The effects of amoxicillin therapy on skin flora in infants

In order to determine the effect of amoxicillin therapy on the perineal ski n microbial flora in infants, we took quantitative bacterial and fungal cul tures of perineal and sternal areas from 25 infants treated with amoxicilli n (40 mg/kg/day) for 10 days. Specimens were obtained prior to therapy, wit hin 3 days of conclusion of therapy, and 14-16 days later. Immediately foll owing therapy, a decline in the number of bacterial isolates occurred on bo th the perineum (89 to 47) and sternum (84 to 39), The greatest decline occ urred in the number of anaerobic bacteria (mostly Peptostreptococcus spp, a nd Propionibacterium acnes), Other organisms that were less often isolated were aerobic streptococci and Staphylococcus epidermidis, The number of Can dida albicans isolates increased from 3 to 11 (p < 0.05) on the perineum, a nd 1 to 7 (0 < 0.025) on the sternum, Four of the infants developed diaper dermatitis, The density of C, albicans increased more than 14-fold followin g amoxicillin therapy. Cultures done 14-16 days after cessation of therapy revealed an increase in the number of bacterial isolates on the perineum (4 7 to 72) and on the sternum (39 to 61) and a decline in recovery of C. albi cans, This study demonstrates the effects of amoxicillin on the ecology of skin microbial flora in infants-a decrease in the number of bacterial isola tes and an increase in recovery of C,albicans.