Comparison of conventional and reversed phage typing procedures for identification of Listeria spp

Of 225 Listeria isolates evaluated, 199 had the same bacteriophage patterns by both the conventional (A. Audurier, A.G. Taylor, B. Carbonelle, and J. McLaughlin, Clin. Invest. Med. 7:229-232, 1984) and the new, easier to apply, "reversed" (M. J. Loessner, Appl. Environ. Microbiol. 57:882-884, 1991) phage typing procedures, 5 had different phage reactions, and the remaining 21 isolates were untypeable. Thus, the overall typeability rate was 90.7%, and 97.6% of the typeable isolates had the same phage patterns by both procedures.