Emergence of unusual vanA/vanB2 genotype in a highly mutated vanB2-vancomycin-resistant hospital-associated E. faecium background in Vietnam

International Journal of Antimicrobial Agents 52 (2018) 586–592 Contents lists available at ScienceDirect International Journal of Antimicrobial Agents journal homepage: www.elsevier.com/locate/ijantimicag Emergence of unusual vanA/vanB 2 genotype in a highly mutated vanB 2 - vancomycin-resistant hospital-associated E. faecium background in Vietnam Antonella Santona a , ∗, Elisa Taviani a , Hoa Minh Hoang a , b , Maura Fiamma a , Massimo Deligios a , Tram Viet Q Ngo b , An Van Le b , Pietro Cappuccinelli a , b , Salvatore Rubino a , Bianca Paglietti a a Department of Biomedical Sciences, University of Sassari, Viale San Pietro 43/b, 07100 Sassari, Italy b Department of Microbiology & Carlo Urbani Center, Hue University of Medicine & Pharmacy, Hue, Viet Nam a r t i c l e i n f o Article history: Received 9 May 2018 Accepted 7 July 2018 Editor: Seydina Diene Keywords: VSEf/VREF WGS Tn1547 Tn1546 vanA/vanB a b s t r a c t Enterococcus faecium has become a globally disseminated nosocomial pathogen mainly because of acqui- sition and diffusion of virulence factors and multidrug resistance determinants, including glycopeptides, which are some of the last resort antimicrobials used to treat more serious infections common in high- risk patients. In this study we investigated and characterized hospital-associated (HA) E. faecium isolates collected at Hue Central Hospital, Vietnam. Our results highlighted the spread among hospital wards of a surprisingly heterogeneous multidrug- resistant E. faecium population comprising five different CC17-related sequence types (STs), of which 46% VREf carry the vanB gene. Whole genome sequencing of selected E. faecium isolates showed that VREf from different STs carried the same chromosomal integrated Tn1549-like transposon, with a highly mu- tated vanB2-operon, showing an increased level of vancomycin resistance (VanB phenotype) and able, in one isolate, to confer resistance to teicoplanin (VanA incongruent phenotype). Two unusual vanA/vanB 2 -type strains were detected within the vanB 2 -type ST17 population, harbour- ing a Tn 1546- vanA-like transposon in pJEG40-like plasmids. Wg-SNPs-based analysis showed the ge- netic relatedness of VSEf/VREf of the same STs and indicated lateral exchange of the Tn 1549 -like ele- ment among isolates followed by clonal expansion. Microevolution among ST17 isolates, including the vanA/vanB 2 -type strains, and inter-wards VREf transmission, were highlighted. The use of teicoplanin is strongly discouraged in the study hospital because of the spreading of Tn 1549 –vanB 2 associated to teicoplanin resistance. A rational use of glycopeptides and effective surveil- lance measures are required to reduce nosocomial VSEF/VREf spread and to avoid the rise of unusual and misleading VREf genotypes.