Thirty-three cefazolin-resistant extraintestinal pathogenic Escherichia coli strains from companion animals were screened for bla CMY−1 , bla CMY−2 , bla SHV , bla TEM , and bla CTX−M genes. Extended-spectrum β-lactamase-producing strains were further characterized by O serotyping and multilocus sequence typing. It was found that 20 and 17 isolates harbored TEM-1 and CMY-2 β-lactamases, respectively, and 13 isolates harbored both β-lactamases. One isolate harbored DHA-1 β-lactamase. Key words cats, dogs, Escherichia coli, extended-spectrum β-lactamase.Extraintestinal pathogenic Escherichia coli (ExPEC) are major pathogens that can cause urinary and genital tract infections in dogs and cats, and are characterized by specific virulence factors that promote extraintestinal infection, such as P fimbriae, hemolysin, and cytotoxic necrotizing factor I (1). The emergence of ExPEC isolates resistant to extended-spectrum cephalosporin, including a worldwide pandemic O25b-ST131 clone producing CTX-M β-lactamase, has been observed among dogs and cats in several countries (2-4). Previously, we reported higher prevalence of cephalosporin (i.e. cefazolin) resistance (31.7%) among ExPEC from dogs and cats in Japan (5), compared with other countries, such as Denmark (5.3-5.6%) (6), Portugal (4.2-8.3%) (7), and Germany (1.0%) (8). However, the mechanism of List of Abbreviations:ESBL, extended-spectrum β-lactamase; ExPEC, extraintestinal pathogenic Escherichia coli; MBL, metallo-β-lactamase; MIC, minimum inhibitory concentration; MLST, multilocus sequence typing; PCR, polymerase chain reaction; PFGE, pulsed-field gel electrophoresis; ST, sequence type.cephalosporin resistance in ExPECs from companion animals in Japan is unknown.In the present study, we determined the prevalence of β-lactamases, including extended-spectrum β-lactamases (ESBLs), and mutations of the ampC promoter region in cephalosporin-resistant ExPEC isolates from Japanese dogs and cats, and characterized ESBL-positive isolates by multilocus sequence typing (MLST) and serotyping.In this study, 33 cefazolin-resistant (minimum inhibitory concentration [MIC] of ≥32 μg/mL) strains of canine and feline ExPEC were used. These isolates were found in 104 consecutive ExPEC isolates obtained from specimens of mainly urine and uterine content of 85 domestic dogs and 19 cats (one isolate per animal). These animals were affected with infections of the urinary tract 480

Objective—To assess the status of antimicrobial resistance (AMR), identify extraintestinal virulence factors (VFs) and phylogenetic origins, and analyze relationships among these traits in extraintestinal pathogenic Escherichia coli (ExPEC) isolates from companion animals. Sample—104 E coli isolates obtained from urine or genital swab samples collected between 2003 and 2010 from 85 dogs and 19 cats with urogenital infections in Japan. Procedures—Antimicrobial susceptibility of isolates was determined by use of the agar dilution method; a multiplex PCR assay was used for VF gene detection and phylogenetic group assessment. Genetic diversity was evaluated via randomly amplified polymorphic DNA analysis. Results—Of the 104 isolates, 45 (43.3%) were resistant to > 2 antimicrobials. Phylogenetically, 64 (61.5%), 22 (21.2%), 13 (12.5%), and 5 (4.8%) isolates belonged to groups B2, D, B1, and A, respectively. Compared with other groups, group B2 isolates were less resistant to all tested antimicrobials and carried the pap, hly, and cnf genes with higher frequency and the aer gene with lower frequency. The aer gene was directly associated and the pap, sfa, hly, and cnf genes were inversely associated with AMR. Randomly amplified polymorphic DNA analysis revealed 3 major clusters, comprised mainly of group B1, B2, and D isolates; 2 subclusters of group B2 isolates had different VF and AMR status. Conclusions and Clinical Relevance—Prevalences of multidrug resistance and human-like phylogenetic origins among ExPEC isolates from companion animals in Japan were high. It is suggested that VFs, phylogenetic origins, and genetic diversity are significantly associated with AMR in ExPEC.

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