SALMONELLA-TYPHIMURIUM PHAGE TYPES FROM HUMAN SALMONELLOSIS IN DENMARK 1988-1993

A total of 989 isolates of Salmonella enterica ssp. enterica serovar T yphimurium from cases of human salmonellosis were investigated by phag e typing, The isolates comprised all isolates recovered during the mon th of August in each of the years from 1988 to 1993. Phage typing assi gned 82.6% of the strains to 36 different definitive types, 11.9% of t he strains belonged to types of unknown lysis pattern (RDNC), and 5.5% could not be typed by the phages used (NT). Three phage types (12, 66 and 110) made up approximately 50% of the isolates in each of the yea rs investigated. During the period in question these types showed majo r changes in prevalence: phage type 12 increased from 4.0% in 1988 to a maximum of 55.2% in 1992, and phage type 66 and phage type 110 were reduced from 40.1% and 27.8% to a minimum of 3.9% and 4.8% in 1993 and 1992, respectively. The increasing prevalence of phage type 12 among isolates from human salmonellosis most likely reflects the increasing significance of pork as a source of human salmonellosis. The reduction in phage types 66 and 110 is paralleled by a reduction in S. Typhimur ium in Danish poultry. Some phage types were associated with travel, n amely 17, 193 and 194. It is concluded that phage typing, although her e performed retrospectively, produces valuable epidemiological informa tion regarding changes in the relative importance of different sources of infection in humans. It is suggested that phage typing be performe d prospectively on both human and animal S. Typhimurium isolates in De nmark.