Contemporary Assessment of Antimicrobial Susceptibility Testing Methods for Polymyxin B and Colistin: Review of Available Interpretative Criteria and Quality Control Guidelines

摘要: The emergence of infections caused by multidrug-resistant Pseudomonas aeruginosa and Acinetobacter spp. has necessitated the search for alternative parenteral agents such as polymyxins. National Committee Clinical Laboratory Standards (NCCLS) documents do not currently provide interpretative criteria testing polymyxins, colistin polymyxin B. Therefore, an evaluation antimicrobial activity B was initiated using 200 bloodstream infection pathogens collected through SENTRY Antimicrobial Surveillance Program. All susceptibility tests were performed according to NCCLS recommendations. Polymyxin displayed a nearly identical spectrum activity, exhibiting excellent potency against P. (MIC(90), 2 microg/ml) sp. microg/ml). In contrast, they showed limited some other nonfermentative bacilli Burkholderia cepacia >/=128 Excellent correlation achieved between broth microdilution agar dilution (r = 0.96 0.98); 94.3% results +/-1 log(2) methods used both compounds. At resistance breakpoint >/=4 microg/ml agents, unacceptable false-susceptible or very major errors noted (5%) (6%). Modified zone ( /=14 mm) suggested, but degree error persisted (>/=3.5%). It is recommended that all susceptible disk diffusion be confirmed MIC preferred reference method. quality control (QC) ranges listed in product package insert require adjusted range approximately 3 mm gram-negative strains. This vitro test class drugs continued serious with method, possible need adjustments, recalculation QC ranges. laboratories should exclusively use assist therapeutic application until modifications are sanctioned published NCCLS.