A cfr-like gene cfr(C) conferring linezolid resistance is common in Clostridium difficile

Clostridium difficile T10 and Clostridium bolteae 90B3 were co-resistant to phenicols, lincosamides, oxazolidinones, pleuromutilins and streptogramin A (PhLOPS Lambda) and harbored an unreported cfr-like determinant that may alter the 23S rRNA by m(8)A2503 methylation. The cfr-like cfr(C) gene was cloned in C. difficile 630 Delta erm in which it conferred PhLOPSA resistance. In C. bolteae 90B3: (i) qRT-PCR analysis indicated that cfr(C) was similarly expressed in the absence or presence of either chloramphenicol or clindamycin or linezolid; and (ii) cfr(C) was part of a putative 24 kb-transposon, which generated a detectable circular intermediate. An element differing by a single nucleotide was found in C. difficile DA00203 from GenBank data, consistent with a recent horizontal transfer. In silico analysis showed cfr(C) in 19 out of 274 C. difficile genomes. This gene was also detected by PCR analysis in 9 out of 80 C. difficile from our laboratory strain collection according to resistance to linezolid and florfenicol. The fact that cfr(C) was mainly confined in C. difficile within polymorphic environments indicates this microorganism is a reservoir for PhLOPSA resistance. (C) 2017 Elsevier B.V. and International Society of Chemotherapy. All rights reserved.