Characterisation of mcr-4.3 in a colistin-resistant Acinetobacter nosocomialis clinical isolate from Cape Town, South Africa
| Autor: | Motlatji Reratilwe Bonnie Maloba, Mae Newton-Foot, Lisa Stein, Sandra Reuter, Andrew Whitelaw, Yolandi Snyman |
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| Rok vydání: | 2020 |
| Předmět: |
0301 basic medicine
Microbiology (medical) 030106 microbiology Immunology Drug resistance medicine.disease_cause Plasmid Microbiology Polymyxin resistance 03 medical and health sciences Minimum inhibitory concentration South Africa 0302 clinical medicine polycyclic compounds medicine Escherichia coli Immunology and Allergy 030212 general & internal medicine Acinetobacter spp Whole-genome sequencing biology Acinetobacter Colistin Broth microdilution biology.organism_classification QR1-502 lipids (amino acids peptides and proteins) mcr-4.3 hormones hormone substitutes and hormone antagonists medicine.drug Acinetobacter nosocomialis |
| Zdroj: | Journal of Global Antimicrobial Resistance, Vol 25, Iss, Pp 102-106 (2021) |
| ISSN: | 2213-7173 |
| Popis: | Objectives Colistin resistance in Acinetobacter spp. is increasing, resulting in potentially untreatable nosocomial infections. Plasmid-mediated colistin resistance is of particular concern due to its low fitness cost and potential transferability to other bacterial strains and species. This study investigated the colistin resistance mechanism in a clinical Acinetobacter nosocomialis isolate from Cape Town, South Africa. Methods A colistin-resistant A. nosocomialis isolate was identified from a blood culture in 2017. PCR and Illumina whole-genome sequencing (WGS) were performed to identify genes and mutations conferring resistance to colistin. Plasmid sequencing was performed on an Oxford Nanopore platform. mcr functionality was assessed by broth microdilution after cloning the mcr gene into pET-48b(+) and expressing it in SHuffle® T7 Escherichia coli and after curing the plasmid using 62.5 mg/L acridine orange. Results The colistin minimum inhibitory concentration (MIC) of the A. nosocomialis isolate was 16 mg/L. The mcr-4.3 gene was detected by PCR and WGS. No other previously described colistin resistance mechanism was found by WGS. The mcr-4.3 gene was identified on a 24 024-bp RepB plasmid (pCAC13a). Functionality studies showed that recombinant mcr-4.3 did not confer colistin resistance in E. coli. However, plasmid curing of pCAC13a restored colistin susceptibility in A. nosocomialis. Conclusion We describe the first detection of a plasmid-mediated mcr-4.3 gene encoding colistin resistance in A. nosocomialis and the first detection of mcr-4.3 in a clinical isolate in Africa. Recombinant expression of mcr-4.3 did not confer colistin resistance in E. coli, suggesting that its functionality may be RepB plasmid-dependent or species-specific. |
| Databáze: | OpenAIRE |
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