[Survival of Salmonella Weltevreden and S. Senftenberg in black tiger shrimp under frozen storage].

Survival of Salmonella in black tiger shrimps during frozen storage was investigated following our previous study on Salmonella contamination in frozen shrimps imported into Japan. Salmonella (S.) Weltevreden and S. Senftenberg were inoculated onto the surface and inside of black tiger shrimps without the shell. After storage at -10 degrees C, -20 degrees C and -30 degrees C for 12 weeks, the Salmonella population decreased in all cases; the decrease was smallest at the lowest temperature. Viability of Salmonella inoculated onto the surface of the shrimp was greater than that inside the shrimp. In addition, viability of S. Senftenberg was greater than that of S. Weltevreden. These results suggest that hygienic handling during thawing of shrimps is important from the viewpoint of Salmonella contamination.

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

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.

[Presence of the genes regarding adherence factors of Escherichia coli isolates and a consideration of the procedure for detection of diarrheagenic strain].

Diarrheagenic Escherichia coli are differentiated from non-pathogenic members with enterotoxin production, enteroinvasiveness and serotyping. However, the serotypic members are rarely sufficient to reliably identify a strain as diarrheagenic on E. coli. Recently, there are many definite articles which the adhesive E. coli strain against intestinal epithelial cells is enterovirulent. In this study, 1,748 E. coli isolates of diarrheagenic and non-diarrheagenic categories which belonged to EHEC, ETEC, EIEC EPEC and non-EPEC were examinated by PCR method for the presence of eaeA, aggR and bfpA regarding adherence factor genes, and astA of EAST1. The strains examined were recognized to variable carrying geno-patterns, and a large number of EHEC, EPEC and non-EPEC had carried either eaeA or aggR genes. In EHEC isolates, a carrying pattern with the most high frequency was only eaeA, and this type was recognized in the isolates of serotype O157, O26 and O111. EPEC and non-EPEC isolates were recognized eaeA or aggR which harboring with astA or not. Of 508 EPEC isolates from human, a total of 137 isolates (27.0%) carried aggR, and a total of 74 isolates (14.6%) had eaeA, while of the 91 isolates from non-human were recognized aggR and eaeA with 2.2% (2 isolates) and 12.1% (11 isolates), respectively. Also, of 266 non-EPEC isolates from human, a total of 16 isolates (6.0%) carried aggR, and a total of 58 isolates (21.8%) had eaeA. On the other hand, 22 (7.0%) of 316 isolates examined from non-human had eaeA, however no isolate had aggR. Thirteen isolates of EIEC and 218 ETEC isolates were screened, and only 6 ETEC isolates had either eaeA or aggR. The astA gene was recognized in the isolates of all categories, and ETEC strains had more frequently. The bfpA gene was recognized with more frequently in a serotype O157: H45, which is obtained from human with diarrhea, however, this strain was not recognized a member of the EPEC serotype. There is no diagnostic system for the strain of E. coli that cause diarrheal diseases, therefore more laboratories are unable to identify them. The authors had confirmed which PCR technique is a useful simple and rapid method for the detection of adherence factor genes on E. coli strains. From the these results, we showed a differentiation method using PCR technique which have relation with adherence factor, enterotoxin-production and invasiveness, and we firmly believe that application of the procedure is a reasonable and useful method for the identification of diarrheagenic E. coli.