Open AccessComparative evaluation of susceptibility testing methods for colistin and polymyxin B among clinical isolates of carbapenem- resistant Klebsiella pneumoniae and Acinetobacter baumannii
Author(s) -
Yamuna Devi Bakthavatchalam,
Abirami Shankar,
Bhuvaneswari Thukaram,
Dhanabhagyam Naveena Krishnan,
Balaji Veeraraghavan
Publication year - 2018
Publication title -
journal of infection in developing countries
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.322
H-Index - 49
eISSN - 2036-6590
pISSN - 1972-2680
DOI - 10.3855/jidc.9660
Subject(s) - colistin , polymyxin b , acinetobacter baumannii , polymyxin , medicine , broth microdilution , klebsiella pneumoniae , microbiology and biotechnology , antibiotics , biology , minimum inhibitory concentration , pseudomonas aeruginosa , bacteria , biochemistry , genetics , escherichia coli , gene
Susceptibility testing (ST) of colistin and polymyxin B is challenging. Disc diffusion testing is not reliable for polymyxin ST, because of poor diffusion. Currently, for polymyxin ST, the EUCAST-CLSI joint commission recommending broth microdilution (BMD) as the reference method. In this study, reliability of E-test and Vitek 2 was compared with BMD, using the susceptible breakpoint of ≤ 2μg/ml for both colistin and polymyxin B. Overall, essential agreement (EA) for colistin between E-test, Vitek2 and BMD were 37% and 74% respectively. EA for polymyxin B between E-test and BMD were 65%. Very major error (VME) for colistin and polymyxin B with E-test were 42% and 55% respectively. An unacceptable VME of 11% was seen for colistin with Vitek2. Major errors (MEs) were rather limited with both E-test and Vitek2. E-test and Vitek2 may lead to inappropriate decision-making for colistin/polymyxin B therapy. Thus, clinical laboratories should consider BMD for polymyxin ST.