An epidemic of late-onset sepsis due to type Ib/c group B Streptococcus (Ib/c-GBS) occurred in a neonatal intensive care unit (NICU). During a seven-week period, five very low birth weight infants (index cases [ICs]) more than four weeks of age became bacteremic. Bacteriologic surveillance of neonates revealed persistent colonization in three ICs and identified three asymptomatic carriers (ACs). All ICs and one AC acquired Ib/c-GBS nosocomially, whereas the other two ACs were colonized at birth. Among nursery personnel, 39% carried GBS, but only two harbored Ib/c-GBS. Although phage typing of Ib/c-GBS isolates identified two patterns of susceptibility, we believe a single strain was involved in the epidemic, because the patterns overlapped and most isolates carried the same lysogenic phage. Analysis of events suggested infant-to-infant spread via the hands of personnel, but acquisition from the colonized staff was also possible. The control measures instituted prevented further spread of Ib/c-GBS in the NICU.

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A commercially available latex agglutination reagent, Directigen (Hynson, Westcott & Dunning, Div. Becton Dickinson & Co., Baltimore, Md.), in which a murine monoclonal antibody to group B streptococcal (GBS) antigen is the active component, was evaluated by using body fluid specimens from 94 sick infants. Antigen was detected in one or more admission specimens from 18 of 19 (94.7%) infants with symptomatic GBS infection. In 15 patients with GBS meningitis, cerebrospinal fluid, serum, and 10-fold-concentrated urine specimens were positive in 87, 50, and 100%, respectively. GBS antigen was detected in 50% of unconcentrated urines, but in no sera from infants with nonmeningitic GBS sepsis. Among specimens from 27 infants with invasive infection due to organisms other than GBS and from 48 culture-negative sick infants, false-positive latex agglutination reactions occurred in only 4 (9.5%) urine specimens and in no cerebrospinal fluid or serum specimens. The 94.7% sensitivity and specificity of the Directigen GBS test indicate that it is a useful reagent for the rapid diagnosis of invasive GBS infection in young infants.