PCR-based typing of Mycobacterium avium isolates in an epidemic among farmed lesser white-fronted geese (Anser erythropus)

Mycobacterium avium is an important veterinary pathogen causing avian tuber culosis in birds. The aim of the study was to evaluate the genetic relatedn ess in M. avium isolates from deep tissues of farmed lesser white-fronted g eese with avian tuberculosis and in samples from the farm environment. The strains were analyzed by two PCR-based typing methods, inverted repeat (IR) typing and random amplified polymorphic DNA (RAPD) analysis. The primers f or the inverted repeats of the insertion sequences IS1245 and IS1311 were u sed in IR typing, and the RAPD analysis was performed with six primers. Sev en of the nine avian strains yielded an identical pattern in the IR typing, but they could be divided into two groups in the RAPD analysis. The remain ing two bird isolates had an identical IR pattern (IR cluster II) which the y shared with two environmental isolates, However, the RAPD analysis reveal ed that these environmental isolates had a RAPD pattern (RAPD cluster VI) d istinct and different from either of the bird isolates (RAPD clusters II an d IV). In all, four M. avium strains were verified as being inducers of avi an tuberculosis in birds, and all were distinct from the three environmenta l strains identified. Thus, the results did not confirm the preliminary ide a that a single strain had caused the epidemic. The polymorphism among M. a vium strains highlighted the great biodiversity among an M. avium populatio n even in a limited environmental setting during a short time span, and ind icated the high susceptibility to avian tuberculosis of lesser white-fronte d geese. (C) 2001 Elsevier Science B.V. All rights reserved.