%0 Journal Article %A Abdul Momin, Muhd Haziq F. %A Bean, David C. %A Hendriksen, Rene S. %A Haenni, Marisa %A Phee, Lynette M. %A Wareham, David W. %T CHROMagar COL-APSE: a selective bacterial culture medium for the isolation and differentiation of colistin-resistant Gram-negative pathogens %D 2017 %J Journal of Medical Microbiology, %V 66 %N 11 %P 1554-1561 %@ 1473-5644 %R https://doi.org/10.1099/jmm.0.000602 %K MCR-1 %K resistance %K colistin %K CHROMagar COL-APSE %I Microbiology Society, %X Purpose. A selective chromogenic culture medium for the laboratory isolation and differentiation of colistin resistant A cinetobacter, Pseudomonas, Stenotrophomonas and E nterobacteriaceae spp. (CHROMagar COL-APSE) was developed, evaluated and compared to an existing selective bacterial culture medium (SuperPolymyxin). Methodology. The medium was challenged with 84 isolates, including polymyxin B (POL B)-susceptible and -resistant type strains and colistin (COL)-resistant organisms recovered from human and animal samples. Susceptibility to COL and POL B was determined by agar dilution and broth microtitre dilution. The lower limit for the detection of COL-resistant organisms was also calculated for both CHROMagar COL-APSE and SuperPolymyxin media. The ability to isolate and correctly differentiate COL-resistant organisms within mixed cultures was also assessed and compared using both media. Results. Using CHROMagar COL-APSE, Gram-negative pathogens (n=71) with intrinsic (n=8) or acquired COL (n=63) resistance were recovered with 100 % specificity down to the lower limit of detection of 101 colony-forming units (c.f.u.). The growth on SuperPolymyxin was similar, but notably weaker for COL-resistant non-fermentative bacteria (Acinetobacter, Pseudomonas and Stenotrophomonas). CHROMagar COL-APSE was also more sensitive in supporting the growth of Enterobacteriaceae with COL resistance associated with the carriage of mcr-1. Conclusion. CHROMagar COL-APSE is a sensitive and specific medium for the growth of COL-resistant bacterial pathogens. Due to the low limit of detection (101 c.f.u.), it may be useful as a primary isolation medium in the surveillance and recovery of COL-resistant bacteria from complex human, veterinary and environmental samples, especially those with plasmid-mediated MCR-1 or novel mechanisms of polymyxin resistance. %U https://www.microbiologyresearch.org/content/journal/jmm/10.1099/jmm.0.000602