Poster Presentation Lancefield International Symposium for Streptococci and Streptococcal Diseases 2025

A 15-year single-centre clinical and genomic analysis of late-onset Group B Streptococcus infection. (#65)

Carl Britto 1 , Lea Cavalli 2 , Madikay Senghore 2 , Alexander McAdam 3 , William P Hanage 2 , Ying-Jie Lu 4 , Richard Malley 4
  1. Division of Critical Care, Department of Anaesthesiology, Boston Children's Hospital, Boston, Massachusetts, United States
  2. Center for Communicable Disease Dynamics, Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, United States
  3. Infectious Diseases Diagnostic Laboratory, Department of Laboratory Medicine, Boston Children's Hospital, Boston, Massachusetts, United States
  4. Division of Infectious Diseases, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts, United States

Group B Streptococcus (GBS) is a leading cause of infant meningitis, but the molecular factors driving severe disease are poorly understood.[1] Additionally, while Late-Onset (LOD) and Very-Late-Onset (VLOD, occurring after 3 months of age) disease are clinically similar, their bacteriological differences remain unexamined.[2,3] Using whole-genome sequencing, we analyzed invasive GBS isolates from infants at Boston Children’s Hospital over 15 years. We used logistic regression and linear mixed models to explore associations between clinical presentations, pathogen virulence factors, and disease severity or age of onset, accounting for population structure and multiple testing. Among 70 infant patients, 2 had Early-Onset Disease (EOD), 48 LOD, and 20 VLOD. The isolates comprised 5 serotypes and 6 clonal complexes, predominantly hypervirulent clones CC17/cpsIII and CC23/cpsIa. All isolates were susceptible to penicillin and vancomycin; but many were erythromycin- (38%) or clindamycin- (29%) resistant. ICU care was provided in 44.3% of patients, and 18.6% had meningitis, indicating severe disease. While ICU admission correlated with certain hematological abnormalities, no virulence factors were directly linked to ICU admission or meningitis. The similar strain distribution in LOD and VLOD suggested acquisition from the same niche. A pair of VLOD twins presenting simultaneously suggested concurrent external acquisition. The PI-2A1 pilus variant was associated with higher odds of VLOD than LOD, nearing significance (OR: 1.40, 95% CI: 1.00-1.95, p=0.057) possibly due to differences in immune responses related to age. These findings, along with our limited understanding of the molecular mechanisms behind severe disease, emphasize the need for more research into host-GBS interactions.

  1. Nanduri, S.A., Petit, S., Smelser, C., Apostol, M., Alden, N.B., Harrison, L.H., Lynfield, R., Vagnone, P.S., Burzlaff, K., Spina, N.L. and Dufort, E.M., 2019. Epidemiology of invasive early-onset and late-onset group B streptococcal disease in the United States, 2006 to 2015: multistate laboratory and population-based surveillance. JAMA pediatrics, 173(3), pp.224-233.
  2. Cantey, J.B., Baldridge, C., Jamison, R. and Shanley, L.A., 2014. Late and very late onset group B Streptococcus sepsis: one and the same?. World Journal of Pediatrics, 10, pp.24-28.
  3. Bartlett, A.W., Smith, B., George, C.R., McMullan, B., Kesson, A., Lahra, M.M. and Palasanthiran, P., 2017. Epidemiology of late and very late onset group B streptococcal disease: fifteen-year experience from two Australian tertiary pediatric facilities. The Pediatric infectious disease journal, 36(1), pp.20-24.