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In vitro activity of five tetracyclines and some other antimicrobial agents against four porcine respiratory tract pathogens
Author(s) -
PIJPERS A.,
KLINGEREN B. VAN,
SCHOEVERS E.J.,
VERHEIJDEN J. H. M.,
MIERT A. S.J. P. A. M. VAN
Publication year - 1989
Publication title -
journal of veterinary pharmacology and therapeutics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.527
H-Index - 60
eISSN - 1365-2885
pISSN - 0140-7783
DOI - 10.1111/j.1365-2885.1989.tb00670.x
Subject(s) - oxytetracycline , microbiology and biotechnology , flumequine , actinobacillus pleuropneumoniae , antimicrobial , lincomycin , bordetella bronchiseptica , pasteurella multocida , spiramycin , tetracycline , tilmicosin , chemistry , antibiotics , biology , ciprofloxacin , enrofloxacin , erythromycin , bacteria , serotype , genetics
The minimal inhibitory concentrations ( MIC ) of five tetracyclines and ten other antimicrobial agents were determined for four porcine bacterial respiratory tract pathogens by the agar dilution method. For the following oxytetracycline‐susceptible strains, the MIC 50 ranges of the tetracyclines were: P. multocida ( n = 17) 0.25–0.5 μg/ml; B. bronchiseptica ( n = 20) 0.25–1.0 μg/ml; H. pleuropneumoniae ( n = 20) 0.25–0.5 μg/ml; S. suis Type 2 ( n = 20) 0.06–0.25 μg/ml. For 19 oxytetracycline‐resistant P. multocida strains the MIC 50 of the tetracyclines varied from 64 μg/ml for oxytetracycline to 0.5 μg/ml for minocycline. Strikingly, minocycline showed no cross‐resistance with oxytetracycline, tetracycline, chlortetracycline and doxycycline in P. multocida and in H. pleuropneumoniae. Moreover, in susceptible strains minocycline showed the highest in vitro activity followed by doxycycline. Low MIC 50 values were observed for chloramphenicol, ampkillin, flumequine, ofloxacin and ciprofloxacin against P. multocida and H. pleuropneumoniae. B. bronchiseptica was moderately susceptible or resistant to these compounds. As expected tiamulin, lindomycin, tylosin and spiramycin were not active against H. pleuropneumoniae. Except for flumequine, the MIC 50 values of nine antimicrobial agents were low for S. suis Type 2. Six strains of this species showed resistance to the macrolides and lincomycin.