(940) Concordance of clinical GBS status with bacterial culture obtained at delivery admission

To evaluate the vaginal microbiome at term and compare routine prenatal GBS screening with culture data obtained through specimen collection at delivery hospital admission.


Study Design:

This prospective cohort study, funded by an institutional Human Health and Wellness grant, enrolled 50 term-pregnant patients to assess the vaginal microbiome through culture and 16S full-length sequencing approaches at delivery admission. Following consent, a sterile speculum examination was performed for vaginal swab and lavage. Records were reviewed for demographics, clinical GBS status, and obstetric outcomes.


Results:

Clinical GBS status was ascertained from routine antenatal care records, and bacterial culture data were obtained from vaginal swab at the time of delivery admission for 39 participants. Of these, 9/38 (24%) were GBS-positive and 19/38 (50%) were GBS-negative by both sampling methods, giving concordant results in 28/38 patients (74%). Four (11%) participants had negative routine GBS screening but were GBS-positive by culture at admission, three (8%) had positive GBS clinical screens without GBS detected by culture at admission, and three (8%) were missing either data point (Figure 1). One participant with GBS bacteriuria followed by negative routine GBS screen was GBS-positive by culture on admission. Twenty-eight (74%) patients were colonized with opportunistic pathogens including S. agalactiae, E. faecalis, E. faecium, S. aureus, S. epidermidis and E. coli.


Conclusion:

While ~75% of clinical GBS status and admission cultures agreed, 14% likely received unnecessary antibiotics during labor. More importantly, 11% of participants did not receive antibiotic prophylaxis due to negative routine screening; however, were found to be colonized with GBS by culture. Future work includes complete microbiome analyses to evaluate unrecognized GBS colonization due to opportunistic pathogen overgrowth and determination of GBS capsular serotype distribution for downstream molecular analyses. Clinical questions still exist regarding the optimal method, timing, and cost efficiency for determining GBS status.