Molecular mechanisms of antimicrobial resistance in fecal Escherichia coli of healthy dogs after enrofloxacin or amoxicillin administration

Abstract

Escherichia coli respond to selective pressure of antimicrobial therapy by developing resistance through a variety of mechanisms. The purpose of this study was to characterize the genetic mechanisms of antimicrobial resistance in fecal E. coli after the routine use of 2 popular antimicrobials. Fourteen resistant E. coli isolates, representing predominant clones that emerged in healthy dogs' feces after treatment with either amoxicillin (11 E. coli isolates) or enrofloxacin (3 E. coli isolates), were tested for mutations in DNA gyrase (gyrA and gyrB) and in topoisomerase IV (parC) and for the presence of β-lactamases (bla(TEM), bla(SHV), bla(PSE-1) and bla(CTX-M)) and plasmid-mediated quinolone resistance (qnrA, qnrB, qnrS, aac(6')-Ib, and qepA), by polymerase chain reaction. Escherichia coli isolates cultured following amoxicillin therapy only expressed single-drug resistance to β-lactams, while the isolates cultured from dogs receiving enrofloxacin therapy expressed multidrug resistance (MDR). The use of RND efflux pump inhibitors increased the susceptibility of the 3 MDR E. coli isolates to doxycycline, chloramphenicol, enrofloxacin, and ciprofloxacin, which indicates a role of the efflux pump in the acquisition of the MDR phenotype. Amplification and sequencing of AcrAB efflux pump regulators (soxR, soxS, marR, and acrR) revealed only the presence of a single mutation in soxS in the 3 MDR isolates.

Isolation of <i>Escherichia coli</i> Strains with AcrAB–TolC Efflux Pump-Associated Intermediate Interpretation or Resistance to Fluoroquinolone, Chloramphenicol and Aminopenicillin from Dogs Admitted to a University Veterinary Hospital

“…We considered that these findings substantially reflect the situation in Japanese companion animal medicine, because the samples in this study were successively. In addition, a previous study also showed that AMP or ENR treatment led to the emergence of aminopenicillin–ENR–CHL-resistant E. coli isolates in dogs in the United States [2, 8]. Moreover, fluoroquinolone–aminopenicillin–CHL-resistant E. coli isolates with overexpression of AcrAB–TolC were frequently isolated from humans in university hospitals [28].…”

“…Resistant bacteria encountered in companion animal medicine also represent a potential hazard to human health [2, 23, 25], because companion animals live in close proximity with humans and receive medical treatment, including antimicrobials used for humans [22]. …”

“…Thus, emergence of fluoroquinolone-resistant bacteria due to antimicrobial treatment may present a serious challenge in clinical treatment of bacterial infections [2, 8]. Therefore, surveillance of fluoroquinolone-resistant bacteria could offer important information for the control of infectious diseases.…”

Association between virulence profile and fluoroquinolone resistance in Escherichia coli isolated from dogs and cats in China

“…All MIC determinations were performed in triplicate, and E. coli ATCC 25922 was used for quality control. In addition, the E. coli isolates with reduced susceptibility to oxyimino-cephalosporins were examined for extended-spectrum β-lactamase (ESBL) production using Sensititre ESBL confirmatory MIC plates (ESB1F, Thermo Scientific, Xi'an, China) as described by Aly et al [14]. …”

Mechanisms of antibiotic resistance to enrofloxacin in uropathogenic Escherichia coli in dog

“…The sim-experimental evidences it is possible to hypothesize the jump of mutated or resistant strains of E. coli from dog to humans. The antibiotic resistance of E. coli isolates from dogs has been as well already documented [15] and in particular to enrofloxacin that actually represents one of the most used antibiotics to counteract this infection [16]. Fluoroquinolones are inhibitors of bacterial DNA replication through the block of topoisomerase and DNA gyrase [17].…”