Maternal colonization and early-onset neonatal bacterial sepsis in the Gambia, West Africa: a genomic analysis of vertical transmission.

OBJECTIVES: To define bacterial aetiology of neonatal sepsis and estimate the prevalence of neonatal infection from maternal genital tract bacterial carriage among mother-newborn pairs. METHODS: We carried out a cross-sectional study of newborns with clinical sepsis admitted to three hospitals in the Gambia neonatal wards. Neonatal blood cultures and maternal genital swabs were obtained at recruitment. We used whole-genome sequencing to explore vertical transmission for neonates with microbiologically confirmed bloodstream infection by comparing phenotypically-matched paired neonatal blood cultures and maternal genital tract bacterial isolates. RESULTS: We enrolled 203 maternal-newborn pairs. Two-thirds (67%; 137/203) of neonates presented with early-onset sepsis (days 0-6 after birth) of which 26% (36/137) were because of a clinically-significant bacterial pathogen. Blood culture isolates from newborns with early-onset sepsis because of Staphylococcus aureus (n = 5), Klebsiella pneumonia (n = 2), and Enterococcus faecalis (n = 1), phenotypically matched their maternal genital tract isolates. Pairwise single-nucleotide variants comparisons showed differences of 12 to 52 single-nucleotide variants only between maternal and newborn S. aureus isolates, presumably representing vertical transmission with a transmission rate of 14% (5/36). CONCLUSIONS: We found a low prevalence of vertical transmission of maternal genital tract colonization in maternal-newborn pairs for early-onset neonatal sepsis in the West African context. Identifying infection acquisition pathways among newborns is essential to prioritize preventive interventions, which could be targeted at the mother or infection control in the hospital environment, depending on the major pathways of transmission.

Declining Trends of Pneumococcal Meningitis in Gambian Children After the Introduction of Pneumococcal Conjugate Vaccines.

BACKGROUND: Acute bacterial meningitis remains a major cause of childhood mortality in sub-Saharan Africa. We document findings from hospital-based sentinel surveillance of bacterial meningitis among children <5 years of age in The Gambia, from 2010 to 2016. METHODS: Cerebrospinal fluid (CSF) was collected from children admitted to the Edward Francis Small Teaching Hospital with suspected meningitis. Identification of Streptococcus pneumoniae (pneumococcus), Neisseria meningitidis (meningococcus), and Haemophilus influenzae was performed by microbiological culture and/or polymerase chain reaction where possible. Whole genome sequencing was performed on pneumococcal isolates. RESULTS: A total of 438 children were admitted with suspected meningitis during the surveillance period. The median age of the patients was 13 (interquartile range, 3-30) months. Bacterial meningitis was confirmed in 21.4% (69/323) of all CSF samples analyzed. Pneumococcus, meningococcus, and H. influenzae accounted for 52.2%, 31.9%, and 16.0% of confirmed cases, respectively. There was a significant reduction of pneumococcal conjugate vaccine (PCV) serotypes, from 44.4% in 2011 to 0.0% in 2014, 5 years after PCV implementation. The majority of serotyped meningococcus and H. influenzae belonged to meningococcus serogroup W (45.5%) and H. influenzae type b (54.5%), respectively. Meningitis pathogens were more frequently isolated during the dry dusty season of the year. Reduced susceptibility to tetracycline, trimethoprim-sulfamethoxazole, and chloramphenicol was observed. No resistance to penicillin was found. CONCLUSIONS: The proportion of meningitis cases due to pneumococcus declined in the post-PCV era. However, the persistence of vaccine-preventable meningitis in children aged <5 years is a major concern and demonstrates the need for sustained high-quality surveillance.