title: Persistent Staphylococcus aureus bacteremia: a prospective analysis of risk factors, outcomes, and microbiologic and genotypic characteristics of isolates.
abstract: Persistent Staphylococcus aureus bacteremia (SAB) that fails to respond to appropriate antibiotic therapy is associated with poor outcomes. Comprehensive prospective studies on risk factors and outcomes of persistent bacteremia are limited. We investigated outcomes and risk factors encompassing clinical, pharmacokinetic, microbiologic, and genotypic characteristics associated with persistent bacteremia using a case-control study nested in a prospective cohort of patients with SAB at a tertiary-care hospital from August 2008 through September 2010. We compared the clinical characteristics, management, and outcomes of patients with persistent bacteremia (≥7 d) with controls with resolving bacteremia (<3 d). To detect associations between microbiologic and genotypic characteristics of methicillin-resistant S. aureus (MRSA) isolates and persistent bacteremia, we determined the heteroresistance phenotype, SCCmec type, agr genotype and functionality, multilocus sequence typing, and presence of 41 virulence genes. Our cohort consisted of 483 patients; 76 (15.7%) had persistent bacteremia, 212 (43.5%) had resolving bacteremia. In the multivariate analysis, independent risk factors associated with persistent bacteremia were community-onset bacteremia (odds ratio [OR], 2.91; 95% confidence interval [CI], 1.24-6.87), bone and joint infection (OR, 5.26; 95% CI, 1.45-19.03), central venous catheter-related infection (OR, 3.36; 95% CI, 1.47-7.65), metastatic infection (OR, 36.22; 95% CI, 12.71-103.23), and methicillin resistance (OR, 16.99; 95% CI, 5.53-52.15). For patients with eradicable foci, delay (>3 d) in the removal of the infection focus was significantly associated with persistent bacteremia (OR, 2.18; 95% CI, 1.05-4.55). There were no significant associations of persistent bacteremia with high vancomycin minimal inhibitory concentration, vancomycin heteroresistance, and microbiologic/genotypic characteristics of MRSA isolates. However, initial vancomycin trough level <15 mg/L was an independent risk factor for persistent MRSA bacteremia (OR, 4.25; 95% CI, 1.51-11.96) in the multivariate analysis. Clinical outcomes were significantly worse for patients with persistent bacteremia. Relapse of bacteremia and attributable mortality within 12 weeks after SAB were significantly higher in patients with persistent bacteremia than in those with resolving bacteremia (9.2% [7/76] vs. 2.4% [5/212], p = 0.02 and 21.1% [16/76] vs. 9.4% [20/212], p = 0.009, respectively). In conclusion, patients with SAB should be given early aggressive treatment strategies, including early source control and maintenance of a vancomycin trough level ≥15 mg/L, to reduce the risk of persistent bacteremia.
authors: From the Department of Infectious Diseases (YPC, KHP, SHK, SOL, SHC, JHW, YSK) and Department of Laboratory Medicine (MNK), Asan Medical Center, University of Ulsan College of Medicine, Center for Antimicrobial Resistance and Microbial Genetics (SJP, HSK, ESK, JYJ, YSK), Seoul, Republic of Korea.
authors: Yong Pil
authors: YP
authors: Chong
authors: Su-Jin
authors: SJ
authors: Park
authors: Hee Sueng
authors: HS
authors: Kim
authors: Eun Sil
authors: ES
authors: Kim
authors: Mi-Na
authors: MN
authors: Kim
authors: Ki-Ho
authors: KH
authors: Park
authors: Sung-Han
authors: SH
authors: Kim
authors: Sang-Oh
authors: SO
authors: Lee
authors: Sang-Ho
authors: SH
authors: Choi
authors: Jin-Yong
authors: JY
authors: Jeong
authors: Jun Hee
authors: JH
authors: Woo
authors: Yang Soo
authors: YS
authors: Kim
mesh_terms: D000368:Aged; D016470:Bacteremia / Q000097:blood / Q000382:microbiology* / Q000401:mortality; D016022:Case-Control Studies; D005260:Female; D005798:Genes, Bacterial; D005838:Genotype; D006801:Humans; D008297:Male; D055624:Methicillin-Resistant Staphylococcus aureus / Q000235:genetics / Q000302:isolation & purification*; D008875:Middle Aged; D011446:Prospective Studies; D056910:Republic of Korea / Q000453:epidemiology; D012307:Risk Factors; D013203:Staphylococcal Infections / Q000097:blood / Q000382:microbiology* / Q000401:mortality; D016896:Treatment Outcome