Sensitivity of certain porcine and bovine mycoplasmas to antimicrobial agents in a liquid medium test compared to a disc assay.

The sensitivity of some porcine and bovine mycoplasmas to potent antimicrobial agents was examined. Minimal inhibitory concentration (MIC) values were estimated for M. hyosynoviae, M. hyopneumoniae, M. dispar and M. bovis against enrofloxacin, lincomycin, tetracycline, tiamulin and tylosin, in a liquid medium test and in a disc assay. All 6 examined strains of each species and the respective type strains were significantly inhibited. The greatest sensitivity was noted for tiamulin against strains of M. hyosynoviae with a final MIC50 broth value of 0.025 micrograms ml-1 and disc value of 0.03 microgram per disc. Enrofloxacin was found very potent against M. hyopneumoniae with a final MIC50 of 0.025 microgram ml-1 and 0.1 microgram per disc, and for M. dispar with 0.05 microgram ml-1 and 0.03 microgram per disc. Most disc assay estimates in micrograms per disc were similar to or moderately greater than corresponding final broth figures in microgram ml-1. It may be possible to convert observed disc assay values into representative final broth MIC values for use in the clinic.

[Study of the elimination of residues and local tissue injury following intramuscular injection of a solution of the combination trimethoprim/sulfatroxazole in pigs]. / Onderzoek naar de eliminatie van residuen en lokale weefselbeschadiging na intramusculaire injectie van een oplossing van de combinatie van trimethoprim/sulfatroxazol bij varkens.

Two different studies are described. The first study deals with the elimination of residues of trimethoprim (TMP), sulfatroxazole (STX) and its main metabolite N4-acetyl-sulfatroxazole (N4-acetyl-STX) in pigs. Thirty -six pigs were treated with trimethoprim/sulfatroxazole IM in the nec k at a dosage of 16 mg/kg body weight for five days. Groups of four pig s were slaughtered at different time intervals. The study showed that concentration of STX, N4-acetyl-STX and TMP in edible tissues and at the injection sites were below 0.1 ppm on day nine after the last injection. S TX was eliminated the slowest, and STX can therefore be selected as a marker for residues of the trimethoprim/sulfatroxazole formulation in the tissues. The second study deals with irritation aspects of this trimethoprim /sulfatroxazole formulation. Four pigs of 32-35 kg were treated IM w with trimethoprim/sulfatroxazole and benzylpenicillin sodium. Each pig received the same injection volume, namely four trimethoprim/sulfatroxazole injections (16 mg/kg body weight per injection site), two in the back and two in the neck muscle, and two benzylpenicillin sodium injections (20,000 I.U./kg body weight per injection site), in the back muscle. All pigs were slaughtered 14 days after treatment and the extent of the irritation was compared. There were no differences between trimethoprim/sulfatroxazole and benzylpenicillin sodium with regard to irritation at the injection site in the back muscle. The irritation in the neck site was statistically less prominent than that in the back muscle and was considered not to affect the quality of the meat.