Microorganisms (Nov 2021)

In Vitro Killing of Canine Urinary Tract Infection Pathogens by Ampicillin, Cephalexin, Marbofloxacin, Pradofloxacin, and Trimethoprim/Sulfamethoxazole

  • Joseph M. Blondeau,
  • Shantelle D. Fitch

DOI
https://doi.org/10.3390/microorganisms9112279
Journal volume & issue
Vol. 9, no. 11
p. 2279

Abstract

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Urinary tract infections are common in dogs, necessitating antimicrobial therapy. We determined the speed and extent of in vitro killing of canine urinary tract infection pathogens by five antimicrobial agents (ampicillin, cephalexin, marbofloxacin, pradofloxacin, and trimethoprim/sulfamethoxazole) following the first 3 h of drug exposure. Minimum inhibitory and mutant prevention drug concentrations were determined for each strain. In vitro killing was determined by exposing bacteria to clinically relevant drug concentrations and recording the log10 reduction and percent kill in viable cells at timed intervals. Marbofloxacin and pradofloxacin killed more bacterial cells, and faster than other agents, depending on the time of sampling and drug concentration. Significant differences were seen between drugs for killing Escherichia coli, Proteus mirabilis, Enterococcus faecalis, and Staphylococcus pseudintermedius strains. At the maximum urine drug concentrations, significantly more E. coli cells were killed by marbofloxacin than by ampicillin (p p p p p < 0.0001), following 5 min of drug exposure. Rapid killing of bacteria should inform thinking on drug selection for short course therapy for uncomplicated UTIs, without compromising patient care, and is consistent with appropriate antimicrobial use and stewardship principles.

Keywords