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Antimicrob Agents Chemother. 2017 Nov 22;61(12). pii: e00841-17. doi: 10.1128/AAC.00841-17. Print 2017 Dec.

Genomic and Molecular Characterization of Clinical Isolates of Enterobacteriaceae Harboring mcr-1 in Colombia, 2002 to 2016.

Author information

1
Grupo de Microbiología, Instituto Nacional de Salud (INS), Bogotá, Colombia sysaavedrar@gmail.com cduarte@ins.gov.co.
2
Molecular Genetics and Antimicrobial Resistance Unit, International Center for Microbial Genomics, Universidad El Bosque, Bogotá, Colombia.
3
Center for Antimicrobial Resistance and Microbial Genomics, University of Texas Health Science Center, McGovern Medical School, Houston, Texas, USA.
4
Grupo de Microbiología, Instituto Nacional de Salud (INS), Bogotá, Colombia.
5
Grupo de Resistencia Bacteriana y Epidemiología Hospitalaria, International Center for Medical Research and Training (CIDEIM), Cali, Colombia.
6
Dirección de Redes en Salud Pública y LNR, Instituto Nacional de Salud (INS), Bogotá, Colombia.

Abstract

Polymyxins are last-resort antimicrobial agents used to treat infections caused by carbapenem-resistant Enterobacteriaceae Due to the worldwide dissemination of polymyxin resistance in animal and human isolates, we aimed to characterize polymyxin resistance associated with the presence of mcr-1 in Enterobacteriaceae and nonfermenter Gram-negative bacilli, using isolates collected retrospectively in Colombia from 2002 to 2016. A total of 5,887 Gram-negative clinical isolates were studied, and 513 were found to be resistant to the polymyxins. Susceptibility to colistin was confirmed by broth microdilution for all mcr-1-positive isolates, and these were further subjected to whole-genome sequencing (WGS). The localization of mcr-1 was confirmed by S1 pulsed-field gel electrophoresis (S1-PFGE) and CeuI-PFGE hybridization. Transferability was evaluated by mating assays. A total of 12 colistin-resistant isolates recovered after 2013 harbored mcr-1, including 8 Escherichia coli, 3 Salmonella enterica serovar Typhimurium, and 1 Klebsiella pneumoniae isolate. E. coli isolates were unrelated by PFGE and belonged to 7 different sequence types (STs) and phylogroups. S Typhimurium and K. pneumoniae isolates belonged to ST34 and ST307, respectively. The mcr-1 gene was plasmid borne in all isolates but two E. coli isolates which harbored it on the chromosome. Conjugation of mcr-1 was successful in 8 of 10 isolates (8.2 × 10-5 to 2.07 × 10-1 cell per recipient). Plasmid sequences showed that the mcr-1 plasmids belonged to four different Inc groups (a new IncP-1 variant and the IncFII, IncHI1, and IncH families). Our results indicate that mcr-1 is circulating in clinical isolates of colistin-resistant Enterobacteriaceae in Colombia and is mainly harbored in transferable plasmids.

KEYWORDS:

Colombia; Enterobacteriaceae; genomic; mcr-1

PMID:
28893788
PMCID:
PMC5700323
DOI:
10.1128/AAC.00841-17
[Indexed for MEDLINE]
Free PMC Article

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