Incidence Of Staphylococcus Aureus Bacteremia Research Articles

Incidence Trends and Epidemiology of Staphylococcus aureus Bacteremia: A Systematic Review of Population-Based Studies.

Objectives: To determine incidence trends of Staphylococcus aureus bacteremia (SAB) from population-based studies from multiple countries.Methods: A contemporary systematic review was conducted using Ovid Cochrane Central Register of Controlled Trials (1991+), Ovid Embase (1974+), Ovid Medical Literature Analysis and Retrieval System Online (MEDLINE) (1946+ including epub ahead of print, in-process & other non-indexed citations), and Web of Science Core Collection (Science Citation Index Expanded 1975+ and Emerging Sources Citation Index 2015+). Two authors (J.R.H. and J.A.Q.M.) independently reviewed all studies and included those that reported population-based incidence of SAB in patients aged 18 years and older.Results: Twenty-six studies met inclusion criteria with the highest number (n=6) of studies conducted in Canada. The incidence of SAB ranged from 9.3 to 65 cases/100,000/year. The median age of patients with SAB ranged from 62 to 72 years and SAB cases were more commonly observed in men than in women. The most common infection sources were intravascular catheters and skin and soft tissue infections. SAB incidence trends demonstrated high variability for geographic regions and calendar years. Overall, there was no change in the incidence trend across all studies during the past two decades.Conclusion: Multiple factors, both pros, and cons are likely responsible for the overall stable SAB incidence in countries included in this systematic review. Some of these factors vary in geographic location and prompt additional investigations from countries not included in the current review so that a more global characterization is defined.

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

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. Residents (> 18years) 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. 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. 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.

Trends in incidence and resistance patterns of Staphylococcus aureus bacteremia

Background: Staphylococcus aureus bacteremia (SAB) causes a significant burden on the population. Several infection control measures have been implemented in Pirkanmaa county to combat a local epidemic with methicillin-resistant Staphylococcus aureus (MRSA). We aimed to study the epidemiology of SAB and antibiotic resistance of S. aureus and the possible influence of improved infection control.Methods: Register data from 2005 to 2015 were retrospectively analysed to study the antimicrobial susceptibility, the incidence and mortality in SAB in a population-based setting.Results: The incidence of SAB increased during the study period from 21.6 to 35.8/100,000 population. The number of both health care-associated (HA) and community-associated (CA) cases has increased. The incidence of MSSA bacteremia increased from 19.9 to 35.2/100,000 population in Pirkanmaa in parallel to other parts of Finland. The incidence of MRSA bacteremia was 10-fold (4.5/100,000 population) higher in 2011 than in other parts of the country, but sank to the national level (0.59/100,000 population) in 2015. The fatality rate decreased from 22% to 17%. The proportion of penicillin-susceptible Staphylococcus aureus (PSSA) increased from 23.9% in 2008 to 43.1% in 2015.Conclusion: The incidence of both HA and CA SAB has increased since 2005. Conversely, the proportion of MRSA and PRSA bacteremia has decreased. Promotion of infection control measures may have reduced the incidence of MRSA bacteremia but not the overall incidence of SAB. The rising proportion of PSSA enables the use of targeted, narrow spectrum antimicrobials.

Trends in the Incidence of Staphylococcus aureus Bacteremia at a Teaching Hospital in Nassau, Bahamas 2012 to 2015

Background Staphylococcus aureus bacteremia (SAB) is a leading cause of infection-related morbidity and mortality within healthcare systems. A rising incidence of SAB has been seen in institutions with advances in medical interventions. Infectious Diseases consultation has proven to result in improved outcomes in affected patients. There are sparse data regarding incidence and outcomes of SAB in the Caribbean healthcare system.MethodsA retrospective sample of adult patients, admitted to a teaching hospital in Nassau, Bahamas with SAB between 1 January, 2012 and 31 December, 2015, was identified using patient medical records and microbiology database. Only patients ≥18 years with a first episode of SAB were included. Corresponding dockets were reviewed and data analyzed using Microsoft Excel and the 2015 version of the Statistical Package for the Social Sciences.ResultsOf all patients ≥18 years of age with positive blood cultures, a first episode of SAB was seen in 10.3% (201) of cases. Males represented 62.69% of cases with the 40–59 age group being most affected (42.52%). Most patients had Diabetes mellitus (37.31%) and End stage renal disease on dialysis (31.34%). No obvious source of infection was identified in 43.78%. Regarding source of acquisition, 12.44% were Nosocomial, 67.66% Healthcare-associated and 19.9% Community acquired.For the study period, there was a significant 4.4% increase in occurrence (range of 8.66% to 11.54%) of SAB. MSSA represented 73.68% of cases with incidence ranging from 55.67/1,000 (2013) to 95.89/1,000 (2014) while MRSA bacteremia had an incidence ranging from 17.96/1,000 (2012) to 35.37/1,000 (2015).30-day SAB mortality for the study period was 29.35% (range of 22.22% to 32.20%). The odds of death within 30 days from MRSA compared with MSSA was 1.90 (P = 0.056). The 30 -day risk of death from community acquisition was 3.25 (P = 0.001) compared with healthcare and 2.57 (P = 0.08) compared with nosocomial.ConclusionSAB remains an important bacterial infection with alarmingly high 30 day mortality rates being demonstrated in this study. Strategies such as Infectious Disease consultation, improved antimicrobial stewardship and timely interventions are warranted to improve outcomes in these patients.Disclosures All authors: No reported disclosures.

