A hospital's investigation into patient laboratory specimens contaminated with Mycobacterium porcinum identified tap water as the source.
The hospital laboratory identified clusters of isolates that tested positive for the nontuberculous mycobacterium from January 2017 into April 2018, according to Morbidity and Mortality Weekly Report, which is published by the U.S. Centers for Disease Control and Prevention (CDC). A total of 20 isolates was obtained from 16 patients. M. porcinum is associated with infections of the respiratory tract, bloodstream, surgical sites and soft tissue.
The investigation was conducted by the hospital's infection prevention team and the Wisconsin State Laboratory of Hygiene. Investigators eventually traced M. porcinum to two ice machines and one water dispenser. Inspection revealed debris on internal parts and dispenser spouts.
New machines and parts were installed in June 2018, and the hospital revised its cleaning protocols. Staff members no longer use tap water when collecting respiratory cultures. CDC stated no further M. porcinum patient isolates have been identified.
As the report concludes, "Tap water is not sterile, can lead to false-positive culture results and should be avoided when collecting biologic specimens intended for culture. Hospital water management programs should engage clinical partners to ensure safe water use as part of patient care and address maintenance of ice machines and water dispensers within their facilities."