title: Antimicrobial susceptibility patterns of clinical Escherichia coli isolates from dogs and cats in the United States: January 2008 through January 2013.
abstract: Escherichia coli is among the most common bacterial pathogens in dogs and cats. The lack of a national monitoring program limits evidence-based empirical antimicrobial choices in the United States. This study describes antimicrobial susceptibility patterns for presumed clinical E. coli isolates from dogs (n=2392) or cats (n=780) collected from six geographic regions in the United States between May 2008 and January 2013. Minimum inhibitory concentrations (MIC) were determined for 17 drugs representing 6 drug classes. Urinary tract isolates were most common (71%). Population MIC distributions were generally bimodal with the second mode above the resistant breakpoint for all drugs except gentamicin, amikacin, and meropenem. The MIC90 exceeded the susceptible breakpoint for ampicillin, amoxicillin-clavulanic acid, cephalothin (surrogate drug for cephalexin), and doxycycline but was below the susceptible breakpoint for all others. None of isolates was susceptible or resistant to all drug tested; 46% were resistant to 1 or 2 antimicrobial categories, and 52% to more than three categories. The resistance percentages were as follows: doxycycline (100%), cephalothin (98%)>ampicillin (48%)>amoxicillin-clavulanic acid (40%)>ticarcillin-clavulanic acid (18%)>cefpodoxime (13%), cefotaxime (12%), cefoxitin (11%), cefazolin (11%), enrofloxacin (10%), chloramphenicol (9.6%)>ciprofloxacin (9.2%), ceftazidime (8.7%), trimethoprim-sulfamethoxazole (7.9%), gentamicin (7.9%)>meropenem (1.5%), amikacin (0.7%) (P<0.05). Resistance to ampicillin and amoxicillin-clavulanic acid was greatest in the South-Central region (P<0.05). E. coli resistance may preclude empirical treatment with doxycycline, cephalexin, ampicillin, or amoxicillin-clavulanic acid. Based on susceptibility patterns, trimethoprim-sulfonamides may be the preferred empirical oral treatment.
authors.affiliation: Departments of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, AL, United States.
authors.forename: Kamoltip
authors.initials: K
authors.lastname: Thungrat
authors.affiliation: Department of Pathobiology, College of Veterinary Medicine, Auburn University, AL, United States.
authors.forename: Stuart B
authors.initials: SB
authors.lastname: Price
authors.affiliation: Department of Mathematics and Statistics, College of Science and Mathematics, Auburn University, AL, United States.
authors.forename: D Mark
authors.initials: DM
authors.lastname: Carpenter
authors.affiliation: Departments of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, AL, United States. Electronic address: boothdm@auburn.edu.
authors.forename: Dawn Merton
authors.initials: DM
authors.lastname: Boothe
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002371:Cat Diseases / Q000453:epidemiology / Q000382:microbiology*; D002415:Cats; D004283:Dog Diseases / Q000453:epidemiology / Q000382:microbiology*; D004285:Dogs; D024881:Drug Resistance, Bacterial / Q000187:drug effects; D004926:Escherichia coli / Q000187:drug effects* / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000453:epidemiology / Q000382:microbiology / Q000662:veterinary*; D008826:Microbial Sensitivity Tests / Q000662:veterinary; D014481:United States / Q000453:epidemiology
chemical_list: D000900:Anti-Bacterial Agents
keywords: Antimicrobials; E. coli; Infections; Resistance