Endemic contamination of clinical specimens by Mycobacterium gordonae

Contamination of clinical specimens by Mycobacterium gordonae is a signific ant endemic problem in many laboratories. To investigate this problem, 84 c ases at 1 hospital were retrospectively identified during 20 months. The ov erall rate of specimen contamination was 2.4%, and 72 of the contaminated s pecimens were respiratory. A case-control comparison showed that the risk o f respiratory specimen contamination was significantly increased If the spe cimen was expectorated (odds ratio [OR], 3.62; 95% confidence interval [CI] , 1.36-9.50) or if the patient consumed fluids within 2 days before specime n collection (OR, 8.92; 95% CI, 1.40-71.20). Cultures of tap water, ice, an d iced drinking water all yielded M. gordonae at 10(-2)-10(0) cfu/ml. A cul ture survey of consenting patients showed contamination of 8 (24%) of 34 sp utum specimens collected immediately after a tap water mouth rinse. These f indings demonstrate that endemic specimen contamination arises from mycobac teria in hospital tap water and provide a foundation for control efforts.