Failure of rifampin to eradicate group B streptococcal colonization in infants

Background. Mucous membrane colonization with group B streptococci (GBS) fr equently persists in infants after treatment of invasive infection and may be associated with recurrent disease. Objective. To determine the frequency with which GBS colonization persists at mucous membrane sites after treatment of invasive early or late onset in fection and to determine the efficacy of oral rifampin in eradicating colon ization in these infants and their mothers. Methods. Cultures for isolation of GBS were obtained from infants and their mothers after completion of the infant's parenteral therapy, 1 week later when rifampin therapy was initiated and at similar to1 and 4 weeks after co mpletion of rifampin therapy. Rifampin was administered (10-mg/kg dose; max imum, 600 mg) twice daily for 4 days. Results. Ten of 21 infants (48%) and 13 (65%) of their 20 mothers were colo nized with GBS at throat or rectal (infant) or vaginal, rectal or breast mi lk (mother) sites before rifampin was initiated. One week or less after rif ampin treatment, 7 (70%) infants and 4 (31%) mothers remained colonized wit h GBS. At study completion 6 infants and 7 mothers had GBS colonization. Pe rsistent colonization was not related to GBS serotype, to initial rifampin minimal inhibitory concentration or to the development of rifampin resistan t strains. Conclusions. Rifampin treatment for four days utilized as a single agent af ter completion of parenteral therapy failed to reliably eradicate GBS colon ization in infants.