Background: Group B Streptococcus (GBS) and Escherichia coli cause serious bacterial infections (SBIs) and are associated with morbidity and mortality in newborn infants. Intrapartum antibiotic prophylaxis reduces early-onset SBIs caused by GBS. The effect of intrapartum antibiotic prophylaxis on late-onset SBIs caused by these organisms is unknown.
Methods: We examined all blood, urine and cerebrospinal fluid culture results from infants admitted from 1997 to 2010 to 322 neonatal intensive care units managed by the Pediatrix Medical Group. We identified infants with positive cultures for GBS or E. coli and compared the incidence of early- and late-onset SBI for each organism in the time period before (1997 to 2001) and after (2002 to 2010) universal intrapartum antibiotic prophylaxis recommendations.
Results: We identified 716,407 infants with cultures, 2520 (0.4%) with cultures positive for GBS and 2476 (0.3%) with cultures positive for E. coli. The incidence of GBS early-onset SBI decreased between 1997 to 2001 and 2002 to 2010 from 3.5 to 2.6 per 1000 admissions, and the incidence for E. coli early-onset SBI remained stable (1.4/1000 admissions in both time periods). Over the same time period, the incidence of GBS late-onset SBI increased from 0.8 to 1.1 per 1000 admissions, and incidence of E. coli late-onset SBI increased from 2.2 to 2.5 per 1000 admissions.
Conclusions: In our cohort, the incidence of GBS early-onset SBI decreased, whereas the incidence of late-onset SBI for E. coli and GBS increased.