Detection of Plasmid-Mediated Resistance against Colistin in Multi-Drug-Resistant Gram-Negative Bacilli Isolated from a Tertiary Hospital

Detection of Plasmid-Mediated Resistance against Colistin in Multi-Drug-Resistant Gram-Negative Bacilli Isolated from a Tertiary Hospital

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The aim of this study was to determine the prevalence of plasmid-mediated colistin resistance mcr-1 to mcr-5 genes among colistin and multi-drug-resistant Gram-negative bacilli strains isolated from patients in a tertiary hospital in Toluca, Mexico.The presence of mcr genes among the 241 strains collected was assessed by PCR.In the case of mcr-carrying E.

coli, further PCR tests were performed to determine yamaha c115v specs the presence of blaCTX-M and whether the strains belonged to the O25b-ST131 clone.Conjugation experiments were also carried out to assess the horizontal transmission of colistin resistance.A total of twelve strains (5.

0%), of which four were E.coli; four were P.aeruginosa; three were K.

pneumoniae, and one E.cloacae, were found to be resistant to colistin.Of these strains, two E.

coli isolates were found to carry mcr-1, and Southern blot hybridization demonstrated its presence on an approximately 60 kb plasmid.Both mcr-1-carrying E.coli strains were found to co-express blaCTX-M, belong to the O25b-ST131 clone, and horizontally transmit their colistin resistance.

The results of this study confirm the presence of al13sxb30en plasmid-mediated colistin resistance in hospitalized patients in Mexico and demonstrated that the multi-drug-resistant O25b-ST131 E.coli clone can acquire mcr genes and transmit such resistance traits to other bacteria.