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OBJECTIVE To study the prevalence of aac(6′)-Ⅰb with its subtypes,one kind of gene for aminoglycoside-modifying enzymes in Escherichia coli.METHODS DNA sequences were analyzed in those strains with aac(6′)-Ⅰb,compared to its family marked in NCBI.Thus,its subtypes were determined.RESULTS Four strains were classical on genotype,the other one with aac(6′)-Ⅰb-Cr,and the last one with a new subtype among the 6 strains of E.coli with aac(6′)-Ⅰb.CONCLUSIONS There exist at least 3 subtypes of aac(6′)-Ⅰb,one kind of gene for aminoglycoside-modifying enzymes in local strains of E.coli.Among those subtypes,the classical type is the main,accompanied by aac(6′)-Ⅰb-Cr and its new subtype.
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OBJECTIVE To explore pathogens and drug resistance in ventilator-associated pneumonia caused by Acinetobacter baumannii,and to provide the corresponding clinical prevention strategies.METHODS The clinical resords and the bacterial susceptibility results of sputum cultivation in 62 cases with VAP caused by A.baumannii between from 2003 and 2006 in ICU of our hospital were reviewed.RESULTS All of the patients suffered from severe underlying diseases,the aged accounted for 77.4%.At least one kind of antibiotic was used in all cases before occurrence of VAP.30.6% of the cases had mixed infection.VAP caused by A.baumannii had the rise trend year by year.The results of bacterial susceptibility showed that A.baumannii had multiple drug resistance,but was lowly resistant to cefoperazone/sulbactam and imipenem.CONCLUSIONS The reasonable choice for antibiotic of VAP caused by A.baumannii should be based on the latest local surveillance on etiology and drug resistance.
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Objective To investigate drug resistance,especially the resistance to aminoglycoside and the prevalence of the genes for aminoglycoside-modifying enzymes in Escherichia coli producing ESBLs.Methods VITEK-32 GNI+ cards and K-B methods were used to identify E.coli and detect the resistance to 18 kinds of antibiotics such as aminoglycoside and ?-lactams respectively in E.coli isolated from our hospital from January to December,2006.PCR method was used to detect the genes for aminoglycoside-modifying enzymes such as aac(3)-Ⅰ,aac(3)-Ⅱ,aac(6')-Ⅰb,aac(6')-Ⅱ,ant(3″)-Ⅰ and ant(2″)-Ⅰ in those 17 strains producing ESBLs.Results Resistance rates were 100.0%,100.0%,41.6%,100.0%,69.5%,30.5%,98.2%,81.0%,81.0%,79.6%,79.2%,34.8%,15.4%,7.1%,7.9%,5.4% and 81.0% for ampicillin,ampicillin/sulbactam,aztreonam,cefazolin,cefepime,ceftazidime,ceftriaxone,ciprofloxacin,levofloxacin,gentamicin,tobramycin,amikacin,cifoxitin,nitrofurantoin,piperacillin/tazobactam,cefoperazone/sulbactam and co-trimoxazole respectively in E.coli producing ESBLs.No drug-resistant strain imepenem was found.Positive rate was 46.4% for ESBLs.Resistance rates were 52.9%(9/17),100.0%(17/17) and 100%(17/17) for amikacin,gentamycin and tobmycin respectively in those 17 strains producing ESBLs.The most genotype for aminoglycoside-modifying enzymes was aac(3)-Ⅱ(94.1%),the second was aac(6')-Ⅰb(35.3%).The positive rates of aac(3″)-Ⅰ and ant(2″)-Ⅰ were 11.8% and 5.9% respectively.of them,one strain was resistant to aminoglycoside on phenotype,but no genes mentioned above was detected.4strains were classical on genotype,one with aac(6')-Ⅰb-Cr,the other one with a new subtype among the 6 strains of E.coli with aac(6')-Ⅰb.Conclusions Drug resistance in E.coli is rather serious.Typically,E.coli producing ESBLs shows multi-drug resistance.Positive rate for aac(3)-Ⅱ takes the first place,followed by aac(6')-Ⅰb among the genes for aminoglycoside-modifying enzymes.Aac(3″)-Ⅰand ant(2″)-Ⅰ show both lower positive rates.Aac(3)-Ⅰ and aac(6')-Ⅱ were not found.There exist at least 3 sub-types of aac(6')-Ⅰb,one kind of gene for aminoglycoside-modifying enzymes in strains of E.coli.Among those sub-types,the classical type is the main,accompanied by aac(6')-Ⅰb-Cr and its new sub-type.
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OBJECTIVE To compare and analyze the drug resistance of Chryseobacterium meningosepticum which producing metallo-?-lactamase(MBL) and extended-spectrum-?-lactamases(ESBLs) from ICU patients′ and non ICU patients′ specimens of sputa so as to guide the rational application of antibiotics.METHODS Identified the strains with VITEK 32,MBL and ESBLs were also screened by double disk synergy;the antimicrobial sensitivity of clinical isolates was tested by VITEK GNS143 and the antimicrobial sensitivity was added and tested by K-B method.RESULTS As a result the rate of producing MBL of C.meningosepticum was 49.0% from ICU patients′ specimens of sputa which was higher than the rate of 13.8% from non ICU patients′;the rate of producing ESBLs of C.meningosepticum was 37.2% from ICU patients′ specimens of sputa which was higher than the rate of 30.6% from non ICU patients′;the rate of drug resistance to AMP/SUB,TZP,CEP,CIP,and LEV from ICU patients′ was higher than that from non ICU patients.CONCLUSIONS Why the high resistance rate of C.mengingosepticum in ICU patients′ specimens of sputa might be due to the high producing ?-lactamases(MBL and ESBLs).
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OBJECTIVE To investigate drug resistance of Escherichia coli,especially the prevalence of the genes for TEM and SHV type ?-lactams in ESBLs-producing E.coli. METHODS A total of 2277 strains of E.coli collected in our hospital from Jan 2006 to Nov 2008 were analyzed for drug resistance to 21 kinds of antibiotics such as aminoglycoside,?-lactams and quinolones using VITEK-32 GNS-145 or GNS-448 card following GNI + for identification.PCR methods were used to analyze TEM and SHV type ?-lactams genes in 36 strains of E.coli with ESBLs so as to study their prevalence. RESULTS From them 1025 strains of E.coli were found positive for ESBLs,with a positive rate of 45.0%.Drug resistance rates were 83.0%,74.0%,52.0%,52.0%,29.1%,27.8%,16.5%,47.0%,31.0%,54.5%,53.0%,56.8%,10.0%,53.9%,38.5%,5.0%,4.0%,5.0% and 5.0%,respectively,for ampicillin,ampicillin/sulbactam,cefazolin,cefuroxime,aztreonam,cefepime,ceftazidime,ceftriaxone,cefotaxime,ciprofloxacin,levofloxacin,gentamicin,amikacin,tobramycin,Co-trimoxazole,nitrofurantoin,piperacillin /tazobactam,cefoperazone/sulbactam and cefoxitin.None was found resistant to imipenem or meropenem.Twenty-five and 14 strains of E.coli were found positive for TEM and SHV genes,respectively(69.4% and 38.9%). CONCLUSIONS Drug resistance of E.coli is severe.The local E.coli with ESBLs shows high positive rates of TEM and SHV genes,which play an important role in its severe drug resistance.