Staphylococcus aureus bacteraemia at Alice Springs Hospital, Central Australia, 2003-2006

Differences in the distribution of pathogens and antimicrobial resistance in bloodstream infections in migrants compared with non-migrants in Denmark

BACKGROUND

We wish to study disparities in bloodstream infections in migrants and non-migrants by comparing the distribution of pathogens and their resistance patterns in long-term migrants with that in non-migrants in Denmark.

METHODS

The study is based on a cohort of migrants, who received residency in Denmark between 1993 and 2015 and a control group of non-migrants. The cohort was linked to a database of bloodstream infections from 2000 to 2015 covering two regions in Denmark. First-time bloodstream infections in individuals ≥18 years of age at the time of sampling were included. We calculated odds ratios adjusted for age, sex, year of sampling, comorbidity, and place of acquisition (hospital- or community-acquired).

RESULTS

We identified 4,703 bloodstream infection cases. Family-reunified migrants and refugees had higher odds of Escherichia coli than non-migrants (OR 1.89 95%CI: 1.46-2.44 and OR 1.55 95%CI: 1.25-1.92) and lower odds of Streptococcus pneumoniae (OR 0.38 95%CI: 0.21-0.67 and OR 0.52 95%CI: 0.34-0.81). Differences in pathogen distribution were only prevalent in community-acquired bloodstream infections. Refugees had higher odds of Escherichia coli resistant to piperacillin-tazobactam, ciprofloxacin, and gentamicin compared with non-migrants. Family-reunified migrants had higher odds of Escherichia coli and other Enterobacterales resistant to ciprofloxacin.

CONCLUSIONS

Migrants had a higher proportion of community-acquired bloodstream infections with Escherichia coli as well as higher odds of bloodstream infections with resistant Escherichia coli compared with non-migrants. These novel results are relevant for improving migrant health by focussing on preventing and treating infections especially with Escherichia coli such as urinary tract and abdominal infections.

Incidence of Monomicrobial Staphylococcus aureus Bacteremia: A Population-Based Study in Olmsted County, Minnesota – 2006 to 2020

Background

Population-based studies of Staphylococcus aureus bacteremia (SAB) in the United States are limited. We provide a contemporary evaluation of SAB incidence in Olmsted County, Minnesota, from 2006 to 2020.

Methods

This was a retrospective population-based study of all adult patients with SAB residing in Olmsted County from 1 January 2006 through 31 December 2020. Initial episodes of SAB were identified using the microbiology laboratory databases at both Olmsted Medical Center and Mayo Clinic Rochester.

Results

Overall, 541 incident SAB cases were identified with a median age of 66.8 (interquartile range, 54.4–78.5) years, and 60.4% were male. Among these cases, 298 (56.2%) were due to methicillin-susceptible S aureus (MSSA) and 232 (43.8%) cases of methicillin-resistant S aureus (MRSA). The overall age- and sex-adjusted SAB incidence rate (IR) was 33.9 (95% confidence interval [CI], 31.0–36.8) cases/100 000 person-years (PY). Males had a higher age-adjusted IR of 46.0 (95% CI, 41.0–51.0) cases/100 000 PY compared to females (IR, 24.4 [95% CI, 21.1–27.7] cases/100 000 PY). Age- and sex-adjusted SAB IRs due to MSSA and MRSA were 18.7 and 14.6 cases/100 000 PY, respectively, and the percentage of incident SAB cases due to MRSA fluctuated across the study period. There was no apparent temporal trend in SAB incidence over the study period (P = .093).

Conclusions

Our investigation represents the only contemporary population-based study in the United States. Despite the impression that SAB incidence may have increased based on Centers for Disease Control and Prevention surveillance data, our finding of no change in SAB incidence was somewhat unanticipated.

Epidemiology and Microbiology of Severe Community-Acquired Pneumonia in Central Australia: A Retrospective Study

BACKGROUND

Severe community-acquired pneumonia (SCAP) has high mortality and morbidity.

AIMS

To describe the epidemiology and microbiology of SCAP in Central Australia.

METHODS

A retrospective epidemiological study describing the characteristics, incidence rates (IR) and microbiological aetiology of SCAP in Central Australia. Adult patients admitted to Alice Springs Hospital Intensive Care Unit (ICU) between 2011-2014 that fitted the IDSA/ATS definition of SCAP were included. Medical records were reviewed and compared between Indigenous and non-Indigenous patients. Primary outcomes were incidence rate and microbiological aetiology of SCAP. Secondary outcomes were 30-day mortality, and ICU and hospital length of stay (LoS).

