Analysis of VanA vancomycin-resistant Enterococcus faecium isolates from Saudi Arabian hospitals reveals the presence of clonal cluster 17 and two new Tn1546 lineage types

Abstract

Objectives: The aim of this study was to characterize 34 vancomycin-resistant VanA Enterococcus faecium isolates obtained from two hospitals in Saudi Arabia and to assess Tn1546 variation within these isolates.

Methods: PFGE and multilocus sequence typing (MLST) genotypes, antibiotic susceptibility patterns, the presence of enterococcal surface protein (esp) and hyaluronidase (hyl) genes and conjugation frequencies were determined. In addition, Tn1546 elements were characterized.

Results: PFGE and MLST analysis revealed the presence of 31 and 6 different genotypes, respectively. Further, three new ST types were discovered. Ninety-seven percent (33/34) of the isolates were associated with clonal complex 17 (CC17), with all isolates but one being resistant to ampicillin and all isolates being susceptible to linezolid. The esp and hyl genes were found in 44% (15/34) and 53% (18/34) of the isolates, respectively. Tn1546 analysis revealed that the isolates belonged to five different groups, including two new lineages. The IS-element insertions described did not abolish the transfer of VanA resistance.

Conclusions: VanA vancomycin-resistant E. faecium isolates obtained from Saudi Arabian hospitals include CC17 MLST types, a clonal cluster associated with E. faecium nosocomial infection worldwide. Novel E. faecium MLST types are circulating in Saudi Arabia, as well as novel Tn1546 types. It seems likely that CC17 E. faecium isolates may be distributed throughout the Middle East as well as Europe, America, Africa and Australia.