Simplified GBS Screening and Prevalence of ESBL in Pregnant Women

Overview

1. At the University Hospital Basel, Switzerland, a simplified screening for group B streptococci (GBS) of vagina and perineum has been performed since several years. Reliable detection of GBS is critical to prevent GBS transmission during delivery with antimicrobial prophylaxis. Transmission of GBS to the neonate may otherwise lead to severe infection and complications in the neonate. Centers for Disease Control and Prevention (CDC) and other international organizations recommend a vaginal and additional rectal swab.We therefore aim to test this simplified screening against the international gold standard. 2. Antibiotic resistant bacteria may reside in the genital tract of an expected mother and may be transmitted to the new-born during delivery. In case of infection of the pregnant woman or the neonate, application of standard antimicrobial treatment will insufficiently cover these extended spectrum beta-lactamase (ESBL) producing bacteria. Therefore, colonization with ESBL in pregnancy needs to be known to potentially deliver adequate antimicrobial treatment.

Transmission of GBS under delivery leads in 1/1000 of live births to severe sepsis in the neonate and may have serious sequelae including death. Most of the cases concern early onset sepsis which occurs in the first three to seven days after birth. Several randomized studies showed that antibiotic prophylaxis during delivery reduces the risk of early onset sepsis in the neonate in 85%, whereas late onset sepsis was not affected. Accurate screening including appropriate culture methods are critical for the wealth of the newborn and the decision regarding application of antibiotic prophylaxis to the mother. In this study we compare a simplified test algorithm taking swabs from the vagina and the perineum only versus a combined vaginal and rectal swab for GBS culture which is the current gold standard of diagnosis as the culture yield for GBS increases substantially when samples are taken from both the lower vagina and the rectum compared to swabbing the vagina or endocervix only. There is certain reluctance for performing a rectal swab as it has been associated with discomfort. The study aims to demonstrate that this simplified vagino-perineal swab leads to a similar GBS detection rate as compared to the gold standard comprising of a combined vaginal and rectal swab. We further aim to systematically assess the degree of discomfort with the rectal swab and compare the costs when applying those different methods. Additionally we aim to determine the prevalence and risk factors of community acquired ESBL by further processing the swabs in the appropriate culture media and filling in a standardized questionnaire. We plan a prospective cohort study with inclusion of 450 pregnant women who attend the outpatient obstetric clinic for routine control in the third trimester.