RESULTS

A total of 185 patents were included (156 Indigenous, 29 non-Indigenous). The overall SCAP IR per 1000 person-years was 3.24 (3.75 Indigenous and 1.87 non-Indigenous) with an IR difference of 2.71 after adjustment (p<0.001). Those aged ≥50 had an IR 74.8% higher than those younger. Male IR was 50% higher than females. There was a significant difference between Indigenous and non-Indigenous groups for age (48 vs. 64 years), but not for 30-day mortality (7.7% vs. 10.3%), ICU LoS (4.8 vs. 4.6 days) and hospital LoS (10.9 vs. 15.1 days), respectively. Likely causative pathogen(s) were identified in 117 patients; Streptococcus pneumoniae was the most common pathogen (28.2%), followed by Haemophilus influenzae (19.7%), Influenza A/B (16.2%) and Staphylococcus aureus (14.5%).

CONCLUSION

A high incidence of SCAP was observed in Central Australia, disproportionately affecting the Indigenous population. Prevention strategies are imperative, as well as early identification of SCAP and appropriate empiric antibiotic regimens. This article is protected by copyright. All rights reserved.

Assessing the impact of a 'bundle of care' approach to Staphylococcus aureus bacteraemia in a tertiary hospital

Background

Staphylococcus aureus bacteraemia is associated with significant morbidity and mortality. There is evidence that standardised care bundle implementation may improve the rates of appropriate investigations and improve overall management. A S. aureus bacteraemia care bundle was introduced at Christchurch Hospital, New Zealand in early 2014. We assessed the impact of the intervention on the management and outcome of S. aureus bacteraemia.

Methods

A cohort study of cases of S. aureus bacteraemia was conducted following standardised care bundle introduction. Prospective enrolment of post-intervention patients occurred from 1^st January 2014 to 30^th June 2015, with retrospective review of pre-intervention cases from 1^st January 2009 to 31^st December 2013.

Results

In the pre-intervention period 447 patients had at least one episode of S. aureus bacteraemia compared to 151 patients in the post-intervention period. The two groups were similar by gender, ethnicity, and age. Significant increases in Infectious Diseases consultation rate (86.6% vs 94.8%; p=0.009), echocardiography (76.3% vs 96.3%; p<0.001), urine culture (74.0% vs 91.9%; p<0.001), follow up blood cultures (44.2% vs 83.0%; p<0.001), and at least 2 weeks of parenteral therapy (83.5% vs 92.9%; p=0.014) were observed after introduction of the bundle. There were no significant differences in rates 30-day mortality (18.6% vs. 20.5%; p=0.596), but there was a reduction in episodes of relapsed infection in the post-intervention cohort (7.4% vs 1.3%; p=0.004).

Conclusion

An integrated care bundle for the management of S. aureus bacteraemia resulted in increased use of quality of care indicators and infectious diseases review and improved patient outcome.

Bacteria-Targeted Clindamycin Loaded Polymeric Nanoparticles: Effect of Surface Charge on Nanoparticle Adhesion to MRSA, Antibacterial Activity, and Wound Healing

Adhesion of nanoparticles (NPs) to the bacterial cell wall by modifying their physicochemical properties can improve the antibacterial activity of antibiotic. In this study, we prepared positively charged clindamycin-loaded poly (lactic-co-glycolic acid)-polyethylenimine (PLGA-PEI) nanoparticles (Cly/PPNPs) and negatively charged clindamycin-loaded PLGA NPs (Cly/PNPs) and investigated the effect of NP adhesion to bacteria on the treatment of methicillin-resistant Staphylococcus aureus (MRSA)-infected wounds. The Cly/PPNPs and Cly/PNPs were characterized according to particle size, polydispersity index, surface charge, and drug loading. Both Cly/PPNPs and Cly/PNPs exhibited sustained drug release over 2 days. The Cly/PPNPs bind to the MRSA surface, thereby enhancing bactericidal efficacy against MRSA compared with the Cly/PNPs. Furthermore, compared with other groups, Cly/PPNPs significantly accelerated the healing and re-epithelialization of wounds in a mouse model of a MRSA-infected wounds. We also found that both NPs are harmless to healthy fibroblast cells. Therefore, our results suggest that the Cly/PPNPs developed in this study improve the efficacy of clindamycin for the treatment of MRSA-infected wounds.

