Identification of floR Variants Associated With a Novel Tn4371-Like Integrative and Conjugative Element in Clinical Pseudomonas aeruginosa Isolates

Abstract

Florfenicol is widely used to control respiratory diseases and intestinal infections in food animals. However, there are increasing reports about florfenicol resistance of various clinical pathogens. <i>floR</i> is a key resistance gene that mediates resistance to florfenicol and could spread among different bacteria. Here, we investigated the prevalence of <i>floR</i> in 430 <i>Pseudomonas aeruginosa</i> isolates from human clinical samples and identified three types of <i>floR</i> genes (designated <i>floR</i>, <i>floR-T1</i> and <i>floR-T2</i>) in these isolates, with <i>floR-T1</i> the most prevalent (5.3%, 23/430). FloR-T2 was a novel <i>floR</i> variant identified in this study, and exhibited less identity with other FloR proteins than FloRv. Moreover, <i>floR-T1</i> and <i>floR-T2</i> identified in <i>P. aeruginosa</i> strain TL1285 were functionally active and located on multi-drug resistance region of a novel incomplete Tn<i>4371</i>-like integrative and conjugative elements (ICE) in the chromosome. The expression of the two <i>floR</i> variants could be induced by florfenicol or chloramphenicol. These results indicated that the two <i>floR</i> variants played an essential role in the host's resistance to amphenicol and the spreading of these <i>floR</i> variants might be related with the Tn<i>4371</i> family ICE.