Abstract

Background:
Staphylococcus aureus (S. aureus) is an important opportunistic pathogen in rabbits, where staphylococcosis can affect animal health and antimicrobial-resistant strains may complicate disease control. Information on phenotypic S. aureus occurrence and antimicrobial resistance (AMR) in rabbit production systems in Vietnam remains limited.

Aim:
This short communication aimed to describe the occurrence of phenotypically identified presumptive S. aureus in rabbit vaginal swabs, cage-floor swabs, and soybean meal samples from a single commercial rabbit farm in Can Tho City, Vietnam, and characterize the antimicrobial susceptibility and multidrug resistance (MDR) profiles of the recovered isolates.

Methods:
A cross-sectional exploratory study was conducted on one purposively selected commercial rabbit farm from November 2023 to May 2024. A total of 180 samples were collected: one vaginal swab from each of 70 sexually mature female rabbits, 50 cage-floor swabs, and 60 soybean meal samples. S. aureus was isolated on mannitol salt agar (MSA) and Baird–Parker agar (BPA) and phenotypically identified by catalase, coagulase and β-hemolysis testing. Antimicrobial susceptibility was assessed using the Kirby–Bauer disc diffusion method. Exact binomial 95% confidence intervals (CIs) were calculated for resistance percentages. Source-based and Jaccard clustering analyses were treated as descriptive and exploratory because of the single-farm design and small number of isolates.

Results:
Phenotypically identified presumptive S. aureus was recovered from 12/180 samples (6.67%): 6/70 rabbit vaginal swabs (8.57%), 3/50 cage-floor swabs (6.00%), and 3/60 soybean meal samples (5.00%). Fisher’s exact test yielded p = 0.752, which was treated as exploratory rather than evidence of population-level equivalence among sources. Resistance was recorded for penicillin in 10/12 isolates (83.33%; 95% CI 51.59–97.91), kanamycin and cephalexin in 7/12 each (58.33%; 27.67–84.83), streptomycin in 6/12 (50.00%; 21.09–78.91), gentamicin and amoxicillin in 5/12 each (41.67%; 15.17–72.33), ceftizoxime and tobramycin in 4/12 each (33.33%; 9.92–65.11), cefotaxime in 3/12 (25.00%; 5.49–57.19), and piperacillin in 1/12 (8.33%; 0.21–38.48). MDR was identified in 10/12 isolates (83.33%).

Conclusion:
This single-farm study provides preliminary phenotypic evidence that putative S. aureus with multidrug-resistant profiles can be recovered from rabbit-associated, cage-floor, and feed-related samples. Because species identity was not molecularly confirmed, no reference quality-control strain was available for disc diffusion testing, methicillin-resistant Staphylococcus aureus (MRSA) screening was not performed, and only 12 isolates were recovered, the findings should not be generalized beyond the sampled farm. Larger multi-farm studies incorporating confirmation of molecular species, validated antimicrobial susceptibility testing (AST) quality control, mecA/mecC testing, and resistance-gene or genomic characterization are required.

Key words: Antimicrobial resistance; Can Tho City; Preliminary phenotypic screening; Rabbit; Staphylococcus aureus.