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Discussion paper
Anti-staphylococcal bundle to
reduce surgical site infections in
orthopaedic and cardiac surgery
November 2016
Anti-staphylococcal bundle to reduce SSIs in orthopaedic and cardiac surgery – Discussion paper page 2
Contents
1. Purpose ......................................................................................................................... 3
2. Background .................................................................................................................... 4
3. Meta-analysis findings.................................................................................................... 6
4. Proposed bundle ............................................................................................................ 7
5. Benefits and risks ........................................................................................................... 8
6. Your feedback requested ............................................................................................... 9
Appendix 1: Orthopaedic SSIs caused by staphylococci: March 2013 to March 2016 ......... 10
Appendix 2: Overview of meta-analysis of S. aureus SSI prevention in orthopaedic and
cardiac surgery ................................................................................................................... 11
Appendix 3: Summary of bundle components from the papers in meta-analysis ................. 19
Appendix 4: SSI bundle costing .......................................................................................... 21
Appendix 5: Back of envelope cost–benefit analysis of an anti-staph bundle in New
Zealand ............................................................................................................................... 23
Appendix 6: Issues relating to screening for S. aureus carriage .......................................... 25
Appendix 7: Susceptibility of staphylococci in New Zealand ................................................ 26
Anti-staphylococcal bundle to reduce SSIs in orthopaedic and cardiac surgery – Discussion paper page 3
1. Purpose
The Health Quality & Safety Commission (the Commission) is considering a bundle of anti-
staphylococcal interventions to reduce orthopaedic and cardiac surgical site infections (SSIs)
caused by staphylococci. The purpose of this paper is to seek the sector’s views on a
proposed bundle.
The potential components of an anti-staphylococcal bundle include:
Staphylococcus aureus preoperative screening
nasal decolonisation
skin decolonisation.
The Commission recently contracted the Royal Australasian College of Surgeons to conduct a systematic review and meta-analysis on all literature related to skin and intranasal decolonisation protocols specific to reducing the risk of staphylococcal SSIs in cardiac and orthopaedic surgical procedures. The review suggests there would be a patient benefit by introducing a standardised set of interventions to reduce the risk of staphylococcal SSIs in elective cardiac and orthopaedic procedures. Anti-staphylococcal bundles for elective surgical patients have been implemented internationally over the past two decades; however, preoperative screening methods and decolonisation agents vary greatly. Recent feedback from district health boards (DHBs) reveals that the current approaches to reducing the risk of staphylococcal SSIs range from no protocol to both preoperative screening and decolonisation protocols in cardiac and orthopaedic surgery. We seek your feedback regarding six issues (please refer to page 9 of this document). The information in this paper is provided to inform your considerations of the following six issues: 1. Potential benefit of introducing an anti-staphylococcal bundle in New Zealand
