Epidemiological characters of Salmonella serovar enteritidis isolated from patients with sporadic diarrhea in Yamanashi prefecture during the last 11 years (1985-1995)

Abstract

A total of 603 strains of Salmonella serovar Enteritidis (SE) isolated from patients with sporadic diarrhea during the period from April 1985 to December 1995 in Yamanashi Prefecture, were examined for their yearly and monthly frequency of SE isolates, drug susceptibility, phage typing and plasmid profile. The results can be summarized as follows: 1) The rate of sporadic diarrhea due to SE to all the Salmonella isolates were 4.4% during the period from 1985 to 1988. However it suddenly increased to 47.1% in 1989. After that, the rates decreased to half every year as compared to 1989. And yet, in the last 3 years it became as high as 69.2%, 68.9% and 73.5% in 1993, 1994, and 1995, respectively. 2) Monthly frequency of isolates was 20.1% in September, 19.4% in August, 15.3% in October, 10.9% in July. 3) The predominant ages of isolates were 2 years of age (7.3%), 1 year of age (6.1%), 4 years of age (5.8%), 3 years of age (5.6%). 4) The rates of isolates from males was higher than females (Male: 59.5%, Female: 40.5%). 5) The rate of resistant isolates was 85.4% in the period. The predominant resistance pattern was SM single (417 strains: 69.2%), SA.SM.TC resistance (76 strains: 12.7%). 6) The phage type (PT) of isolates were classified into 15 different patterns. After 1990, the most prevalent PT was PT4. And recently, new types of PT appeared in isolation of PT22 in 1994, PT5 in 1995. 7) The predominant plasmid profile (PP) of SE isolates was 60 kb plasmid. Almost all SE strains of PT4 carried 60 kb plasmid. SE strains of PT1 possessed 2 patterns of PP. One pattern showed that SM single resistance strains carried only 60 kb plasmid, on the other hand SA. SM.TC resistance strains carried 60, 50, 7.5 kb plasmids.