TY - JOUR
T1 - Aminoglycoside-Resistant Streptococcus and Enterococcus Species Isolated from Bovine Mammary Secretions
AU - Jayarao, B. M.
AU - Oliver, S. P.
N1 - Funding Information:
This investigation was supported by the Tennessee Agricultural Experiment Station and the University of Tennessee College of Veterinary Medicine Center of Excellence Research Program in Livestock Diseases and Human Health. Authors express their appreciation to Arlene Stewart for excellent clerical assistance.
PY - 1992
Y1 - 1992
N2 - A total of 117 isolates representing four Streptococcus species and 20 isolates representing two Enterococcus species from bovine mammary secretions were examined for resistance to streptomycin, kanamycin, and gentamicin. Resistance to streptomycin (85.4%) was most prevalent, followed by kanamycin (19%) and gentamicin (2.2%). Minimum inhibitory concentration of streptomycin for most organisms examined ranged from 16 to 250 µg/ml. For kanamycin, the minimum inhibitory concentration for most organisms was .5 to 62.5 µg/ml. Minimum inhibitory concentration for gentamicin was lower than for kanamycin. Two strains each of Streptococcus uberis and Enterococcus faecalis had minimum inhibitory concentration for streptomycin of >2000 µg/ml, and two strains of E. faecalis had similar minimum inhibitory concentration for kanamycin. The minimum bactericidal concentration for all organisms was one to four times higher than minimum inhibitory concentration. None of the organisms evaluated was found to carry plasmids. Transfer of antibiotic resistance in plasmid-free strains was not achieved by mobilization with the aid of plasmid pAD1, indicating the absence of conjugative transposons. These data suggest that expression of aminoglycoside resistance of Streptococcus and Enterococcus species of bovine origin is likely due to factors other than plasmids or conjugative transposons.
AB - A total of 117 isolates representing four Streptococcus species and 20 isolates representing two Enterococcus species from bovine mammary secretions were examined for resistance to streptomycin, kanamycin, and gentamicin. Resistance to streptomycin (85.4%) was most prevalent, followed by kanamycin (19%) and gentamicin (2.2%). Minimum inhibitory concentration of streptomycin for most organisms examined ranged from 16 to 250 µg/ml. For kanamycin, the minimum inhibitory concentration for most organisms was .5 to 62.5 µg/ml. Minimum inhibitory concentration for gentamicin was lower than for kanamycin. Two strains each of Streptococcus uberis and Enterococcus faecalis had minimum inhibitory concentration for streptomycin of >2000 µg/ml, and two strains of E. faecalis had similar minimum inhibitory concentration for kanamycin. The minimum bactericidal concentration for all organisms was one to four times higher than minimum inhibitory concentration. None of the organisms evaluated was found to carry plasmids. Transfer of antibiotic resistance in plasmid-free strains was not achieved by mobilization with the aid of plasmid pAD1, indicating the absence of conjugative transposons. These data suggest that expression of aminoglycoside resistance of Streptococcus and Enterococcus species of bovine origin is likely due to factors other than plasmids or conjugative transposons.
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U2 - 10.3168/jds.S0022-0302(92)77841-2
DO - 10.3168/jds.S0022-0302(92)77841-2
M3 - Article
C2 - 1578037
AN - SCOPUS:0026842211
SN - 0022-0302
VL - 75
SP - 991
EP - 997
JO - Journal of dairy science
JF - Journal of dairy science
IS - 4
ER -