E test를 이용한 그람음성 간균의 항균제 MIC측정

Abstract

For the adequate treatment to infectious disease, it is necessary to identify the etiologic organisms and evaluate the susceptibility to antimicrobial agents. As the patterns of resistance to various antimicrobial agents is persistently changing, the significance of the antimicrobial susceptibility test is enhanced more and more. We investigated that the usefulness of the E test(AB Biodisk, Solna, Sweden) for antimicrobial susceptibility test to gram negative bacilli. From December, 1996 to March, 1997,118 strains of gram negative bacilli isolated from Dongsan Medical Center, Keimyung University were investigated. The minimal inhibitory concentration(MIC) was estimated by E test. Antimicrobial agents used in E test were imipenem, ceftazidime, piperacillin/tazobactam, ciprofloxacin, gentamicin, ceftriaxone, amikacin, amoxicillin/clavulanic acid, aztreonam, cefotaxime, cefuroxime, and piperacillin. The criteria for antimicrobial susceptibillity was the guidelines of the National Committee for Clinical Laboratory Standards(1993). Among the 118 strains of gram negative bacilli analyzed by E test, A. baumanii, E. coli, P. aeruginosa and K. pneumoniae were each 20. 19. 26. and 9 strains. In the cases of A. baumanii, all strains were sensitive to imipenem and MIC range was 0.5-2㎍/mL, MIC50 WAS 0.5㎍/mL, and MI90 was 2 ㎍/mL. The half of the strains were sensitive to aztreonam, and the majority were resistant to most antimicrobial agents, except amikacin, aztreonam and imipenem. Among 19 strains of E. coli, all strains were sensitive to imipenem and MIc range was 0.13-2 ㎍/mL, MIC50 was 0.5㎍/mL, and MIC90 was 2 ㎍/mL. The majority were resistant to amoxicillin/clavulanic acid and piperacillin(9 and 12 strains). In the 26 strains of P. aeruginosa, 22 strains were sensitive to imipenem and each 2 strains were imtermediate and resistant to resistant to imipenem. MIC range to imipenem was 0.38-64 ㎍/mL, MIC50 was 2 ㎍/mL, and MIC90 was 8 ㎍/mL. Most of strains were sensitive to ceftazidime, piperacillin/tazobactam, ciprofloxacin, amikacin, aztreonam, and piperacillin, but most of strains were resistant to gentamicin, ceftriaxone, amoxicillin/clavulanic acid, cefotaxime, cefuroxime. The E test had been found to be valuable and to be a rapid, convenient and reliable method for estimating MIC and detecting high-resistance to various antimicrobial agents.