BRONCHOSCOPY-ASSOCIATED MYCOBACTERIUM-XENOPI PSEUDOINFECTIONS

Mycobacterium xenopi typically accounts for less than 0.3% of all clin ical mycobacterial isolates. Over a 37-mo period, 21 (35%) of 60 mycob acterial isolates from a Michigan hospital were identified as M. xenop i. Hospital, laboratory, and bronchoscopy records were reviewed to det ermine case characteristics, develop a case series, and calculate proc edure-specific M. xenopi isolation rates. A case-control study was con ducted to elucidate aspects of the bronchoscopy procedure associated w ith M. xenopi isolation. Bronchoscope cleaning procedures were reviewe d, and hospital water systems were cultured. Four isolates were from t hree patients with disease attributable to M. xenopi. Of the other iso lates, specimens obtained by bronchoscopy were more likely to yield M. xenopi than were specimens obtained by other routes (relative risk, 9 .7; 95% confidence intervals, 3.2, 29.6). Bronchoscopes were disinfect ed in a 0.13% glutaraldehyde-phenate and tap-water bath and then were rinsed in tap water. Water from the hot water tank supplying this area yielded M. xenopi. Mycobacteria were cultured from bronchoscopes afte r disinfection. M. xenopi in the tap water appears to have contaminate d the bronchoscopes during cleaning. Adequate disinfection of contamin ated bronchoscopes and careful collection of specimens to avoid contam ination with contaminated water are essential, both for limiting diagn ostic confusion caused by mycobacterial pseudoinfections and for reduc ing risks of disease transmission.