Administrative data has poor accuracy for surveillance of Staphylococcus aureus bacteraemia

Abstract Background To determine the accuracy of the International Classification of Diseases (ICD-10) coding for Staphylococcus aureus bacteremia (SAB) compared with laboratory results during a ten-year period (January 2002–December 2011). Methods A retrospective comparison of ICD-10 code A41.0 for S. aureus sepsis with SAB identified from the laboratory information system (LIS). Patients with LIS identified SAB (LIS+) and/or the ICD-10 A41.0 code (ICD-10) were identified and classified as concordant (LIS+/ICD+) or discordant (LIS+/ICD− or LIS-/ICD+). From July 2010 an additional code for healthcare associated SAB (HA-SAB), U90.0, was introduced and evaluated against prospectively designated episodes of HA-SAB. Results and Conclusions There were 740 laboratory confirmed episodes of SAB however, only 408 of these were recorded by ICD-10 A41.0whilst 106 patients with negative blood cultures were miscoded as ICD-10 A41.0. The sensitivity and PPV for ICD-10 A41.0 were 55% [95% CI: 51–59%] and 72% [95% CI: 68–76%]. For the subset of HA-SAB, the sensitivity and PPV for ICD-10 U90.0 were only 12% [95% CI: 5–24%] and 32% [95% CI: 15–54%] respectively. Surveillance based solely on ICD-10 A41.0, code underestimates the true incidence of SAB even while including non-bacteremic episodes. ICD-10 U90.0 for HA-SAB has even poorer sensitivity and PPV. Laboratory culture results should become the major criterion for ICD-10 coding for SAB to improve the accuracy of surveillance data.

Epidemiology and Mortality of Staphylococcus aureus Bacteremia in Australian and New Zealand Children.

Staphylococcus aureus bacteremia (SAB) in children causes significant morbidity and mortality, but the epidemiology in children is not well characterized. To describe the epidemiology of SAB in children and adolescents younger than 18 years from Australia and New Zealand. A prospective cohort study, using data from the Australian New Zealand Cooperative on Outcomes in Staphylococcal Sepsis cohort for 1153 children with SAB from birth to less than 18 years in pediatric and general hospitals across Australia and New Zealand, collected between January 1, 2007, and December 31, 2012. Multivariate analysis was performed to identify risk factors for mortality. Incidence calculations were calculated separately for Australasian children younger than 15 years using postcode population denominator data from Australian and New Zealand census data. Demographic data, hospital length of stay, principal diagnosis, place of SAB onset (community or hospital), antibiotic susceptibility and principal antibiotic treatment, and 7- and 30-day mortality. Of the 1153 children with SAB, complete outcome data were available for 1073 children (93.1%); of these, males accounted for 684 episodes (63.7%) of SAB. The median age was 57 months (interquartile range, 2 months to 12 years). The annual incidence of SAB for Australian children was 8.3 per 100 000 population and was higher in indigenous children (incident rate ratio, 3.0 [95% CI, 2.4-3.7]), and the incidence for New Zealand children was 14.4 per 100 000 population and was higher in Māori children (incident rate ratio, 5.4 [95% CI, 4.1-7.0]). Community-onset SAB occurred in 761 cases (70.9%), and 142 cases (13.2%) of the infections were methicillin-resistant S aureus (MRSA). Bone or joint infection was most common with 348 cases (32.4%), and endocarditis was uncommon with 30 cases (2.8%). Seven- and 30-day mortality rates were 2.6% (n = 28) and 4.7% (n = 50), respectively. Risk factors for mortality were age younger than 1 year; Māori or Pacific ethnicity; endocarditis, pneumonia, or sepsis; and receiving no treatment or treatment with vancomycin. Mortality was 14.0% (6 of 43) in children with methicillin-susceptible S aureus (MSSA) treated with vancomycin compared with 2.6% (22 of 851) in children treated with alternative agents (OR, 6.1 [95% CI, 1.9-16.7]). MRSA infection was associated with increased length of stay but not mortality. In this large cohort study of the epidemiology of SAB in children, death was uncommon, but the incidence was higher for infants and varied by treatment, ethnicity, and clinical presentation. This study provides important information on the epidemiology of SAB in children and risk factors for mortality.

