ErmB gene

Restricting the use of clindamycin has been successful in terminating outbreaks of C. difficile diarrhea associated with its use (29). Between 1989 and 1992, outbreaks of diarrhea due to a clindamycin-resistant strain of C. difficile occurred in different parts of the USA. Resistance was mediated by the ermB gene. The use of chndamycin was a specific risk factor for diarrhea due to this strain (30). 

In this case, intron insertions are selected on the basis of acquisition of resistance to erythromycin due to the incorporation of an inactivated ermB gene, or RAM (Retrotransposition-Activated Marker), that became functional as a consequence of the successful insertion of the group II intron-encoding DNA into the genomic target [133,134]. 

Cockeran, R., 2012. Effects of clarithromycin at sub-minimum inhibitory concentrations on early ermB gene expression, metabolic activity and growth of an eim(B)-expressing macrolide-resistant strain of streptococcus pneumoniae. Open J. Respir. Dis. 02 (01), 1—8. Available from http //dx.doi.org/10.4236/ojrd.2012.21001. 

The MLS resistance was found in four of 137 consecutive clinical isolates of Streptococcus pyogenes (47). In two, both ermB and ermTR genes were present. In the other two, these genes were not identified, suggesting a new mechanism of high-level resistance to these antibiotics. Erm genes were detected in 45% of 173 strains of Streptococcus pneumoniae isolated from surveillance studies in day-care centers in Central Italy... 

---