An outbreak of extended-spectrum β-lactamase-producing Klebsiella pneumoniae in a neonatal intensive care unit.

We present a large outbreak of ESBL-producing Klebsiella pneumoniae in a neonatal intensive care unit that resulted in 31 colonized infants, 10 invasive infections, and 5 attributable deaths over a 5-month period. Although the source of infection was unknown, overcrowding and understaffing appeared to have been aggravating factors.