Differenzierung von Listeria innocua-Isolaten aus einem österreichischen Käsereibetrieb mittels einer multipriming Random Amplification of Polymorphic DNA (RAPD)-PCR Technik

Twenty-nine Listeria isolates which originated from an Austrian cheeses making facility were investigated using a multipriming Random Amplification of Polymorphic DNA-procedure. 155 genetic markers were evaluated in the examined strains using a PAUP software package (PAUP= Phylogenetic Analysis Using Parsimony). All isolates were assigned to fifteen RAPD groups. Eleven RAPD groups were comprised of a single isolate, three RAPD groups were comprised of two isolates and a single RAPD group was comprised of twelve isolates. A couple of identical strains which was isolated in the facility in 1992 was not distinguished from the RAPD group XIII strains originating from 1995. The results embark on considerations that the facility was recontaminated by identical strains both in 1992 and 1995. This fact fits the theme that another couple of identical strains occured in January (strain 14) and July 1993 (strain 16). These findings make strict demands upon the improvement of the unsufficient hygienic and sanitary conditions which may have enabled the Listeria innocua strains to persistently contaminate the plant and the cheese products. Obviously the implemented hygienic protocols concerning technical standards, personnel and management of production were not reliably efficient to minimize the contamination risk of the critical production aera.