A hospital-wide outbreak of Pseudomonas aeruginosa infections associated with the use of bottled mineral water

Abstract number: 1133_95

Eckmanns T., Martin M., Weist K., Rüden H.

Objectives:  

Mineral water (MW) should be free of P. aeruginosa according to the legal force of the mineral and table water act in Germany. We investigated an outbreak of P. aeruginosa where the pathogen was introduced into the hospital by MW in bottles.

Methods:  

One medical intensive care unit (ICU) noticed an increase of pneumonias with P. aeruginosa. Environmental samples (tap water samples, siphons, surfaces, equipment for oropharyngeal hygiene, MW bottle) from the unit were cultured and typed. Clinical P. aeruginosa isolates were collected from five further ICUs. Microbiologic results were reviewed to determine the numbers of P. aeruginosa on a weekly time scale for the ICUs. All isolates were genotyped by PFGE and an AFLP PCR–method.

Results:  

Clinical specimens from five medical ICU patients yielded the same P. aeruginosa strain. In 4 from 103 environmental samples (3 × siphon, 1 × MW) P. aeruginosa was isolated. The isolates of the siphons were different to all patient isolates. The MW isolate was genetically indistinguishable to the 5 ICU patient isolates. Later the same strain was isolated in 4 more MW bottles of the same batch and in clinical specimens from 3 more medical ICU patients and seven patients of five other ICUs, respectively. Ten of the total 15 patients with P. aeruginosa developed pneumonia. After recognising the outbreak and the potential source delivery of this mineral water to the patients was stopped.

The mean number of all ICU patients with newly detection of P. aeruginosa was 3.8 per week (Std. Dev. 1.6) in the 42 weeks prior to the outbreak. During the 6 weeks of the outbreak the weekly occurrence of new P. aeruginosa was 6, 6, 10, 9, 3, and 9 respectively (mean 7.2). In the four weeks after the outbreak on the ICUs the mean weekly occurrence of new patient with P. aeruginosa was 3.3.

Conclusions:  

This hospital wide outbreak was related to bottled MW contaminated with P. aeruginosa. The water was drunken by patients with tracheostomy tubes and used for oral (enteral tube) drug preparation. The outbreak ceased after determining the delivery of MW of this brand to the patients. Production control of MW needs to be improved and use of MW for ICU patients, especially those with endotracheal ventilation may increase the risk of nosocomial pneumonia.