Correlation Analysis Between Antimicrobial Resistance Of Streptococcu Spneumoniae Clinic Isolates From Children And Usage Of Macrolide Antibiotic And Its Mechanism Study In Chongqing Children's Hospital

Objective: 1) To investigate the relationship between the change in the resistance of Streptococcus pneumoniae (SP) against macrolide antibiotic and the usage of macrolide antibiotic ; 2) Analyze the mechanisms of SP resistant to macrolide;3) To comprehend in invasive disease, how many were caused by SP and the antibiotic resistance of SP clinic isolates from children with IPD in Chongqing Children's Hospital.Methods: A retrospective method was employed to measure the minimal inhibition concentrations (MIC) of macrolide antibiotic against 1210 strains of SP,and the defined doses (DDDs) of macrolide antibiotic were calculated. The correlation analysis between the change of DDDs and the change in drug-resistance rate were carried out. PCR was used to determine the presence of the erythromycin-resistant genes in 70 strains macrolide-resistant Streptococcus pneumoniae clinic isolates from sputum culture in Chongqing Children's Hospital. Retrospective analysis of patients with septicemia,purulent meningitis,purulent pleurisy and culture results of blood,cerebrospinal fluid (CSF),pleural fluid respectively from 2003 to 2005.Results: The DDDs of first-generation,second-generation and third-generation of macrolide antibiotic was not correlated with the resistance level of SP from 2002-2005. In 70 macrolide-resistant SP isolates, 62.86% had both ermB and mefA genotypes, 6 only had the ermB, 19 only had the mefA, and neither ermB nor mefA genotype was found in one strain of clinic isolate. There were 63 septicemia,60 had blood culture and 4 SP isolates were found. 3 were Erythromycin resister, 1 was sensitive to all antibiotics. In 197 purulent meningitis, 131 had CSF culture, only 1 SP isolate was found but did not do drug sensitive analysis. In 44 purulent pleurisy, 36 had pleural fluid culture, 1 SP isolates was found and it resistanted to erythromycin. There were 1027 SP isolates cultured in clinic lab this 3 years. The erythromycin resistant rate were 92.9%. Among the total, there were 6 strains from blood (4 were septicemia, 2 from other diseases), 1 from CSF, 1 from pleural fluid. 6 were resistant to erythromycin, 1 from blood was sensitive to all antibiotics and 1 from CSF not do drug sensitive analysis.Conclusion: Resistance rate of SP against macrolide antibiotic increaser from 2002 to 2005, but increased resistance rate was not correlated with the usage of macrolide antibiotic. Co-exist of Ribosomal modification coded by ermB gene and efflux effect coded by mefA gene are the main resistance mechanism against macrolides in Chongqing. In 304 patients with septicemia,purulent meningitis and purulent pleurisy, 6 were caused by SP. The rate was 1.9%. Invasive SP clinic isolates have high resistant to erythromycin. Simple macrolide antibiotic use is not recommend in clinic.