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Recently it was developed the Colistin Broth Disk Elution test which uses colistin disks as a source of these antibiotics. The aim of this study was to evaluate the performance of protocols that used diminished volumes of the reagents: the Colistin Broth Microelution (CBM) (1 mL) and the Microelution-Plates Test (MPT) (200 μL), as well as the Colistin Susceptibility Test Tube (CSTT), which uses only one colistin disk added to a tube containing broth. The tests were performed with 85 Gram-negative isolates collected from surveillance studies. The CBM, MPT, and CSTT tests presented a good Categorical Agreement (CA), Essential Agreement (EA), sensitivity and specificity to Enterobacterales isolates, however the ME and VME were less satisfactory. The results for non-fermentative isolates were not satisfactory. In conclusion, the proposed methods, mainly the CSTT, can be used as screening tests to detect colistin resistant among Enterobacterales, as they are an easy and inexpensive option to the reference method., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Two hundred isolates of Enterobacterales were tested by Rapid Polymyxins NP for the detection of polymyxin resistance and compared to the reference test broth microdilution (BMD). The sensitivity and specificity of the NP test were 98% and the results are faster than the BMD, decreasing from approximately 24 to 2 h.

We identified one clinical isolate of K. pneumoniae harboring the mcr 1 (plasmid of IncX4 family) and bla KPC-2 (plasmid of IncFIB family) genes in southern Brazil. These findings highlight that K. pneumoniae isolates carrying both mcr-1 and bla KPC-2 may emergence as a serious threat to antimicrobial therapy., (Copyright © 2017 Elsevier Inc. All rights reserved.)