ABSTRACT
Objective To analyze the resistance of Stenotrophomonas maltophilia to commonly used antibacterial drugs,and to investigate the existence status of 3 kinds of integron(Ⅰ,Ⅱand Ⅲ)and the carrying drug resistance gene cassettes so as to offer help for better preventing and controlling the infectious diseases caused by stenotrophomonas maltophilia in local place.Methods 51 strains of Stenotrophomonas maltophilia from clinical samples were collected and the minimum inhibitory concentration(MIC)of 17 kinds of antibacterial drugs to stenotrophomonas maltophilia was measured by the broth microdilution antifungal susceptibility test(Mi-AFST).3 kinds of integron(Ⅰ,Ⅱand Ⅲ)were amplified by PCR with primers designed according to registrated DNA se-quence in GenBank.The variable region products in the positive integron strains were amplified and performed the sequencing analy-sis.The homological comparison in the Genebank database was performed on the sequencing results for finding out what gene was included in variable domain of those integrons.Results (1)Among 51 strains of stenotrophomonas maltophilia,41 srains (80.39%) were collected from sputum samples,and the infected crowd was dominated by individuals aged over 60 years,38 strains accounted for 74.5%.In the department distribution,20 strains(39.22%)were collected from ICU,13 strains (25.49%)from the respiratory department and 6 strains(11 .76%)from the veteran cardres wards,which accounted for the larger proportion.(2)The drug suscep-tibility test demonstrated that stenotrophomonas maltophilia strains had the higher resistance to most of commonly used antibacteri-al drugs,some strains even showed the multi-drug resistance to over 9 kinds of antibacterial drugs.(3)The PCR gene amplification results showed that 7 strains (13.7%)were positive integronⅠ,while no strains containing integron Ⅱ or ⅢI were detected;the resistance genes carried in the variable region of integron I included the 5 kinds of aacA4,aadA1,catB8,dfrA17 and aphA15.Conclu-sion Stenotrophomonas maltophilias has relatively high resistance to majority of commonly used antibacterial drugs in clinic,and some strains show the muti-drug resitance.IntegronⅠis one of important factors for the multi-drug resistance of Stenotrophomonas maltophilias.
ABSTRACT
OBJECTIVE To investigate the antimicrobial susceptibility of Streptococcus pneumoniae isolated in Yantai and their mechanisms of resistance to macrolides.METHODS Antimicrobial susceptibility of S.pneumoniae was determined by agar dilution method.Phenotypes of macrolide-resistant S.pneumoniae were determined using double disk test with erythromycin and clindamycin disks.ermB And mefE genes were amplified by PCR.RESULTS Among 42 strains of S.pneumoniae,65.0% were intermediate to and no strain was resistant to penicillin.The resistance rates to erythromycin and clindamycin were 93.0%,respectively.Of 41 erythromycin resistantstrains,93.0% were constitutive resistant.ermB Was detected in 40 strains and mefE in 1 strain,both ermB and mefE genes were found in 9 strains.CONCLUSIONS The resistance rate of S.pneumoniae to penicillin is high in Yantai area,the resistance rates to erythromycin and clindamycin are very high.Target modification by ermB methylase is the predominant mechanism in macrolide-resistant S.pneumoniae in Yantai.