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Prophylactic antimicrobials administered in rams before elective castration are detectable in resected tissues and
Ronan J J Chapuis1,2, Sean Moore3, Walter R Vandaveer3
11Institut Polytechnique UniLaSalle, Université d'Artois, IDEALISS, Mont-Saint-Aignan, France.
Objective:
To report the incidence of intraoperative surgical site positive bacterial cultures and occurrence of postoperative infection following elective castration in rams and to measure, in different units, the concentrations of benzylpenicillin, ampicillin, and oxytetracycline in resected tissues following preoperative SC administration.
Methods:
In January and February 2016, healthy rams were enrolled before elective castration and were randomly assigned to the control group (saline) or subcutaneous treatment groups (22,000 IU/kg of procaine benzylpenicillin, 6.6 mg/kg of ampicillin trihydrate, or 6.6 mg/kg of oxytetracycline dihydrate administered within 2 hours before resection of the tissues). Excised tissues were sampled to measure drug concentrations by reverse phase high-performance liquid chromatography-tandem mass spectrometry. The surgical site was swabbed at the end of the procedure for anaerobic and aerobic cultures. Rams were monitored for 2 weeks after surgery. The tissues' weight-to-volume ratio in 10 additional rams was measured in May 2022 to allow conversion of drug concentration from ng/g to µg/mL.
Results:
No microbial growth or postoperative complications were detected in 46 rams. The concentration of benzylpenicillin, ampicillin, and oxytetracycline was successfully measured in all tissues and reported in ng/mL and µg/mL.
Conclusions:
Prophylactic administration of antimicrobials is unlikely indicated for elective castration in rams in a hospital setting. Concentrations of antimicrobials were detected in resected tissues within 2 hours after SC injection. The relevance of the conversion of drug concentration from ng/g to µg/mL needs further investigation.
Clinical Relevance:
Avoiding prophylactic administration of antimicrobials for elective castration aligns with the principles of antimicrobial stewardship. Without sound rationales, extralabel routes of injection should be discouraged in rams undergoing castration.
Insights
Prophylactic antibiotics are not recommended for elective ram castration, as no infections occurred. Antimicrobial concentrations were detected in tissues post-injection, but their clinical significance requires further study.
Area of Science:
- Veterinary Medicine
- Pharmacology
- Surgical Science
Background:
- Elective castration in rams is a common procedure.
- The use of prophylactic antimicrobials in this context is debated.
- Understanding antimicrobial tissue concentrations is crucial for drug efficacy and resistance management.
Purpose of the Study:
- To determine the incidence of surgical site infections and positive bacterial cultures after elective ram castration.
- To measure benzylpenicillin, ampicillin, and oxytetracycline concentrations in resected tissues after preoperative subcutaneous administration.
- To evaluate the necessity of prophylactic antimicrobial use in this procedure.
Main Methods:
- Healthy rams underwent elective castration and were assigned to control or antimicrobial treatment groups (benzylpenicillin, ampicillin, or oxytetracycline).
- Drug concentrations in resected tissues were quantified using high-performance liquid chromatography-tandem mass spectrometry.
- Surgical sites were cultured, and rams were monitored for postoperative complications.
Main Results:
- No microbial growth or postoperative complications were observed in any of the rams.
- Antimicrobial concentrations (benzylpenicillin, ampicillin, oxytetracycline) were successfully measured in all tested tissues.
- Drug concentrations were reported in both ng/mL and µg/mL.
Conclusions:
- Prophylactic antimicrobial administration is likely unnecessary for elective castration in rams within a hospital setting.
- Detected antimicrobial concentrations in tissues confirm drug absorption post-subcutaneous injection.
- Further research is needed to clarify the clinical relevance of measured antimicrobial concentrations and the conversion between units (ng/g to µg/mL).
