Open AccessCharacterization of Vancomycin-Heteroresistant Staphylococcus aureus from the Metropolitan Area of Detroit, Michigan, over a 22-Year Period (1986 to 2007)
Author(s) -
Michael J. Rybak,
Steven N. Leonard,
Kerri L. Rossi,
Chrissy M. Cheung,
Helio S. Sadar,
Ronald N. Jones
Publication year - 2008
Publication title -
journal of clinical microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.349
H-Index - 255
eISSN - 1070-633X
pISSN - 0095-1137
DOI - 10.1128/jcm.00582-08
Subject(s) - etest , staphylococcus aureus , microbiology and biotechnology , population , vancomycin , medicine , sccmec , micrococcaceae , methicillin resistant staphylococcus aureus , antibiotics , biology , antibacterial agent , bacteria , genetics , environmental health
We screened for heteroresistant, vancomycin-intermediateStaphylococcus aureus (hVISA) among clinical isolates of methicillin-resistantS. aureus collected from three hospitals (two urban teaching hospitals and one community hospital) in the Detroit metropolitan area over a 22-year period. The Macro Etest method was used to screen all available isolates. Confirmation of hVISA-positive screens were confirmed by population-area under the concentration-time curve (AUC) analysis. A total of 1,499 isolates revealed hVISA/VISA rates of 2.2/0.4% (n = 225; 1986 to 1993), 7.6/2.3% (n = 356; 1994 to 2002), and 8.3/0.3% (n = 917; 2003 to 2007). Population-AUC analysis confirmed 92.6% of the hVISA-positive strains determined by the Macro Etest method. For the isolates with known sources (1,208), the predominant source of hVISA was blood (60%), followed by lung (21%), skin and wound infections (14%), abscess (1%), and other (4%). The percentage of hVISA-positive strains appeared to increase as a function of the vancomycin MIC. Staphylococcal cassette chromosomemec (SCCmec ) typing revealed that the majority (56.9%) of the hVISA strains were SCCmec type II and 39.4% were type IV; the majority of these strains were collected from 2000 to 2007. Our data indicate that the prevalence of hVISA may be increasing. Based on the association of vancomycin treatment failure in patients with hVISA, surveillance of hVISA strains is warranted.