Co-infection of enterovirus 71 and Staphylococcus aureus in a 6-month-old male infant.

Co-infection of enterovirus 71 and Staphylococcus aureus in a 6-month-old male infant.

Stable incidence and continued improvement in short term mortality of Staphylococcus aureus bacteraemia between 1995 and 2008

BackgroundThe objective of this study was to assess temporal changes in incidence and short term mortality of Staphylococcus aureus bacteraemia (SAB) from 1995 through 2008.MethodsThe study was conducted as a nation-wide observational cohort study with matched population controls. The setting was hospitalized patients in Denmark 1995-2008. Uni- and multivariate analyses were used to analyze the hazard of death within 30 days from SAB.ResultsA total of 16 330 cases of SAB were identified: 57% were hospital-associated (HA), 31% were community-acquired (CA) and 13% were of undetermined acquisition. The overall adjusted incidence rate remained stable at 23 per 100 000 population but the proportion of SAB cases older than 75 years increased significantly. Comorbidity in the cohort as measured by Charlson comorbidity index (CCI) score and alcohol-related diagnoses increased over the study period. In contrast, among the population controls the CCI remained stable and alcohol-related diagnoses increased slightly. For HA SAB crude 30-day mortality decreased from 27.8% to 21.8% (22% reduction) whereas the change for CA SAB was small (26.5% to 25.8%). By multivariate Cox regression, age, female sex, time period, CCI score and alcohol-related diagnoses were associated with increased mortality regardless of mode of acquisition.ConclusionsThroughout a 14-year period the overall incidence of SAB remained stable while the overall short term prognosis continued to improve despite increased age and accumulation of comorbidity in the cohort. However, age and comorbidity were strong prognostic indicators for short term mortality.

The epidemiology of Staphylococcus aureus bacteraemia in Tasmania

The seriousness of Staphylococcus aureus bacteraemia (SAB), coupled with the potential to reduce its occurrence, suggests that each case of SAB demands rigorous investigation and epidemiological understanding. To accurately determine the incidence and better understand the epidemiology of SAB at a population level, detailed data about SAB need to be collected from all settings, not just publicly funded hospitals. The aim of this study was to understand the epidemiology of SAB in Tasmania and to quantify the extent to which SAB incidence is under reported if only public hospital data are reported. A population-based observational study for all people who had laboratory-identified SAB during 2009 and 2010 in Tasmania was conducted. The incidence of SAB was calculated using population data. Incidence of SAB was calculated as 21.3 per 100 000 population per year (95% CI 18.51–24.31). The majority of SAB cases were community associated (58.4%) and were caused by methicillin-sensitive Staphylococcus aureus (90.7%). Fifty-five percent of healthcare-associated SAB cases were associated with an intravascular device. Eleven percent of all SAB cases were identified in a private hospital. This study represents the first known Australian study to capture and analyse data from all cases of SAB in a well-defined population, enabling calculation of incidence. The incidence of SAB in Tasmania is lower than in other Australian studies. Community-associated SAB is more common than healthcare-associated SAB yet little attention is paid to this community burden nationally. Current national surveillance programs for SAB focus only on public hospitals and, in doing so, a significant number of cases of SAB are missed.

Major but differential decline in the incidence of Staphylococcus aureus bacteraemia in HIV‐infected individuals from 1995 to 2007: a nationwide cohort study*

