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Detection of carbapenemases and other mechanisms of enzymatic resistance to β-lactams in Enterobacteriaceae with diminished susceptibility to carbapenems in a tertiary care hospital

2017; Elsevier BV; Volume: 36; Issue: 5 Linguagem: Espanhol

10.1016/j.eimc.2017.07.006

1695-4114

Marta Gómara-Lomero, Ana Isabel López‐Calleja, Berta María Pilar Vela Iglesia, Isabel Ferrer Cerón, Antonio Rezusta, María José Revillo Pinilla,

Enterobacteriaceae and Cronobacter Research

Our objective was to characterize the enzymatic β-lactam resistance in clinical Enterobacteriaceae isolates with diminished susceptibility to carbapenems from 2013 to 2014 at Hospital Universitario Miguel Servet. A total of 63 clinical isolates were analyzed for the presence of carbapenemases (KPC, OXA-48 and MBL), ESBLs and AmpC enzymes by combined disk methods and PCR detection of carbapenemase-encoding and beta-lactamase-encoding genes. Fifteen isolates had a phenotypic test compatible with carbapenemase production; two of these were confirmed by PCR as OXA-48 producers. ESBL detection was positive in 27 isolates (43%); plasmid-mediated AmpC was detected in nine isolates (14.2%) and derepressed AmpC β-lactamase was present in 18 isolates (28%). During the study period, the decreased susceptibility to carbapenems in Enterobacteriaceae in our area was not due to true carbapenemases but rather to β-lactamase activity (82.5% were ESBL or AmpC producers), probably in combination with decreased permeability of the outer membrane. Nuestro objetivo fue caracterizar la resistencia enzimática a β-lactámicos en aislados clínicos de Enterobacteriaceae con sensibilidad disminuida a carbapenems desde 2013 a 2014 en el Hospital Universitario Miguel Servet. Se analizaron un total de 63 aislados clínicos para presencia de carbapenemasas (KPC, OXA-48 y MBL), BLEE y AmpC por método de discos combinados y detección de genes codificantes de carbapenemasas y betalactamasas por PCR. Quince aislados tuvieron un test fenotípico compatible con producción de carbapenemasas; dos de ellos confirmados por PCR como productores de OXA-48. La detección BLEE fue positiva en 27 aislados (43%); se detectó AmpC plasmídica en 9 aislados (14,2%) y se observó β-lactamasa AmpC desreprimida en 18 aislados (28%). Durante el período de estudio, la sensibilidad disminuida a carbapenems en Enterobacteriaceae en nuestra área no se debió a verdaderas carbapenemasas sino a actividad β-lactamasa (82,5% eran productores de BLEE o AmpC) probablemente en combinación con permeabilidad disminuida de la membrana externa.