Effects of intrapartum antimicrobial prophylaxis for prevention of group-B-streptococcal disease on the incidence and ecology of early-onset neonatal sepsis.

Sepsis occurring in the first week of life can be a devastating neonatal problem. Group B streptococci (GBS) and enterobacteriaceae are the main causes of early-onset sepsis in more developed countries. Intrapartum antimicrobial prophylaxis (IAP) has lowered the incidence of early-onset GBS sepsis by 50-80%. However, there are concerns that the use of IAP may select for infections caused by enterobacteriaceae, including some strains resistant to antimicrobials. We explored potential associations between IAP use and changes in the causes of early-onset sepsis. We concluded that there have been substantial declines in the incidence of early-onset infections due to GBS and, in some settings, other bacteria. Increases in the frequencies of non-GBS or antimicrobial-resistant early-onset sepsis have been limited to preterm, low-birthweight, or very-low-birthweight neonates. We propose systematic monitoring of early-onset sepsis, coupled with targeted research, to inform periodic reassessment of prevention strategies.