OBJECTIVE To investigate the prevalence of extended-spectrum ?-lactamases (ESBLs) and antibiotic resistance in Klebsiella pneumoniae isolates.METHODS ESBLs-producers were detected by CLSI phenotypic confirmatory test and susceptibilities were tested by agar dilution method.RESULTS 41.1% Of isolates were ESBLs producers in those isolates. ESBLs producers were highly resistant to piperacillin,cefazolin,cefuroxime,fluoroquinolones,chloramphenicol,SMZ-TMP and amikacin. The resistant rate to piperacillin-tazobactam,and ceftazidime was 26.3% and 34.2%. None was resistant to imipenem and meropenem in ESBLs producers. Except for carbapenems,the resistant rate to other antimicrobial agents was significantly higher in ESBLs producers than non ESBLs producers.CONCLUSIONS With resistance to most of antimicrobial agents,ESBLs-producers are highly prevalent in K. pneumoniae isolates,more attention should be paid to monitor these strains.

Objective To investigate the ESBL gene in a Klebsiella pneumoniae strain isolated from a patient in Huashan Hospital, Shanghai. Methods ESBL gene in the transconjugant from Klebsiella pneumoniae isolate was amplified by PCR. The PCR products were cloned into pHSG398 vector. The antibiotic susceptiblity and ?-lactamases activity of the clone strain were tested; The PCR product was sequenced and analyzed. Results The ESBL gene was identified as CTX-M-12 gene and CTX-M-12 is much more active against cefotaxime than against ceftazidine.Conclusions A clinical isolate of Klebsiella pneumoniae k99-442 isolated from a patient in Huashan Hospital, Shanghai produced ESBL type CTX-M-12 which caused this isolate resistant to most ?-lactams.

OBJECTIVE To analyze the drug resistance of 141 clinical strains of Acinetobacter baumannii to 15 kinds of antimicrobial agents for the rational application of antimicrobial agents.METHODS All 141 strains of A.baumannii isolates were tested for minimal inhibitory concentration(MIC) to 15 kinds of antimicrobial agents included meropenem,imipenem,piperacillin,and so on using agar dilution method.RESULTS The lowest resistance rate of A.baumannii to the antimicrobial agents was to imipenem(22.7%),then was to meropenem and cefoperazone/sulbactam.The highest resistance rate was tetracycline(81.5%).The resistance rate to other antimicrobial agents was to about or more than 50%.CONCLUSIONS Most of A.baumannii isolates are susceptible to meropenem,imipenem,and cefoperazone/sulbactam and resistant to other antimicrobial agents,therefore,we should enhance to this kind of isolates detection.

OBJECTIVE To investigate the resistance and molecular epidemiology of Pseudomonas aeruginosa isolated from ICU. METHODS Susceptibility of P. aeruginosa isolates to 14 antimicrobial agents were tested by microScan WalkAway-40 system,and Molecular typing was analyzed by enterobacterial repetitive intergenic consensus(ERIC-PCR). RESULTS The lowest resistance rate of P. aeruginosa to the antimicrobial agents was to ceftazidime (27.3%),then to cefepime (45.5%). The highest resistance rate was to cefotaxime (100.0%) and the resistance rate to other antimicrobial agents was more than 60.0%. Patterns of ERIC-PCR were same in 5 strains of P. aeruginosa. CONCLUSIONS P. aeruginosa isolated from ICU is resistant to most of antimicrobial agents and clone spread is found in them. We should enhance detection and surveying of these isolates.

OBJECTIVE To investigate the prevalence of meticillin-resistant Staphylococcus haemolyticus(MRSH)and resistance in S.haemolyticus isolates. METHODS MRSH was detected by cefoxitin disc test and susceptibilities were tested by agar dilution method. RESULTS There were 86.4% of MRSH isolates.MRSH was highly resistant to penicillin,cefazolin,cefuroxime,ceftriaxone,tetracycline,ciprofloxacin,and clindamycin.The resistance rate to amikacin,rifampicine and chloramphenicol was 16.9%,11.2% and 28.1%,respectively.All isolates were susceptible to vancomycin and teicoplanin.Except for tetracycline,amikacin,rifampicin,and chloramphenicol,the resistant rate to other antimicrobial agents was significantly higher in MRSH than in MSSH. CONCLUSIONS MRSH is mostly occupied in S.haemolyticus isolates and resistant to most of antimicrobial agents.More attention should be paid to survey and detect these strains.

