Poster Presentation 20th Lancefield International Symposium on Streptococci and Streptococcal Diseases 2017

Bacterial load and bacterial molecular markers associated with neonatal Group B Streptococcus (GBS): A systematic review (#143)

Farah Seedat 1 , Colin S Brown 2 , Chris Stinton 1 , Jacoby Patterson 1 , Julia Geppert 1 , Olalekan A Uthman 1 , Esther R Robinson 3 , Noel D McCarthy 1 , Karoline Freeman 1 , Bee Tan 1 , Samantha A Johnson 1 , Hannah Fraser 1 , Aileen Clarke 1 , Sian Taylor-Phillips 1
  1. University of Warwick Medical School, University of Warwick, Coventry, United Kingdom
  2. Bacteria Reference Department, National Infection Service, Public Health England, London, United Kingdom
  3. Birmingham Public Health Laboratory, Heartlands Hospital, Birmingham, United Kingdom

Background: GBS is the leading cause of morbidity and mortality from neonatal sepsis. Vaginal GBS colonisation during labour can cause GBS transmission to neonates in 36% of women, and this can progress to early-onset GBS disease (EOGBS, <7 days) in 1-3% of colonised neonates. We conducted a systematic review investigating whether bacterial load and bacterial molecular markers are associated with GBS vertical transmission, neonatal GBS colonisation, and EOGBS.

Methods: We searched Medline, Embase, Cochrane, and Science Citation Index from inception to 10th October 2016 for observational studies in English. We also hand-searched reference lists of publications and experts cross-checked included studies. Two reviewers independently conducted study selection, data extraction, and quality assessment. Random-effects meta-analyses were conducted where possible.

Results: 19 studies were included from 1107 records. In addition to bacterial load, molecular markers investigated were c-protein antigens, serotypes, and sequence types. Most evidence was published before 2000 and at risk of bias. Meta-analyses showed that neonates colonised by serotype III had a higher risk of developing EOGBS than neonates colonised by serotype Ia (pooled risk ratio [RR] = 1.51, 95% confidence interval [CI] 1.12-2.03) and serotype II (RR = 1.95, 95% CI 1.10-3.45). In twelve studies, neonatal colonisation was approximately 2-3 times higher in heavily colonised mothers, and EOGBS was up to 15 times higher in heavily colonised neonates, compared with light colonisation.

Conclusions: Higher quality studies are needed to assess the predictive value of pathogen subtype and heavy bacterial load; they might be suitable for better-targeted prevention.