Incidence and Outcomes of Staphylococcus aureus Bacteriuria: A Population-based Study

Predictive value of urine microscopy and urine culture in bacteraemic adults without localising urinary features

BACKGROUND

Urine microscopy (UM) and urine culture (UC) are used in bacteraemic patients to identify a urinary focus of infection. However, their positive and negative predictive values (PPV and NPV) in patients without localising urinary features are uncertain.

AIMS

We aimed to determine the predictive value of UM/UC for diagnosing bacteraemic urinary tract infection (bUTI) in bacteraemic patients without localising urinary features.

METHODS

A retrospective study of bacteraemic adults was conducted. PPV and NPV of UM/UC for bacteraemic urinary tract infection (bUTI) was determined in two subgroups of patients without localising urinary features: those with an unclear focus of infection, and those with a suspected non-urinary focus of infection. In those with an unclear focus, univariate analysis for risk factors associated with bUTI was performed.

RESULTS

A total of 871 patients were included. Localising urinary features were absent in 110 of 342 patients (32.2%) with bUTI. In patients with an unclear focus, UM had a PPV of 51.5% and an NPV of 96% for bUTI, and UC had a PPV of 75% and an NPV of 88.6%. In patients with a suspected non-urinary focus, UM had a PPV of 5.2% and an NPV of 100%, and UC had a PPV of 25% and an NPV of 99.5%. While some risk factors for bUTI in patients with an unclear focus were identified, 22 of 98 patients (22.4%) had bUTI despite no risk factors.

CONCLUSIONS

bUTI without localising urinary features is common. In bacteraemia of unclear focus, UM/UC has a high NPV for excluding bUTI, although PPV is limited and non-urinary foci require consideration despite a positive result. UM/UC is low yield in those with a suspected non-urinary focus of infection.

Long-Term Outcomes of Multidrug-Resistant Pseudomonas aeruginosa Bacteriuria: A Retrospective Cohort Study

The relationship between bacteriuria and subsequent symptomatic infections, particularly bacteraemia, has been a subject of ongoing research. We aim to investigate the clinical characteristics, long-term outcomes, and factors associated with subsequent symptomatic infection following an initial multidrug-resistant P. aeruginosa (MDRP) bacteriuria episode. A retrospective cohort study was conducted among patients with MDRP bacteriuria who were hospitalized at a tertiary care hospital from 2009 to 2018, with a 12-month follow-up period for each patient. The primary endpoint was the incidence of subsequent symptomatic MDRP infections at any site, and the secondary endpoint was the overall mortality rate. A total of 260 patients with MDRP bacteriuria were included in the analysis, of whom 155 patients (59.6%) had asymptomatic bacteriuria. Subsequent symptomatic MDRP infections were documented in 79 patients (30.3%) within 12 months of the initial bacteriuria episode: UTI (n = 47, 18.1%), pneumonia (n = 21, 8.1%), bacteraemia (n = 9, 3.5%), soft tissue infection (n = 7, 2.7%), and bone and joint infection (n = 4, 1.5%). Intensive care unit (ICU) acquisition and recurrent bacteriuria were independent risk factors of subsequent symptomatic infections in patients with MDRP bacteriuria. The overall mortality rate was 16.9%, with 31.8% of deaths estimated to be associated with MDRP infection. Solid tumours, cardiovascular diseases, chronic liver disease, chronic lung disease, ICU acquisition, absence of pyuria, and concurrent MDRP bacteraemia were independent predictors of mortality. MDRP bacteriuria has the potential for progression to symptomatic infection and associated mortality. Targeted interventions and prevention strategies were crucial to reduce subsequent infections in patients with MDRP bacteriuria, especially in high-risk patients.

