Nosocomial outbreak of multidrug-resistant Pseudomonas aeruginosa caused by damaged transesophageal echocardiogram probe used in cardiovascular surgical operations.

Multidrug-resistant Pseudomonas aeruginosa (MDRP) is a major problem among hospital-acquired infections. We had a one-month outbreak of this strain at a university hospital in Osaka, Japan, from May to June 2004. To determine the cause of the outbreak, we collected and analyzed epidemiological information about the patients from whom MDRP was isolated, and performed microbiological investigations. MDRP was detected in respiratory specimens from eight patients in the intensive care unit. One of these patients developed severe lethal pneumonia accompanied by septicemia, and two contracted less severe non-lethal pneumonia. All the MDRP patients had been monitored with a contaminated transesophageal echocardiography (TOE) probe during their cardiac surgery. The TOE probe proved to have a defect 5 mm in diameter at the surface near the transducer, and the MDRP strain was traced to this defect. Pulsed-field gel electrophoresis showed that the strain isolated from the patients and from the TOE probe were genetically indistinguishable. After use of the damaged TOE probe was terminated, MDRP was not isolated from any patients who underwent cardiac surgery in the subsequent 8 years. In conclusion, TOE is routinely used during cardiac surgery and has been shown to have a significant clinical effect. Prevention of similar post-operative pneumonia outbreaks will require thorough infection control of TOE probes used for monitoring during cardiovascular surgery.