New type F lineage-related Tn1546 and a vanA/vanB type vancomycin-resistant Enterococcus faecium isolated from patients in Dammam, Saudi Arabia during 2006-2007.

Knowledge regarding vancomycin-resistant enterococci (VRE) from Middle Eastern countries is scarce. We therefore investigated the antimicrobial resistance profiles and genetic relationships of VRE Enterococcus faecium isolates obtained from patients attending the King Fahad Specialist Hospital, Dammam, during 2006-2007. The predominant VRE comprised 20 vanB, five vanA and one vanA/vanB type isolates, which tended to fall into two genetic clusters that were identifiable phenotypically by their susceptibility to tetracycline. Multi-locus sequence typing of a random selection of isolates showed that they were part of clonal cluster 17, showing the importance of this genotype in nosocomial VRE infections in Saudi Arabia. Further analysis showed that four of the vanA genotype isolates possessed a new type F Tn1546 transposon, associated with IS1216V and IS1251. Finally, E. faecium vanA/B isolates are rarely reported in the clinical setting including in Saudi Arabia.