[Antibiotic therapy in maternal-fetal infections]

The selection of first-line antimicrobial therapy in neonates with maternofetal infection is based on probability data from epidemiologic studies of bacterial infections. Because of the high prevalence of ampicillin-resistant E. coli strains and of the lack of susceptibility of Listeria and group D streptococci to cephalosporins, combined use of two complementary drugs, such as amoxicillin and cefotaxime with an aminoglycoside, is recommended. Each dose should be increased twofold in patients with meningeal involvement. The interval between aminoglycoside doses depends on the degree of renal maturity and therefore on gestational age. Discontinuation of treatment on the third day when clinical and biologic monitoring disproves the suspected infection avoids the occurrence of untoward effects, especially on the intestinal flora. In other cases, administration of two drugs selected on the basis of bacteriologic findings is needed beyond the third day. Specific therapy is required in infrequent infections (Candida, tuberculosis, syphilis, Helicobacter). The dosage of antimicrobials with narrow therapeutic margins (vancomycin, aminoglycosides) should be adjusted on the basis of serum assays performed at four-day intervals. Duration of therapy is usually ten days but may reach 21 days in neonates with meningitis. Prevention, in the absence of specific vaccines, rests on antenatal and perinatal treatment of women at high risk for infection. Management of neonates with group B streptococcal infection is controversial; close clinical and biologic monitoring over 48 hours may allow to reduce the use of antimicrobials.