Late-onset neonatal infections: incidences and pathogens in the era of antenatal antibiotics

Widespread use of intrapartum antimicrobial prophylaxis has significantly reduced the incidence of early-onset neonatal infection (EONI); however, little is known about the effects of increased maternal exposure to antibiotics on late-onset neonatal infection (LONI). This study aims to evaluate LONI epidemiology in our region after the application of French recommendations and to determine whether LONI-causing organisms and their antibiotic susceptibility are influenced by peripartum antibiotic exposure. We performed a prospective epidemiologic study of 139 confirmed and possible cases of bacterial LONI in patients treated with antibiotics for at least 5 days of the 22,458 infants born in our region in the year 2007. The overall incidence of LONI caused by all pathogens, Group B streptococcus (GBS) and Escherichia coli (E. coli) were 6.19, 0.36 and 2.72, respectively, per 1,000 live births. Our findings revealed three major types of LONI: E. coli-induced urinary tract infection (UTI) among term infants, coagulase negative Staphylococcus septicemia affecting preterm infants, and GBS infections with severe clinical presentation. Univariable analysis revealed that maternal antibiotic exposure was significantly associated with the risk of amoxicillin-resistant E. coli infection (p=0.01). Postnatal antibiotic exposure was associated with an increased risk of E. coli LONI (p=0.048). This link persisted upon multi-variable analysis; however, no additional risk factors were identified for LONI caused by antibiotic-resistant E. coli. Conclusion Our findings confirm that despite the benefits of antenatal antibiotics, this treatment can increase the risk of antibiotic-resistant cases of LONI. National and international surveillance of LONI epidemiology is essential to assess benefits and potential negative consequences of perinatal antibiotic exposure.