Caracterización Molecular de Enterococcus faecium multirresistentes causantes de infecciones en sangre en un Hospital Universitario del norte de España

Abstract

Introduction Multi-resistant CC17 Enterococcus faecium represent an important cause of nosocomial infections. Our main objective is the analysis of the multi-resistant E. faecium local epidemiology in the Hospital Universitario Marqués de Valdecilla. To do this, the isolates clonal relationship, the profile of antibiotic resistance and the presence of virulence determinants will be determined. Methods 157 E. faecium were isolated from blood cultures between 2009, January and 2016, August. The identification and antimicrobial resistance profile were determined by “VITEK 2” system. The resistance and virulence genes determination was performed by PCR and sequencing. The clonal relationship between the strains was analyzed by PFGE and MLST. Results 96% of the studied strains showed high level resistance to β-lactams, 99% to quinolones, 98% to erythromycin and 92% showed high level resistance to streptomycin. Furthermore, 28% of the isolates were tetracycline-R, 7% gentamycin-R, 2% linezolid-R and 2% chloramphenicol-R. Glycopeptide resistance was not detected. The identified resistance genes were: ermB, ermT and mrsC (encoding macrolide-resistance), ant6-Ia, and aph(3’)-III (high level resistance to streptomycin and kanamycin, respectively), aac(6’)-Ie_aph(2’)-Ia (high level gentamycin-resistance), tetM and tetL (tetracycline-resistance). The resistance to quinolones was due to the amino acid alterations S80I or S80R in ParC and S83Y or S83R in GyrA. The determination of mutations involved in the resistance to ampicillin is now in course. The detected virulence genes were: entA (96%), acm (96%), scm (94%), pilA (94%), sgrA (92%), ecbA (85%), esp (82%) and hyl (17%). The isolates were classified in 20 pulse-types, highlighting the presence of two main clones with 111 and 24 isolates, corresponding to MLST sequence types ST117 and ST17, respectively. Conclusions Most of the strains are part of the sub-cluster CC17 that is well adapted to the hospital environment. The multi-resistant E. faecium clone ST117 has emerged and disseminated in our hospital where it has become endemic and represents the 70% of the isolates.