Erythromycin Resistance Phenotype and Resistance Gene to Streptococcus pneumoniae

OBJECTIVE To investigate the prevalence of erythromycin resistance genes ermB and mefA and the relationship of drug resistance and genes in Streptococcus pneumoniae.METHODS Forty three strains of S. pneumoniae were collected from respiratory system infected children from Dec 2004 to Oct 2005 at Yuying Pediatric Hospital of Wenzhou Medical College.Erythromycin sensitivity test was done by using MIC method.The erythromycin resistance genes ermB and mefA were detected by PCR.RESULTS In all forty three strains,forty were erythromycin resistant(93%),three were erythromycin sensitive.The total detection rate of erythromycin resistance genes ermB and mefA was 76.7% and 23.3%,respectively.There were neither gene ermB nor gene mefA in 3 erythromycin-sensitive S.pneumoniae.In 40 strains the detection rate of gene ermB was 82.5% and that of gene mefA was 25%.The erythromycin resistance gene ermB or mefA were detected in 35 of the 43 strains.The total detection rate of erythromycin resistance gene was 81.4%.In the 35 erythromycin resistance strains there were 25 strains in which gene ermB existed lonely and 2 strains in which gene mefA existed lonely.There were both genes ermB and gene mefA in 8 of the 35 erythromycin resistance strains.CONCLUSIONS The erythromycin resistance of S.pneumoniae can be caused mainly by gene expression of ermB or mefA,but the gene mefA seems to be less important than gene ermB.Obviously the erythromycin isn′t useful in treating S.pneumoniae infection.