Group B Streptococcus (GBS) infection can cause a life-threatening blood infection and meningitis in newborns. Over one-third of women receive antibiotics during labor to prevent the transmission of GBS from themselves to their newborns. Intrapartum antibiotics (IPA) have been very successful in preventing early-onset (first week of life) neonatal GBS infection. However, a new study shows a relationship between exposure to broad-spectrum IPA and occurrence of late-onset (7-90 days after birth) serious bacterial infections (SBIs). Tiffany S. Glasgow, M.D., and Paul C. Young, M.D., and their University of Utah colleagues, supported in part by the Agency for Healthcare Research and Quality (HS11826), found that infants with late-onset SBI were more likely to have been exposed to IPA than uninfected infants. Also, pathogens that caused late-onset SBIs were more likely to be resistant to ampicillin, if the mother was treated with ampicillin. Thus, penicillin, an antibiotic that treats a narrow range of bacteria, is recommended for IPA to prevent GBS instead. The researchers compared the use of IPA and antibiotic-resistant strains of bacteria in 90 previously healthy full-term infants hospitalized for late-onset SBI (case infants) with 92 healthy full-term infants, who were known not to have an SBI in the first 90 days (control infants).
Considering all types of IPA, nearly twice as many case infants (41 percent) than control infants (27 percent) had been exposed to IPA, after controlling for hospital of delivery and other factors. The association was much stronger when IPA was with broad-spectrum antibiotics. Bacteria that were isolated from infected infants who had been exposed to IPA were nearly 6 times more likely to exhibit ampicillin resistance, but not resistance to other antibiotics commonly used to treat SBI in infants. The researchers recommend that clinicians find out infants' exposure to IPA when they are seen for late-onset SBI, so that they can gauge which antibiotics will be more effective for treatment.
See "Association of intrapartum antibiotic exposure and late-onset serious bacterial infections in infants," by Dr. Glasgow, Dr. Young, Jordan Wallin, B.S., and others in the September 2005 Pediatrics 116(3), pp. 696-702.