Comparison of IS1245 restriction fragment length polymorphism and pulsed-field gel electrophoresis for typing clinical isolates of Mycobacterium avium subsp avium

SETTING: Little is still known about the epidemiology and pathogenesis of M ycobacterium avium subsp avium (MASA) infection. OBJECTIVE: Examination of the reproducibility and the stability over time o f pulsed-field gel electrophoresis (PFGE) and IS1245 restriction fragment l ength polymorphism (IS1245-RFLP) techniques. The ability of these typing sy stems for differentiating clinical isolates of MASA was also assessed. DESIGN: Clinical isolates recovered from 63 patients (59 human immunodefici ency virus [HIV] positive and four HIV-negative) were studied by insertion sequence IS1245 and PFGE. For the study of in vivo and in vitro stability, strains collected over time from four patients and five strains chosen at r andom, respectively, were used. RESULTS: The stability of PFGE and IS1245-RFLP in vitro was excellent. PFGE was also stable in vivo, but IS1245-RFLP patterns showed some variation. T he discriminatory power of IS1245-RFLP and PFGE was 0.995 and 0.989, respec tively. The cluster analysis did not reveal differences between strains rec overed from HIV-negative and HIV-positive patients or between patients with colonisation, local infection or disseminated disease. CONCLUSION: IS1245-RFLP and PFGE are useful tools for typing MASA strains. However, IS1245 variations in vivo may complicate the analysis of epidemiol ogical relationships.