Flow-FISH as an Estimator of Erythromycin Resistance in Enterococcal Isolates from Rtx Patients

Macrolide-lincosamide-streptogramin (MLS) antibiotics are still an alternative therapy for the insidious enterococcal infection. However, resistance to macrolides increase and therefore an investigation into the erythromycin-resistance has become imperative. The most common mechanism of resistance is the target modification to the binding site of macrolides, lincosamides, and streptogramin B antibiotics mediated by Erm – rRNA methylase alters a site in 23S rRNA. In current study authors evaluate the detection of ermB gene at a single cell level by Flow–FISH technique. Thirty six enterococcal strains were isolated from urine of RTx patients hospitalized at Medical University of Gdansk. The MIC value for all isolates varied from 0,25 to above 256 µg/ml. 22 out of 36 strains were found to be resistant to erythromycin. Coincidence of phenotypic and genotypic results confirm reasonability of FLOW-FISH attitude: the difference between resistant and susceptible strains was significant at p = 0,037.

Keywords: marcrolide resistance , enterococci, FLOW-FISH, RTx