Derivation and validation of clinical prediction rules for reduced vancomycin susceptibility in Staphylococcus aureus bacteraemia

• Published in: Epidemiology and infection 2013-01, Vol.141 (1), p.165-173
• Main Authors: HAN, J. H., BILKER, W. B., EDELSTEIN, P. H., MASCITTI, K. B., LAUTENBACH, E.
• Format: Article
• Language: English
• Subjects: Antimicrobials; Bacteremia; Bacteremia - diagnosis; Bacteremia - microbiology; Bacteremia - pathology; Bacterial diseases; Bacterial sepsis; Bacteriology; Biological and medical sciences; Broths; Cohort Studies; Comorbidity; Decision Support Techniques; Diagnosis related groups; DRGs; Female; Fundamental and applied biological sciences. Psychology; Health outcomes; Hospitals, University; Human bacterial diseases; Humans; Infections; Infectious diseases; Male; Medical sciences; Methicillin resistant staphylococcus aureus; Microbial Sensitivity Tests; Microbiology; Miscellaneous; Modeling; Mortality; Original Papers; Retrospective Studies; Staphylococcal Infections - diagnosis; Staphylococcal Infections - microbiology; Staphylococcal Infections - pathology; Staphylococci, Bloodstream Infections; Staphylococcus aureus; Staphylococcus aureus - drug effects; Staphylococcus aureus - isolation & purification; Staphylococcus infections; Statistical models; Vancomycin Resistance; Variables
• ISSN: 0950-2688; 1469-4409
• DOI: 10.1017/S0950268812000295

Reduced vancomycin susceptibility (RVS) may lead to poor clinical outcomes in Staphylococcus aureus bacteraemia. We conducted a cohort study of 392 patients with S. aureus bacteraemia within a university health system. The association between RVS, as defined by both Etest [vancomycin minimum inhibitory concentration (MIC) > 1·0 μg/ml] and broth microdilution (vancomycin MIC ≥ 1·0 μg/ml), and patient and clinical variables were evaluated to create separate predictive models for RVS. In total, 134 (34·2%) and 73 (18·6%) patients had S. aureus isolates with RVS by Etest and broth microdilution, respectively. The final model for RVS by Etest included methicillin resistance [odds ratio (OR) 1·51, 95% confidence interval (CI) 0·97—2·34], non-white race (OR 0·67, 95% CI 0·42—1·07), healthcare-associated infection (OR 0·56, 95% CI 0·32—0·96), and receipt of any antimicrobial therapy ≤ 30 days prior to the culture date (OR 3·06, 95% CI 1·72—5·44). The final model for RVS by broth microdilution included methicillin resistance (OR 2·45, 95% CI 1·42—4·24), admission through the emergency department (OR 0·54, 95% CI 0·32—0·92), presence of an intravascular device (OR 2·24, 95% CI 1·30—3·86), and malignancy (OR 0·51, 95% CI 0·26—1·00). The availability of an easy and rapid clinical prediction rule for early identification of RVS can be used to help guide the timely and individualized management of these serious infections.