A survey of antimicrobial-resistant Escherichia coli prevalence in wild mammals in Japan using antimicrobial-containing media

Traces of pandemic fluoroquinolone-resistant Escherichia coli clone ST131 transmitted from human society to aquatic environments and wildlife in Japan

Transmission of antimicrobial-resistant bacteria among humans, animals, and the environment is a growing concern worldwide. The distribution of an international high-risk fluoroquinolone-resistant Escherichia coli clone, ST131, has been documented in clinical settings. However, the transmission of ST131 from humans to surrounding environments remains poorly elucidated. To comprehend the current situation and identify the source of ST131 in nature, we analyzed the genetic features of ST131 isolates from the aquatic environment (lake/river water) and wildlife (fox, raccoon, raccoon dog, and deer) and compared them with the features of isolates from humans in Japan using accessory and core genome single nucleotide polymorphism (SNP) analyses. We identified ST131 isolates belonging to the same phylotype and genome clusters (four of eight clusters were concomitant) with low SNP distance between the human isolates and those from the aquatic environment and wildlife. These findings warn of ST131 transmission between humans and the surrounding environment in Japan.

Characterization of antibiotic resistance genes and mobile genetic elements in Escherichia coli isolated from captive black bears

The objective of this study was to analyze the antimicrobial resistance (AMR) characteristics produced by antibiotic resistance genes (ARGs), mobile genetic elements (MGEs) and gene cassettes in Escherichia coli isolated from the feces of captive black bears. Antimicrobial susceptibility testing was performed by using the disk diffusion method, and both MGEs and integron gene cassettes were detected by polymerase chain reaction. Our results showed that 43.7% (62/142) of the isolates were multidrug resistant strains and 97.9% (139/142) of the isolates were resistant to at least one antibiotic. The highest AMR phenotype was observed for tetracycline (79.6%, 113/142), followed by ampicillin (50.0%, 71/142), trimethoprim-sulfamethoxazole (43.7%, 62/142) and cefotaxime (35.9%, 51/142). However, all isolates were susceptible to tobramycin. tetA had the highest occurrence in 6 ARGs in 142 E. coli isolates (76.8%, 109/142). Ten mobile genetic elements were observed and IS26 was dominant (88.0%, 125/142). ISECP1 was positively associated with five β-lactam antibiotics. ISCR3/14, IS1133 and intI3 were not detected. Seventy-five E. coli isolates (65 intI1-positive isolates, 2 intI2-positive isolates and 8 intI1 + intI2-positive isolates) carried integrons. Five gene cassettes (dfrA1, aadA2, dfrA17-aadA5, aadA2-dfrA12 and dfrA1-aadA1) were identified in the intI1-positive isolates and 2 gene cassettes (dfrA1-catB2-sat2-aadA1 and dfrA1-catB2-sat1-aadA1) were observed in the intI2-positive isolates. Monitoring of ARGs, MGEs and gene cassettes is important to understand the prevalence of AMR, which may help to introduce measures to prevent and control of AMR in E. coli for captive black bears.

Characterization of quinolone-resistant and extended-spectrum β-lactamase-producing Escherichia coli derived from sika deer populations of the Nara Prefecture, Japan

Wildlife in urban areas have the potential to disseminate antimicrobial-resistant bacteria (ARB) across a wider environment. Using antimicrobial-supplemented agar plates, we isolated extended-spectrum β-lactamase-producing Escherichia coli (EEC) and quinolone-resistant E. coli (QREC) from 144, 23, and 30 deer feces from Nara Park (NP), rural area neighboring NP (RA), and Mt. Odaigahara (MO), respectively. In NP and RA, the prevalence of EEC was 24.3 and 4.3%, respectively; that of QREC was 11.1 and 17.4%, respectively. Neither EEC nor QREC were detected in MO. The pulsotypes of EEC and QREC isolates differed between NP and RA. Our study suggests that deer of the Nara Prefecture are potential carriers of ARB, but long-distance dissemination is unlikely due to limited deer movement.

Genomic Characterization of Fecal Escherichia coli Isolates with Reduced Susceptibility to Beta-Lactam Antimicrobials from Wild Hogs and Coyotes

This study was carried out to determine the antimicrobial resistance (AMR) genes and mobile genetic elements of 16 Escherichia coli isolates-with reduced susceptibility to ceftazidime and imipenem-that were recovered from the fecal samples of coyotes and wild hogs from West Texas, USA. Whole-genome sequencing data analyses revealed distinct isolates with a unique sequence type and serotype designation. Among 16 isolates, 4 isolates were multidrug resistant, and 5 isolates harbored at least 1 beta-lactamase gene (bla_CMY-2, bla_CTX-M-55, or bla_CTX-M-27) that confers resistance to beta-lactam antimicrobials. Several isolates carried genes conferring resistance to tetracyclines (tet(A), tet(B), and tet(C)), aminoglycosides (aac(3)-IId, ant(3″)-Ia, aph(3')-Ia, aph(3″)-lb, aadA5, and aph(6)-ld), sulfonamides (sul1, sul2, and sul3), amphenicol (floR), trimethoprim (dfrA1 and dfrA17), and macrolide, lincosamide, and streptogramin B (MLSB) agents (Inu(F), erm(B), and mph(A)). Nine isolates showed chromosomal mutations in the promoter region G of ampC beta-lactamase gene, while three isolates showed mutations in gyrA, parC, and parE quinolone resistance-determining regions, which confer resistance to quinolones. We also detected seven incompatibility plasmid groups, with incF being the most common. Different types of virulence genes were detected, including those that enhance bacterial fitness and pathogenicity. One bla_CMY-2 positive isolate (O8:H28) from a wild hog was also a Shiga toxin-producing E. coli and was a carrier of the stx2A virulence toxin subtype. We report the detection of bla_CMY-2, bla_CTX-M-55, and bla_CTX-M-27 beta-lactamase genes in E. coli from coyotes for the first time. This study demonstrates the importance of wildlife as reservoirs of important multi-drug-resistant bacteria and provides information for future comparative genomic analysis with the limited literature on antimicrobial resistance dynamics in wildlife such as coyotes.