To investigate the mechanisms of erythromycin-resisant streptococcus isolated from animals,the minimal inhibitory concentrations(MICs) of pencillin, erythromycin and clindamycin against streptococcus were detected by ...To investigate the mechanisms of erythromycin-resisant streptococcus isolated from animals,the minimal inhibitory concentrations(MICs) of pencillin, erythromycin and clindamycin against streptococcus were detected by agar two-fold dilution, the resistance phenotypes of erythromycin-resistant streptococcus were determined by the double disk test, and the presence of mefA, ermB genes were determined by PCR amplification. The results showed that the rate of resistance to penicillin, erythromycin and clindamycin of 111 strains studied were 54.95%,68.47%and 64.86%,respectively. In 76 erythromycin resistant strains, 62 isolates (81.58%) were assigned to the cMLS_B phenotype, 5 isolates (6.6%) were M phenotype and 9 isolates (11.84%) were inducibly resistant, expressing the iMLS_B phenotype by the double disk test. The mefA gene was present in all of the strains showing the M-resistance phenotype. Some isolates expressing a cMLS_B phenotype and iMLSB phenotype were confirmed genotypically by the presence of the ermB gene, but 6 isolates were n’t detected the ermB and mefA gene. Genes coding for both resistance mechanisms were found in one strain. No amplification was detected in all the erythromycin susceptible streptococcus isolates. Erythromycin resistant Streptococcus isolated from animals mediated by ermB was predominant in China. The PCR amplification can be a useful method to rapidly screen the erythromycin resistant strains.展开更多
Objectives: This study focuses on the antibiotic susceptibility pattern and distribution of the ermB and mefA virulence genes among the Streptococcus pneumoniae due to an increase in erythromycin resistance in S. pneu...Objectives: This study focuses on the antibiotic susceptibility pattern and distribution of the ermB and mefA virulence genes among the Streptococcus pneumoniae due to an increase in erythromycin resistance in S. pneumoniae worldwide. Methodology: We investigated 255 clinical isolates collected from 2005-2010 to determine the serotype distribution and resistance to erythromycin in comparison to penicillin, clindamycin, clarithromycin, azithromycin, and trimethoprim sulfamethoxazole. Multiplex PCR was carried out to detect erythromycin resistance genes (ermB and mefA). Results: There were 146 (57.3%) isolates resistant to erythromycin. MIC<sub>90</sub> for erythromycin is at >256 mg/L and MIC<sub>50</sub> is at 16 mg/L. The ermB gene was detected in 25.3% of the erythromycin-resistant isolates and mefA gene was detected in 50.7% of the isolates. The four most common serotypes encountered are 19F, 19A, 23F and 14. The serotype distribution among the erythromycin resistant isolates was 19F (42.0%) followed by serotype 19A (11.3%), serotype 23F (9.2%) and serogroup 14 (7.0%). Conclusion: In conclusion, there is a significant rise in erythromycin resistance among the Malaysian pneumococcal isolates. The emergence of serotype 19A together with increasing prevalence of resistance to macrolide warrants for a more extensive surveillance study.展开更多
文摘To investigate the mechanisms of erythromycin-resisant streptococcus isolated from animals,the minimal inhibitory concentrations(MICs) of pencillin, erythromycin and clindamycin against streptococcus were detected by agar two-fold dilution, the resistance phenotypes of erythromycin-resistant streptococcus were determined by the double disk test, and the presence of mefA, ermB genes were determined by PCR amplification. The results showed that the rate of resistance to penicillin, erythromycin and clindamycin of 111 strains studied were 54.95%,68.47%and 64.86%,respectively. In 76 erythromycin resistant strains, 62 isolates (81.58%) were assigned to the cMLS_B phenotype, 5 isolates (6.6%) were M phenotype and 9 isolates (11.84%) were inducibly resistant, expressing the iMLS_B phenotype by the double disk test. The mefA gene was present in all of the strains showing the M-resistance phenotype. Some isolates expressing a cMLS_B phenotype and iMLSB phenotype were confirmed genotypically by the presence of the ermB gene, but 6 isolates were n’t detected the ermB and mefA gene. Genes coding for both resistance mechanisms were found in one strain. No amplification was detected in all the erythromycin susceptible streptococcus isolates. Erythromycin resistant Streptococcus isolated from animals mediated by ermB was predominant in China. The PCR amplification can be a useful method to rapidly screen the erythromycin resistant strains.
文摘Objectives: This study focuses on the antibiotic susceptibility pattern and distribution of the ermB and mefA virulence genes among the Streptococcus pneumoniae due to an increase in erythromycin resistance in S. pneumoniae worldwide. Methodology: We investigated 255 clinical isolates collected from 2005-2010 to determine the serotype distribution and resistance to erythromycin in comparison to penicillin, clindamycin, clarithromycin, azithromycin, and trimethoprim sulfamethoxazole. Multiplex PCR was carried out to detect erythromycin resistance genes (ermB and mefA). Results: There were 146 (57.3%) isolates resistant to erythromycin. MIC<sub>90</sub> for erythromycin is at >256 mg/L and MIC<sub>50</sub> is at 16 mg/L. The ermB gene was detected in 25.3% of the erythromycin-resistant isolates and mefA gene was detected in 50.7% of the isolates. The four most common serotypes encountered are 19F, 19A, 23F and 14. The serotype distribution among the erythromycin resistant isolates was 19F (42.0%) followed by serotype 19A (11.3%), serotype 23F (9.2%) and serogroup 14 (7.0%). Conclusion: In conclusion, there is a significant rise in erythromycin resistance among the Malaysian pneumococcal isolates. The emergence of serotype 19A together with increasing prevalence of resistance to macrolide warrants for a more extensive surveillance study.
