Serratia marcescens nosocomial outbreak due to contamination of hexetidine solution.

During a 10-week period, 16 patients in a neurosurgery intensive care unit were involved in an outbreak of Serratia marcescens. The epidemic strain was found in several flasks of 1:4 diluted hexetidine solution, an antiseptic used for patient mouth washing. Testing of the bactericidal activity of the diluted antiseptic revealed that all the epidemic strains were able to grow in the diluted antiseptic solution. Strains isolated from clinical samples and from the antiseptic solution were compared by random amplification of polymorphic DNA. Epidemiologic typing data implicated the diluted antiseptic solution as the single source of this S. marcescens outbreak.