A nationwide surveillance for antimicrobial susceptibility in Escherichia coli strains isolated from foodproducing animals in Japan was conducted from 1999 to 2002. Eighteen cefazolin-resistant E. coli strains were isolated from broilers. Six were CTX-M-type producing, and eight were CMY-2 producing, while eight had mutations at the ampC promoter region.

Pseudomonas aeruginosa is an opportunistic pathogen responsible for morbidity and mortality in humans, animals, and plants. This bacterium has been regarded to be widely present in terrestrial and freshwater environments, but not in open ocean environments. Our purpose was to clarify its presence in open ocean, and their genotypic and physiological characteristics were compared with those of isolates from clinical, animal, and freshwater sources. Water samples were collected from freshwater, bays, and offshore environments in Japan. Sixty-two isolates, including 26 from the open ocean, were identified as P. aeruginosa by phenotypic characteristics and the BD Phoenix System. Pulsed-field gel electrophoresis (PFGE) was performed on all strains, together with 21 clinical and 8 animal strains. The results showed that open ocean strains are composed of a few genotypes, which are separated from other strains. Although some clinical isolates made a cluster, other strains tended to mix together. Different antibiotypes were observed among marine isolates that had similar PFGE and serotyping patterns. Some were multidrug-resistant. Laboratory-based microcosm study were carried out to see the responses of P. aeruginosa toward increased NaCl concentrations in deionized water (DW). Marine strains showed better survival with the increase, whereas river and clinical strains were suppressed by the increase. These findings illustrate the potential significance of open ocean as a possible reservoir of P. aeruginosa, and there may be clones unique to this environment. To our knowledge, this is the first report on the presence and characterization of P. aeruginosa in the open ocean.

Aims:  To investigate the existing antimicrobial susceptibility and genetic characteristics of Lactococcus garvieae isolates from cultured Seriola in Japan. Methods and Results:  Minimum inhibitory concentrations (MICs) of 14 antimicrobial agents for 170 isolates were determined using the agar dilution method. Seventy‐five isolates (44·1%) were simultaneously resistant to erythromycin (EM) (MIC ≥ 2 μg ml−1), lincomycin (LCM) (MIC ≥ 128 μg ml−1) and oxytetracycline (OTC) (MIC ≥4 μg ml−1). Resistance to EM was grouped as intermediate‐ and high‐level resistant by MIC values. All resistant isolates possessed ermB and tet(S) genes. The number of different bands between pulsed‐field gel electrophoresis patterns of 25 isolates and two ATCC strains (isolated in 1974), determined using two enzymes (ApaI and SmaI), did not exceed 3. Conclusions:  The present resistance pattern observed with ermB and tet(S) is similar to that observed in previous reports. Moreover, the genetic characteristics of L. garvieae isolates from a wide area in Japan in 2002 and ATCC strains were closely related. Significance and Impact of the Study:  This study suggests that EM‐, LCM‐ and OTC‐resistant isolates have been present for 15 years and that L. garvieae strains with same origin have spread among Seriola spp. in Japan since 1974.

ABSTRACT. Antimicrobial susceptibility of 183 Salmonella isolates from apparently healthy food-producing animals obtained during the period from 2000 to 2003 throughout Japan was examined. Of 29 serovars identified, Salmonella Infantis (37.7%) was the most prevalent, followed by S. Typhimurium (19.7%). Salmonella bacteria resistant to dihydrostreptomycin (77.6%) were about 10% more prevalent than those resistant to oxytetracycline (67.8%), though the nation-level veterinary use of tetracycline antibiotics is much greater than that of streptomycin in Japan. In seventeen isolates (9.3%) resistant to nalidixic acid, single point mutations were detected at 84 or 87 in the quinolone resistance-determining region of the gyrA gene.

h Sixty-five CTX-M-2/15/14 extended-spectrum-␤-lactamase-producing Enterobacteriaceae were isolated from 258,888 mastitic milk samples from Japanese dairy farms between 2007 and 2011. CTX-M-2-producing Klebsiella pneumoniae and CTX-M-15-producing Escherichia coli were the predominant strains isolated. There was no predominant clonal type, and clonal diversity was found even in strains isolated from a single farm. Since 2000, Escherichia coli and other Enterobacteriaceae species producing CTX-M-type extended-spectrum ␤-lactamases (ESBLs) (CTX-M) have been commonly isolated from community-acquired extraintestinal infections in humans and their companion animals (1, 2, 3, 4), from food-producing animals (3,5,6,7,8), and from retail meats, including chicken, beef, and pork (3), worldwide. The CTX-M-type genes are assumed to have been transferred separately to plasmids, including complex class 1 integrons and transposons (9), from chromosomes of different Kluyvera species (i.e., Kluyvera ascorbata, K. georgiana, and K. cryocrescens) that live in water, soil, and human and animal intestinal tracts; therefore, CTX-M has been divided into five clusters (CTX-M-1, CTX-M-2, CTX-M-8, CTX-M-9, and CTX-M-25) from base sequence homology (1, 9). CTX-M confers resistance against penicillins, oxyimino-cephalosporins, and monobactams (1, 4). Recently, the CTX-M-15-producing E. coli ST131 (O25: H4) clone has emerged as a multidrug-resistant pandemic strain affecting humans worldwide (4).Bovine mastitis is the most common disease affecting dairy cattle (10). Both E. coli and Klebsiella pneumoniae often cause life-threatening clinical mastitis (5, 11). The incidence of bovine mastitis has been reported to be higher in Japan (30 to 35 cases per 100 cow-years at risk) (12) than in North America, Europe, and New Zealand (10 to 30 cases per 100 cow-years) (10). Only a few classes of antimicrobials are approved for the treatment of mastitis in Japan; however, large amounts of antimicrobials are used for mastitis treatment, creating selective pressure for drug-resistant organisms (13). In our previous report, we showed that Japanese dairy cattle might be a source of CTX-M-15/2/14-and CMY-2-producing Enterobacteriaceae (7). However, few studies have reported the prevalence of Enterobacteriaceae producing CTX-M in bovine mastitis (5). The aims of this study were to determine the genetic characteristics, antimicrobial susceptibility, and genetic relatedness of ESBL-and plasmid-mediated AmpC ␤-lactamaseproducing Enterobacteriaceae isolated from bovine mastitis cases.Screening of ESBLs. Bacterial cultures were carried out using standard procedures on a total of milk samples from 258,888 quarters obtained from 176,808 cows affected by (mainly clinical) mastitis on 1,000 dairy farms in the Nemuro Subprefecture of Hokkaido Prefecture, Japan, between February 2007 and April 2011 (14). Streptococcus spp. (mainly Streptococcus uberis) and Enterococcus spp., coagulase-negative staphylococci, Staphylococcus aureus, E. coli, and Klebsiella spp. were the...