Molecular Methodology Identifies Cause of Outbreak

Genotyping has been used identify the source of a hematology clinic outbreak of Mycobacterium mucogenicum, a gram-positive, acid-fast bacteria found in tap water.

The use of repetitive sequence-based polymerase chain reaction system enabled the identification of M. mucogenicum in a water sample from an examination-room faucet with an aerator, which has the same bacteria as the infected patients.

Scientists at the East Carolina University (Greenville, NC, USA) collected water samples from two faucets in the examination rooms and performed an audit of infection control practices, including hand hygiene compliance, use of appropriate techniques for injections, and other procedures. The outbreak involved four young sickle cell patients and all four patients had long-term lines implanted to deliver medication into the bloodstream. They were probably exposed to M. mucogenicum during outpatient visits when the lines were accessed. All four developed blood cultures positive for M. mucogenicum in May or June 2008.

A healthcare worker prepared injections at the sink counter during the period of infection. It is likely that the fluid bag being used to prepare injections became contaminated when the worker washed her hands. The four patient isolates and the tap water isolate from the room with the aerator were found to have greater than 98.5% similarity. The source of the M. mucogenicum bacteremia outbreak in the clinic tap water supply was identified by the Diversilab genotyping analysis (bioMérieux, Marcy l'Etoile, France). The preparation of intravenous medications near the sink was likely an important factor in transmission, along with the presence of a faucet aerator.

Muhammad Salman Ashraf, MD, assistant professor at The Brody School of Medicine at East Carolina University, said, "This study demonstrates the efficacy of using genotyping technology in identifying the source of the outbreak. But it also points to the need for proper infection control practice in clinic settings, and that faucet aerators should be avoided in all healthcare facilities, especially those caring for immunosuppressed patients." The study was published online on September 19, 2012, in the journal Infection Control and Hospital Epidemiology.

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