Further results and experiences with phage-typing of Listeria.

Results of phage-typing of 22 strains from 16 listeriosis cases, which were isolated during an epidemic outbreak in the district of Magdeburg, showed that most strains were determined by the octal codes 73611, 73615, 73655, 73645. We suppose that this was the epidemic strain, although also other phage-patterns (40000, 00600, 03200) were found. The source of the epidemic outbreak could not cleared up. The purpose of further investigations was to establish how far phage-patterns of Listeria from the same patients from different materials might be identified as identical, similar or different. We give examples of typing results in 1/2a and 4b strains and compare the results concerning an significant or non-significant alteration.