The prevalence of the heterogeneous vancomycin-intermediate Staphylococcus aureus (hVISA) phenotype among methicillin-resistant S. aureus (MRSA) blood isolates can reach 38%. hVISA
bacteremia is known to be associated with
vancomycin treatment failure, including persistent
bacteremia. We conducted this study to evaluate risk factors for 12-week mortality in patients with hVISA
bacteremia through a detailed clinical and microbiological analysis of a prospective cohort of patients with S. aureus
bacteremia. All isolates were collected on the first day of
bacteremia and subjected to population analysis profiling for hVISA detection, genotyping, and PCR analysis for 39
virulence factors. Of 382 patient with MRSA
bacteremia, 121 (32%) had hVISA
bacteremia. Deceased patients were more likely to have
hematologic malignancy (P = 0.033), ultimately or rapidly fatal disease (P = 0.007), and a higher Pitt
bacteremia score (P = 0.010) than surviving patients. The sequence type 239 (ST239) clonal type and definitive
linezolid treatment were associated with a trend toward reduced mortality (P = 0.061 and 0.072, respectively), but a high
vancomycin MIC (≥2 mg/liter) was not associated with increased mortality (P = 0.368). In a multivariate analysis, ultimately or rapidly fatal disease (adjusted odds ratio [aOR], 2.80; 95% confidence interval [CI], 1.14 to 6.85) and a high Pitt
bacteremia score (aOR, 1.26; 95% CI, 1.07 to 1.48) were independent risk factors for mortality.
Hematologic malignancy was associated with a trend toward increased mortality (P = 0.094), and ST239 was associated with a trend toward reduced mortality (P = 0.095). Our study suggests that ST239 hVISA is a possible predictor of survival in hVISA
bacteremia.