The rise of methicillin resistant Staphylococcus aureus: now the dominant cause of skin and soft tissue infection in Central Australia

This study aimed to examine the epidemiology and treatment outcomes of community-onset purulent staphylococcal skin and soft tissue infections (SSTI) in Central Australia. We performed a prospective observational study of patients hospitalised with community-onset purulent staphylococcal SSTI (n = 160). Indigenous patients accounted for 78% of cases. Patients were predominantly young adults; however, there were high rates of co-morbid disease. Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) was the dominant phenotype, accounting for 60% of cases. Hospitalisation during the preceding 6 months, and haemodialysis dependence were significant predictors of CA-MRSA infection on univariate analysis. Clinical presentation and treatment outcomes were found to be comparable for methicillin-susceptible S. aureus (MSSA) and methicillin-resistant cases. All MRSA isolates were characterised as non-multi-resistant, with this term used interchangeably with CA-MRSA in this analysis. We did not find an association between receipt of an active antimicrobial agent within the first 48 h, and progression of infection; need for further surgical debridement; unplanned General Practitioner or hospital re-presentation; or need for further antibiotics. At least one adverse outcome was experienced by 39% of patients. Clindamycin resistance was common, while rates of trimethoprim-sulfamethoxazole resistance were low. This study suggested the possibility of healthcare-associated transmission of CA-MRSA. This is the first Australian report of CA-MRSA superseding MSSA as the cause of community onset staphylococcal SSTI.

High burden of complicated skin and soft tissue infections in the Indigenous population of Central Australia due to dominant Panton Valentine leucocidin clones ST93-MRSA and CC121-MSSA

Background

Superficial skin and soft tissue infections (SSTIs) are common among the Indigenous population of the desert regions of Central Australia. However, the overall burden of disease and molecular epidemiology of Staphylococcus aureus complicated SSTIs has yet to be described in this unique population.

Methods

Alice Springs Hospital (ASH) admission data was interrogated to establish the population incidence of SSTIs. A prospective observational study was conducted on a subset of S. aureus complicated SSTIs (carbuncles and furuncles requiring surgical intervention) presenting during a one month period to further characterize the clinical and molecular epidemiology. High resolution melting analysis was used for clonal complex discrimination. Real-time polymerase chain reaction identifying the lukF component of the Panton Valentine leucocidin (pvl) gene determined pvl status. Clinical and outcome data was obtained from the ASH medical and Northern Territory shared electronic health records.

Results

SSTIs represented 2.1% of ASH admissions during 2014. 82.6% occurred in Indigenous patients (n = 382) with an estimated incidence of 18.9 per 1, 000 people years compared to the non-Indigenous population of 2.9 per 1000, with an incident rate ratio of 6.6 (95% confidence interval 5.1–8.5). Clinical and molecular analysis was performed on 50 isolates from 47 patients. Community-associated methicillin-resistant S. aureus (CA-MRSA) predominated (57% of isolates). The high burden of SSTIs is partly explained by the prevalence of pvl positive strains of S. aureus (90% isolates) for both CA-MRSA and methicillin-susceptible S. aureus (MSSA). ST93-MRSA and CC121-MSSA were the most prevalent clones. SSTIs due to ST93-MRSA were more likely to require further debridement (p = 0.039), however they also more frequently received inactive antimicrobial therapy (p < 0.001).

Conclusions

ST93-MRSA and CC121-MSSA are the dominant causes of carbuncles and furuncles in Central Australia. Both of these virulent clones harbor pvl but the impact on clinical outcomes remains uncertain. The high prevalence of CA-MRSA supports empiric vancomycin use in this population when antimicrobial therapy is indicated. Prompt surgical intervention remains the cornerstone of treatment.

Paediatric Staphylococcus aureus bacteraemia: A single-centre retrospective cohort

AIM

We aimed to describe the clinical epidemiology of Staphylococcus aureus bacteraemia (SAB) at a large, tertiary/quaternary children's hospital in Australia.

METHODS

We performed a retrospective chart review of SAB cases at the Children's Hospital at Westmead (CHW) over 5 years; 2006-2011. We compared frequency, clinical profile and outcomes of SAB with published data from CHW; 1994-1998. We compared health-care associated with community-associated (HCA-SAB and CA-SAB; defined epidemiologically) and methicillin-resistant with methicillin susceptible S. aureus (MRSA and MSSA).