Effect of Food Restriction on Food Grinding in Brandt's Voles

Food grinding is supposed to be influenced by multiple factors. However, how those factors affecting this behavior remain unclear. In this study, we investigated the effect of food restriction on food grinding in Brandt's voles (Lasiopodomys brandtii), as well as the potential role of the gut microbiota in this process, through a comparison of the variations between voles with different food supplies. Food restriction reduced the relative amount of ground food to a greater extent than it lowered the relative food consumption, and altered the abundance of Staphylococcus, Aerococcus, Jeotgalicoccus, and Un--s-Clostridiaceae bacterium GM1. Fecal acetate content for the 7.5 g-food supply group was lower than that for the 15 g-food supply group. Our study indicated that food restriction could effectively inhibit food grinding. Further, Un--s-Clostridiaceae bacterium GM1 abundance, Aerococcus abundance, and acetate content were strongly related to food grinding. Variations in gut microbial abundance and short-chain fatty acid content induced by food restriction likely promote the inhibition of food grinding. These results could potentially provide guidance for reducing food waste during laboratory rodent maintenance.

Staphylococcus aureus bacteriuria: implications and management

Background

Staphylococcus aureus is isolated in around 0.2%-4% of positive urinary cultures, more commonly in the contexts of long-term care, urological abnormalities and procedures, male sex, older age and comorbidities. Isolation may represent contamination, colonization, urinary tract infection or bacteraemic seeding from another site, and may be linked to S. aureus bacteraemia. However, there is little guidance on investigation and management of S. aureus bacteriuria. We performed a retrospective analysis of cases in our service, including clinical characteristics, investigations and treatment.

Methods

Data were collected on all urine samples taken from adult patients over a 5-year period from which S. aureus was isolated. Detailed analysis including investigations and management was conducted in those collected over a 1-year period.

Results

From 511 patients, 668 urine cultures positive for S. aureus were identified; 6.5% of cases were positive for MRSA. Of 93 patients who had blood cultures taken, there were 6 cases of S. aureus bacteraemia, 4 of which were associated with urological instrumentation. Of 94 cases analysed in detail, 57% were treated with antibiotics, and 49% had repeat urine cultures. Factors associated with recurrence were urinary catheterization, urological abnormality, diabetes and inpatient status.

Conclusions

Our experience does not support the routine taking of blood cultures or treatment of asymptomatic bacteriuria in well patients with S. aureus bacteriuria in this setting. However, repeat urine culture, and investigation and treatment of higher risk patients, for example, prior to bladder instrumentation, may be warranted. We propose a simple algorithm to guide clinicians.

The Golden Grapes of Wrath - Staphylococcus aureus Bacteremia: A Clinical Review

Staphylococcus aureus bacteremia is common and associated with fatality rates approximating 25%. We provide a brief overview of S. aureus bacteremia from a clinical and microbiological lens and review the relevant evidence and literature gaps in its management. Using a case-based approach, evidence and clinical judgement are meshed to highlight and justify the 5 core interventions that ought to be performed for all cases of S. aureus bacteremia: 1) appropriate anti-staphylococcal therapy, 2) screening echocardiography, 3) assessment for metastatic phenomena and source control, 4) decision on duration of antimicrobial therapy, and 5) Infectious Diseases consultation.

Occurrence of urinary schistosomiasis and associated bacteria in parts of Ondo State, Nigeria

Schistosomiasis is a parasitic disease caused by blood flukes (trematode worms) of the genus Schistosoma and is common among the rural community dwellers that have occupation or recreation activities that link them with infected water bodies. The disease wreak a lot of havoc in the victims which range from anaemia, increase risk of liver fibrosis and bladder cancer, enlarged liver, difficult and painful urination, infertility etc. Nigeria has been reported to be the most endemic country in the world for schistosomiasis with about 29 million infected cases. However, people with urinary schistosomiasis are vulnerable to secondary infections caused by bacteria as a result of the break down in the mucosa barrier occasioned by the wear and tear of the spiny eggs of the schistosomes. Meanwhile, the control measures instituted by various agencies against schistosomiasis paid little attention to its co-infection with bacteria. This study was designed to evaluate the occurrence of urinary schistosomiasis and co-infection with bacteria in parts of Ondo State, Nigeria. Ethical approval was obtained from the Ethical Committee of the Ondo State Ministry of Health, Akure. Macroscopic and microscopic examinations, and microbiological analysis of the urine samples collected were performed using standard techniques. Of the five hundred and nine (509) urine collected, ova of Schistosoma haematobium were detected in one hundred and twenty one 121 (23.77%), significant bacteriuria was detected in 104 (20.43%) and co-infection was detected in thirty six 36 (29.75%) of schistosomiasis cases. There was a positive association between urinary schistosomiasis and bacteriuria (X2(1) = 8.481, p = 0.004). This study revealed a high occurrence of urinary schistosomiasis and significant bacteriuria in the study areas which suggests that bacterial presence may be a potent complication in the management of urinary schistosomiasis.