Objective To identify small non-coding RNAs encoded by plasmid pPCP1 and investigate their roles in biofilm formation, stress tolerance and/or virulence in Yersinia pestis.Methods Seven plasmid pPCP1-encoded sRNAs were identified by RNA-seq results in Y.pestis in our previous studies.Northern blot was used to validate the presence of the seven sRNAs.The sRNA-deletion mutants were constructed via λ-Red homologous recombination system.The biofilm formation, high salt tolerance and virulence of the phenotypes were compared between Y.pestis WT strain and sRNA mutants.Results and Conclusion The expression of seven pPCP1-encoded sRNAs was validated and the transcript length detected by Northern blotting corresponded to the length observed by RNA-seq.On this basis, five sRNA-deletion mutants were obtained.The capacity of biofilm formation was weakened upon deletion of sR3446.The tolerance of sR3446, sR3457, sR4338 and sR4340 mutants was found weakened in vitro compared to that of wild-type strain,but the tolerance of sR6143 was found increased.Slight virulence attenuation was found in two sRNA mutants ( sR4338 and sR4340 ) .The results suggest that pPCP1-deriving sRNA might be implicated in stress response, biofilm and virulence in Y.pestis.

OBJECTIVE To investigate the resistance to ?-lactam antibiotics and meropenem of non-ESBLs-producing Escherichia coli isolates.METHODS Non-ESBLs producers of E.coli isolates were detected by CLSI phenotypic confirmatory test,and susceptibility of these isolates to ?-lactam antibiotics and meropenem was tested by agar dilution method.RESULTS The resistance rate of these isolates to ampicillin,cefazolin and cefoxime was more than 60% and that to cefoperazone-sulbactam,cefmetazole and cefepime was 19.2%,23.8% and 31.8%,respectively,but most were susceptible to cefotaxime,ceftazidime,and meropenem.CONCLUSIONS The most isolates of non-ESBLs-producing E.coli are resistant to ampicillin and to the first and second generation cephalosporins,but they are susceptible to meropenem and the third generation cephalosporins.

OBJECTIVE To investigate the genotypes of meticillin-resistant Staphylococcus aureus(MRSA)and its resistance.METHODS A total of 73 MRSA clinical isolates were collected in Anhui Province,MIC of sixteen different antibacterial agents against the isolates were determined by agar dilution method.PCR amplified the mec associated hypervariable region(HVR)of MRSA,and the genotypes were classified based on the fragments of amplified products.The correlation of genotypes and antimicrobial resistance was analyzed.RESULTS Seventy three strains of MRSA from Anhui Province were grouped into A,B and C genotypes based on HVR polymorphism,and respectively 17.8%,23.3%,and 58.8%.All strains were sensitive to vancomycin.CONCLUSIONS MRSA is multi-drug resistant and can be divided into 3 genotypes based on the HVR PCR amplified products.HVR PCR method is a rapid and convenient method for molecular epidemiology study of MRSA infections.

OBJECTIVE To investigate the resistance in clinical isolates of Stenotrophomonas maltophilia to antimicrobial agents. METHODS Susceptibility of 48 S. maltophilia isolates were tested by agar dilution or K-B method. RESULTS The lowest resistance rate of isolates to the antimicrobial agents was to ticarcillin/clavulanic acid (12.5%),then to minocycline (25.0%) and trimethoprim/sulfamethoxazole (31.3%). The resistance rate to ceftazidime,ceftazidime/sulbactam,levofloxacin,and chloramphenicol was 62.5%,52.1%,52.1%,and 50.0%,respectively. CONCLUSIONS Most of S. maltophilia isolates are susceptible to ticarcillin/clavulanic acid,minocycline,trimethoprim/sulfamethoxazole and resistant to other antimicrobial agents. More mornitoring should be enhanced.

OBJECTIVE To investigate pathogens and their resistance in infective endocarditis patients.METHODS Pathogens and their resistance were detected by MicroScan WalkAway-40 system.RESULTS Most of pathogens were Streptococcus pyogenes and Staphylococcus.The resistant rate of S.pyogenes to tetracycline,erythromycin,ampicillin,penicillin,gentamicin and chloramphenicol was 78.6%,42.9%,14.3%,0,0 and 0,respectively.Four were MRS in 10 Staphylococcus isolates and they were resistant to most antimicrobial agents except vancomycin and higher than MSS.CONCLUSIONS Most of pathogens are S.pyogenes and Staphylococcus in infective endocarditis patients;most S.pyogenes isolates are resistant to tetracycline,erythromycin,but susceptible to penicillins;MRS are resistant to most of antimicrobial agents except vancomycin.