1509. Clinical Significance of Staphylococcus aureus Bacteriuria

BACKGROUND: The clinical significance of Staphylococcus aureus bacteriuria (SABU) is unclear and often presumed to represent hematogenous spread of occult S. aureus bacteremia (SAB). The aim of this study was to evaluate the clinical significance of SABU by assessing factors associated with the development of invasive S. aureus disease and 12-month mortality. We also describe the proportion of patients with methicillin-resistant S. aureus (MRSA), symptomatic urinary tract infection (UTI), asymptomatic bacteriuria, concomitant SAB, and calculate Charlson comorbidity scores. METHODS: This is a retrospective cohort study of all SABU isolates in a tertiary care hospital from 1 January 2007 to 31 December 2016. Cases were identified by screening specimens processed in the microbiology laboratory with records in the Phoenix/BG data system. Demographic data, Charlson comorbidity score, antimicrobial susceptibility profiles, urinary catheter use, residence in a long-term care facility, and UTI symptoms were obtained through chart review. RESULTS: A total of 356 patients with SABU were identified and 237 met inclusion criteria. Seventeen patients had concurrent invasive S. aureus infections and 220 patients had SABU without invasive infection or SAB. Of the 220 patients with SABU and no invasive S. aureus infection, none developed invasive disease. The 12-month mortality rate was 6.8% in those without concurrent SAB and 52.9% in those with invasive infection. In those without concurrent invasive S. aureus infection, male sex (P = 0.033), MRSA (P = 0.008), collection of blood cultures (P = 0.005), and Charlson comorbidity score (P ≤ 0.001) were identified as risk factors for 12-month mortality. Race, inpatient status, specimen type, pyuria, UTI symptoms, and urologic instrumentation were not significantly associated with mortality. CONCLUSION: Patients without evident invasive S. aureus infection at the time of urine culture were not observed to present with invasive disease in the following year. Mortality increases with Charlson score and invasive infection in patients with SABU. Clinicians may consider isolated UTI, contamination, and colonization before embarking on extensive searches for occult staphylococcal infection in patients who present without obvious invasive infection, particularly in those without comorbid disease. DISCLOSURES: All authors: No reported disclosures.