Investigation of hub gene associated with the infection of Staphylococcus aureus via weighted gene co-expression network analysis

Introduction

Staphylococcus aureus is a gram-positive bacterium that causes serious infection. With the increasing resistance of bacteria to current antibiotics, it is necessary to learn more about the molecular mechanism and cellular pathways involved in the Staphylococcus aureus infection.

Methods

We downloaded the GSE33341 dataset from the GEO database and applied the weighted gene co-expression network analysis (WGCNA), from which we obtained some critical modules. Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) were applied to illustrate the biological functions of genes in these modules. We constructed the protein-protein interaction (PPI) network by Cytoscape and selected five candidate hub genes. Five potential hub genes were validated in GSE30119 by GraphPad Prism 8.0. The diagnostic values of these genes were calculated and present in the ROC curve based on the GSE13670 dataset. Their gene functions were analyzed by Gene Set Enrichment Analysis (GSEA).

Results

A co-expression network was built with 5000 genes divided into 11 modules. The genes in green and turquoise modules demonstrated a high correlation. According to the KEGG and GO analyses, genes in the green module were closely related to ubiquitination and autophagy. Subsequently, we picked out the top five hub genes in the green module. And UBB was determined as the hub gene in the GSE30119 dataset. The expression level of UBB, ASB, and MKRN1 could significantly differentiate between Staphylococcus aureus infection and healthy controls based on the ROC curve. The GSEA analysis indicated that lower expression levels of UBB were associated with the P53 signal pathway.

Conclusions

We identified some hub genes and significant signal enrichment pathways in Staphylococcus aureus infection via bioinformatics analysis, which may facilitate the development of potential clinical therapeutic strategies.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12866-021-02392-y.

Prospective assessment of catheter-associated bacteriuria clinical presentation, epidemiology, and colonization dynamics in nursing home residents

BACKGROUND

Catheterization facilitates continuous bacteriuria, for which the clinical significance remains unclear. This study aimed to determine the clinical presentation, epidemiology, and dynamics of bacteriuria in a cohort of long-term catheterized nursing home residents.

METHODS

Prospective urine culture, urinalysis, chart review, and assessment of signs and symptoms of infection were performed weekly for 19 study participants over 7 months. All bacteria ≥ 1 × 10³ cfu/mL were cultured, isolated, identified, and tested for susceptibility to select antimicrobials.

RESULTS

In total, 226 of the 234 urine samples were polymicrobial (97%), with an average of 4.7 isolates per weekly specimen. A total of 228 urine samples (97%) exhibited ≥ 1 × 10⁶ CFU/mL, 220 (94%) exhibited abnormal urinalysis, 126 (54%) were associated with at least 1 possible sign or symptom of infection, and 82 (35%) would potentially meet a standardized definition of catheter-associated urinary tract infection (CAUTI), but only 3 had a caregiver diagnosis of CAUTI. Bacterial isolates (286; 30%) were resistant to a tested antimicrobial agent, and bacteriuria composition was remarkably stable despite a combined total of 54 catheter changes and 23 weeks of antimicrobial use.

