title: Dissemination of an Enterococcus Inc18-Like vanA plasmid associated with vancomycin-resistant Staphylococcus aureus.
abstract: Of the 9 vancomycin-resistant Staphylococcus aureus (VRSA) cases reported to date in the literature, 7 occurred in Michigan. In 5 of the 7 Michigan VRSA cases, an Inc18-like vanA plasmid was identified in the VRSA isolate and/or an associated vancomycin-resistant Enterococcus (VRE) isolate from the same patient. This plasmid may play a critical role in the emergence of VRSA. We studied the geographical distribution of the plasmid by testing 1,641 VRE isolates from three separate collections by PCR for plasmid-specific genes traA, repR, and vanA. Isolates from one collection (phase 2) were recovered from surveillance cultures collected in 17 hospitals in 13 states. All VRE isolates from 2 Michigan institutions (n = 386) and between 60 and 70 VRE isolates (n = 883) from the other hospitals were tested. Fifteen VRE isolates (3.9%) from Michigan were positive for an Inc18-like vanA plasmid (9 E. faecalis [12.5%], 3 E. faecium [1.0%], 2 E. avium, and 1 E. raffinosus). Six VRE isolates (0.6%) from outside Michigan were positive (3 E. faecalis [2.7%] and 3 E. faecium [0.4%]). Of all E. faecalis isolates tested, 6.0% were positive for the plasmid, compared to 0.6% for E. faecium and 3.0% for other spp. Fourteen of the 15 plasmid-positive isolates from Michigan had the same Tn1546 insertion site location as the VRSA-associated Inc18-like plasmid, whereas 5 of 6 plasmid-positive isolates from outside Michigan differed in this characteristic. Most plasmid-positive E. faecalis isolates demonstrated diverse patterns by PFGE, with the exception of three pairs with indistinguishable patterns, suggesting that the plasmid is mobile in nature. Although VRE isolates with the VRSA-associated Inc18-like vanA plasmid were more common in Michigan, they remain rare. Periodic surveillance of VRE isolates for the plasmid may be useful in predicting the occurrence of VRSA.
authors.affiliation: Division of Healthcare Quality Promotion1 and Division of Scientific Resources,4 Centers for Disease Control and Prevention, MS-G08, 1600 Clifton Road, Atlanta, Georgia 30333, USA.
authors.forename: Wenming
authors.initials: W
authors.lastname: Zhu
authors.forename: Patrick R
authors.initials: PR
authors.lastname: Murray
authors.forename: W Charles
authors.initials: WC
authors.lastname: Huskins
authors.forename: John A
authors.initials: JA
authors.lastname: Jernigan
authors.forename: Lawrence C
authors.initials: LC
authors.lastname: McDonald
authors.forename: Nancye C
authors.initials: NC
authors.lastname: Clark
authors.forename: Karen F
authors.initials: KF
authors.lastname: Anderson
authors.forename: Linda K
authors.initials: LK
authors.lastname: McDougal
authors.forename: Jeff C
authors.initials: JC
authors.lastname: Hageman
authors.forename: Melissa
authors.initials: M
authors.lastname: Olsen-Rasmussen
authors.forename: Mike
authors.initials: M
authors.lastname: Frace
authors.forename: George J
authors.initials: GJ
authors.lastname: Alangaden
authors.forename: Carol
authors.initials: C
authors.lastname: Chenoweth
authors.forename: Marcus J
authors.initials: MJ
authors.lastname: Zervos
authors.forename: Barbara
authors.initials: B
authors.lastname: Robinson-Dunn
authors.forename: Paul C
authors.initials: PC
authors.lastname: Schreckenberger
authors.forename: L Barth
authors.initials: LB
authors.lastname: Reller
authors.forename: James T
authors.initials: JT
authors.lastname: Rudrik
authors.forename: Jean B
authors.initials: JB
authors.lastname: Patel
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics; D016521:Electrophoresis, Gel, Pulsed-Field; D016983:Enterococcus / Q000187:drug effects* / Q000235:genetics*; D013293:Enterococcus faecalis / Q000187:drug effects / Q000235:genetics; D016984:Enterococcus faecium / Q000187:drug effects / Q000235:genetics; D010957:Plasmids / Q000235:genetics*; D016133:Polymerase Chain Reaction; D013211:Staphylococcus aureus / Q000187:drug effects / Q000235:genetics*; D020713:Vancomycin Resistance / Q000235:genetics*
chemical_list: D001426:Bacterial Proteins