RESULTS

We identified 174 episodes of paediatric SAB with an average annual admission rate of 1.3/1000 which has not increased compared with a decade earlier. Half of the cases (49%) were CA-SAB; 18% were MRSA. The proportion of CA-MRSA bacteraemia (22%) has increased. The proportion of SAB associated with central venous access devices (CVADs; 40%) has increased. CA-SAB cases were more likely to present with a tissue focus of disease (e.g. osteo-articular, pneumonia) and often required surgery. HCA-SAB less frequently required surgery, a minority is MRSA, and vascular device intervention (removal, sterilisation) is common. Six cases (4%) of infective endocarditis (IE) were identified; three with a history of congenital heart disease, two with CVADs in situ. There were no deaths in this cohort.

CONCLUSIONS

Over an 18-year period, the proportion of SAB due to CA-MRSA and SAB associated with CVADs has increased. Categorisation of SAB as HCA and CA reveals two broad phenotypes of paediatric SAB. SAB in children is infrequently associated with IE. The health-care burden of paediatric SAB is considerable', but mortality is low.

The Epidemiology of Staphylococcus aureus and Panton-Valentine Leucocidin (pvl) in Central Australia, 2006-2010

Background

The Central Australian Indigenous population has a high incidence of Staphylococcus aureus bacteremia (SAB) but little is known about the local molecular epidemiology.

Methods

Prospective observational study of bacteremic and nasal colonizing S.aureus isolates between June 2006 to June 2010. All isolates underwent single nucleotide polymorphism (SNP) genotyping and testing for the presence of the Panton-Valentine Leucocidin (pvl) gene.

Results

Invasive isolates (n = 97) were predominantly ST93 (26.6 %) and pvl positive (54.3 %), which was associated with skin and soft tissue infections (OR 4.35, 95 % CI 1.16, 16.31). Non-multiresistant MRSA accounted for 31.9 % of bacteremic samples and showed a trend to being healthcare associated (OR 2.16, 95 % CI 0.86, 5.40). Non-invasive isolates (n = 54) were rarely ST93 (1.9 %) or pvl positive (7.4 %).

Conclusions

In Central Australia, ST93 was the dominant S.aureus clone, and was frequently pvl positive and associated with an aggressive clinical phenotype. Whether non-nasal carriage is more important with invasive clones or whether colonization occurs only transiently remains to be elucidated.

A brief review of the application and pharmacology of ethnomedicines of Indigenous Australians

OBJECTIVE

Indigenous Australians suffer higher mortality and have statistically worse outcomes for many chronic disease states than the non-Indigenous population. Although many of these people are prescribed pharmaceutical drugs for their illnesses, some still use medicines that were traditional to their culture. This report reviews some of the traditional medicines used for ailments seen in Indigenous Australian communities.

DESIGN

A literature search was conducted, with the period between the publication of an 'Aboriginal Pharmacopoeia' in 1988 and 'current' our target interval for searching. The ethics of publishing knowledge belonging to Aboriginal people is briefly discussed in this context.

RESULTS

Ailments were grouped into communicable diseases, pain and inflammation, skin disorders and gastrointestinal disorders. Although cancer is regarded as a disease of the 'white man', it is briefly discussed in the context that several traditional medicines and foods may have provided some protective effects. Where known, the ethnopharmacology of these medicines is discussed, as well as a brief description of their preparation and application.

CONCLUSION

Some Indigenous Australians continue to use traditional medicines. We have tabulated these according to ailment, and have listed pharmacological actions where known. What is not known, however, is their potential to interact with pharmaceutical drugs. Further study in this area is needed to optimise health outcomes for Indigenous Australians, especially those in remote communities.

Staphylococcus aureus infections: epidemiology, pathophysiology, clinical manifestations, and management

Staphylococcus aureus is a major human pathogen that causes a wide range of clinical infections. It is a leading cause of bacteremia and infective endocarditis as well as osteoarticular, skin and soft tissue, pleuropulmonary, and device-related infections. This review comprehensively covers the epidemiology, pathophysiology, clinical manifestations, and management of each of these clinical entities. The past 2 decades have witnessed two clear shifts in the epidemiology of S. aureus infections: first, a growing number of health care-associated infections, particularly seen in infective endocarditis and prosthetic device infections, and second, an epidemic of community-associated skin and soft tissue infections driven by strains with certain virulence factors and resistance to β-lactam antibiotics. In reviewing the literature to support management strategies for these clinical manifestations, we also highlight the paucity of high-quality evidence for many key clinical questions.

