Susceptibility of Mycoplasma bovis field isolates to antimicrobial agents

Abstract

ABSTRACT:The purpose of this study was to determine the antibacterial susceptibility of field isolates of Mycoplasma bovis originating from the upper respiratory tract of cattle of different ages. Bacteriological examination of 90 nasal swabs collected from calves at three months of age identified M. bovis in 31 (34.44%) samples. Seventeen (18.88%) of these animals still housed M. bovis in their nasal cavity at nine months and five animals (5.55%) still at seventeen months of age. M. bovis were confirmed by biochemical and antigenic methods. To confirm that these belonged to the M. bovis species isolated mycoplasmas were tested using the PCR method. Fifteen field strains of M. bovis isolated from the same cattle at three, nine and seventeen months (five strains from each age group) were selected for antibacterial susceptibility testing against six groups of antimicrobial agents using an agar dilution method. The MIC 90 ranges established for tylosin, tulathromycin, enrofloxacin, florfenicol and lincomycin were 0.39-0.78 µg/ml, 0.50-1.00 µg/ml, 0.78-1.56 µg/ml, 3.12 µg/ml and 0.39-0.78 µg/ml, respectively. The range of MIC 90 for oxytetracycline was from 50 to 100 µg/ml. Preliminary examination of the antimicrobial susceptibility of field strains of M. bovis did not reveal significant differences between different age groups of cattle. After evaluation of the MIC 90 data with the SPSS 13.0 statistical package it was found that M. bovis isolates from animals at three, nine and seventeen months were similarly susceptible to tylosin and tulathromycin. Statistically significant differences in susceptibility of M. bovis isolated from cattle of different ages were found to florfenicol compared with tulathromycin (P < 0.01), lincomycin (P < 0.01) and enrofloxacin (P < 0.05). The susceptibility of all M. bovis isolates to oxytetracycline and penicillin G significantly differed from the sensitivity to all other antimicrobial agents used in the present study (P < 0.05). The in vitro susceptibility test showed that field isolates of M. bovis isolated from cattle of different ages were similarly sensitive to tylosin, tulathromycin, lincomycin and enrofloxacin. It was also determined that the field strains are resistant to oxytetracycline.

Mycoplasma dispar prevalence in the upper respiratory tract of cattle and the antimicrobial susceptibility of the isolates

“…High susceptibility of M. dispar isolates to tulathromycin makes it an attractive drug for treating mycoplasma infections in the field. Furthermore, in vivo investigations of tulathromycin have demonstrated a broad spectrum of efficiency in the therapy of bovine respiratory disease [13].…”

“…DNA from isolated mycoplasma was extracted with 5 % solution of Chelex (Sigma, USA). Isolated microorganisms were analyzed by PCR using forward primer, MW28 (5'-CCAGACTCCTACGGGAGGCA -3') and reverse oligonucleotide primer MW29 (5'-T GCGAGCATACTACTCAGGC -3') (Grida Lab, Lithuania) that are specific for the Mollicutes class [13]. This pair of primer generates a 560 bp product.…”

Untitled

“…Once these plates were cooled a bacterial lawn was prepared by spreading 100 μl from the above prepared bacterial suspension using sterile swabs. Wells of 6 mm in diameter were punched into the agar and filled with 100μl of the antimicrobial under investigation at a concentration of 1 μg/ml 13 . The plates were then incubated at 37 o C for 24 hours before zones of inhibition were measured using a caliper 14 .Each extract was analyzed in triplicate; the mean values are presented.…”

Mycoplasma bovis in Australian feeder cattle

“…Infrequent or no resistance has been reported to enrofloxacin or florfenicol (Francoz et al, 2005, Gerchman et al, 2009, Hirose et al, 2003, Rosenbusch et al, 2005, Siugzdaite et al, 2012. Successful treatment of M. bovis pneumonia and arthritis in calves using valnemulin in the milk from four days of age for three weeks has also been reported (Stipkovits et al, 2001).…”

“…In addition, in the past decade, in vitro susceptibility studies have shown an increased resistance to antimicrobials commonly used to treat infections associated with M. bovis; in particular oxytetracyclines, spectinomycin, tilmicosin and chlortetracycline (Francoz et al, 2005, Gerchman et al, 2009, Hirose et al, 2003, Rosenbusch et al, 2005, Siugzdaite et al, 2012. Infrequent or no resistance has been reported to enrofloxacin or florfenicol (Francoz et al, 2005, Gerchman et al, 2009, Hirose et al, 2003, Rosenbusch et al, 2005, Siugzdaite et al, 2012.…”