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Objective To investigate the drug resistance genes of Acinetobacter baumanii in some areas of Nanjing City,and to explore the molecular epidemiology characteristics of different antibiotic resistant strains.Methods A total of 75 strains of Acinetobacter baumanii were isolated from three hospitals of Nanjing city from May 2015 to May 2016 and the strains were identified by microbial identification system.Drug resistances of the strains were determined by KB method.The genotypes of strains were analyzed by pulsed field gel electrophoresis,and PCR was used to amplify the resistance genes.The molecular epidemiology of Acinetobacter baumanii was studied.Results Seventy five strains of Acinetobacter baumanii all had high drug resistance to antibiotics except tigecycline and colistin.The rates of resistance to cefepime,ceftazidime,cefotaxime,ciprofloxacin,cefotaxime,tetracycline were all higher than 90％.The strains were mainly divided into 5 types,and the proportion of A type and B type accounted for 42.67％ and 37.33 ％.The positive rates of genes OXA-23,OXA-24,TEM,SHV,CTX-M,IMP-1,IMP-2 and VIM-2 were 81.33 ％,9.33％,66.67％,10.67％,42.67％,26.67％,16.00％ and 21.33％ respectively.Conclusion A type and B type of the Acinetobacter baumanii are the most popular in hospitals of Nanjing,and the strains are multiple drug resistance.The expression of main resistance genes OXA-23 and TEM strains may be the main mechanism for the higher resistance of the bacteria to antibiotics and β-amide antibiotics.
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Objective:To investigate the relationship between antibiotics use and antimicrobial resistance of Acinetobacter bauman-nii to provide reference for rational antibiotics use. Methods:The DDDs of antibiotics in the inpatients and the drug resistance rate of A. baumannii were analyzed in our hospital from 2010 to 2014. The relationship between the antibiotics use and the antimicrobial re-sistance of A. baumannii was analyzed by SPSS 19. 0. Results:From 2010 to 2014, the total DDDs of antimicrobials in our hospital were decreased year by year in the first three years, while increased significantly in the last two years. The total DDDs of cephalospo-rins always ranked the first and the DDDs of carbapenem were increased year by year. The resistance rate of Acinetobacter baumannii a-gainst multiple antibacterials was increased in varying degrees in the past five years. In addition to levofloxacin, cefoperazone/sulbac-tam and tigecycline, the resistance rate against the other antibacterials was increased up to 50% in 2014. The resistant rate of A. bau-mannii against ciprofloxacin, gentamycin, cefepime, imipenem and tazobactam/piperacillin presented a positive correlation with the DDDs of cephalosporins and quinolones(P<0. 05). The resistance rate of A. baumannii against cefepime, imipenem tazobactam/pip-eracillin and levofloxacin was also positively correlated with the DDDs of carbapenem(P<0. 05). Conclusion: Antibiotics consump-tion is related to drug resistance of A. baumannii,so it is necessary to strengthen the management of clinical antibiotics use to decrease the multidrug-resistant strains.
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Objective To investigate the resistance-mechanism of the carbapenems-resistant Klebsiella pneumoniae isolated from clinical.Methods The clinical isolates of carbapenems-resistant Klebsiella pneumoniae from top three comprehensive hospitals of Nanjing area were examined by 40 beta-lactamase,porin-coding genes and linkage of KPC-ISKpn6 using PCR method,the PCR positive results were picked out for sequencing and sequencing BLAST search for comparison analysis.Results Twenty-four strains of carbapenems-resistant Klebsiella pneumoniae were detected,the positive rate of A beta-lactamase TEM-1 and SHV was 100％ (24/24),KPC-2 and LAP-2 was 95.8％ (23/24),45.8％ (11/24) respectively,and C beta-lactamase DHA was 4.2％ (1/24).Meanwhile,the positive detection rates of KPC-ISKpn6 linkage was 95.8％ (23/24),and the mutation rate of porin-coding genes ompK35 and ompK36 were up to 95.8％ (23/24) and 100％ (24/24).Conclusion High incidence of beta-lactamase TEM-1,SHV,KPC-2 and LAP-2 was found in the group of Klebsiella pneumoniae isolates,and carbapenems-resistant of which was primarily due to the high carrying rate of KPC-2 and the high mutation rate of porin-coding genes ompK35 and ompK36.The Insertion sequence ISKpn6 may be involved in the KPC-2 gene mediated-expression.
