[Comparison of 3 commercial metallo-beta-lactamase detection kits].

Using 41 metallo-beta-lactamase producing isolates and 8 metallo-beta-lactamase nonproducing and ceftazidime-resistant isolates from Kyushu Island, metallo-beta-lactamase was detected by 3 commercial metallo-beta-lactamase detection kits, which were Metallo-beta-lactamase SMA Eiken (SMA, disk diffusion, Eiken Chemical Co.), dry plate Eiken DPD1 (DPD, two-fold serial broth microdilution, Eiken Chemical Co). and Cica beta test I/ MBL (CIC, coloring reaction, Kanto Chemical Co.). Detection rate by SMA, DPD, and CIC was 97.5, 100, and 100%. Neither method used in this study produced false-positive or false-negative results. The rates of metallo-beta-lactamase nonproducer identification were 37.5%, 62.5%, and 100% for the SMA, DPD, and CIC kits, respectivily. These three methods have the following features, SMA is useful for routine work because SMA utilizes disk diffusion, which is widely used by medical technologists, and it is the least expensive of the three kits. CIC can detect metallo-beta-lactamase after only 15 minutes and can determine the presence of non-metallo-beta-lactamase producers at a high rate. DPD can simultaneously identify the MIC of some agents. Consequently these three metallo-beta-lactamase detection kits were very useful for detecting metallo-beta-lactamase producing isolates.

[Antimicrobial susceptibility and mechanism of resistance to antibiotics for Escherichia coli O157 and verotoxin-producing E. coli isolated in northern Kyushu and Yamaguchi area].

The purpose of this study was to investigate the biochemical characteristics and antimicrobial susceptibility of Escherichia (E.) coli O157 and verotoxin-producing E. coli isolates from the Northern Kyushu Island and Yamaguchi area of Japan. A total of 54 isolates- 50 E. coli O157, 3 verotoxin-producing E. coli O26 and 1 verotoxin-producing E. coli O111 - were used in this study. Regarding H antigen, H7 type in E. coli O157 accounted for 98% (49/50), and residual 1 strain of E. coli O157 was untypable H type. Two of 3 E. coli O26 isolates were H11 type, residual 1 strain of E. coli O26 was untypable H type, and E. coli O111 isolate was non-motile strain. All 54 isolates were susceptible to cephems, fosfomycin, kanamycin, amikacin and co-trimoxazole. Tetracycline-resistant isolates existed in 13 of all 54 isolates, 5 of those 13 isolates had tetA, and the other 7 isolates had tetB. Eight amoxicillin-resistant isolates had TEM-1 beta-lactamase. Four of the 5 isolates that had tetA also had TEM-1 beta-lactamase. Nalidixic acid and 6 fluoroquinolone used had no insensitive or resistant isolates. Kanamycin-resistant isolates, fosfomycin- and nalidixic acid-insensitive isolates have been reported, so we must notice the antibiogram of such strains. It is important that the surveillance of antimicrobial susceptibility of enterohemorragic E. coli should be continued after this.