Antibacterial susceptibility patterns of Pseudomonas strains isolated fromchronic canine otitis externa

Development of antibiotic resistance in bacteria is a problem of great conc ern. It is important to establish the convenience of antimicrobial suscepti bility tests in animal infections. Thr aim of this study was to test the su sceptibility to antibiotics of Pseudomonas strains isolated from chronic ca nine otitis esterna. We tested 23 strains of Pseudomonas: 19 Ps. aeruginosa , three Ps. fluorescens and one Pseudomonas spp The most effective antibiot ics were tobramycin (100 % susceptible), marbofloxacin (91.3 %) and ceftazi dime (91.3 %). Ticarcillin and gentamicin, commonly used fur the treatment of otitis externa also showed good results (susceptibility of strains was 8 6 and 65.2 % respectively). Lower susceptibility was found using enrofloxac in (52.1 %) probably due to its indiscriminate use. We emphasize the need f or a rational policy of antibiotic prescribing in order to prevent the sele ction of resistant strains.