A conjugative macrolide resistance gene, mef(A), in environmental Clostridium perfringens carrying multiple macrolide and/or tetracycline resistance genes

To determine if environmental Clostridium perfringens carry antibiotic resistance genes and if the genes are mobile. Clostridium perfringens from water, soil and sewage (2003-2006) were screened for the tetracycline and macrolide resistance genes previously described in animal and human C. perfringens [erm(B), erm(Q), tetA(P), tetB(P) and tet(M) genes] and the macrolide resistance mef(A) gene. Of the 160 isolates, 108 (67.5%) carried >= 1 of the six antibiotic resistance gene(s). The tetA(P), tetB(P) and tet(M) genes were in 53%, 22% and 8%, and the erm(B), erm(Q) and mef(A) genes in 26%, 1% and 18% of the isolates, respectively. The mef(A) gene and flanking regions were sequenced. The tet(M), erm(B), erm(Q) and mef(A) genes transfer independently from C. perfringens donors to the Enterococcus faecalis recipient. Six resistance genes were found in the environmental C. perfringens with the most common being the tetA(P) gene and the erm(Q) gene the least common. This is the first time conjugal transfer of macrolide resistance genes and/or the tet(M) gene from C. perfringens has been demonstrated. The data presented supports the hypothesis that antibiotic-resistant environmental C. perfringens are capable of acting as reservoirs for these antibiotic resistance genes.