CHROMagar COL-APSE : A selective bacterial culture medium for the isolation and differentiation of colistin-resistant gram-negative pathogens
- Authors: Abdul Momin, Muhd , Bean, David , Hendriksen, Rene , Haenni, Marisa , Phee, Lynette , Wareham, David
- Date: 2017
- Type: Text , Journal article
- Relation: Journal of Medical Microbiology Vol. 66, no. 11 (2017), p. 1554-1561
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- Description: Purpose. A selective chromogenic culture medium for the laboratory isolation and differentiation of colistin resistant Acinetobacter, Pseudomonas, Stenotrophomonas and Enterobacteriaceae 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 plasmidmediated MCR-1 or novel mechanisms of polymyxin resistance. © 2017 The Authors.
Polymyxin resistant bacteria in Australian poultry
- Authors: Bean, David , Wigmore, Sarah , Abdul Momin, Muhd , Wareham, David
- Date: 2020
- Type: Text , Journal article
- Relation: Frontiers in Sustainable Food Systems Vol. 4, no. (2020), p. 1-7
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- Description: Resistance to last-resort antibiotics is significant public health issue. Antibiotic use in animal husbandry may be a driver of resistance that can subsequently be disseminated via the food chain. This study sought to determine the level of polymyxin resistance in Gram-negative pathogens present in Australian poultry, particularly the presence of mobilizable mechanisms of polymyxin resistance. Cloacal swabs from 213 birds were taken in a point prevalence survey from six different farms at a Victorian chicken processing facility. Colistin resistant organisms were recovered by direct plating on CHROMagar COL-APSE media. Bacterial isolates were identified and analyzed by MALDI-TOF, biochemical and genotypic assays. The 213 specimens yielded 57 (26.8%) colistin-resistant Gram-negative organisms, all of which have been previously described as exhibiting intrinsic resistance to polymyxin antibiotics. The most frequent organism was identified as Hafnia paralvei (40/57; 70%). Other colistin-resistant organisms included Aeromonas hydrophila (16%), Myroides odoratus (7%), Alcaligenes faecalis (5%), and Pseudochrobactrum spp. (2%). No mobile colistin resistance (mcr) genes were detected, although the arnA gene was identified in two A. hydrophila isolates and may mediate colistin resistance in these isolates. Intrinsic polymyxin-resistant organisms are widely distributed in the food chain, with over a quarter of the birds tested yielding a polymyxin-resistant organism. However, strains containing mcr genes remain rare in Australian poultry. © Copyright © 2020 Bean, Wigmore, Abdul Momin and Wareham.