CONCLUSION

Bacteriuria composition was largely polymicrobial, including persistent colonization by organisms previously considered to be urine culture contaminants. Neither antimicrobial use nor catheter changes sterilized the urine, at most resulting in transient reductions in bacterial burden followed by new acquisition of resistant isolates. Thus, this patient population exhibits a high prevalence of bacteriuria coupled with potential indicators of infection, necessitating further exploration to identify sensitive markers of true infection.

FUNDING

This work was supported by the NIH (R00 DK105205, R01 DK123158, UL1 TR001412).

How to investigate and manage a patient with a Staphylococcus aureus bacteraemia

Staphylococcus aureus bacteraemia is common, and associated with significant morbidity and mortality as a result of its high relapse rate and the risk of complicated infection. A positive blood culture for S. aureus should prompt a thorough patient assessment to identify a potential focus of infection, and the risk factors for the development or presence of complicated infection. Clinical management depends on the patient's characteristics and presenting features. This article gives a systematic approach to the patient with S. aureus bacteraemia, including points to look for on history and examination, the markers of complicated infection, and when to request transoesophageal echocardiography and further imaging. Treatment principles outlined include the rationale for choice of antibiotic treatment and need to involve infection specialists.

Human Urine Alters Methicillin-Resistant Staphylococcus aureus Virulence and Transcriptome

Gram-positive methicillin-resistant Staphylococcus aureus (MRSA) is an emerging cause of hospital-associated urinary tract infections (UTI), especially in catheterized individuals. Despite being rare, MRSA UTI are prone to potentially life-threatening exacerbations such as bacteremia that can be refractory to routine antibiotic therapy. To delineate the molecular mechanisms governing MRSA urinary pathogenesis, we exposed three S. aureus clinical isolates, including two MRSA strains, to human urine for 2 h and analyzed virulence characteristics and changes in gene expression. The in vitro virulence assays showed that human urine rapidly alters adherence to human bladder epithelial cells and fibronectin, hemolysis of sheep red blood cells (RBCs), and surface hydrophobicity in a staphylococcal strain-specific manner. In addition, transcriptome sequencing (RNA-Seq) analysis of uropathogenic strain MRSA-1369 revealed that 2-h-long exposure to human urine alters MRSA transcriptome by modifying expression of genes encoding enzymes catalyzing metabolic pathways, virulence factors, and transcriptional regulators. In summary, our results provide important insights into how human urine specifically and rapidly alters MRSA physiology and facilitates MRSA survival in the nutrient-limiting and hostile urinary microenvironment. IMPORTANCE Methicillin-resistant Staphylococcus aureus (MRSA) is an uncommon cause of urinary tract infections (UTI) in the general population. However, it is important to understand MRSA pathophysiology in the urinary tract because isolation of MRSA in urine samples often precedes potentially life-threatening MRSA bacteremia. In this report, we describe how exposure to human urine alters MRSA global gene expression and virulence. We hypothesize that these alterations may aid MRSA in acclimating to the nutrient-limiting, immunologically hostile conditions within the urinary tract leading to MRSA UTI.

Purposeful microbiology comment added to urine cultures with Staphylococcus aureus increases orders for follow-up blood cultures

Introduction

Patients with Staphylococcus aureus bacteriuria (SABU) often have underlying invasive disease, including S. aureus bacteremia (SAB). It has been proposed that most patients with SABU should have a blood culture done to rule out SAB. A preliminary audit suggested that our local hospitals had a low rate of follow-up blood culture orders for patients with SABU. In response to this, our microbiology laboratory changed the comment appended to urine cultures with growth of S. aureus to make a more assertive link between SABU and SAB and to recommend follow-up blood cultures.

Aim

We designed a retrospective quasi-experimental study to see if the change in microbiology comment wording had an effect on clinician behaviour. We hypothesized that this simple comment change to make a more assertive link between SABU and SAB would lead to an increase in follow-up blood culture orders.

Methodology

We used microbiology records to identify adult patients with urine cultures positive for Staphylococcus aureus at three acute-care hospitals in Hamilton, Ontario, Canada, for 1 year pre- and post-intervention. We recorded urine and blood culture results, timing, patient demographics, and in-hospital mortality.

