Outbreak of Bacillus cereus infections in a neonatal intensive care unit traced to balloons used in manual ventilation

In 1998, an outbreak of systemic infections caused by Bacillus cereus occur red in the Neonatal Intensive Care Unit of the University Hospital Vrije Un iversiteit, Amsterdam, The Netherlands. Three neonates developed sepsis wit h positive blood cultures. One neonate died, and the other two neonates rec overed. An environmental survey, a prospective surveillance study of neonat es, and a case control study were performed, in combination with molecular typing, in order to identify potential sources and transmission routes of i nfection. Genotypic fingerprinting by amplified-fragment length polymorphis m (AFLP) showed that the three infections were caused by a single clonal ty pe of B. cereus. The same strain was found in trachea aspirate specimens of 35 other neonates. The case control study showed mechanical ventilation wi th a Sensormedics ventilation machine to be a risk factor for colonization and/or infection (odds ratio, 9.8; 95% confidence interval, 1.1 to 88.2). P rospective surveillance showed that colonization with B. cereus occurred ex clusively in the respiratory tract of mechanically ventilated neonates. The epidemic strain of B. cereus was found on the hands of nursing staff and i n balloons used for manual ventilation. Sterilization of these balloons end ed the outbreak We conclude that B. cereus can cause outbreaks of severe op portunistic infection in neonates. Typing by AFLP proved very useful in the identification of the outbreak and in the analysis of strains recovered fr om the environment to trace the cause of the epidemic.