Comparison of antimicrobial resistance in bacterial isolates from dogs in a veterinary diagnostic laboratory in Colombia between two consecutive four-year periods

Abstract

Background: Antimicrobial resistance (AMR) and the increase in multi-drug-resistant bacteria are among the most important threats to human and veterinary medicine, according to the World Health Organization. Objective: To compare the antimicrobial susceptibility patterns in bacterial isolates from dogs over two consecutive four-year periods. Methods: The Animal Microbiology Laboratory database of the Agrarian Sciences Faculty at the University of Antioquia (Medellín, Colombia) was searched for routine canine submissions in which culture and antibiograms were performed. Results: A total of 1,146 samples were submitted between 2020 and August 2023 for culture and susceptibility testing, from which 805 (70.2%) isolates were recovered. Of these 805 isolates, susceptibility testing was performed on 799 samples. A significant decrease in susceptibility between 2016-2019 and 2020-August 2023 was noted in dog isolates for some antimicrobials: Escherichia coli to amoxicillin-clavulanate (66.7-53.1%; p<0.01) and ampicillin (67.7-58%; p<0.05), Enterobacteriaceae to amikacin (100-94.3%; p<0.01), ampicillin (61.8-45.7%; p<0.01), and trimethoprim-sulfadiazine (83.9-75.6%; p<0.05), Staphylococcus pseudointermedius to gentamicin (63.9-52.5%; p<0.01), trimethoprim-sulfadiazine (57-50%; p<0.05), and doxycycline (60.9-43.4%; p<0.01). Significantly increased susceptibilities were also noted in E. coli to enrofloxacin (69.2-78.7%; p<0.05) and doxycycline (68.7-76.2%; p=0.0745) and in Enterobacteriaceae to enrofloxacin (64.4-79.3%; p<0.01), and doxycycline (38.7-47.7%; p=0.06). For all bacterial isolates, an increasing resistance trend was observed for amoxicillin-clavulanate. All Staphylococcus species showed low resistance to amikacin (<10%); moderate resistance (10-20%) to amoxicillin-clavulanate, cephalexin, cefovecin, and enrofloxacin; high resistance (20-50%) to ampicillin, gentamicin, trimethoprim-sulfadiazine, and clindamycin; and very high resistance (50-70%) to doxycycline. For other bacterial families, the number of antimicrobials with high (20-50%) or very high (50-70%) resistance rates was: Enterobacteriaceae (7/9), Enterococcus spp. (4/7), E. coli (10/12), and Streptococcus spp. (4/6). For urinary tract infections caused by E. coli or Enterobacteriaceae (Klebsiella spp., Proteus spp.), amikacin and gentamicin were the only drugs that demonstrated low (<10%) in vitro resistance. Multidrug resistance slightly increased from 2016-2019 (18.7%; 247/1,316) to 2020-August 2023 (19.7%; 150/761). decrease in susceptibility rather than an increase in resistance (28 vs. 20). Conclusion: High resistance rates highlight the need for continued surveillance and reinforce the importance of antibiograms to guide clinical decisions.