Methicillin-resistant staphylococcus aureus (MRSA) staphylococcal cassette chromosome mec genotype effects outcomes of patients with healthcare-associated MRSA bacteremia independently of vancomycin minimum inhibitory concentration
Journal
Clinical Infectious Diseases
Journal Volume
55
Journal Issue
10
Pages
1329-1337
Date Issued
2012
Author(s)
Liao C.-H.
Wang J.-L.
Lai M.-S.
Abstract
Background. Recent evidence has shown that community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) is less virulent than traditional hospital-associated MRSA. We explored whether the antimicrobial susceptibilities of the different strains account for their disparity in clinical virulence. Methods. This 10-year retrospective cohort study enrolled 291 patients with community-onset, healthcare-associated MRSA bacteremia. The vancomycin minimum inhibitory concentration (MIC) and staphylococcal cassette chromosome mec (SCCmec) type were determined for all isolates. CA-MRSA was defined as an isolate possessing the SCCmec type IV or V genes, and hospital-associated MRSA (HA-MRSA) was defined as an isolate possessing SCCmec type I, II, or III genes. Low and high vancomycin MICs were defined as MICs of ?1 and ?2 g/mL, respectively. Patients with bacteremia due to CA-MRSA with a low vancomycin MIC (n = 111), due to HA-MRSA with a low vancomycin MIC (n = 127), or due to HA-MRSA with a high vancomycin MIC (n = 47) entered the outcome analysis. The outcomes of the 2 HA-MRSA bacteremia groups were compared to those of the CA-MRSA bacteremia group. Results. Treatment failure was observed in 35 (31.5), 59 (46.5), and 27 (57.4) of patients with low-vancomycin-MIC CA-MRSA, low-vancomycin-MIC HA-MRSA, and high-vancomycin-MIC HA-MRSA bacteremia, respectively. After adjustment for potential confounding factors, the risk of treatment failure was significantly higher among patients with low-vancomycin-MIC HA-MRSA (adjusted odds ratio [aOR], 1.853; 95 confidence interval [CI], 1.006-3.413) and high-vancomycin-MIC HA-MRSA (aOR, 2.393; 95 CI, 1.079-5.309), compared with patients with low-vancomycin-MIC CA-MRSA. Conclusions. The higher risk for treatment failure among patients with traditional hospital-associated MRSA infections, compared with patients with CA-MRSA infections, is independent of the vancomycin MIC, suggesting a potential intrinsic strain-specific virulence effect. ? 2012 The Author.
SDGs
Other Subjects
daptomycin; linezolid; vancomycin; adult; aged; article; bacterial chromosome; bacterium isolate; chromosome identification; community onset methicillin resistant Staphylococcus aureus infection; female; genotype; health care associated methicillin resistant Staphylococcus aureus infection; human; major clinical study; male; methicillin resistant Staphylococcus aureus infection; minimum inhibitory concentration; priority journal; risk factor; Staphylococcal cassette chromosome mec; treatment failure; treatment outcome; Aged; Aged, 80 and over; Analysis of Variance; Anti-Bacterial Agents; Bacteremia; Bacterial Proteins; Cohort Studies; Community-Acquired Infections; Cross Infection; Female; Genotype; Humans; Male; Methicillin-Resistant Staphylococcus aureus; Microbial Sensitivity Tests; Middle Aged; Odds Ratio; Retrospective Studies; Staphylococcal Infections; Treatment Outcome; Vancomycin
Type
journal article