Tetracycline resistance determinants in Staphylococcus intermedius isolated from dogs in Jeju

Abstract

One hundred-two Staphylococcus intermedius were isolated from diseased dogs and healthy dogs to investigate the antimicrobial resistant rates on 15 commonly used drugs and tetracycline resistant gene (tet gene) was analysed on 78 tetracycline resistant isolates. Fifty-four S. intermedius isolates were recovered from oral cavity, nasal cavity and/or cranial hair coat cultures of 20 clinically healthy dogs. S. intermedius was colonized at more than one sites, including 18 (90.0%) cranial hair coat, 10 (50.0%) oral cavity, and 8(40.0%) nasal cavity of healthy dogs. Antibiograms of these commensal isolates were compared to antibiograms from 48 historical clinical isolates (2003-2006) obtained from cases of canine pyoderma (24), otitis externa (8), nasal discharge (12), pyometra (2) or cystitis (2). Antimicrobial resistant test were performed by disk diffusion test of CLSI and final resistance decisions on oxacillin and vancomycin were made by minimum inhibitory concentration. All isolates from both healthy and diseased dog were susceptible to vancomycin and only those from the former were sensitive to amoxicilline/clavulanic acid, and cefazolin, while 8 % of those from the latter were resistant to both antibiotics. Among S. intermedius isolates recovered from diseased dogs, resistance was most often seen to penicillin (85%), ampicillin (81%) tetracycline (79%), erythromycin (52%), trimethoprim/sulfamethoxazole (48%), kanamycin (44%), norfloxacin and ciplofloxacin (38%), and gentamicin (35%). Resistance was also noted, but to a lesser degree, to neomycin (23%) and cloramphenicol (17%). Among the S. intermedius isolates recovered from healthy dogs, resistance was most often observed to penicillin (80%), ampicillin (80%), tetracycline (78%), kanamycin (65%), and erythromycin (44%), trimethoprim/ sulfamethoxazole (43%) and gentamicin (33%). Resistance was also noted, but to a lesser degree, to chloramphenicol (28%), norfloxacin (22%), ciprofloxacin (20%) and neomycin (24%). The commensal isolates were lesser resistant to most antimicrobials than those of diseased dogs, exception with chloramphenicol, kanamycin, and neomycin. The data from this study might serve as a guideline in selecting drugs to be used for treating dogs with staphylococcal infections. S. intermedius harboring tet(M) and tet(K) were 62 (79.5%) and 3 (3.8%) strains, respectively and 3 (3.8%) and 4 (5.1%) isolates were harboring both tet(M) and tet(K), and tet(M) and tet(L), respectively.