Objective To explore the prevalence of 11 efflux pumps in isolates of multidrugresistant Escherichia coli(MDR-ECO). Methods Efflux pumps emrB, emrD , emrE, mdfA, sugE, mdtl,tehA, oqxA, qacE△1, qacE and smr-2 were detected by polymerase chain reaction(PCR)in 20 MDR-ECOs isolated from clinical samples. Results Efflux pumps emrB, emrD, emrE, mdfA, sugE, mdtI, qacE △1, tehA and oqxA were detected, and 8 efflux pumps were found in the same strain. Conclusion Multidrug- resistance in Escherichia coli may be related with efflux pumps.

Objective To investigate the correlation between acquired drug resistance-related genes and mobile genetic elements from pandrug-resistant Acinetobacter baumannii. Methods Fifty-three horizontal transfer drug resistance-related genes ( β-lactamases,aminoglycoside and quinolones resistance related) and 12 mobile genetic elements (including zygosity plasmid,transposon,insertion sequence and integron) were detected by polymerase chain reaction (PCR) in 20 clinical isolates of pandrug-resistant Acinetobacter baumannii.Index cluster analysis was performed to explore the correlation.Results In 20 strains of pandrug-resistant Acinetobacter baumannii,there were 3 types of β-lactamases related genes (TEM-1,ADC-30,OXA-23 ),4 types of aminoglycoside modifying enzyme genes [ aac (3)-Ⅰ,aac(6′)-Ⅰ b,ant( 3″)-Ⅰ and aph( 3′)-Ⅰ ],and 5 kinds of mobile genetic elements ( int Ⅰ 1,tnpU,tnp513,IS26 and ISAba1 ). Index cluster analysis showed high correlations between resistance genes [TEM-1,ADC-30,aac( 6′)-Ⅰ b,ant( 3″)-Ⅰ,abeB,qacE Δ1] and mobile genetic elements ( int Ⅰ 1,tnpU,tnp513,IS26,ISAba1 ).Conclusion Clinical isolated pandrug-resistant Acinetobacter baumannii carries several acquired drug resistance-related genes and mobile genetic elements,and there may be a close association between them.

Objective To investigate the multi-drug resistance of Klebsiella strains and its mechanism.Methods Twenty strains of Klebsiella were isolated from the Affiliated Hospital of Medical College,Ningbo University from October 2009 to March 2011,in which 18 isolates were Klebsiella pneumonia and 2 were Klebsiella planticola. Drug sensitivity was determined by K-B tests. Drug resistant genes gyrA,parC (chromosome mediated) and aac( 6′)-I b-Cr,qnrA,qnrB,qnrS,qepA (plasmid mediated) were amplified by PCR and verified by direct automated fluorogenic sequencing. Results Resistance to β-1actams,aminoglycosides and quinolones was observed in 20 strains,and resistant rates were all above 80％.Klebsiella planticola strains were sensitive to imipenem and meropenem.Mutations of gyrA and parC genes existed in 18 strains (90％),and the positive rates of aac (6') -I b-C r,qnrB and qnrS were 60％ (12/20),20％ (4/20) and 20％ (4/20),respectively.Conclusion The mutations ofgyrA and parC genes may be the main cause of the resistance to quinolones in these strains.