Incidence rates (IRs) of Staphylococcus aureus bacteraemia (SAB) are known to be higher in HIV-infected individuals than in the general population, but have not been assessed in the era of highly active antiretroviral therapy. From 1 January 1995 to 31 December 2007, all Danish HIV-infected individuals (n=4871) and population controls (n=92 116) matched on age and sex were enrolled in a cohort and all cases of SAB were registered. IRs and risk factors were estimated using time-updated Poisson regression analysis. We identified 329 cases of SAB in 284 individuals, of whom 132 individuals were infected with HIV and 152 were not [crude IR ratio (IRR) 24.2; 95% confidence interval (CI) 19.5-30.0, for HIV-infected vs. non-HIV-infected individuals]. Over time, IR declined for HIV-infected individuals (IRR 0.40). Injecting drug users (IDUs) had the highest incidence and the smallest decline in IR, while men who have sex with men (MSM) had the largest decline over time. Among HIV-infected individuals, a latest CD4 count <100 cells/μL was the strongest independent predictor of SAB (IRR 10.2). Additionally, HIV transmission group was associated with risk of SAB. MSM were more likely to have hospital-acquired SAB, a low CD4 cell count and AIDS at the time of HIV acquisition compared with IDUs. We found that the incidence of SAB among HIV-infected individuals declined during the study period, but remained higher than that among HIV-uninfected individuals. There was an unevenly distributed burden of SAB among HIV transmission groups (IDU>MSM). Low CD4 cell count and IDU were strong predictors of SAB among HIV-infected individuals.

Temporal Trends in the Incidence ofStaphylococcus aureusBacteremia in Olmsted County, Minnesota, 1998 to 2005: A Population‐Based Study

There is a paucity of population-based studies on Staphylococcus aureus bacteremia (SAB) in the United States. We determined the incidence of and trends in SAB in Olmsted County, Minnesota, over an 8-year period. A retrospective, population-based, cohort study was done to evaluate the initial episodes of SAB occurring in adult residents of Olmsted County, Minnesota, from 1 January 1998 through 31 December 2005, using the microbiology databases at Mayo Clinic and Olmsted Medical Center in Rochester, Minnesota. Of 247 evaluable adult patients with SAB who were included in the incidence calculation, 143 (57.9%) were males, and the median age was 72.1 years (range, 19.5-98.5 years). Episodes of bacteremia were classified according to acquisition type: 58 (23.5%) were nosocomial (N-SAB), 145 (58.7%) were healthcare-associated (HCA-SAB), and 44 (17.8%) were community-acquired (CA-SAB). Methicillin-resistant S. aureus (MRSA) constituted 31.6% of the cases. No community-acquired MRSA bacteremia was noted. The age-adjusted incidence of SAB was 28.3 episodes/100,000 person-years for females and 53.5 episodes/100,000 person-years for males, with an age- and sex-adjusted rate of 38.2 episodes/100,000 person-years. The age- and sex-adjusted incidence of N-SAB, HCA-SAB, and CA-SAB was 9.0, 22.6, and 6.6 episodes/100,000 person-years, respectively. The age- and sex-adjusted incidence of methicillin-susceptible S. aureus was 25.4 episodes/100,000 person-years, and that of MRSA was 12.4 episodes/100,000 person-years. Overall, the incidence rate increased with age but not over the calendar year. The exception was MRSA bacteremia, which increased at a rate of 19.8% (standard error, +/-5.5%) per year during the study. The incidence of SAB in adults remained stable in Olmsted County, Minnesota, from 1998 to 2005, but the proportion of episodes due to MRSA significantly increased over the 8-year period.

Staphylococcus aureus bacteraemia of unknown primary source: Where do we stand?

There is no generally held definition of Staphylococcus aureus bacteraemia (SAB) of unknown source. For this paper, we consider it to occur when one or more positive blood cultures obtained from a patient grows S. aureus and the origin of the bacteraemia is uncertain after history, physical examination, chest radiography and any further investigations provoked by clinical findings. The incidence of SAB appears to be rising, particularly community-acquired (CA), but also hospital- or healthcare-acquired (HA). Major drivers appear to be intravenous drug use and increasing use of indwelling intravascular devices. There is an increasing prevalence of meticillin-resistant S. aureus (MRSA), both CA and HA. There is increasing hospital acquisition of MRSA that is phenotypically like CA strains, and there is increasing community-based treatment of HA infection. Metastatic infection is a risk of SAB. Infective endocarditis (IE) is a longstanding dreaded concern of SAB. Transoesophageal echocardiography appears to be a superior modality of recognising IE in the context of SAB and can guide the duration of therapy. Prosthetic joints and heart valves are at particular risk of haematogenous seeding from SAB. Implications of the rise of CA-MRSA in terms of metastatic infection warrant further study.