2. Universal decolonisation vs. preoperative screening
3. Povidone-iodine as first-choice nasal agent
4. Nasal treatment administered twice the day before and once the morning of surgery
5. Skin application administered twice the day before and once the morning of surgery
6. Both skin and nasal components should be part of the bundle.
Anti-staphylococcal bundle to reduce SSIs in orthopaedic and cardiac surgery – Discussion paper page 4
2. Background
SSIs are associated with prolonged hospital stay and increased re-hospitalisation and mortality rates, as well as additional healthcare costs.1 In order to reduce the risk of SSIs, a number of interventions are used, and there is a drive for these to become applied in a consistent manner. Standard practice in hip, knee and cardiac surgery includes antibiotic prophylaxis with ≥ 2 g dose of cefazolin as the first-choice antibiotic (≥ 1.5 g of cefuroxime is an acceptable alternative) with vancomycin or clindamycin reserved for patients with β-lactam allergy. It is also recommended vancomycin should be added to cefazolin for known methicillin-resistant Staphylococcus aureus (MRSA) carriers. The most commonly isolated pathogen in SSIs is Staphylococcus aureus.2,3 Staphylococcal infections cause the largest proportion of SSIs in New Zealand and globally. S. aureus accounts for about 30% of orthopaedic and cardiac SSIs identified in DHB patients. The current overall burden of staphylococcal SSI, due to pure growth cultures of staphylococci, is referenced in Appendix 1. Most patients who develop an S. aureus SSI are carriers of the strain causing the infection.4 In SSI cases, S. aureus isolates have been reported to match those from the patient’s nares approximately 85% of the time.5 S. aureus carriage is a well-established significant risk factor for prosthetic joint surgery as SSI rates are up to nine times greater among S. aureus carriers compared to non-carriers undergoing surgery.6 S. aureus lives on the human skin as a commensal. In developed countries, approximately 30% of the general adult population are colonised.7 Most colonised individuals who develop a staphylococcal infection at the site of a total joint arthroplasty have molecularly identical S. aureus isolates in their nares and wounds. The anterior nares is the most frequent carriage site for S. aureus.8 Other body sites that harbour this organism include the skin, perineum, pharynx, axillae, and gastrointestinal tract. For patients undergoing elective surgery, particularly procedures where implants are anticipated, preoperative screening for S. aureus and mupirocin for those identified as carriers is found to be a cost-effective means
1 Bratzler DW, Houck PM. 2005. Antimicrobial prophylaxis for surgery: An advisory statement from the
National Surgical Infection Prevention Project. American Journal of Surgery 189(4): 395–404. 2 Saadatian-Elahi M, Teyssou R, Vanhems P. 2008. Staphylococcus aureus, the major pathogen in
orthopaedic and cardiac surgical site infections: A literature review. International Journal of Surgery 6: 238–45. 3 Cantlon CA, Stemper ME, Schwan WR, et al. 2006. Significant pathogens isolation from surgical site
infections at a community hospital in the Midwest. American Journal of Infection Control 34(8): 526–9. 4 Kluytmans J, van Belkum A, Vergrugh H. 1997. Nasal carriage of Staphylococcus aureus:
epidemiology, underlying mechanisms, and associated risks. Clinical Microbiology Reviews 10: 505–20. 5 Perl TM, Cullen JJ, Wenzel RP, et al. 2002. Intranasal mupirocin to prevent postoperative
Staphylococcus aureus infections. New England Journal of Medicine 345: 1871–7. 6 Kalmeijer MD, van Nieuwland-Bollen D, Bogaers-Hofman D, et al. 2000. Nasal carriage of
Staphylococcus aureus is a major risk factor of surgical site infections in orthopedic surgery. Infection Control and Hospital Epidemiology 21(5): 319–23. 7 Coates T, Bax R, Coates A. 2009. Nasal decolonization of Staphylococcus aureus with mupirocin:
strengths, weaknesses, and future prospects. Journal of Antimicrobial Chemotherapy 64: 9–15. 8 Wertheim HFL, Melles DC, Vos MC, et al. 2005. The role of nasal carriage in Staphylococcus
aureus infections. The Lancet Infectious Disease 5: 751–62.
Anti-staphylococcal bundle to reduce SSIs in orthopaedic and cardiac surgery – Discussion paper page 5
to reduce SSIs.9,10 However, the most commonly used agent for nasal decolonisation, mupirocin, comes with potential risk of resistance if widely employed. Protocols for the screening and/or decolonisation of S. aureus prior to implant surgery have become widely adopted internationally. Decolonisation is a strategy to reduce the patient’s microbial load of S. aureus just before their surgical procedure so their risk of infection is decreased. A recent study identified that screened and subsequently treated patients were 50% less likely to require revision due to prosthetic joint infection compared to those not screened and treated.11
An ‘anti-staphylococcal bundle’ consists of pre-theatre prophylactic nasal and/or skin decolonisation, in addition to standard care. Decolonisation often involves topical applications of ointment such as mupirocin or povidone-iodine with or without chlorhexidine body washes or wipes before admission to theatre.
9 Abad CL, Pulia MS, Safdar Nl. 2013. Does the nose know? An update on MRSA decolonization
strategies. Current Infectious Disease Reports 15(6):455–64. 10
Chen AF, Wessel CB, Rao N. 2013. Staphylococcus aureus screening and decolonization in orthopaedic surgery and reduction of surgical site infections. Clinical Orthopaedics and Related Research 471: 2383–99. 11
Malcolm TI, Robinson LD, Klika AK, et al. 2016. Predictors of Staphylococcus aureus colonization and results after decolonization. Interdisciplinary Perspectives on Infectious Diseases 2016: 1–8.
