Paenibacillus macerans pseudobacteremia resulting from contaminated blood culture bottles in a neonatal intensive care unit

Paenibacillus species are gram-positive, rod-shaped, spore-forming aerobes that are abundant in nature and closely related to Bacillus. Between June 2 4 and June 30, 1999, 8 neonates in our neonatal intensive care unit had pos itive blood cultures for Paenibacillus macerans . This cluster of positive blood cultures with an unusual pathogen suggested a pseudoepidemic. investi gation revealed that the most likely etiology of the pseudobacteremia was e nvironmental contamination of the rubber stoppers in blood culture bottles. This was confirmed by environmental sampling and simulated inoculation stu dies. This pseudobacteremia outbreak highlights the importance of adhering to well-established methods for blood culture collection ongoing infection control surveillance.