Nosocomial transmission of bacteriophage type 7/11/12 group B streptococci in a special care nursery.

Two premature infants in a special care nursery acquired late-onset group B streptococcal (GBS) sepsis within a 24-hour period. The infecting strains were serotype III organisms with bacteriophage type 7/11/12. Cultures of the mothers of the two affected infants were negative for GBS, implying nosocomial acquisition of infection. Although 32% of nursery personnel had mucosal carriage of GBS, none of the seven isolates of GBS type III was the same bacteriophage type as the two infecting strains. Of the other infants hospitalized in the nursery, five were asymptomatically colonized with GBS. These infants were in bassinets adjacent to the affected infants; all five of their isolates were identical to the two infecting strains. We conclude that infant-to-infant transmission may result in nosocomial late-onset GBS septicemia.