Anti-staphylococcal bundle to reduce SSIs in orthopaedic and cardiac surgery – Discussion paper page 6
3. Meta-analysis findings
The Commission contracted the Royal Australasian College of Surgeons to conduct a
systematic literature review and meta-analysis pertaining to anti-staphylococcal bundles
published through to the end of 2015. The anti-staphylococcal bundle was defined as skin
and/or nasal decolonisation. This work was built on the Schweizer et al12 meta-analysis (the
base reference) by identifying appropriate literature published between January 2011 and
December 2015. The methods and reporting have been aligned with those used in the base
reference.
Please review the meta-analysis summary in the attached PDF document (Appendix 2) and the summary of bundle components from the meta-analysis (Appendix 3). The full meta-analysis report is available on request. The impact of S. aureus screening itself was not a research question of the meta-analysis. Nevertheless, previous systematic reviews have already established the effectiveness of the intervention based on pre-surgery S. aureus screening in preventing SSIs.13,14 The choice between combining screening with a personalised treatment regimen versus universal application of a decolonisation intervention to reduce the occurrence of SSIs will depend on local factors – for example, how the patient’s clinical pathway is organised and national antibiotic susceptibility profiles.
12
Schweizer M, Perencevich E, McDanel J, et al. 2013. Effectiveness of a bundled intervention of decolonization and prophylaxis to decrease Gram positive surgical site infections after cardiac or orthopedic surgery: systematic review and meta-analysis. BMJ 346: f2743. 13
Chen AF, Wessel CB, Rao N. 2013. Staphylococcus aureus screening and decolonization in orthopaedic surgery and reduction of surgical site infections. Clinical Orthopaedics and Related Research 471(7): 2383–99. 14
Rodriguez-Merchan EC. 2014. Screening and decolonization of MRSA among joint arthroplasty patients: Efficacy, cost-effectiveness and durability. Journal of Acute Disease 3(3): 218–20.
Anti-staphylococcal bundle to reduce SSIs in orthopaedic and cardiac surgery – Discussion paper page 7
4. Proposed bundle
As a result of the meta-analysis findings, the Commission’s Strategic Infection Prevention and Control Advisory Group (SIPCAG) along with the orthopaedic and cardiac expert faculty groups recommended that there was enough evidence to support further discussion with the sector on the benefits and components of an anti-staphylococcal bundle to reduce S. aureus SSIs in orthopaedic and cardiac surgical patients.
The current processes used in New Zealand vary among DHBs. For example:
Some DHBs pre-screen their orthopaedic and cardiac surgical patients for MRSA but not
for methicillin-sensitive Staphylococcus aureus (MSSA). Confirmed MRSA-colonised
patients are then decolonised.
Some DHBs implement skin decolonisation but not nasal decolonisation.
Some DHBs leave the preoperative screening and decolonisation practice up to the
discretion of the surgeon.
Most DHBs have no preoperative screening or decolonisation protocols.
Introducing a standardised process would reduce the risk of staphylococcal SSI and provide an additional way to improve patient safety. The Commission would work with the sector to develop a bundle comprising either targeted or universal decolonisation. The two approaches being considered are:
Targeted decolonisation: Surgical patients would be screened for S. aureus colonisation
and decolonised if positive.
Universal decolonisation: No screening would occur; all patients would receive the same
decolonisation bundle regardless of colonisation.
If targeted decolonisation was chosen as the national approach, specific screening methods and decolonisation agents would be recommended. If universal decolonisation was chosen, specific decolonisation agents would be recommended.
The meta-analysis concluded that ‘S. aureus SSIs in orthopaedic and cardiac surgeries can be effectively reduced with an appropriate and standardised bundle of prophylactic antibiotics and nasal and skin decolonisation’.
Anti-staphylococcal bundle to reduce SSIs in orthopaedic and cardiac surgery – Discussion paper page 8
5. Benefits and risks
Benefits:
A standardised process for reducing the risk of staphylococcal SSI will reduce harm and
improve patient safety.
Patients can pro-actively participate in reducing their risk of SSI following surgery.
