Towards Understanding MCR-like Colistin Resistance

Carriage of Distinct mcr‐1‐Harboring Plasmids by Unusual Serotypes of Salmonella

“…Colistin was considered one of the last lines of defense against lethal CRE infections 1–5. Unfortunately, many species of Enterobacteriaceae are becoming increasingly resistant to colistin 2,4,6,7. One colistin resistant mechanism is the modification of Lipid A of LPS, catalyzed by the chromosome encoded machinery in Klebsiella pneumoniae , the LptA (EptA) in Neisseria , or mobile colistin resistance mcr‐1 in Enterobacteriaceae 5,8–11.…”

Antibiotic exposure elicits the emergence of colistin- and carbapenem-resistant Escherichia coli coharboring MCR-1 and NDM-5 in a patient

“…In general, carbapenems are used as a last line of defense antibiotics against severe infections with MDR-possessing Enteriobactericeae. Colistin, a cationic antimicrobial polypeptide, is clinically regarded as a final line of defense to treat lethal challenges with carbapenem-resistant pathogens [4,5]. Unfortunately, it seems likely that the clinical use of carbapenems and colistin has been significantly challenged by the occurrence of mobilized colistin resistance determinant (MCR-1) in clinical carbapenem-resistant isolates producing New Delhi metallo- β -lactamase 1 (NDM-1) [6,7] or its variant NDM-5 [8,9].…”

“…Unfortunately, it seems likely that the clinical use of carbapenems and colistin has been significantly challenged by the occurrence of mobilized colistin resistance determinant (MCR-1) in clinical carbapenem-resistant isolates producing New Delhi metallo- β -lactamase 1 (NDM-1) [6,7] or its variant NDM-5 [8,9]. In addition to the intrinsic determinants of colistin resistance (e.g., EptA [10,11] and ICR-Mo [12]), the transferable determinants (MCR-1 and MCR-2 [10,13,14]) consistently encode members of phosphoethanolamine (PEA)-lipid A transferases, which adopt a ‘ping-pong’ catalysis reaction in transferring of the PEA moiety to the 4ʹ-phosphate position of the lipopolysaccharide (LPS)-lipid A species anchored on bacterial surface [4,5]. …”

Preventive antibiotic treatment of calves: emergence of dysbiosis causing propagation of obese state‐associated and mobile multidrug resistance‐carrying bacteria

“…The mcr ‐1 resistance gene is found on a highly transmissible plasmid, namely IncX 4 which is a narrow host range mobile element of Enterobacteriaceae with a lack of fitness burden on bacterial host (Liu et al , ). Recent evidence strongly suggests transfer of mcr ‐1 from animals to humans while it also can be spread in hospitals without colistin pressure (Paterson and Harris, ; Al‐Tawfiq et al , ; references therein Sun et al , ). Subsequently, mcr ‐2, another plasmid‐mediated colistin resistance gene, has been identified in porcine and bovine colistin‐resistant E. coli (Xavier et al , ).…”