Pulsed-field gel electrophoresis (PFGE) has been used as a reliable epidemiological tool to identify the possible source and route of infection by Shiga-toxin producing Escherichia coli (STEC) O157. However, it has been found that some strains could not be subjected to the analysis because their DNAs are easily degraded. To produce strain-specific profiles of such strains, we used a method of amplifying DNA sequences flanking infrequent restriction sites (infrequent-restriction-site PCR; IRS-PCR) . Fifty-two strains of E. coli O157 were typed into 12 and 14 types by IRS-PCR patterns from DNAs digested with XbaI and HhaI and those with BlnI and HhaI, respectively. These data suggest that selection of an appropriate set of restriction enzymes will provides more discrimination patterns. In 18 of the 52 strains, that gave individual PFGE patterns, 11 IRS-PCR patterns were shown. Remaining 34 strains that were untypeable by PFGE were classified into 3 IRS-PCR types, indicating that some of those strains were possibly related.

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Management program in the broiler farm, which was suffered from infectious bursal disease (IBD) and E.coli infection, were evaluated with the production result, meat inspection and economic index.
Four groups (A: IBD and E.coli infection were observed. B: the best applicable antibiotic was selected and another medications were reduced. C: The improved vaccination program was performed and another medications were reduced. D: The feeding system was improved to product healthy chickens with minimum budget for disease control.) in the farm feeding 50, 000 broilers were compared for evaluation. Rate of raising was gradually increased, However, the production index is decreased at once in group B. In meat inspection, the discard rate of meat gradually decreased, and economical loss decreased from \10, 221 (group A) to \2, 608 (group D) per 1, 000 broilers. Calculating gross margin as economic index, the increase or decrease of gross margin was compared with the basis of group A. The gross margin of group B decreased by \2, 456 per 1, 000 broilers. However, the increase in group C \19, 625 and in group D \32, 168 were shown, respectively. Finally, it is necessary to investigate in detail after this because the test of group D was carried out in autumn where the production index becomes the best through the year.

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Erysipelothrix species were isolated from the tonsils of 79 (6.4%) of 1, 236 healthy cattle slaughtered in 4 prefectures, Yamagata, Miyagi, Nagasaki, and Tokyo, in Japan from September, 1998, to August, 1999.
A combination, modified culture medium consisted of brain heart infusion (BHI) broth containing 0.1% Tween 80, 5% horse serum, 50μg/ml gentamicin, 0.1% sodium azide and 0.001% crystal violet, and BHI agar containing 0.1% Tween 80, 50μg/ml gentamicin, and 0.1% sodium azide was compared with two traditional media for isolation of Erysipelothrix species. The modified media were the most effective since they produced the highest number of Erysipelothrix isolates (p<0.01) as well as the greatest degree of inhibition of the growth of contaminated organisms.
The isolation rates in summer (10.3%) and spring (7.1%) was higher than those in autumn (2.6%) or winter (1.3%) (p<0.01) .

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