[Phage typing of Salmonella typhimurium in 20 provinces, autonomous regions and municipalities of China].

Thirty strains of Salmonella bacteriophages were isolated from hospital sewage. Eleven strains selected from them, in combination with Felix Salmonella Phage O-I, were used as a phage typing set for serotyping Salmonella. Thirty-one identified types and 20 undefined types were detected in 2348 strains of Salmonella typhimurium collected from 20 provinces, autonomous regions and municipalities in China. The nine types with higher frequencies were 7774 (accounted for 48.0%), 0774 (17.1%), 6774 (7.7%), 4774 (7.3%), 5774 (3.3%). 3774 (2.2%), 4000(2.1%), 0000 (1.8%) and 7000 (1.7%). Most outbreaks of nosocomial infection and food poisoning were caused by phage types 7774 and 4774. Phage types of Salmonella typhimurium in domestic ducks, pigs, rats, snails, and in sewages were analyzed, and their significance in epidemics was discussed.