NOTI MACRORESTRICTION ANALYSIS SUGGESTS A CLONAL RELATIONSHIP OF SALMONELLA-ENTERICA, SER ENTERITIDIS PHAGE LYSOTYPE-4 STRAINS

30 different strains of Salmonella enterica ser. enteritidis (S. enteritidis) isolated at the Institute for Medical Microbiology, Hannover, were subjected to a NotI macrorestriction analysis. The results were compared with the respective phage lysis patterns. 25 of 30 isolates belonged to phage lysotype 4; all these strains displayed an identical genomic NotI restriction fragment pattern. In contrast, five isolates of other phage lysotypes revealed more or less prominent differences in their NotI restriction fragment pattern. These results provide genetic evidence for a clonal expansion of a single phage lysotype 4 strain underlying the recent surge in salmonella infections and support phage lysotyping as a reliable epidemiological typing method for S. enteritidis.