Bacteremia, Sepsis, and Infective Endocarditis Associated with Staphylococcus aureus

Bacteremia and infective endocarditis (IE) are important causes of morbidity and mortality associated with Staphylococcus aureus infections. Increasing exposure to healthcare, invasive procedures, and prosthetic implants has been associated with a rising incidence of S. aureus bacteremia (SAB) and IE since the late twentieth century. S. aureus is now the most common cause of bacteremia and IE in industrialized nations worldwide and is associated with excess mortality when compared to other pathogens. Central tenets of management include identification of complicated bacteremia, eradicating foci of infection, and, for many, prolonged antimicrobial therapy. Evolving multidrug resistance and limited therapeutic options highlight the many unanswered clinical questions and urgent need for further high-quality clinical research.

Invasive Staphylococcus aureus Infections in Children in Tropical Northern Australia

BACKGROUND

Despite a high burden of staphylococcal skin disease in children and high incidence of Staphylococcus aureus bacteremia in adult Indigenous populations in northern Australia, there are few studies describing incidence or clinical information of invasive S aureus (ISA) infections in children.

METHODS

We conducted a retrospective review for all cases of S aureus bacteremia and sterile site infections, for children under 15 years, in northern Australia over a 4-year period (2007-2010). Cases were categorized as neonatal (<28 days) and pediatric (≥28 days).

RESULTS

Forty-four cases (9 neonatal, 35 pediatric) were identified. The annual incidence of ISA was 27.9 cases per 100 000 population. Among pediatric cases, the annual incidence was significantly higher in the Indigenous (46.6) compared with the non-Indigenous (4.4) population (IRR: 10.6 [95% confidence interval, 3.8-41.4]). Pediatric infections were predominantly community-associated (86%). Clinical infection sites included osteoarticular (66%), pleuropulmonary (29%), and endocarditis (9%), and multifocal disease was common (20%). Eighty-three percent of pediatric cases presented with sepsis; 34% resulted in intensive care admission. Neonatal cases were all born prematurely; 89% were late-onset infections. Overall, 27% of infections were due to methicillin-resistant S aureus (MRSA). Compared with methicillin-sensitive S aureus (MSSA), there was no difference in severity or presentation in pediatric MRSA cases, but a higher proportion of MRSA cases were readmitted.

CONCLUSIONS

The annual incidence of ISA infection in this study is among the highest described, largely due to a disproportionate burden in Indigenous children. Infections are frequently severe and infection with MRSA is common. Children presenting with suspected ISA in this region should be treated empirically for MRSA.

Neglected tropical diseases of Oceania: review of their prevalence, distribution, and opportunities for control

Among Oceania's population of 35 million people, the greatest number living in poverty currently live in Papua New Guinea (PNG), Fiji, Vanuatu, and the Solomon Islands. These impoverished populations are at high risk for selected NTDs, including Necator americanus hookworm infection, strongyloidiasis, lymphatic filariasis (LF), balantidiasis, yaws, trachoma, leprosy, and scabies, in addition to outbreaks of dengue and other arboviral infections including Japanese encephalitis virus infection. PNG stands out for having the largest number of cases and highest prevalence for most of these NTDs. However, Australia's Aboriginal population also suffers from a range of significant NTDs. Through the Pacific Programme to Eliminate Lymphatic Filariasis, enormous strides have been made in eliminating LF in Oceania through programs of mass drug administration (MDA), although LF remains widespread in PNG. There are opportunities to scale up MDA for PNG's major NTDs, which could be accomplished through an integrated package that combines albendazole, ivermectin, diethylcarbamazine, and azithromycin, in a program of national control. Australia's Aboriginal population may benefit from appropriately integrated MDA into primary health care systems. Several emerging viral NTDs remain important threats to the region.

Non-communicable diseases, infection and survival in a retrospective cohort of Indigenous and non-Indigenous adults in central Australia

OBJECTIVES

We hypothesise that rising prevalence rates of non-communicable diseases (NCDs) increase infection risk and worsen outcomes among socially disadvantaged Indigenous Australians undergoing a rapid epidemiological transition.

DESIGN

Available pathology, imaging and discharge morbidity codes were retrospectively reviewed for a period of 5 years prior to admission with a bloodstream infection (BSI), 1 January 2003 to 30 June 2007.

PARTICIPANTS

558 Indigenous and 55 non-Indigenous community residents of central Australia.

OUTCOME MEASURES

The effects of NCDs on risk of infection and death were determined after stratifying by ethnicity.

