已有報告指出氯黴素乙醯轉移酶(chloramphenicol acetyltransferas, CAT)是造成雷氏桿菌（Riemerella anatipestifer, RA）產生氯黴素(chloramphenicol, CHL)抗藥性之原因之一。

The cat gene, coding for chloramphenicol acetyltransferase has been reported for conferring the chloramphenicol resistance for Riemerella anatipestifer. Chloramphenicol acetyltransferases, however, are unable to inactivate florfenicol. In this study, sixty-six R. anatipestifer isolates were investigated for their susceptibility to chloramphenicol and florfenicol and the presence of floR gene.