Antibiotic selection in obstetric patients.

Penicillin and ampicillin are valuable antibiotics in obstetrics because of their excellent activity against group A and group B streptococci. In addition, ampicillin is the treatment of choice for enterococcal infections, particularly urinary tract infections. Limited spectrum cephalosporins are of primary value as prophylactic agents. Ceftriaxone, an intermediate spectrum agent, is an excellent drug for treatment of infections caused by N. gonorrhoeae. Extended spectrum cephalosporins, penicillins, and carbapenems provide sufficient coverage against pathogenic organisms to be used as single agents for treatment of polymicrobial infections such as chorioamnionitis and puerperal endometritis. Alternatively, combination regimens such as clindamycin or metronidazole plus an aminoglycoside or aztreonam are also highly effective in this clinical situation. Erythromycin and azithromycin have value primarily for treatment of endocervical chlamydial infections and mycoplasma pneumonia in obstetric patients and for intrapartum prophylaxis against group B streptococcal infection in patients who are allergic to beta-lactam antibiotics.