We report on two premature infants who developed nosocomial infection caused by Chryseobacterium meningosepticum in a neonatal intensive care unit (NICU). One premature infant developed sepsis, meningitis, and hydrocephalus, and was treated successfully with ciprofloxacin plus trimethoprim-sulfamethoxazole combination therapy for 4 weeks and with a ventriculoperitoneal shunt. The other premature infant, who was in a chronically debilitated state, had infection that had colonized only in the respiratory tract but had no clinical signs for 66 days. Extensive environmental surveillance demonstrated that the suction bottle apparatus was the source of infection. We prevented the spread of infection by closing the NICU temporarily, isolating the patients early in their infection, and eradicating the source of infection source.