The pulsed field gel electrophoresis (PFGE) method was applied for molecular typing of 130 Mannheimia haemolytica serotype A1 isolates obtained from 13 prefectures in Japan. These isolates were divided into 15 ApaI PFGE profiles that formed 6 distinct clusters (cluster A to F). Fifty-three (40.7%) isolates were classified in cluster B, and 20.0%, 13.8%, 12.3%, 6.9% and 6.1% of isolates were in cluster E, A, F, D, and C, respectively. The isolates of cluster B were differentiated into 7 subtypes (B1 to B7) and subtype B5 contained 34 isolates. We associated the PFGE clusters with the year of isolation and the geographical origin. Before 1994 all isolates were grouped into clusters A, B or C. The numbers of isolates belonging to clusters D to F have increased since 1994, and since 1997 half of the isolates belong to these groups. There was no relationship between molecular typing and geographic origin of these isolates. These results indicate that isolates of M. haemolytica A1 strain with various molecular profiles have already spread in Japan and may have caused sporadic infections.a,br /> (Environmental Hygiene Section, Shichinohe Research Unit TEL +81-176-62-5115)
References:
Katsuda et al. (2003) Epidemiol. Infect. 113:939-946.