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Evaluation of a polymyxin drop test for polymyxin resistance detection among non‐fermentative gram‐negative rods and enterobacterales resistant to carbapenems
Author(s) -
Perez Leandro Reus Rodrigues,
Carniel Eliana,
Narvaez Gabriel Azambuja,
Dias Cícero Gomes
Publication year - 2021
Publication title -
apmis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.909
H-Index - 88
eISSN - 1600-0463
pISSN - 0903-4641
DOI - 10.1111/apm.13096
Subject(s) - polymyxin , polymyxin b , klebsiella pneumoniae , microbiology and biotechnology , broth microdilution , medicine , minimum inhibitory concentration , biology , antibiotics , escherichia coli , biochemistry , gene
To assess the performance of the drop test for polymyxin B resistance detection among Enterobacterales and non‐fermentative gram‐negative rods resistant to carbapenems. Seven hundred and fifteen carbapenem‐resistant isolates were tested: 628 Enterobacterales species and 87 non‐fermentative gram‐negative rods. For the polymyxin drop test, concentrations range from 0.25 to 8.0 µg/mL. Broth microdilution, as gold standard, was performed using in‐house‐prepared panels and interpreted according to the CLSI guidelines. Results were interpreted in terms of categorical agreements and discrepancies. Accuracy for a drop of polymyxin B at 2.0, 4.0 and 8.0 was calculated as better cutoff for resistance determination. No very major error was observed among all isolates, and 95.5% of agreement was observed among Enterobacterales, particularly for Klebsiella pneumoniae . A higher accuracy (95.1%) was obtained when a single drop of polymyxin B at 4.0 μg/mL was applied. Polymyxin drop test presented >95% of categorical agreement, without very major errors, for KPC‐producing K. pneumoniae isolates. An accuracy of 95.1% was obtained with a single drop at 4.0 μg/mL polymyxin B. Polymyxin B drop is an easy and feasible test and may allow a reduction on the turnaround time for polymyxin resistance detection and impacting on early implementation of accurate therapeutic interventions.