Interrelationships between strains ofSalmonella enteritidisbelonging to phage types 4, 7, 7a, 8, 13, 13a, 23, 24 and 30

摘要

Salmonella enteritidis strain P278849 expressed long‐chain lipopolysaccharide (LPS, termed ‘smooth’), carried plasmids of 38, 34 (pDEP 44, incompatibility group N, R‐type AS), 2.0 and 1 MDa, and belonged to phage type (PT) 23. Introduction of pDEP 44 into a smooth strain ofSalm. enteritidisPT 4 produced a smooth strain ofSalm. enteritidisof PT 24. Transfer of this plasmid into a strain of PT 8 also resulted in formation of a smooth strain ofSalm. enteritidisof PT 24. Moving pDEP 44 into strains ofSalm. enteritidisof PTs 7 or 7a which did not express LPS (termed ‘rough’) resulted in rough strains of PT 23. In contrast, transfer of this plasmid into a smooth strain ofSalm. enteritidisPT 7a resulted in a smooth strain of PT 23. Introduction of pDEP 44 into strains ofSalm. enteritidisof PT 13 or PT 13a did not change the phage type, whereas transferring the plasmid into strains of PT 30 caused strains to become resistant to lysis by the typing phages and therefore untypable. The possibility of strains ofSalm. enteritidisof PT 8 being the progenitors of strains ofSalm. enteritidisof PT 24 must now be considered when investigating the epidemiology ofSalm. enteritidisof PT 24 infections in areas whereSalm. enteritidisPT