Authors:Éva J. Kaszanyitzky, Zsuzsanna Egyed, Sz. Jánosi, Judit Keserű, Zsuzsanna Gál, I. Szabó, Zoltán Veres, and P. Somogyi
The antibiotic resistance pattern of 1921 Staphylococcus strains isolated from animals and food within the last two years were examined using diffusion tests. Among them there were only 35 strains of S. aureus having an inhibition zone diameter of 15 mm or less, and 4 strains of coagulase-negative staphylococci (CNS) having a zone diameter of 18 mm or less to 1-µg oxacillin disk. These 39 strains were examined also by E-test to oxacillin and for the detection of the mecA gene by PCR in order to determine whether they might be real methicillin-resistant staphylococci. Among the 39 strains there were only two that were susceptible to penicillin by disk diffusion method; however, further examination by the penicillinase test showed that they produced ß-lactamase. While 19 (15 S. aureus, 4 CNS) strains were resistant and 7 strains were intermediate to oxacillin in disk diffusion test, the E-test gave 8 resistant and 5 intermediate results. Six out of the 8 oxacillin-resistant strains examined by disk diffusion and E-test harboured the mecA gene. Thus only 6 out of the examined 1921 strains proved to be mecA positive. These methicillin-resistant, mecA-positive strains (5 of the S. aureus strains and 1 of the S. epidermidis) originated from two dairy herds. The results prove that methicillin-resistant S. aureus (MRSA) strains in animals are really rare in Hungary. Eighteen strains were chosen and screened for minimal inhibitory concentration (MIC) of oxacillin with or without clavulanic acid or sulbactam, and three of them produced methicillinase enzyme.
Authors:Éva J. Kaszanyitzky, Sz. Jánosi, Zsuzsanna Egyed, Gizella Ágost, and G. Semjén
Based on data of the Hungarian resistance monitoring system the antibiotic resistance of Staphylococcus strains of human and animal origin was studied. No methicillin-resistant staphylococci harbouring mecA gene were isolated from animals in 2001. Penicillin resistance, mediated by penicillinase production, was the most frequent among Staphylococcus aureus strains isolated from humans (96%), from bovine mastitis (55%), from foods (45%) and from dogs. In staphylococci isolated from animals low resistance percentages to aminoglycosides (0-2%), fluoroquinolones (0.5-3%) and sulphonamides (0.5-4%) were found but in strains isolated humans these figures were higher (1-14%, 5-18% and 3-31%, respectively). The most frequent antibiotic resistance profiles of strains isolated from animals and food were penicillin/tetracycline, penicillin/lincomycin and penicillin/lincomycin/tetracycline. Penicillin/tetracycline resistance was exhibited by strains from mastitis (3), samples from the meat industry (31), poultry flocks (1), poultry industry (1), noodle (1) and horses (2). Penicillin/lincomycin resistance was found in 10 Staphylococcus strains from mastitis, 1 from the dairy industry, 1 from the meat industry and 6 from dogs. Isolates from mastitis (2), from the dairy industry (2), from pigs (1), from the meat industry (1) and from poultry (1) harboured penicillin/lincomycin/tetracycline resistance pattern. Multiresistant strains were usually isolated only from one and sometimes from two animal species; therefore, the spread of defined resistant strains (clones) among different animal species could not be demonstrated. These results also suggest that the transfer of antibiotic resistance of S. aureus from animals to humans probably occurs less frequently than is generally assumed.