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Prevalence of erythromycin resistance genes among clinical isolates of viridians group Streptococci

Viridans Group Streptococci (VGS) are part of normal oral flora, causing serious infections including infective endocarditis, septicemia, and meningitis are often associated with infections in neutropenic and immunocompromised patients. Recent studies have reported that there is a concomitant increase in resistance towards erythromycin among VGS. Two hundred and twelve VGS isolates were subjected for the determination of erythromycin resistance by MIC. Isolates were tested for macrolide resistance phenotype by double disk diffusion method. Erythromycin resistance genes (mefA, ermB, ermTR) were detected by PCR. Fifty out of 212 isolates were found to be resistant to erythromycin by MIC respectively. Fifty out of 212 isolates were found to be resistant by double disk diffusion test, of which 44 (20.75%) isolates showed M-phenotype and amplified for mefA gene, 12 (2.83%) isolates showed cMLSB phenotype and amplified for ermB gene. All the isolates which showed M-phenotype amplified mefA gene and those showed cMLSB phenotype amplified ermB gene. MefA was the most common gene amplified.

Author(s): Li-qiang Zhu, Qin-hua Li, Gong-chang Li, Wu-jia Wu, Ning Pei, Yan-xia He