Relationship between antimicrobial resistance and aminoglycoside-modifying enzyme gene expressions i

• 出 处: Chinese Medical Journal
• 发表日期: 2005年02期
• 关键词: Acinetobacter modifying antimicrobial minutes minute systemin Marker urine dried

Background Acinetobacter baumannii is one of the mrrrrrrrrnain gramnegative bacilli in clinical practice Nosocomial infections caused brrrrrrrrny multidrug resistance Acinetobacter baumannii is very difficult to treatrrrrrrrrn This study was designed to investigate the antimicrobial resistance characterrrrrrrrnristics and four resistant gene expressions of aminoglycosidemodifying enzymesrrrrrrrrn rrrrrrrrnincluding Nacetyltransferases and Ophosphotransferases in Acinetobacter barrrrrrrrnumannii rrrrrrrrnMethods Bacterial identification and antimicrobial susceptibilirrrrrrrrnty test were performed by PhoenixTM system in 247 strains of Acinetobrrrrrrrrnacter brrrrrrrrnaumannii Minimal inhibitory concentrations (MICs) of seven aminoglycosiderrrrrrrrns including gentamicin, amikacin, kanamycin, tobramycin, netilmicin, neomycin anrrrrrrrrnd streptomycin in 15 strains of multidrug resistant Acinetobacter baumanrrrrrrrrnnii were detected by agar dilution Four aminoglycosidemodifying enzyme gerrrrrrrrnnes rrrrrrrrnwere amplified by polymerase chain　reaction (PCR) and verified by DNA sequencerrrrrrrrrnrrrrrrrrnResults The resistance rates of 247 strains of Acinetobacter rrrrrrrrnbaumannii against cefotaxime, levofloxacin, piperacillin, aztreonam, tetracyclrrrrrrrrnine, ciprofloxacin and chloramphenicol were more than 50% Imipenem and meropenrrrrrrrrnem showed high antibacterial activities with resistance rates of 32% and 41rrrrrrrrn% MIC50 and MIC90 of gentamicin, amikacin, streptomycin and kanarrrrrrrrnmycin in 15 strains of multidrug resistant Acinetobacter baumanii were allrrrrrrrrn morrrrrrrrrne than 1024 mg/L, and the resistance rates were 100%, 100%, 100% and 933%, rerrrrrrrrnsrrrrrrrrnpectively But their resistance rates to tobramycin, netilmicin and neomycin werrrrrrrrnre 86rrrrrrrrn7%, 933% and 467%, respectively Three modifying enzyme genes, including rrrrrrrrnaacC1, aacC2 and aacA4 genes, were found in 15 strains, but aphA6 had not been rrrrrrrrndetected Their positive rates were 933%, 200% and 200%, respectively rrrrrrrrnThese three genes existed simultaneously in No19 strain Nucleotide sequencesrrrrrrrrn of aacC1, aacC2 and aacA4 genes shared 100%, 979% and 997% identities with rrrrrrrrnGenBank genes (AY307113, S68058 and AY307114)rrrrrrrrnConclusion Multidrug resistant Acinetobacter baumannii strarrrrrrrrnins arerrrrrrrrn rapidly spreading in our hospital, and their resistance to aminoglycosides mayrrrrrrrrn brrrrrrrrne associated with aminoglycosidemodifying enzyme gene expressions

Background Acinetobacter baumannii is one of the m r r r r r r nain gramnegative bacilli in clinical practice  Nosocomial infections caused b r r r r r r r r ny multi-drug resistance Acinetobacter baumannii is very difficult to treat r r r r r r r r n This study was designed to investigate the antimicrobial resistance characte r r r r r r r r nristics and four resistant gene expressions of aminoglycosidemodifying enzymes r r r r r r r r n r r r r r r r r nincluding Nacetyltransferases and Ophosphotransferases in Acinetobacter ba r r r r r r r numannii r r r r r r r r nMethods Bacterial identification and antimicrobial susceptibili r r r r r r r r r r r r r r r r r r r r nty test were performed by Phoenix  TM  system in 247 strain of Acinetob r r r r r r r nacter b r r r r r r n naumannii Minimal inhibitory concentrations (MICs) of seven aminoglycoside r r r r r r r ns including gentamicin, amikacin, kanamycin, tobramycin, netilmicin, neomycin an r r r r r r r nd streptomycin in 15 strains of multidrug resistant Acinetobacter bauman r r r r r r r nnii  were detected by agar dilution Four aminoglycosidemodifying enzyme ge r r r r r r r nnes r r r r r r r n n n n nwere amplified by polymerase chain reaction (PCR) and verified by DNA sequencer r r r r r r r n r r r r r r r r nResults The resistance rates of 247 strains of Acinetobacter r r r r r r r nbaumannii against cefotaxime, levofloxacin, piperacillin, aztreonam, tetracycl r r r r r r r r nine, ciprofloxacin and chloramphenicol were more than 50%  Imipenem and meropen r r r r r r nem showed high antibacterial activities with resistance rates of 3  2% and 4  1 r r r r r r r n%  MIC50 and MIC90 of gentamicin, amikacin, streptomycin and kana r r r r r r r r nmycin in 15 strains of multidrug resistant Acinetobacter baumanii were all r r r r r r r n mor r r r r r r r r ne than 1024 mg / L, and the resistance rates were 100%, 100%, 100% and 933%, re r r r r r r r ns r r r r r r r r nlyly But their resistance rates to tobramycin, netilmicin and neomycin we r r r r r r r nre 86 r r r r r r r r n  7%, 933% and 46  7%, respectively Three modifying enzyme genes, including r r r r r r r naacC1, aacA2 had not been r r r r r r r r r n ndetected their positive rates were 93 3%, 20 0% and 20  0%, respectively r r r r r r r n These three genes existed simultaneously in No19 strain  Nucleotide sequences r r r r r r r r n of aacC1, aacC2 and aacA4 genes shared 100%, 979% and 997% identities with r r r r r r r nGenBank genes (AY307113, S68058 and AY307114)  r r r r r r r r nConclusion Multidrug resistant Acinetobacter baumannii stra r r r r r r r nins are r r r r r r r n rapidly spreading in our hospital, and their resistance to aminoglycosides may r r r r r r r n r r r r r r r ne associated with aminoglycoside -modifying enzyme gene expres sions 