An outbreak of Pseudomonas aeruginosa pneumonia and bloodstream infection associated with intermittent otitis externa in a healthcare worker

Abstract

Objectives: To investigate an outbreak of Pseudomonas aeruginosa pneumonia and bloodstream infection among four neonates, determine risk factors for infection, and implement preventive strategies.

Design: Retrospective case finding; prospective surveillance cultures of patients, personnel, and environmental sites; molecular typing by pulsed-field gel electrophoresis; and a matched case-control study.

Patients and setting: Neonates in the level-III neonatal intensive care unit of a tertiary-care pediatric institution.

Interventions: Cohorting of patients with positive results for P. aeruginosa, work restrictions for staff with positive results, implementation of an alcohol-based hand product, review of infection control policies and procedures, and closure of the unit until completion of the investigation.

Results: Seven (4%) of 190 environmental cultures and 5 (3%) of 178 cultures of individual healthcare workers' hands grew P. aeruginosa. All four outbreak isolates and one previous bloodstream isolate were genotypically identical, as were the P. aeruginosa isolates from the hands and external auditory canal of a healthcare worker with intermittent otitis externa. Four of 5 case-patients versus 5 of 15 matched control-patients had been cared for by this healthcare worker (P = .05). The healthcare worker was treated and no further cases occurred.

Conclusions: These findings suggest that a healthcare worker with intermittent otitis externa may have caused this cluster of fatal P. aeruginosa infections, adding the external ear to the list of colonized body sites that may serve as a source of potentially pathogenic organisms.