Universal decolonisation may be more cost-effective and logistically easier than
implementing a screening protocol (refer to Appendices 4, 5 and 6).
The cost of nasal and skin bundle components would be in the order of $15, and there
would be a saving of ~$40,000 for each SSI prevented (refer to Appendices 4 & 5).
The dollar saving of the bundle would be ~14:1 (saved to spent) for a 50% reduction in
all SSIs, an optimistic assumption (refer Appendix 5, Table 1, row 2).
The dollar saving of the bundle would be ~2:1 for only a 30% reduction in S. aureus
SSIs, a conservative assumption (refer to Appendix 5, Table 1, row 8).
Risks:
Logistical complexities of preoperative screening patients (targeted decolonisation) could
lead to gaps in patients being screened and hence decolonised (please refer to more
detailed issues related to preoperative screening for S. aureus in Appendix 6).
If patient education is not implemented correctly, this process may not result in
decreased SSI risk.
Universal decolonisation may compromise the ability to watch for the emergence of new
clones of S. aureus, contribute to mupirocin resistance if mupirocin is used in the bundle,
and prevent the adjustment of surgical prophylaxis for MRSA (eg, vancomycin or other
glycopeptide added to β-lactam agent). Refer to Appendix 7 for mupirocin and fusidic
acid resistance patterns in New Zealand.
In the effort to eliminate S. aureus carriage, there is the potential risk of adverse events.
Preoperative screening for intranasal carriage does not capture 100% of the S. aureus
carriers. Although the anterior nares is the most frequent site of carriage for both MRSA
and MSSA, only about 74% of people that are colonised with MRSA carry it in their nasal
cavity. Evidence indicates this percentage may be less for MSSA carriers. There are
other locations on the body (eg, axillae, groin, perineum) that an S. aureus carrier can be
colonised.
Anti-staphylococcal bundle to reduce SSIs in orthopaedic and cardiac surgery – Discussion paper page 9
6. Your feedback requested
Please provide your feedback to the following questions. These questions below relate to an
anti-staphylococcal bundle for elective cardiac and hip and knee joint replacement
procedures with the bundle being used the day before and day of surgery. We also welcome
general feedback related to the introduction of such a bundle.
Please provide your feedback to the following questions via survey monkey link:
https://www.surveymonkey.com/r/anti-staphylococcalbundle
1. Do you think there would be benefit in adding an anti-staphylococcal bundle to the existing interventions associated with the Surgical Site Infection Improvement (SSII) programme? Y / N
Comments:
2. Based on logistics and simplicity, we recommend universal decolonisation (decolonise all orthopaedic and cardiac surgical patients with topical nasal and skin agents). Do you agree? Y / N
Comments:
3. Based on potential resistance with mupirocin use, we recommend povidone-iodine for nasal decolonisation as our first choice. Mupirocin is considered an alternative agent. Do you agree? Y / N
Comments:
4. Based on logistics and simplicity, we recommend the chosen nasal preparation is administered twice the day before and once the morning of surgery. Do you agree? Y / N
Comments:
5. Based on logistics and simplicity, our first choice for skin decolonisation is chlorhexidine (wash or wipes) administered twice the day before and once the morning of surgery. Triclosan would be recommended as a second choice for chlorhexidine allergy. Do you agree? Y / N
Comments:
6. Based on the meta-analysis, we recommend that any bundle should consist of both nasal and skin components. Do you agree? Y / N
Comments:
7. Other comments?
Anti-staphylococcal bundle to reduce SSIs in orthopaedic and cardiac surgery – Discussion paper page 10
Appendix 1: Orthopaedic SSIs caused by staphylococci: March
2013 to March 2016
Between March 2013 and March 2016 there were 340 SSIs.
Out of 328 isolates, thirty-six SSI cases (12%) grew polymicrobial cultures.
The SSI cases in the table below were due only to staphylococcal species – that is, all
mixed cultures with staphylococci were ignored and only SSIs with a pure growth of
staphylococci are included in the table below.
SSI type Superficial Deep and organ space
Total (%)
n 118 222 340
Staphylococcus aureus 39 68 107
% 33% 31% 31%
Coagulase-negative staphylococci
6 42 48
% 5% 19% 14%
All staphylococci 45 110 155
% 38% 50% 46%
Overall, 46% of all SSIs were due to staphylococci.
