Fluoroquinolone resistance has been described for and isolates has very rarely been studied
Fluoroquinolone resistance has been described for and isolates has very rarely been studied. Antimicrobial susceptibility testing with Floxuridine ENR, CIP and orbifloxacin (ORB) was performed using the broth microdilution method, as recommended by the Clinical and Laboratory Standards Institute guidelines in VET01-A4 . The reference strain ATCC 25922 served as an internal control. The method for measuring MPC values has been previously described ; the lowest drug concentration that prevented the emergence of mutants after a 5-day incubation period was recorded as the MPC, and the values for mutant selection windows (MSWs) were calculated. Each experiment was repeated two times. A mutant of each original strain (were obtained from wild-type (of this suspension was added into a tube containing BHI medium (1,800 strains with a fourfold or greater reduction in their MICs in the presence of inhibitors were considered positive for CCCP efflux . Each experiment was repeated three times. The QRDR mutation types and fluoroquinolone MICs and MPCs for isolates are shown in Table 1. Nine (39.1%) isolates (wild type) were susceptible, and the remaining 14 (60.9%) isolates (Type I, Asp87 to Asn in isolates resistant to fluoroquinolones. The fluoroquinolone MICs for Type I and II isolates were 8- to 16-fold higher than those of the wild type, and fluoroquinolone MPCs for Type I and II isolates were 32- to 256-fold higher than those of the wild type. A previous study suggested that wild-type strains had lower mutation frequencies compared with single-mutation strains . Table 1. QRDR mutation genotypes and fluoroquinolone MICs and KSHV ORF26 antibody MPCs for mutants had double mutations in infections in cattle in China. The present study results suggested that for infections involving with high MPCs, especially those containing mutations in 39: 333C338. doi: 10.1080/03079457.2010.507761 [PubMed] [CrossRef] [Google Scholar] 2. Clinical and Laboratory Standards Institute. 2013. Performance Standards for Antimicrobial Disk and Dilution Susceptibility Tests for Bacteria Isolated From Animals. Approved Standard-Fourth Edition. 54: 2692C2695. doi: 10.1128/AAC.00033-10 [PMC free article] [PubMed] [CrossRef] [Google Scholar] 4. Ewers C., Lbke-Becker A., Bethe A., Kiebling S., Filter M., Wieler L. H.2006. Virulence genotype of strains isolated from different hosts with various disease status. 114: 304C317. doi: 10.1016/j.vetmic.2005.12.012 [PubMed] [CrossRef] [Google Scholar] 5. Kadlec K., Brenner Michael G., Sweeney M. T., Brzuszkiewicz E., Liesegang H., Daniel R., Watts J. L., Schwarz S.2011. Molecular basis of macrolide, triamilide, and lincosamide resistance in from bovine respiratory Floxuridine disease. 55: 2475C2477. doi: 10.1128/AAC.00092-11 [PMC free article] [PubMed] [CrossRef] [Google Scholar] 6. Katsuda K., Hoshinoo K., Ueno Y., Kohmoto M., Mikami Floxuridine O.2013. Virulence genes and antimicrobial susceptibility in isolates from calves. 167: 737C741. doi: 10.1016/j.vetmic.2013.09.029 [PubMed] [CrossRef] [Google Scholar] 7. Katsuda K., Kohmoto M., Mikami O., Uchida I.2009. Antimicrobial resistance and genetic characterization of fluoroquinolone-resistant 139: 74C79. doi: 10.1016/j.vetmic.2009.04.020 [PubMed] [CrossRef] [Google Scholar] 8. Li Q., Bi X., Diao Y., Deng X.2007. Mutant-prevention concentrations of enrofloxacin for isolates from chickens. 68: 812C815. doi: 10.2460/ajvr.68.8.812 [PubMed] [CrossRef] [Google Scholar] 9. Ma J., Zeng Z., Chen Z., Xu X., Wang X., Deng Y., L D., Huang L., Zhang Y., Liu J., Wang M.2009. High prevalence of plasmid-mediated quinolone resistance determinants qnr, aac(6)-Ib-cr, and qepA among ceftiofur-resistant Enterobacteriaceae isolates from companion and food-producing animals. 53: 519C524. doi: 10.1128/AAC.00886-08 [PMC free article] [PubMed] [CrossRef] [Google Scholar] 10. Michael G. B., Eidam C., Kadlec K., Meyer K., Sweeney M. T., Murray R. W., Watts J. L., Schwarz S.2012. Increased MICs of gamithromycin and tildipirosin in the presence of the genes erm(42) and msr(E)-mph(E).