Multiple Infections among Newborns Resulting from Colonization with Staphylococcus Aureus 502A

Staphylococcus aureus 502A was used to colonize newborns in the nursery of a hospital experiencing staphylococcal cross-infection problems. Within 1 to 4 days after implantation, 34% of 50 infants developed pustules. The daily transfer through broth of cultures used to implant infants resulted in population changes which revealed the instability and heterogeneity of the original 502A culture. Although the lack of concordance between colony morphology, phage type, and serotype prevented precise grouping of the strains isolated, there was little doubt that strains from implantation sites and lesions on infants came from the original inocula. The higher incidence of lesions observed in these procedures could possibly be attributed to the increase in numbers of mutants occuring during transfers through broth of cultures used for colonizing infants, coupled with the implanting of heavy concentractions of cells.