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Healthcare Associated Infections CEC Indicators Healthcare Associated Infections eChartbook
Staphylococcus Aureus Bacteraemias (SAB)
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Why is this important?


Staphylococcus aureus (S. aureus) bacteraemias  (SAB)  are common and a serious cause of morbidity and mortality worldwide [1-3]. Patients who develop bloodstream infections, such as SAB, are more likely to suffer serious complications associated with the infection (e.g. infective endocarditis) that may have a negative impact on patient outcomes, including longer hospital stays, increased morbidity, increased risk of mortality, and additional healthcare costs [1-3]. SAB is the most common cause of healthcare associated bacteraemias, with over half of all SAB episodes in Australia being attributed as a healthcare associated infection (HAI) [3].One of the biggest challenges in treating SAB is that many strains of S. aureus have developed resistance against a number of different antibiotics, including methicillin [4]. These bacteria are known as methicillin-resistant S. aureus (MRSA). If a SAB is able to be treated with common antibiotics, and does not demonstrate any resistance to the antibiotic, the infection is considered to be caused by methicillin-sensitive S. aureus (MSSA). Despite being associated with high mortality, a substantial proportion of healthcare acquired SAB cases are potentially preventable [1].


Reporting of SAB infections caused by MRSA has been mandatory in the UK since 2003 [5-6]. National reporting of healthcare associated SAB was introduced in Australia in 2008. SAB incidences and rates also are a key performance indicator for jurisdictions under the National Healthcare Agreement [7]. The rationale for monitoring SAB infections is that the incidence and rate of SAB are considered to be a good proxy marker for the measurement of clinical quality in healthcare facilities [2], [8]. This section will present overall SAB data (combined MRSA and MSSA) which include both 'inpatient'and 'non-inpatient' infections.



References

[1] Corey GR. Staphylococcus aureus Bloodstream Infections: Definitions and Treatment. Clin Infect Dis. 2009; 48 (Suppl 4):S254-9.
[2] Collignon PJ, Wilkinson IJ, Gilbert GL, Grayson ML, Whitby RM. Health care-associated Staphylococcus aureus bloodstream infections:a clinical quality indicator for all hospitals. MedJ Aust 2006; 184: 404-6.
[3] Collignon P, Nimmo GR, Gottlieb T, Gosbell IB. Staphylococcus aureus Bacteremia, Australia. Emerging Infectious Diseases 2005; 11(4):554-561
[4] Lowy FD. Staphylococcus aureusinfections. N Engl J Med 1998; 339:520-32.
[5] Health Protection Agency (HPA), Health Protection Agency bacteraemia; England, Wales, and Northern Ireland; Jan - Dec 2005 - http://www.hpa.org.uk/web/HPAweb&HPAwebStandard/HPAweb_C/1202115578601 (accessed Sept 2013)
[6] Public Health England. Quarterly Analyses: Mandatory MRSA, MSSA and E. coli Bacteraemia and CDI in England (up to April-June 2013). London: Public Health England, September 2013.
[7] Standing Council on Federal Financial Relations. National Healthcare Agreement 2012. AccessedNovember 2013 [Online]: http://www.federalfinancialrelations.gov.au/content/npa/healthcare/national-agreement.pdf
[8] Dendle C, Martin RD, Cameron DR, et al. Staphylococcus aureus bacteraemia as a quality indicator for hospital infection control. Med J Aust. 2009; 191(7): 389-92.


Findings


The data for SAB infections (MRSA and MSSA) rates per 10,000 occupied bed days was calculated for the period January 2011 to June 2016.  In the first two years of this reporting period, the annual rate of SAB infections was centred around 1.0 (Chart SA01). The annual rates continued to decline from 0.99 in 2011 to 0.70 infections per 10,000 occupied bed days in 2015. Overall SAB infections rates in NSW were consistently lower than the National Health Agreement benchmark of 2.0 per 10,000 occupied bed days. Data for the three peer groups shows a consistent decreasing trend of infections over the last 5 years in response to infection prevention and control measures (Chart SA02). As the complexity of patients decreases between the peer groups, the average rate of SAB infections is lower.


Implications


Patients who develop bacteraemias, such as SAB, are more likely to suffer complications, resulting in prolonged hospitalisation and increased hospitalisation costs. Serious infections may also result in death. Spread of SAB is generally through human-to-human contact, or related to improper use and/or a management an intravenous vascular device. The virulent nature of SAB demands rigorous management of both suspected and confirmed cases [1]. One of the most effective ways to minimise the risk of SAB and other healthcare-associated infections is through the use of good hand hygiene [9]. The application of infection and prevention control interventions has resulted in a decrease in the rate of SAB infections at a state and peer group level. There is room for further improvements, such as improved hand hygiene, to drive infection rates even lower.



