Use of aminoglycoside antibiotics in equine clinical practice; a questionnaire‐based study of current use

Abstract

Veterinary use of the aminoglycoside antibiotics is under increasing scrutiny. This questionnaire‐based study aimed to document the use of aminoglycosides with a particular focus on gentamicin. An online questionnaire was delivered to generalist equine veterinary surgeons and specialists in internal medicine to determine the perceived importance, frequency of use and routes of administration of the aminoglycoside antibiotics. A series of hypothetical scenarios were also evaluated regarding gentamicin. Data were compared to evaluate the impact of the level of specialisation on prescribing practices for different antibiotics using Chi‐squared and Fischer's exact tests. Data were analysed from 111 responses. Gentamicin was commonly used empirically without culture and susceptibility testing. Generalists were more likely to use gentamicin only after susceptibility testing than specialists in a variety of clinical presentations including respiratory diseases, septic peritonitis, acute febrile diarrhoea, cellulitis and contaminated limb wounds (p < 0.01). Intravenous administration of gentamicin was most common, although inhaled and regional administration of gentamicin and amikacin were also described. Amikacin was most commonly used by intra‐articular administration. Gentamicin was more likely to be used in high‐risk procedures or contaminated surgeries (86% and 74%, respectively) compared with clean surgery (32%; p < 0.0001). Gentamicin was often used perioperatively in horses undergoing exploratory celiotomy and more commonly used in horses undergoing an enterotomy (90%) than without and enterotomy (79%; p = 0.04). Most respondents (86%) used gentamicin at a dose of 6.6 mg/kg in adults, with few changing their dosing strategies based on the presence of sepsis, although higher doses were more reported in foals (7–15 mg/kg) irrespective of the presence of sepsis. Aminoglycosides are widely used in equine practice and use outside current EU marketing authorisations is common. Stewardship of the aminoglycoside antibiotics could be enhanced in both generalists and specialists through the more frequent use of susceptibility testing, regional administration and dose adjustment, especially in foals.

Current Antimicrobial Use in Horses Undergoing Exploratory Celiotomy: A Survey of Board-Certified Equine Specialists

“…Guidelines for antibiotic selection in equine patients have been adapted from human medicine and typically include the implementation of early-generation broad-spectrum antimicrobials given intravenously prior to surgery [1,5,20,27]. The findings of this study were generally in concordance with that recommendation as well as previous reports [9], with two drug classes being administered most commonly preoperatively, frequently potassium penicillin and gentamicin [28]. As surgical site infections (SSI) are the second most commonly reported short-term complication following celiotomy (after persistent postoperative signs of colic) [29], antimicrobial selection should be dictated by efficacy against common pathogens.…”

“…Aminoglycosides such as gentamicin are effective against Enterobacteriaceae and, in some instances, Staphylococci, although systemic administration is considered extra-label use as the only FDA-approved indication for horses is via intra-uterine infusion [28]. Penicillin is also used extra-label to treat infections in horses, including Streptococcus.…”

Expanded catalogue of metagenome-assembled genomes reveals resistome characteristics and athletic performance-associated microbes in horse

“…However, the aminoglycoside resistance genes were the most abundant ARG in the intestines of horses. The high abundance of aminoglycoside resistance genes has a potential negative impact on horse health given that aminoglycoside was widely used to treat respiratory diseases, septic peritonitis, acute febrile diarrhoea, and cellulitis in horses [ 83 , 84 ].

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Surgical antimicrobial prophylaxis: Current standards of care

“…There are limited options in equine surgery and the most commonly used surgical prophylactic antimicrobials are penicillin and gentamicin(Traub-Dargatz et al, 2002). Importantly, the World Health Organization (WHO) has reclassified aminoglycoside antimicrobials as critically important antimicrobials (CIA,Redpath et al, 2021; WHO, 2018) and it might be time to reconsider their use, particularly the use of gentamicin for SAP. Highest priority critically important antimicrobials (HPCIAs), such as quinolones, third, fourth and fifth generation cephalosporins, macrolides, rifampicin and polymixin B, should not be used for SAP or non-antimicrobial purposes in horses.Whilst there have been numerous studies on SAP in human surgery, there have been fewer studies in equine surgery.…”