Results

A total of 243 adult patients with urine cultures with S. aureus were identified for inclusion. The primary outcome was met, as there was a significant increase in blood culture orders between the pre-intervention and post-intervention groups (66.9 % vs 80.4 %). This difference was mainly driven by an increase for emergency department and urgent care patients (30.6 % vs 63.6 %). The inpatient group had a high baseline rate of blood culture orders that did not change significantly (80.0 % vs 84.7 %). There was no significant change in detection of SAB (23.5 % vs 32.7 %) or inpatient mortality (18.0 % vs 24.7 %).

Conclusion

Our study shows that a simple, purposeful comment appended to urine cultures with S. aureus leads to a significant increase in follow-up blood culture orders.

A Narrative Review on the Role of Staphylococcus aureus Bacteriuria in S. aureus Bacteremia

Staphylococcus aureus bacteriuria (SABU) can occur in patients with S. aureus bacteremia (SAB). However, little is known on the (molecular) pathomechanisms of the renal passage of S. aureus. This review discusses the epidemiology and pathogenesis of SABU in patients with SAB and identifies knowledge gaps. The literature search was restricted to the English language. The prevalence of SABU in patients with SAB is 7.8%-39% depending on the study design. The main risk factor for SABU is urinary tract catheterization. SABU in SAB patients is associated with increased mortality. Given present evidence, hematogenous seeding-as seen in animal models-and the development of micro-abscesses best describe the translocation of S. aureus from blood to urine. Virulence factors that might be involved are adhesion factors, sortase A, and coagulase, among others. Other potential routes of bacterial translocation (eg, transcytosis, paracytosis, translocation via "Trojan horses") were identified as knowledge gaps.

A diagnostic algorithm for detection of urinary tract infections in hospitalized patients with bacteriuria: The "Triple F" approach supported by Procalcitonin and paired blood and urine cultures

For acute medicine physicians, distinguishing between asymptomatic bacteriuria (ABU) and clinically relevant urinary tract infections (UTI) is challenging, resulting in overtreatment of ABU and under-recognition of urinary-source bacteraemia without genitourinary symptoms (USB). We conducted a retrospective analysis of ED encounters in a university hospital between October 2013 and September 2018 who met the following inclusion criteria: Suspected UTI with simultaneous collection of paired urinary cultures and blood cultures (PUB) and determination of Procalcitonin (PCT). We sought to develop a simple algorithm based on clinical signs and PCT for the management of suspected UTI. Individual patient presentations were retrospectively evaluated by a clinical "triple F" algorithm (F1 ="fever", F2 ="failure", F3 ="focus") supported by PCT and PUB. We identified 183 ED patients meeting the inclusion criteria. We introduced the term UTI with systemic involvement (SUTI) with three degrees of diagnostic certainty: bacteremic UTI (24.0%; 44/183), probable SUTI (14.2%; 26/183) and possible SUTI (27.9%; 51/183). In bacteremic UTI, half of patients (54.5%; 24/44) presented without genitourinary symptoms. Discordant bacteraemia was diagnosed in 16 patients (24.6% of all bacteremic patients). An alternative focus was identified in 67 patients, five patients presented with S. aureus bacteremia. 62 patients were diagnosed with possible UTI (n = 20) or ABU (n = 42). Using the proposed "triple F" algorithm, dichotomised PCT of < 0.25 pg/ml had a negative predictive value of 88.7% and 96.2% for bacteraemia und accordant bacteraemia respectively. The application of the algorithm to our cohort could have resulted in 33.3% reduction of BCs. Using the diagnostic categories "possible" or "probable" SUTI as a trigger for initiation of antimicrobial treatment would have reduced or streamlined antimicrobial use in 30.6% and 58.5% of cases, respectively. In conclusion, the "3F" algorithm supported by PCT and PUB is a promising diagnostic and antimicrobial stewardship tool.

