title: Enterococcus faecium low-affinity pbp5 is a transferable determinant.
abstract: Using 15 unrelated Enterococcus faecium isolates as donors, we demonstrated that ampicillin resistance was transferable to an E. faecium recipient containing a pbp5 deletion for all but four strains. The transfers occurred at low frequencies (generally ca. 10(-9) transconjugants/recipient CFU), consistent with chromosome-to-chromosome transfer. pbp5 transfer occurred within large genetic regions, and insertion into the recipient genome occurred most commonly into the recipient SmaI restriction fragment that had been created by the previous pbp5 deletion. Restriction mapping of the region upstream of pbp5 revealed a commonality of fragment sizes among the clinical isolates from the United States which differed significantly from those of three strains that were isolated from turkey feces. These data prove conclusively that E. faecium pbp5 is a transferable determinant, even in the absence of a coresiding vancomycin resistance mobile element. They also suggest that the spread of high-level ampicillin resistance among U.S. E. faecium strains is due in part to the transfer of low-affinity pbp5 between clinical isolates.
authors.affiliation: Medical Service 111(W), Louis Stokes Cleveland VA Medical Center, 10701 East Blvd., Cleveland,Ohio 44106, USA. louis.rice@med.va.gov
authors.forename: Louis B
authors.initials: LB
authors.lastname: Rice
authors.forename: Lenore L
authors.initials: LL
authors.lastname: Carias
authors.forename: Susan
authors.initials: S
authors.lastname: Rudin
authors.forename: Viera
authors.initials: V
authors.lastname: Lakticová
authors.forename: Aaron
authors.initials: A
authors.lastname: Wood
authors.forename: Rebecca
authors.initials: R
authors.lastname: Hutton-Thomas
mesh_terms: D003227:Conjugation, Genetic; D004352:Drug Resistance, Microbial / Q000235:genetics; D016984:Enterococcus faecium / Q000187:drug effects / Q000235:genetics*; D046915:Penicillin-Binding Proteins / Q000235:genetics*; D014640:Vancomycin / Q000494:pharmacology
chemical_list: D046915:Penicillin-Binding Proteins; D014640:Vancomycin