reported to provide high bacterial yields [10,25,[30][31][32] and have therefore been recommended for GBS screening [10]. However, Nomura et al [33] found no significant difference in detection rates between vaginal and rectal samples and Gupta and Briski [34] reported a similar detection rate of 23.8% of GBS when using rectovaginal and vaginal sampling.…”

“…Meyn et al [28] showed that rectal colonization with GBS was the most significant predictor of vaginal colonization, suggesting that the vagina becomes colonized with GBS as a result of transfer of the organism from the rectum to the vagina. Our previous culture-based genotyping study showed a high correspondence of vaginal and rectal colonization with GBS, also at the strain level [25], because a total of 19 women was colonized by GBS in both rectum and vagina and moreover, 18 of these women had at least one vaginal and one rectal isolate with the same genotype.…”

“…in patients with candidal vulvovaginitis [24]. We previously showed a high correlation between vaginal and rectal microflora, not only with regard to species composition but also with regard to the presence of genotypically identical strains [25].…”

Multitasking models for quantitative structure–biological effect relationships: current status and future perspectives to speed up drug discovery

“…We can say that species belonging to genera such as Mycobacterium, Staphylococcus and Streptococcus have caused altogether > 700 million cases of infections annually, with > 2 million deaths [81][82][83][84] due to both community-acquired and nosocomial infections. In the particular case of nosocomial infections, other genera like Enteroroccus, Pseudomonas and Escherichia (and many others) have inflicted a serious impact in health-care facilities around the world, exhibiting high mortalities rates even in developed countries [85].…”