Prevalence and risk factors for bacteremia in patients with Staphylococcus aureus bacteriuria: A retrospective cohort study

OBJECTIVES

Staphylococcus aureus bacteriuria (SABU) is rare but can be an indicator of S. aureus bacteremia (SAB). The objective of this study was to assess the proportion of SAB in patients with SABU and identify risk factors in a hospital-based population.

METHODS

We used electronic databases to identify eligible patients to be enrolled in a retrospective cohort study. Inclusion criteria were (i) SABU, (ii) ≥18 years of age, and (iii) ≥1 blood culture sampled ±3 months of SABU. Patients with missing values for demographic (e.g., age, sex) or clinical characteristics (e.g., comorbidities) and laboratory analyses were excluded.

RESULTS

In total, 245 patients attending the University Hospital Münster, Germany, between 1 January 2012 and 31 December 2019 met the inclusion/exclusion criteria. Of the 245 patients with SABU, 66 had a concomitant SAB (26.9%). Elevated C-reactive protein (CRP) levels were associated with SAB. Other parameters (e.g., leukocytes, comorbidities) were not associated with SAB in a multivariate analysis.

CONCLUSION

The frequency of SAB in patients with SABU was high and warrants active screening for bloodstream infections in hospitalized patients, particularly if CRP levels are elevated.

Characteristics and Outcomes of Staphylococcus aureus Bloodstream Infection Originating From the Urinary Tract: A Multicenter Cohort Study

Background

Staphylococcus aureus bloodstream infection (SABSI) arising from a urinary tract source (UTS) is poorly understood.

Methods

We conducted a retrospective analysis in 3 major teaching hospitals in Spain of prospectively collected data of hospitalized patients with SABSI. SABSI-UTS was diagnosed in patients with urinary tract symptoms and/or signs, no evidence of an extra-urinary source of infection, and a urinary S. aureus count of ≥10⁵ cfu/mL. Susceptibility of S. aureus strains and patient mortality were compared between SABSI from UTS (SABSI-UTS) and other sources (SABSI-other).

Results

Of 4181 episodes of SABSI, we identified 132 (3.16%) cases of SABSI-UTS that occurred predominantly in patients who were male, had high Charlson comorbidity scores, were dependent for daily life activities, and who had undergone urinary catheterization and/or urinary manipulation before the infection. SABSI-UTS was more often caused by MRSA strains compared with SABSI-other (40.9% vs 17.5%; P < .001). Patients with SABSI-UTS caused by MRSA more often received inadequate empirical treatment compared with those caused by susceptible strains (59.7% vs 23.1%; P < .001). The 30-day case fatality rate was lower in patients with SABSI-UTS than in those with SABSI-other (14.4% vs 23.8%; P = .02). Factors independently associated with mortality were dependence for daily activities (aOR, 3.877; 95% CI, 1.08–13.8; P = .037) and persistent bacteremia (aOR, 7.88; 95% CI, 1.57–39.46; P = .012).

Conclusions

SABSI-UTS occurs predominantly in patients with severe underlying conditions and in those who have undergone urinary tract manipulation. Moreover, it is frequently due to MRSA strains and causes significant mortality.

Indwelling catheterization, renal stones, and hydronephrosis are risk factors for symptomatic Staphylococcus aureus-related urinary tract infection

PURPOSE

Staphylococcus aureus is a relatively uncommon causative agent of urinary tract infection (UTI). However, the clinical features of S. aureus-related UTI are unclear. Thus, we aimed to clarify how patients with S. aureus bacteriuria develop UTI and determine the features and clinical risk factors of symptomatic S. aureus-related UTI.

METHODS

We performed a retrospective study of patients at the Hiroshima University Hospital for whom S. aureus had been isolated from urine culture from January 2010 to December 2017. The characteristics (age, sex, body mass index, indwelling catheterization, renal stones, hydronephrosis, anticancer drug use, diabetes mellitus, steroid use, serum albumin, antibiotic use in the past 1 month, estimated glomerular filtration rate, benign prostate hyperplasia, and neurogenic bladder) of patients with UTI and those without UTI were compared, and the risk factors for S. aureus-related UTI were identified by multiple logistic regression model.