References

[1] Corey GR. Staphylococcus aureus Bloodstream Infections: Definitions and Treatment Clinical Infectious Diseases 2009; 48:S254-9
[9] Grayson ML, Russo PL, Cruickshank M, et al. Outcomes from the first 2 years of the Australian National Hand Hygiene Initiative. Med J Aust. 2011; 195 (10): 615-9


What we don't know


S. aureus is a normal human commensal that can also behave as a versatile and virulent pathogen [4]. Treatment of these infections is becoming more difficult, because of the increasing prevalence of multi-drug-resistant strains [10-11]. Underlying patient factors are important in determining the likelihood of pathogen transmission and complicated bacteraemias  and require further investigation beyond the data presented here. The relative effectiveness of the different infection prevention and control measures is unknown. Further research would enable better targeting of activities.



References

[4] Lowy FD. Staphylococcus aureus infections. N Engl J Med 1998; 339:520-32.
[10] Bauer TM, Ofner E, Just HM, et al. An epidemiological study assessing the relative importance of airborne and direct contact transmission of microorganisms in the medical intensivecare unit. J Hosp Infect. 1990; 15 (4):301-309.
[11] Rosenthal K. Targeting never events. Nursing Management, 2008; 39(2): 35-38.


Chart SA01 - Staphylococcus aureus bacteraemias (SAB)
 

Staphylococcus aureus bacteraemias rate per 10,000 occupied bed days*,
NSW, Jan 2011 - Jun 2016


eChartbook
Source: Clinical Excellence Commission, NSW Ministry of Health. *Public hospitals only

Chart SA02 - Staphylococcus aureus bacteraemias (SAB)
 

Six-monthly SAB  rate per 10,000 occupied bed days by selected Hospital peer groups*,
NSW, Jul 2011# - Jun 2016




eChartbook
Source: Clinical Excellence Commission, NSW Ministry of Health .* Public hospitals only. #The data for SAB infection rates from July 2011 are based on a revised national definition which differs from the NSW definition used prior to this date.


End Matter


Contributors
Drafted by: CEC eChartbook team and CEC Clinical Governance Directorate
Data analysis by: CEC eChartbook team
Reviewed by: CEC Clinical Governance Directorate
Edited by: CEC eChartbook team


Suggested citation
Clinical Excellence Commission [access year]. eChartbook Portal: Safety and Quality of Healthcare in New South Wales. Sydney: Clinical Excellence Commission. Available at: http://www.cec.health.nsw.gov.au/echartbook/cec-indicators-intro-chartbook/sab Accessed (insert date of access).


© Clinical Excellence Commission 2016
This work is copyright. Apart from any use as permitted under the Copyright Act 1968, no part may be reproduced without prior written permission from the Clinical Excellence Commission (CEC). Requests and enquiries concerning reproduction and rights should be directed to the Director, Director, Information Management, Locked Bag 8, Haymarket, NSW 1240.


Evidence-base for this initiative
N/A


Reported elsewhere
Healthcare Associated Infection, NSW MOH - www.health.nsw.gov.au/professionals/hai/


Definitions


Chart: SA01

Admin Status: Current, Jun 2016

Indicator Name: Staphylococcus aureus bacteraemias (SAB)

Description: Staphylococcus aureus bacteraemias (SAB) rate per 10,000 occupied bed days in NSW, Jan 2011 - Jun 2016

Dimension: Patient safety

Clinical Area: Initiatives in safety and quality health care

Data Inclusions: All staphylococcus aureus bacteraemias (including MSSA and MRSA)

Data Exclusions: None

Numerator: Total number of staphylococcus aureus bacteraemias

Denominator: Total number of occupied bed days

Standardisation: None (crude infection rate per 10,000 occupied bed days calculated)

Data Source: NSW Healthcare Associated Infections Data Collection, NSW Ministry of Health

Comments: The data for Staphylococcus aureus bacteraemia rates from July 2011 are based on a revised national definition which differs from the NSW definition used prior to that date. This revised surveillance definition means in some cases it is more difficult to determine if these infections were associated with performance of a particular hospital. Infections reported now include both those that are Methicillin resistant (MRSA) and those that are Methicillin sensitive (MSSA).
 
Chart: SA02

Admin Status: Current, Jun 2016

Indicator Name: Staphylococcus aureus bacteraemias (SAB) rate per 10,000 occupied bed days by selected Hospital peer groups and year

Description: Six-monthly SAB infection rate per 10,000 occupied bed days by selected Hospital peer groups and NSW, Jul 2011 - Jun 2016

Dimension: Patient safety

Clinical Area: Initiatives in safety and quality health care

Data Inclusions: All staphylococcus aureus bacteraemias (including MSSA and MRSA) occurred in hospital peer groups A1, B (consisting of B, B1, B2, BM and BNM) and C (consisting of C1 and C2)

Data Exclusions: None

Numerator: Total number of staphylococcus aureus bacteraemias in the selected peer groups

Denominator: Total number of occupied bed days in the selected peer groups

Standardisation: None (crude infection rate per 10,000 occupied bed days calculated)

Data Source: NSW Healthcare Associated Infections Data Collection, NSW Ministry of Health

Comments: The data for Staphylococcus aureus bacteraemia rate from July 2011 are based on a revised national definition which differs from the NSW definition used prior to that date. This revised surveillance definition means in some cases it is more difficult to determine if these infections were associated with performance of a particular hospital. Infections reported now include both those that are Methicillin resistant (MRSA) and those that are Methicillin sensitive (MSSA).