A variety of Gram-positive bacteria carry mobile mef genes

Abstract

The mefE gene codes for a membrane bound efflux protein, which confers resistance to macrolides, and has been identified in Streptococcus pneumoniae. A variety of gram-positive organisms were examined. Twenty-six isolates of S. pneumoniae carried mefE and were resistant to erythromycin (MIC of 2-16 mg/L). Two additional isolates of Emr S. pneumoniae carried both ermB and mefE(MIC of 16-128 mg/L). One Micrococcus luteus, one Corynebacterium jeikeium, three Corynebacterium spp., two viridans streptococci and seven Enterocccus spp. also carried mef genes. It was possible to move the mef gene from all 11 S. pneumoniae tested to susceptible S. pneumoniae and/or Enterococcus faecalis recipients. The addition of DNase (1 g/L) did not affect the gene transfer. It was also possible to move the mef gene from donor Enterococcus spp., viridans streptococci, M. luteus, C. jeikeium and Corynebacterium spp. to E. faecalis recipients. Transconjugant isolates were resistant to erythromycin (MIC = 16 mg/L). Hybridization with a labelled mef oligonucleotide probe against Southern blots and bacterial dot blots confirmed the presence of the mef genes. This is the first time that a mobile mef gene has been identified in four different genera, from three distinct geographical locations.

Occurrence of Tylosin-Resistant Enterococci in Swine Manure and Tile Drainage Systems under No-Till Management

“…in different Enterococcus spieces have been described in recent studies (Jost et al, 2004;Luna et al, 1999;Portillo et al, 2000). As claimed by Portillo et al (2000), the most commonly erm class found in streptococci and enterococci is erm(B) class, followed by erm (TR), a subset of erm(A) class.…”

“…Acquired resistance to macrolides by active efflux has been detected in various bacteria including streptococci and staphylococci (Bean and Klena, 2002;Del Grosso et al, 2002;Descheemaeker et al, 2000;Luna et al, 1999 Wierzbowski et al, 2005).…”

“…Target site modification is mediated by an erythromycin resistant methylase (erm) which prevents macrolide binding and allows synthesis of bacterial proteins to continue. The active efflux mechanism produces transporters to discharge macrolide antibiotics out of the cell before reaching the target (Luna et al, 1999).…”

Mechanisms of Antibiotic Resistance in Corynebacterium spp. Causing Infections in People

“…Beside gene ermX, in strains of Corynebacterium Group A with the MLSB mechanism of resistance, also gene erm class B has been found (Luna et al, 1999), which occurs in Enterococcus spp. and Streptococcus spp., which may also suggest the participation of these microorganisms in spread of the MLSB mechanism in Corynebacterium spp.…”

Campylobacter

“…More importantly, efflux mediated resistance mechanisms can spread between phylogenically very different species. This has been exemplified by the macrolide-mediated efflux, not only among streptococci, but also to other Gram-negative bacteria [83]. Co-transfer with genes for other resistance classes may also take place if these are present together on large mobile genetic elements.…”