RESULTS

A total of 286 patients with S. aureus bacteriuria were analyzed; 33 patients developed UTI. The causative pathogens were methicillin-sensitive S. aureus and methicillin-resistant S. aureus (MRSA) in 14 and 19 patients, respectively, who developed UTI. This study demonstrated that indwelling catheterization, hydronephrosis, and renal stones are significantly associated with S. aureus-related UTI (p = 0.01, odds ratio = 3.1; and p < 0.01, odds ratio = 7.0; and p = 0.02, odds ratio = 1.2; respectively) and hypoalbuminemia in MRSA-related UTI (p < 0.01).

CONCLUSION

Paying attention to risk factors, specifically indwelling catheterization, renal stones, and hydronephrosis, will be an effective strategy for prevention of S. aureus-related UTI with persistent staphylococcal bacteriuria.

Staphylococcus Aureus Bacteriuria as a Predictor of In-Hospital Mortality in Patients with Staphylococcus Aureus Bacteremia. Results of a Retrospective Cohort Study

Staphylococcus aureus bloodstream infection (SA-BSI) is an infection with increasing morbidity and mortality. Concomitant Staphylococcus aureus bacteriuria (SABU) frequently occurs in patients with SA-BSI. It is considered as either a sign of exacerbation of SA-BSI or a primary source in terms of urosepsis. The clinical implications are still under investigation. In this study, we investigated the role of SABU in patients with SA-BSI and its effect on the patients' mortality. We performed a retrospective cohort study that included all patients in our university hospital (Charité Universitätsmedizin Berlin) between 1 January 2014 and 31 March 2017. We included all patients with positive blood cultures for Staphylococcus aureus who had a urine culture 48 h before or after the first positive blood culture. We identified cases while using the microbiology database and collected additional demographic and clinical parameters, retrospectively, from patient files and charts. We conducted univariate analyses and multivariable Cox regression analysis to evaluate the risk factors for in-hospital mortality. 202 patients met the eligibility criteria. Overall, 55 patients (27.5%) died during their hospital stay. Cox regression showed SABU (OR 2.3), Pitt Bacteremia Score (OR 1.2), as well as moderate to severe liver disease (OR 2.1) to be independent risk factors for in-hospital mortality. Our data indicates that SABU in patients with concurrent SA-BSI is a prognostic marker for in-hospital death. Further studies are needed for evaluating implications for therapeutic optimization.

Epidemiology and Outcome Determinants of Staphylococcus aureus Bacteremia Revisited: A Population-Based Study

PURPOSE

Staphylococcus aureus bacteremia (SAB) is associated with significant morbidity and mortality. We sought to re-define the burden, epidemiology and mortality-associated risk factors of SAB in a large Canadian health region.

METHODS

Residents (> 18 years) experiencing SAB from 2012 to 2014 were assessed. Incidence rates were calculated using civic census results. Factors associated with 30-day mortality were determined through multivariate logistic regression. Incidence and risk factors for SAB were compared to 2000-2006 data.

RESULTS

780 residents experienced 840 episodes of SAB (MRSA; 20%). Incidence rates increased from 23.5 to 32.0 cases/100,000 from 2012 to 2014; [IRR 1.15 (95% CI 1.07-1.23); p < 0.001]. Compared to a decade ago, incidence of SAB has increased [IRR 1.28 (95% CI 1.21-1.36); p < 0.001] despite minimal change in nosocomial SAB. MRSA proportion did not change through the study (p = 0.3), but did increase relative to a decade ago (20.0% vs 11.0%, p < 0.001). Thirty-day mortality rates were 30.6% and 21.3% for MRSA and MSSA, respectively (p = 0.01), similar to rates from 2000 to 2006. Several clinical, demographic, and biochemical factors were independently associated with SAB mortality.

CONCLUSIONS

SAB is common within our population resulting in significant mortality. Incidence rates of SAB are increasing in our health region; however, 30-day mortality rates remain stable.