EVALUATION OF THE RELATEDNESS OF STRAINS OF MYCOBACTERIUM-AVIUM USINGPULSED-FIELD GEL-ELECTROPHORESIS

The application of molecular techniques to investigate strain relatedn ess may help define the local epidemiology of Mycobacterium avium infe ction, and, by identifying false isolates (i.e. neither pathogens nor colonizers) resulting from contamination, may serve as a tool for qual ity control in the laboratory. For this purpose, isolates from all pat ients (n = 129) with Mycobacterium avium infections identified over a two-year period were investigated by pulsed-field gel electrophoresis (PFGE). Of 38 PFGE patterns identified, 34 corresponded to unique stra ins or to isolates present in no more than two or th ree individuals, One prevalent strain was identified among HIV-infected patients and th ree patterns were related to culture contamination events. PFGE (i) es tablished the diversity of Mycobacterium avium strains in a community; (ii) identified the existence of a unique strain that may account for one-fifth of Mycobacterium avium isolated from HIV-infected patients locally; (iii) documented the extent and resolution of a suspected pse udo-outbreak; and (iv) uncovered an additional unsuspected contaminati on event.