Distribution of mef(A) in gram-positive bacteria from healthy Portuguese children

We screened 615 gram-positive isolates from 150 healthy children for the presence of the erm (A), erm (B), erm (C), erm (F), and mef (A) genes. The mef (A) genes were found in 20 (9%) of the macrolide-resistant isolates, including Enterococcus spp., Staphylococcus spp., and Streptococcus spp. Sixteen of the 19 gram-positive isolates tested carried the other seven open reading frames (ORFs) described in Tn 1207.1 , a genetic element carrying mef (A) recently described in Streptococcus pneumoniae . The three Staphylococcus spp. did not carry orf1 to orf3 . A gram-negative Acinetobacter junii isolate also carried the other seven ORFs described in Tn 1207.1. A Staphylococcus aureus isolate, a Streptococcus intermedius isolate, a Streptococcus sp. isolate, and an Enterococcus sp. isolate had their mef (A) genes completely sequenced and showed 100% identity at the DNA and amino acid levels with the mef (A) gene from S. pneumoniae .