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OBJECTIVE To explore the clinical characteristics of nosocomial infection of lower respiratory tract by coagulase negative staphtylococci(CNS) and their drug resistance to common antibiotics.METHODS The clinical data and drug resistance of CNS of 37 nosocomial infection cases and 68 cases with colonization of lower respiratory tract by CNS were analyzed retrospectively,and the study mainly was focused on the risk factors and basic clinical features of nosocomial infection of lower respiratory tract by CNS.The resistance to common antibiotics of CNS was also summarized.RESULTS The risk factors were determined,which included long duration,age more than 65 years old,chronic obstructive pulmonary disease,the use of antibiotic suchs as carbapenems,the third generation cephalosporin,fluoroquinolones and concurrent infection of fungus.The mortality rate of infection was higher than after colonization.The clinical characteristics of nosocomial infection of lower respiratory tract by CNS included that the temperature of patients was focus on 37.5-38.5 ℃,peripheral blood routine of patients appearsed normal mostly and the lung imaging displayed the bilateral exudation changing near 50% the total.The 105 isolates of CNS were resistant to multi-antibiotics,the drug resistance rate to rifampicin and sodium fusidate was relatively low and resistant strains to vancomycin and teicoplanin were not detected.CONCLUSIONS The toxemia symptoms of nosocomial infection of lower respiratory tract by CNS are mild and the clinical manifestation is atypical.It is more likely to catch nosocomial infection of lower respiratory tract by CNS for the patients who are with low immunity and applied with broad spectrum antibiotic for long-term.
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OBJECTIVE To analyze the situation of extended spectrum ?-lactamases(ESBLs)and AmpC enzyme produced by nosocomial Escherichia coli isolates in 2005-2007.METHODS ESBLs were detected by double disk synergy test and disk diffusion confirmatory test.AmpC enzyme was detected by the three dimensional assay.Chi square test was used to test the significance.The application of different kinds of antimicrobials before the results of etiology be presented and the resistence rate of the ESBLs both producing and no producing were compared respectively.RESULTS The detectable rate of ESBLs in E.coli isolates of nosocomial and community infection was 55.1% and 21.3% and the detectable rate of AmpC enzyme nosocomial E.coli isolates was 17.4%.All strains were 100% susceptible to meropenem and imipenem but resistant to 15 other antimicrobials in different degree.The sensitivity to Piperacillin/tazobactam,cefoperazone/sulbactam and amikacin were relatively high.CONCLUSIONS The carrying rate of ESBLs from nosocomial E.coli isolates is high and AmpC enzyme and other resistance genes,which lead to multiple drug resistance.Standardized management of antimicrobials application should be strengthened and the consciousness of rational antimicrobials utilization should be raised.
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Objective To investigate the genetic features related to drug-resistance of a strain of pan-drug resistant Acinetobacter baumannii. Methods The susceptibilities to 15 antibacterial agents were detected in Acinetobacter baumannii by K-B paper diffusing method. A strain of pan-drug resistant Acinetobacter baumannii was selected. The drug-resistant genes of the selected strain were amplified by polymerase chain reaction (PCR) , including 15 extended-spectrum β-lactamase genes, 3 metal β-lactamase genes, 2 AmpC enzyme genes, 7 aminoglycoside modifying enzyme genes and the genetic markers of integron I and transposons. Results The strain was resistant to 14 antibacterial agents except cefoperazone sodium/ sulbactam. β-lactamases genes ( TEM, OXA-23 and ADC) , aminoglycosides modification enzyme genes [aac(3)- I , aac(6')- I b and ant(3")- I ] , integron I qacEAi-sull and transposon tnpU were positive in PCR amplification. A new subtype of AmpC (chromosome) desoxyribonucleic acid ( DNA) was detected. Conclusion Acinetobacter baumannii is of high resistance to most antibacterial agents, and the mechanisms of the resistance are complex.
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OBJECTIVE To study the current status of the AmpC enzyme and ?-lactamases genes for multi-resistant Acinetobacter baumannii isolates in clinic in Nanjing.METHODS The samples of 20 multi-resistant A.baumannii isolates were collected from Jul 2007 to Oct 2007 from the patients in hospitals of Nanjing.To determine the sensitivity to the 11 antibacterials by using a broth induction method,and two kinds of AmpC enzyme genes and eighteen kinds of ?-lactamases genes of multi-resistant A.baumannii analyzed by polymerase chain reaction(PCR).RESULTS In all of the 20 A.baumannii isolates,the AmpC genes of chromosome type were found in 14 isolates(70.0%),there were the AmpC genes of plasmid type in 1 isolate(5.0%),the TEM genes in 12 isolates(60.0%),the SHV genes in 1 isolate(5.0%),CTX-M-1 genes in 2 isolates(10.0%),OXA-23 genes in 1 isolate(5.0%),and OXA-24 genes in 1 isolate(5.0%),respectively.The OXA-24 genes from No.9 isolate was the type of OXA-72 after DNA sequencing.The amino acid sequence translated by AmpC genes of chromosome type from No.16 and No.17 isolates was the new subtype.CONCLUSIONS The A.baumannii has not only TEM,VEB,GES,IMP,VIM,OXA-10 and OXA-23 genes,but also the type of chromosome and plasmid of AmpC,SHV,CTX-M-1 and OXA-24 genes in Nanjing.It is the first time that activity of AmpC enzyme and the genotype of chromosome and plasmid of AmpC enzyme for matching are tested at the same time.