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

Abstract

Staphylococcal infections represent a challenge in companion animals and hospitalized patients. This study aimed to assess the resistance of Staphylococcus pseudintermedius isolates, against a broad panel of antibacterials, including exclusive to human medicine. A total of 40 S. pseudintermedius were collected from clinical specimens of dogs (n = 31) and cats (n = 5). All strains were tested for 20 antibacterials, namely 14 Critical Important and eight Highly Important Antibacterials (CIA and HIA, respectively), indicative for 18 antimicrobial classes. All strains were susceptible to seven antibiotics (daptomycin, fosfomycin, fusidic acid, linezolid, quinupristin-dalfopristin, teicoplanin/vancomycin, tigecycline). The highest resistance was against penicillin (97.5% Confidence Interval [CI]: 83.8-100.0), whereas the lowest against telavancin (2.5%, CI: 0.0-16.2). Resistance versus Highest Priority CIA was observed, namely against macrolides (70.0, CI: 52.1-84.3), quinolones (62.5, CI: 44.5-78.3), 5th generation cephalosporins (7.5, CI: 1.3-21.6), and glycopeptides (2.5%, CI: 0.0-14.2). Among High Priority CIA, strains were resistant only to aminoglycosides (65.0, CI: 47.0-80.4) and ansamycins (12.5, CI: 3.8-28.1). We observed the highest resistance against veterinary medicine antibacterials, but there was also resistance against antibacterials exclusive to human medicine, namely ceftaroline (7.5, CI: 1.0-23.8) and telavancin. S. pseudintermedius zoonotic potential and its rate of acquisition of new resistance should encourage surveillance on a broad spectrum of antibacterials.

Keywords: Italy; Staphylococcus pseudintermedius; antimicrobial resistance; antimicrobial susceptibility testing; cat; critically important antimicrobials; dog.

Figure 1

Bar plot of the prevalence of resistant strains (a). The height of the bars represents the point estimate prevalence of resistantstrains (R) to each antibacterial, with error bars indicating the 90% confidence intervals. Under the antibacterial name, World Health Organization (WHO and AWaRe) and European Medicines Agency (AMEG) classifications are reported. Box plots of the frequency of R strains (b). Data are aggregated by WHO, AWaRe and AMEG categories (*: p < 0.05; **: p < 0.01). Category abbreviations: HPCIA: Highest Priority, Critically Important Antimicrobials; HCIA: High priority, Critically Important Antimicrobials; HIA: Highly Important Antimicrobials. Antibacterial abbreviations: P: penicillin G; OX: oxacillin; FOS: fosfomycin; ENR: enrofloxacin; CIP: ciprofloxacin; SXT: trimethoprim-sulfamethoxazole; RD: rifampicin; C: chloramphenicol; E: erythromycin; DA: clindamycin; TE: tetracycline; TGC: tigecycline; CN: gentamycin; FD: fusidic acid; CPT: ceftaroline; TEC/VA: teicoplanin/vancomycin; TLV: telavancin; DAP: daptomycin; QDA: quinupristin-dalfopristin; LNZ: linezolid. Note: the colours are those used by WHO and EMA to identify the categories of antibacterials.