RESULTS

The mean annual BSI incidence rates were far higher among Indigenous residents (Indigenous, 937/100 000; non-Indigenous, 64/100 000 person-years; IRR=14.6; 95% CI 14.61 to 14.65, p<0.001). Indigenous patients were also more likely to have previous bacterial infections (68.7% vs 34.6%; respectively, p<0.001), diabetes (44.3% vs 20%; p<0.001), harmful alcohol consumption (37% vs 12.7%; p<0.001) and other communicable diseases (human T-lymphotropic virus type 1, 45.2%; strongyloidiasis, 36.1%; hepatitis B virus, 12.9%). Among Indigenous patients, diabetes increased the odds of current Staphylococcus aureus BSI (OR=1.6, 95% CI 1.0 to 2.5) and prior skin infections (adjusted OR=2.1, 95% CI 1.4 to 3.3). Harmful alcohol consumption increased the odds of current Streptococcus pneumoniae BSI (OR=1.57, 95% CI 1.02 to 2.40) and of previous BSI (OR=1.7, 95% CI 1.1 to 2.5), skin infection (OR=1.7, 95% CI 1.1 to 2.6) or pneumonia (OR=4.3, 95% CI 2.8 to 6.7). Twenty-six per cent of Indigenous patients died at a mean (SD) age of 47±15 years. Complications of diabetes and harmful alcohol consumption predicted 28-day mortality (non-rheumatic heart disease, HR=2.9; 95% CI 1.4 to 6.2; chronic renal failure, HR=2.6, 95%CI 1.0 to 6.5; chronic liver disease, HR=3.3, 95% CI 1.6 to 6.7).

CONCLUSIONS

In a socially disadvantaged population undergoing a rapid epidemiological transition, NCDs are associated with an increased risk of infection and BSI-related mortality. Complex interactions between communicable diseases and NCDs demand an integrated approach to management, which must include the empowerment of affected populations to promote behavioural change.

Impact of ethnicity and socio-economic status on Staphylococcus aureus bacteremia incidence and mortality: a heavy burden in Indigenous Australians

Background

Investigations of the impact of ethnicity and socio-economic status on incidence and outcomes of Staphylococcus aureus bacteraemia are limited.

Methods

We prospectively identified all S. aureus bacteraemia episodes in the Australian New Zealand Cooperative on Outcomes in Staphylococcal Sepsis cohort study between 2007 and 2010. We calculated population level incidence rates using regional postcodes and stratified the analysis by ethnicity, age and socio-economic status indexes.

Results

There were 7539 episodes of S. aureus bacteraemia with an annual incidence of 11·2 episodes per 100,000 population. The age-adjusted incidence in the Indigenous population was 62·5 per 100,000 population with an age standardized incidence rate ratio of 5·9 compared to the non-Indigenous population and an incidence rate ratio of 29.2 for community-associated methicillin-resistant S. aureus (MRSA). Populations in the lowest socio-economic status quintile had an increased S. aureus bacteraemia incidence compared to higher quintiles. However, there was a disparity between Indigenous and non-Indigenous populations across all socio-economic status quintiles. The lower 30-day mortality for Indigenous patients (7%) compared to non-Indigenous patients (17%) was explained by differences in age.

Conclusions

Indigenous Australians suffer from a higher rate of S. aureus bacteraemia than non-Indigenous Australians, particularly for community-associated MRSA. Ethnicity and socio-economic status had little impact on subsequent mortality, with other host factors contributing more significantly.

Predictors of mortality in Staphylococcus aureus Bacteremia

Staphylococcus aureus bacteremia (SAB) is an important infection with an incidence rate ranging from 20 to 50 cases/100,000 population per year. Between 10% and 30% of these patients will die from SAB. Comparatively, this accounts for a greater number of deaths than for AIDS, tuberculosis, and viral hepatitis combined. Multiple factors influence outcomes for SAB patients. The most consistent predictor of mortality is age, with older patients being twice as likely to die. Except for the presence of comorbidities, the impacts of other host factors, including gender, ethnicity, socioeconomic status, and immune status, are unclear. Pathogen-host interactions, especially the presence of shock and the source of SAB, are strong predictors of outcomes. Although antibiotic resistance may be associated with increased mortality, questions remain as to whether this reflects pathogen-specific factors or poorer responses to antibiotic therapy, namely, vancomycin. Optimal management relies on starting appropriate antibiotics in a timely fashion, resulting in improved outcomes for certain patient subgroups. The roles of surgery and infectious disease consultations require further study. Although the rate of mortality from SAB is declining, it remains high. Future international collaborative studies are required to tease out the relative contributions of various factors to mortality, which would enable the optimization of SAB management and patient outcomes.