Serovars and epidemiological properties of Salmonella isolated from patients with sporadic diarrhea in Yamanashi prefecture during the last 22 years (1985-2006)

Abstract

We studied the serovars, yearly and monthly frequency of isolates, and drug susceptibility of 3,028 strains of Salmonella isolated from patients with sporadic diarrhea during April 1985 to December 2006 in Yamanashi Prefecture. Results are as follows : 1) Isolates were serologically classified into 72 different serovars. Predominant serovars were S. Enteritidis (59.3%), S. Typhimurium (10.5%), S. Oranienburg (2.9%), S. Hadar (2.4%), S. Litchfield (2.3%), and S. Infantis (2.0%). 2) Serovars of S. Haifa, S. Schleissheim, S. Livingstone, S. Mikawasima, S. Manhattan, S. Muenchen, S. Emek, S. Dublin, S. Javiana, S. Miami, S. Miyazaki, S. Weltevreden, S. Orion, S. Give, S. Aberdeen, S. Surat and S. Orientalis were isolated from human sources for the first time since 1995 in Yamanashi Prefecture. 3) Yearly frequency of isolation was 305 strains (10.1%) for 1996, 283 strains (9.3%) for 1999, 273 strains (9.0%) for 2000, 238 strains (7.9%) for 1989 and 228 strains (7.5%) for 1997. 4) Monthly frequency of isolation was 567 strains (18.7%) for August, 471 strains (15.6%) for September, 430 strains (14.2%) for July, 340 strains (11.2%) for October and 266 strains (8.8%) for June. 5) Predominant ages of patients from whom Salmonella strains were isolated were 2 years for 199 strains (6.6%), 1 year for 192 strains (6.4%), 3 years for 169 strains (5.6%), 4 years for 161 strains (5.3%), and under 1 year for 110 strains (3.6%). 6) The rate of isolation from males was higher at 56.3% than for females at 43.7%. 7) The isolation frequency of drug-resistant strains was 64.8% in 1985-2006. The most predominant resistance pattern was SM single resistance because of the increase in S. Enteritidis. 8) The number of resistant strains of was 1,435 of 1,780 strains (80.6%) for S. Enteritidis, and 214 of 322 strains (66.5%) for S. Typhimurium, 1 of 87 strains (1.1%) for S. Oranienburg and 73 of 73 strains (100%) for S. Hadar. 9) The serovar S. Typhimurium had much multiple drug resistance strains, being resistant ever to fluoroquinolone.