An outbreak of Bacillus cereus respiratory tract infections on a neonatal unit due to contaminated ventilator circuits

An outbreak of Bacillus cereus respiratory tract infections affecting six v entilated preterm neonates over a two week period is described. Reusable ve ntilator circuits were identified as the cause of the outbreak. Ordinarily these were reprocessed on the Neonatal Unit (NNU), first through a washing machine and then through a low temperature steam (LTS) disinfector. The ons et of the outbreak coincided with a breakdown of the LTS facility, which ne cessitated sending the washed circuits off site for LTS disinfection. The w ashing machine was shown to be contaminated with the same serovars of B. ce reus as those isolated from patients. Two critical steps in the off site LT S disinfection process allowed exsporulation and multiplication of B. cereu s: the circuits were inadequately dried after processing, whilst return of the moist circuits to the NNU was often delayed. The outbreak was terminate d by withdrawal of the heat-disinfected ventilator circuits. This outbreak emphasizes the need for high standards where medical equipment is reprocess ed, especially for use in vulnerable patients.