Clinical and molecular epidemiology of nursing home–associated Staphylococcus aureus bacteremia

Although nursing home residents who have Staphylococcus aureus bacteremia (SAB) have been included in large studies of this infection, there are no published descriptions of SAB solely in nursing home residents. The objectives were to describe the clinical and molecular epidemiology of SAB in nursing home residents admitted to one hospital. This was a retrospective review of hospital medical records of nursing home residents from 22 separate facilities who had SAB and were admitted to a specialty unit at one hospital from 1997 to 2003. For the seven-year study period, 39 episodes of SAB were identified; 15 were due to methicillin-susceptible S. aureus (MSSA) and 24 were due to methicillin-resistant S. aureus (MRSA). The incidence of SAB among all residents admitted to the specialty unit increased by more than eightfold primarily because of an increased incidence of bacteremia due to MRSA. The most common identified source was the urinary tract (18% of all episodes) but for 17 (44%) episodes, no focus was identified. Hospital mortality was 28% with all deaths occurring within 15 days of admission. Analysis of the MRSA strains by pulsed-field gel electrophoresis revealed that two pulsed-field types predominated when compared with the CDC national database: USA100- (N = 13) and USA 800-like strains (N = 7). In the study population there was a substantial increase in incidence of SAB over a 7-year period due almost exclusively to an increased occurrence of MRSA. Hospital strains of MRSA predominated, as one would expect. Mortality was high but complications were low among survivors. These findings have important implications for choosing empiric antibiotic therapy in nursing home residents who have suspected S. aureus infection.

Staphylococcus aureusBacteremia, Europe

To the Editor: In their article, Collignon et al. (1) present a table comparing absolute numbers and incidence rates of Staphylococcus aureus bacteremia (SAB) in Australia to those of 5 other countries, and state that data are available from other countries for comparison and 2 countries, Denmark and England, appeared to have comprehensive collection systems. We would like to add data from the European Antimicrobial Resistance Surveillance System (EARSS) to their table. EARSS is a multinational surveillance system that links national networks by collecting comparable and validated data on the prevalence of antimicrobial resistance of 5 microorganisms, including S. aureus (2). A total of 30 countries participate in EARSS. To ensure representativeness of the data it publishes, EARSS has set criteria, which can be found elsewhere (3). In 2003, through a questionnaire, we collected background information on all hospitals served by laboratories participating in EARSS, including the estimated hospitals' catchment populations. Proportion of the country population covered by EARSS was then calculated by dividing the sum of catchment populations by the total population of the country (4). Catchment populations of hospitals providing single specialty or supra-regional type of care were not counted to avoid overlap with other hospitals within the same country. Only the countries that provided denominator data for at least 60% of the isolates were included to ensure that the sample of hospitals was still representative of the country as a whole. The number of SAB and the incidence of SAB per 100,000 inhabitants in 2003 were calculated from EARSS data, adjusted for population coverage, and are presented in the Table. These are crude estimates of the true number of SAB and should, thus, be interpreted with caution. For example, we assumed that the isolates for which hospital background information was not available did not differ from isolates for which we had this information, and that hospitals that participated in EARSS in 2003 were a representative sample of the countries' hospitals. Additionally, the incidence of SAB was positively correlated with the blood culturing rate (Spearman r = 0.74, p = 0.002), which means that the incidence of SAB is likely to have been underestimated in countries that reported few blood cultures. Although some countries did not report their blood culturing rate, the incidences of SAB in these countries were among the highest and are unlikely to be underestimated. For example, the EARSS data for Denmark and Ireland nicely fitted those presented in Table 4 of the article by Collignon et al. (1). Finally, reporting to the EARSS system greatly improved over the years, which is why this study was performed on the last available year, 2003. Nevertheless, one cannot exclude underreporting of SAB by EARSS participating hospitals since EARSS is a voluntary reporting system. For example, England reported 18,403 SAB cases or an incidence of 37 SAB per 100,000 inhabitants from April 2002 to March 2003 through its mandatory surveillance scheme (5), whereas an estimate for the United Kingdom from the EARSS database would only give 7,800 SAB cases for 2003. However, it is impossible to determine whether this discrepancy was due to poor voluntary reporting of SAB cases, a lower blood culturing rate in EARSS participating hospitals, or a poorly representative sample of the country's hospitals. Data from the United Kingdom were excluded from the present study on the basis of the latter possibility; denominator information for <60% of the isolates was available. Table Absolute numbers, rates of Staphylococcus aureus bacteremia (SAB), and percentage of methicillin-resistant Staphylococcus aureus (MRSA), European Antimicrobial Resistance Surveillance System (EARSS), 2003* In conclusion, EARSS is the first comprehensive surveillance system on antimicrobial resistance in Europe. Within certain limitations, EARSS can also provide valuable information on blood-culturing practices and the incidence of SAB in Europe. The system is continuously being improved, and additional information on the representativeness of EARSS data is being collected. This will allow us to improve the quality and accuracy of the reported incidence rates. In the future, the system should allow reporting of similar data for an even larger number of European countries and for additional microorganisms, such as Escherichia coli.