Typing of Listeria strains by random amplification of polymorphic DNA.

The polymerase chain reaction (PCR) was used to obtain randomly amplified polymorphic DNA (RAPD) profiles for typing of Listeria strains. In this procedure, whole cells were incubated in the reaction mixture. The discriminating ability of a randomly designed 10-mer primer, HLWL74, was assessed. A total of 60 collection strains of Listeria, encompassing all 7 Listeria species and all known serovars was submitted to PCR with the primer HLWL74. Upon agarose gel electrophoresis, 29 different banding profiles were reproducibly obtained. No common profiles were recorded for strains from different Listeria species. For various groups of strains sharing the same serotype (e.g. 4b, 1/2a, 1/2b), RAPD analysis could generate further subdivision. On the other hand, some strains from different serotypes produced identical RAPD profiles with the primer HLWL74. The RAPD typing method from whole cells is proposed as an attractive alternative for other Listeria typing systems, and the 10-mer HLWL74 as a primer to include in a forthcoming set of standard primers for RAPD typing of Listeria isolates.