Incidence and serotype characterisation ofStreptococcus agalactiaein a Portuguese hospital

Abstract

AimsStreptococcus agalactiae,commonly known as group BStreptococcus(GBS), has been recognised as a worldwide causative pathogenic agent of neonatal sepsis, meningitis and pneumonia. To better understand the behaviour ofS. agalactiaein pregnant women from a hospital from the North of Portugal, retrospective analyses were performed to describe epidemiological, clinical and microbiological characteristics of the isolates obtained.MethodsBased on laboratorial records and the hospital’s patient files, a 6-year retrospective study was performed to analyseS. agalactiaeisolates from screened pregnant women between 35 and 37 weeks of gestation and hospitalised neonates from pregnant women between 24 and 41 weeks of gestation admitted in Hospital Pedro Hispano. Serotype characterisation was also performed in 67 GBS strains.ResultsIn 6692 pregnant women between 35 and 37 weeks of gestation screened between 2011 and 2016, a total of 1377S. agalactiaeisolates (21%) were found. A high percentage (40%) of unknown colonisation status among hospitalised neonates from pregnant women between 24 and 41 weeks of gestations was also found. The incidence of neonatal sepsis was 8.7 (95% CI 7.0 to 10.8) cases per 1000 live births. Regarding serotype characterisation, serotype III (22.4%) was the most frequent, followed by serotype Ia (19.4%) and serotypes Ib and V (both with 17.9%).ConclusionHigh epidemiological values of GBS colonisation and incidence were found in this study. In Portugal studies on the epidemiology and behaviour ofS. agalactiaeremain limited, reinforcing the importance and need forS. agalactiaescreening across the country.