Unusual Occurrence of an Epidemic of Type Ib/c Group B Streptococcal Sepsis in a Neonatal Intensive Care Unit

Abstract

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.

Neonatal group B streptococcal disease associated with infected breast milk

“…Late onset disease is believed to reflect delayed infection after early colonisation, or cross infection 1. Early colonisation is less likely in this case because there was no maternal carriage of GBS before delivery.…”

“…Most cases occur in the first week of life and are related to vaginal carriage in the mother. Late onset GBS disease (more than seven days after birth) is less common, and has been linked to cross infection from the hands of healthcare workers 1. Alternatively, it may reflect delayed infection after early colonisation.…”

Clinical Microbiology of Bacterial and Fungal Sepsis in Very-Low-Birth-Weight Infants

“…Infants may have persistent colonization from birth or may acquire the organism through nosocomial routes. Transmission of GBS from breast milk, patient-to-patient spread, and colonized nursery personnel has been reported (119,350). Increased adherence of GBS to buccal epithelial cells from preterm compared to term infants may also be an contributing factor (97).…”

Group B streptococcal disease in infants: a case control study

“…Major risk factors include maternal GBS carriage, prematurity, low birth weight, prolonged rupture of membranes, intrapartum fever, young maternal age, black ethnic group, previous delivery of an affected baby and low levels of anticapsular antibody 1 2 3. The risk factors for late-onset (LO) GBS disease are less clear, although maternal, nosocomial and breast milk sources have all been described 2 4 5 6 7 8…”