Multidrug resistance gene cfr in methicillin-resistant coagulase-negative staphylococci from chickens, ducks, and pigs in China.

The multidrug-resistance gene cfr was detected in coagulase-negative staphylococci from 3/401 pigs, 15/305 chickens, and 3/78 ducks from 31 different farms and one slaughterhouse in 2 provinces of China. Twenty of the 21 cfr-positive isolates were methicillin-resistant. Various SmaI-PFGE patterns were observed among the isolates of the same staphylococcal species and suggested horizontal transfer of cfr rather than clonal expansion. The detection of cfr on plasmids in the majority of the isolates supported this assumption. Analysis of the drug usage records of the farms strongly correlated with the resistance patterns of the cfr-positive isolates and suggested that antimicrobial use on farms supports the spread of the cfr gene.