Prevalence, Resistance profile & Virulence genes of Streptococcus Agalactiae Colonizing Near-Term Pregnant Women Attending Ain Shams University Hospital

Abstract

G BS is detected in 10-30% of pregnant women as a colonizing agent in the vagina and/or rectum. Early-onset infection, the most prevalent kind of newborn GBS disease, and late-onset infection are the two types of GBS infections in neonates. Intrapartum antibiotic prophylaxis (IAP) has been shown to interrupt the transmission of GBS from mother to infant & so reduce the incidence of early-onset GBS disease. In developed countries prenatal screening in pregnant women have been widely established and successfully reduced the incidence of GBS neonatal disease. In low-income settings screening for prevention of invasive neonatal disease are mostly not implemented due to limitations in resources and infrastructure. GBS strains are able to cause infections not only because of the development of resistance to antibiotics but also due to their virulence traits. The most important virulence factor is capsule, but other virulence factors include; surface protein Rib & C5a peptidase. The present study aimed to determine the prevalence of GBS carriage among pregnant women, the antimicrobial susceptibility pattern of colonizing GBS isolates and check the presence of scpB & rib virulence genes. This study was conducted at the Maternity Hospital outpatient clinic at the Faculty of Medicine, Ain Shams University from September 2020 to February 2021. The study included 203 pregnant women. The mean age among cases was 26.2±5.9 and the mean gestational age was 36.1 ±0.8. A complete medical history as well as clinical data were obtained. A sterile cotton swab was rotated against the vaginal wall for vaginal sample then inoculated directly onto CHROMagarTM StrepB (CHROMagar microbiology, France) as well as a sheep blood agar. The 23 GBS isolates were identified using conventional techniques, antibiotic susceptibility testing was done by disc diffusion test and conventional PCR was done for the detection of scpB and rib genes. Positive GBS result was present in 11.3% of case (23 cases out of 203 total candidates). There was no significant difference between negative and positive GBS cases as regard age, gestational age and parity. On the other hand, there was a highly significant difference between cases with and without history of previous abortion and previous preterm birth as regard the GBS result. Direct plating of GBS from vaginal specimens onto CHROMagar strepB or sheep blood agar was similarly sensitive in detecting GBS. GBS isolates were 100% sensitive to penicillin, ampicillin, cefepime, ceftriaxone, cefotaxime, vancomycin, levofloxacin and linezolid. Sensitivity to clindamycin and erythromycin was (73.91%, 60.86%) respectively. scpB gene was found in all GBS isolates (100%) while only 18 isolates tested positive for the rib gene (78.26%).