Antimicrobial and Biocide Resistance among Feline and Canine Staphylococcus aureus and Staphylococcus pseudintermedius Isolates from Diagnostic Submissions

Abstract

A total of 114 Staphylococcus isolates from various infections of companion animals, including 43 feline Staphylococcus aureus, 19 canine S. aureus, 11 feline Staphylococcus pseudintermedius and 41 canine S. pseudintermedius were investigated for (i) their susceptibility to 24 antimicrobial agents and three combinations of antimicrobial agents by broth microdilution following CLSI recommendations and (ii) the corresponding resistance genes. In addition, the isolates were tested for their susceptibility to the four biocides benzalkonium chloride, chlorhexidine, polyhexanide and octenidine by a recently developed biocide susceptibility testing protocol. Penicillin resistance via blaZ was the dominant resistance property in all four groups of isolates ranging between 76.7 and 90.9%. About one quarter of the isolates (25.4%) proved to be methicillin-resistant and carried the genes mecA or mecC. Macrolide resistance was the second most prevalent resistance property (27.2%) and all isolates harbored the resistance genes erm(A), erm(B), erm(C), erm(T) or msr(A), alone or in combinations. Fluoroquinolone resistance was detected in 21.1% of all isolates tested, whereas tetracycline resistance via tet(K) and/or tet(M) occurred in 19.3% of the isolates. Resistance to last resort antimicrobial agents in human medicine was seen only in single isolates, if at all. The minimal inhibitory concentrations (MICs) of the four biocides showed unimodal distributions and were very similar for the four groups of staphylococci. Because of the large number of (multi)resistant isolates, antimicrobial susceptibility testing of feline and canine S. aureus and S. pseudintermedius isolates is highly recommended before the start of an antimicrobial chemotherapy. Moreover, no hints towards the development of biocide resistance were detected.

Resistance to Critical Important Antibacterials in Staphylococcus pseudintermedius Strains of Veterinary Origin

“…Noticeably, all strains were susceptible to fusidic acid, conversely more than what was reported elsewhere [ 10 ]. The prevalence of resistant strains is similar to a previous report in Italy [ 11 ] but higher than reported in other geographical areas [ 4 , 10 , 19 , 20 , 21 ]. Most strains were resistant to penicillin and up to 60% were resistant to oxacillin, a percentage higher than recently reported in dogs [ 10 , 20 , 21 ] and cats [ 19 , 20 ].…”

“…The prevalence of resistant strains is similar to a previous report in Italy [ 11 ] but higher than reported in other geographical areas [ 4 , 10 , 19 , 20 , 21 ]. Most strains were resistant to penicillin and up to 60% were resistant to oxacillin, a percentage higher than recently reported in dogs [ 10 , 20 , 21 ] and cats [ 19 , 20 ]. In staphylococci, methicillin-resistance is noticeable not only because it involves the resistance to many beta-lactams and cephalosporins but also because it is related to increased resistance towards other antibacterials [ 21 ].…”

“…The strains resistant to aminoglycosides, macrolides and lincosamides, quinolones, sulfamethoxazole-trimethoprim, and tetracyclines were over 50%, again, percentages higher than recently reported in recent studies [ 19 , 20 , 21 ] but in line with others [ 10 , 11 ]. Accordingly, the 60%prevalence of multi-drug resistant strains was higher as well.…”

“…The sample size was satisfactory for a preliminary assessment in terms of prevalence of resistant strains, even if having collected cases over a longer period would have helped the generalizability of the results. The proportion of feline patients confirmed the low prevalence observed in cats [ 19 ] and the higher occurrence of S. pseudintermedius infection in dogs [ 20 ].…”

Exploring Efflux as a Mechanism of Reduced Susceptibility towards Biocides and Fluoroquinolones in Staphylococcus pseudintermedius

“…Similarly to Staphylococcus aureus , the emergence of methicillin-resistant S. pseudintermedius (MRSP) strains, frequently associated with multidrug resistance (MDR) phenotypes is a public health concern [ 10 ]. One approach to mitigate the rising antibiotic resistance in this pathogen include the use of biocides on topical therapy [ 6 , 7 ], since these are effective and show low rates of emergence of resistance [ 4 , 11 , 12 ].…”