In vitro activity of fifteen antimicrobial agents against methicillin‐resistant and methicillin‐susceptible Staphylococcus intermedius

Abstract

In this study the susceptibility of 91 methicillin-resistant and -susceptible Staphylococcus intermedius strains (MRSI and MSSI, respectively) against 15 antimicrobial agents was determined. The activity of the antimicrobial agents was studied at pH 7.2 and pH 8.5. Methicillin was more active at pH 7.2 (28 strains methicillin-resistant) than at pH 8.5 (55 strains methicillin-resistant). Gentamicin showed excellent activity, with only 3 strains resistant at pH 8.5. However, gentamicin would have to be administered parenterally. Oxytetracycline cannot be recommended for treatment of canine staphylococcal dermatitis, due to the high percentage (over 25%) of strains that were found to be resistant. Clindamycin showed little activity in inhibiting growth of the strains studied, the percent resistance at pH 7.2 was 93.4%. Rifampin behaved differently at the two pH values. However, a close relationship was noted between methicillin-resistant and rifampin-resistant strains, particularly at the lower pH. Of the fluoroquinolones, ciprofloxacin or enrofloxacin would be a good useful alternative for the treatment of methicillin-resistant strains of S. intermedius. Lastly, very high resistance to sulphamethoxypyridazine was found, as was the case with trimethoprim and a combination of trimethoprim/sulphamethoxypyridazine, against not only MRSI but also MSSI strains.

Antimicrobial Susceptibility of Staphylococcus intermedius Isolated from Healthy and Diseased Dogs.

“…Thus, at present, chemotherapy is the most practical way to treat staphylococcal infections. There have been many studies on the in vitro effect of antimicrobial agents against strains of S. intermedius isolated from dogs [3,4,9,[11][12][13][14][15]17,18] and humans [21] in countries outside of Japan. However, no study of the antimicrobial susceptibility patterns of these isolates from dogs in Japan has been reported.…”

“…The increasing resistance of strains of S. intermedius to tetracyclines may be a reflection of tetracyclines' much wider use than other antimicrobial agents for veterinary use in many countries including Japan. Piriz et al [15] stated that OTC cannot be recommended for treatment of canine staphylococcal dermatitis, due to the high percentage (over 25%) of strains that were found to be resistant. In Japan, the frequency of resistance to KM (9 out of 90, 10%) and EM (7 out of 90, 7.8%) was slightly low compared with those in the United States (KM resistance, 7.6 to 25.7%; EM, 10.5 to 23.9%) [3,4,9,13].…”

“…However, methicillin-resistant S. intermedius strains have been isolated from dogs [6,14,15], but the frequency of isolation is of a low level [6].…”

Characterization of New Staphylococcal Cassette Chromosome mec (SCC mec ) and Topoisomerase Genes in Fluoroquinolone- and Methicillin-Resistant Staphylococcus pseudintermedius

“…Fluoroquinolones and cephalosporins are widely used to treat staphylococcal infections in veterinary medicine (23). The frequent use of these antibiotics may augment the risk of rapidly selecting for bacteria resistant to both classes of antibiotics.…”

Necessary Usage of Antibiotics in Animals

“…Resistance had been reported in Enterococcal strains obtained from animals to the macroloide lincosamide-streptogramin group including the common antibiotic of tylosin [48]. Resistant non-enteric bacteria were also commonly reported in respiratory tract pathogens in all livestocks and resistant Staphylococci from bovine mastitis and small animal infections [49].…”