To determine the cause of an outbreak of Pseudomonas aeruginosa cerebral ventriculitis among eight patients at a community hospital neurosurgical intensive care unit. All had percutaneous external ventricular catheters (EVCs) to monitor cerebrospinal fluid (CSF) pressure.

Cohort study of all patients who had EVCs placed during the epidemic period (August 8-October 22, 1997). A case-patient was any patient with P aeruginosa ventriculitis during the epidemic period. Pulsed-field gel electrophoresis (PFGE) was performed on all isolates.

P aeruginosa was significantly more likely to be isolated from CSF per EVC placed in the epidemic than pre-epidemic (January 1-August 7, 1997) periods (8/61 [13%] vs 2/131 [1.5%], P = 002). During the epidemic period, ventriculitis was significantly more likely after EVC placement in the operating room than in other units (8/24 vs 0/22, P = .004). EVC placement technique differed for EVCs placed in the operating room (little hair was removed, preventing application of an occlusive dressing) versus other hospital units (more hair was removed, and an occlusive dressing was applied). Among patients who had operating room EVC placement, contact with one healthcare worker was statistically significant (7/13 vs 0/8, P = .02). Hand cultures of this worker were negative. All isolates had closely related PFGE patterns.

These data suggest that a single healthcare worker may have contaminated EVC insertion sites, resulting in an outbreak of P aeruginosa ventriculitis. Affected patients were unlikely to have had an occlusive dressing at the EVC insertion site. Application of a sterile occlusive dressing may decrease the risk of ventriculitis in patients with EVCs.