Comparison of Danish isolates of Salmonella enterica serovar Enteritidis PT9a and PT11 from hedgehogs (Erinaceus europaeus) and humans by plasmid profiling and pulsed-field gel electrophoresis

During the years 1994 to 1998, 10 strains of Salmonella enter ica serovar E nteritidis phage type 11 (PT11) and 6 PT9a strains were isolated from Danis h hedgehogs, together with 7 strains that did not yield phage susceptibilit y patterns conforming with any known phage type (routine dilution no confor mity [RDNC]). From 1995 to 1998, five Danish patients were reported infecte d with serovar Enteritidis PT11 and two with PT9a, All serovar Enteritidis PT11, PT9a, and RDNC isolates from hedgehogs and humans were analyzed by pu lsed-field gel electrophoresis (PFGE), plasmid profiling, and restriction f ragment length polymorphism (RFLP) of plasmids, By use of S1 nuclease and H indIII, the PT11 and PT9a isolates had identical plasmid profiles and RFLP patterns, which differed from the RDNC profiles. The PFGE profiles were ide ntical for all serovar Enteritidis PT11 and PT9a strains from hedgehogs, fo ur of five human strains of serovar Enteritidis PT11, and two human strains of serovar Enteritidis PT9a, irrespective of restriction enzyme, whereas t he last human strain deviated slightly when NotI was used but not when XbaI or SpeI was used, The results indicate that serovar Enteritidis PT9a and P T11 are closely related and that PT11 and PT9a from Danish hedgehogs and hu mans belong to the same clonal lineage.