RESUMO
The increase in infections caused by Enterobacterales resistant to carbapenems and other antimicrobials has limited the therapeutic alternatives which have led to the recovery of the use of colistin in clinical practices. Since 2015, a mechanism that confers resistance to colistin through plasmids related to the mcr-1 gene (Mobile Colistin Resistance) was detected, increasing the importance of its susceptibility test in the laboratory. Colistin susceptibility was evaluated by the disk elution method in 24 strains of Carbapenemase-producing type KPC Klebsiella pneumoniae, resulting 4 strains (17 %) resistant to colistin and 20 strains (83 %) intermediate. Also, in these strains, sensitivity to meropenem was evaluated by the E-test® method, finding that 10 strains (41,6 %) were within the acceptable range for their combination with colistin, 5 strains (20, 8 %) were within the uncertain range and 9 strains (37,4 %) were not appropriate for combination with colistin. For the combination of colistin with meropenem to be considered as a therapeutic alternative the MIC of colistin must be ≤ 2 µg /mL with meropenem ≤8 µg /mL, while the MIC between 12-16 µg/mL of meropenem may or not may work; and with a MIC of 32 µg/mL meropenem, the combination is not effective.
RESUMO
La resistencia a las polimixinas mediada por plásmidos (gen mcr-1) representa una amenaza para la salud pública, puesto que colistina es utilizada en la práctica médica como una de las últimas alternativas para el tratamiento de gérmenes multiresistentes. Este estudio describe la circulaciónde cepas de Enterobacterias que portan este gen de resistencia, aisladas de pacientes hospitalizados, así como también de la comunidad. Los hallazgos de la Red de Vigilancia de la Resistencia a los Antimicrobianos-Paraguay fueron de casi el 5 % (4,7) en cepas remitidas con criterio de sospecha, siendo las especies involucradas Escherichiacoli, Klebsiella pneumoniae y Salmonella Schwarzengrund. Además, por métodos moleculares se confirmaron en todas ellas la portación de otros genes de resistencia (KPC, CTX-M, Qnr B, Qnr S, aac (6`)-Ib-cr) asociados al mcr-1. Palabras claves: Enterobacterias, resistencia, colistina, mcr-1.
Resistance to polymyxins mediated by plasmids (mcr-1 gene) represents a threat to public health, since colistin is used in medical practice, as one of the last alternatives, for the treatment of multi-resistant germs. This study describes the circulation of strains of Enterobacteria that carry this resistance gene, isolated from hospitalized patients, as well as from the community. The findings of the Red de Vigilancia de la Resistencia a los AntimicrobianosParaguay were almost 5% (4.7) in strains submitted with suspicion criteria; the species involved being Escherichia coli, Klebsiella pneumoniae and Salmonella Schwarzengrund. In addition, molecular methods confirmed in all of them the carrying of other resistance genes (KPC, CTX-M, Qnr B, Qnr S, aac (6`)-Ib-cr) associated with mcr-1. Key words: Enterobacteria, resistance, colistin, mcr-1.