How Restrictive Legislation Influences Antimicrobial Susceptibility in Selected Bacterial Isolates from the Canine Vagina

Abstract

Antimicrobial stewardship is one of the cornerstones in the battle against antimicrobial resistance. Restrictive legislation aims to foster antimicrobial stewardship. Prophylactic prescription of antimicrobials is still a widespread practice in canine breeding management to prevent suspected infectious infertility. The aim of this study was to evaluate the efficacy of restrictive legislation in Germany (Veterinary Home Pharmacy Ordinance, TÄHAV) based on resistance profiles of common bacterial isolates from the vaginal tract by comparing the resistance situation before (time frame (TF1)) and after (TF2) its amendment. In total, results of 13,373 antimicrobial susceptibility tests of bacterial isolates of Escherichia coli (n = 5209), beta-hemolytic streptococci (n = 4010), and Staphylococcus (Staph.) intermedius group (n = 4154) derived from canine vaginal swabs were assessed. Antimicrobial susceptibility testing was performed on pure cultures using the broth microdilution method. Susceptibility to selected antimicrobials was evaluated. Susceptibility of Escherichia coli generally increased within TF2 with, however, a significant increase in the number of non-susceptible isolates to cefalexin (p < 0.0001). Beta-hemolytic streptococci exhibited good susceptibility to most antimicrobials. Susceptibility developed ambivalently within the Staphylococcus intermedius group. Despite an overall positive effect of increased susceptibility, an increase in non-susceptibility to single antimicrobials was detected, possibly indicating a need for refinement of the legislation.

Keywords: antibiotics; antimicrobial resistance; antimicrobial susceptibility; canine reproduction; canine vaginal flora; dog; vaginal flora; veterinary microbiology.

Figure 1

Development of susceptibility of E. coli before (time frame 1 (TF1), n = 1902) and after (time frame 2 (TF2), n = 3307) the 2018 amendment to the Veterinary Home Pharmacy Ordinance (Tierärztliche Hausapothekenverordnung, TÄHAV). Results are presented as percentage (%) of susceptible isolates. Penicillin G was excluded from the analysis due to intrinsic resistance. * p < 0.05.

Figure 2

Development of susceptibility of beta-hemolytic streptococci before (time frame 1 (TF1), n = 1537) and after (time frame 2 (TF2), n = 2473) the 2018 amendment to the Veterinary Home Pharmacy Ordinance (Tierärztliche Hausapothekenverordnung, TÄHAV). Results are presented as percentage (%) of susceptible isolates. Gentamicin was excluded from the analysis due to intrinsic resistance. * p < 0.05.

Figure 3

Development of susceptibility of Staph. intermedius group before (time frame 1 (TF1), n = 1603) and after (time frame 2 (TF2), n = 2551) the 2018 amendment to the Veterinary Home Pharmacy Ordinance (Tierärztliche Hausapothekenverordnung, TÄHAV). Results are presented as percentage (%) of susceptible isolates. * p < 0.05.