S. aureus caused 31% of all SSIs.
Coagulase-negative staphylococci caused 14% of all SSIs, including 19% of deep and
organ space SSIs.
Anti-staphylococcal bundle to reduce SSIs in orthopaedic and cardiac surgery – Discussion paper page 11
Appendix 2: Overview of meta-analysis of S. aureus SSI prevention
in orthopaedic and cardiac surgery
Anti-staphylococcal bundle to reduce SSIs in orthopaedic and cardiac surgery – Discussion paper page 12
Anti-staphylococcal bundle to reduce SSIs in orthopaedic and cardiac surgery – Discussion paper page 13
PICO criteria
Anti-staphylococcal bundle to reduce SSIs in orthopaedic and cardiac surgery – Discussion paper page 14
Anti-staphylococcal bundle to reduce SSIs in orthopaedic and cardiac surgery – Discussion paper page 15
Anti-staphylococcal bundle to reduce SSIs in orthopaedic and cardiac surgery – Discussion paper page 16
Anti-staphylococcal bundle to reduce SSIs in orthopaedic and cardiac surgery – Discussion paper page 17
Anti-staphylococcal bundle to reduce SSIs in orthopaedic and cardiac surgery – Discussion paper page 18
The full meta-analysis report is available on request. Please email Nikki Grae at
Anti-staphylococcal bundle to reduce SSIs in orthopaedic and cardiac surgery – Discussion paper page 19
Appendix 3: Summary of bundle components from the papers in
meta-analysis
Of twenty-five reports, all used nasal intervention and 18 also used skin component.
Nose agents:
Twenty-three used mupirocin, three used povidone-iodine (two also used mupirocin),
one used chlorhexidine.
For mupirocin: 13 described frequency as BD (twice a day), one as TDS (three times a
day), one as ×2 night before and ×1 morning of surgery. Rest no comment. Duration
mentioned by 21; 11 were ≥ 5 days, and 8 were day before and day of surgery.
Most common was BD for 5 days (9 studies). Almost the same for day before and day of
group, (8 studies).
Five studies carried on post-op for 2–5 days.
Nasal povidone-iodine was applied the day of surgery in two of the three studies using
it.15,16 The other paper no information provided.
Skin agents:
Chlorhexidine (CHX) used for 15 of the 18 studies with a skin component, 14 as sole
agent.
Preparations: shower/(soap) = 3, bath = 1, soap = 9, rest = not stated.
Most used it once a day.
Duration 3–5 days 9 studies, 5 with night before and day of surgery.
Triclosan used in two studies, povidone-iodine soap in one.
Nasal povidone-iodine vs nasal mupirocin study15
Spinal fusion or arthroplasty patients, total = 1697 (82% arthroplasty), 1539 on per protocol
basis.
All patients had six 2% CHX wipes on specific body surfaces from chin to toes the evening
before and morning of surgery. End point = deep SSI within 90 days. Centers for Disease
Control and Prevention (CDC) definitions used.
Nasal regimens:
Nasal mupirocin 2%, BD, 5 days before surgery
Nasal solution povidone-iodine 5%, two 30-second applications to each nostril within 2
hours of surgery.
15
Phillips M, Rosenberg A, Shopsin B, et al. 2014. Preventing surgical site infections: a randomised, open-label trial of nasal mupirocin ointment and nasal povidone iodine solution. Infection Control and Hospital Epidemiology 35: 826–32. 16
Bebko SP, Green DM, Awad SS. 2015. Effect of a preoperative decontamination protocol on surgical site infections in patients undergoing elective orthopaedic surgery with hardware implantation. JAMA Surgery 150: 390–95.
Anti-staphylococcal bundle to reduce SSIs in orthopaedic and cardiac surgery – Discussion paper page 20
Results:15
Mupirocin Povidone-iodine P value
Intention to treat protocol
Any deep SSI 14/855 (1.6%) 6/842 (0.7%) 0.1
S. aureus SSI 5/855 (0.6%) 1/842 (0.1%) 0.2
Per protocol
S. aureus 5/763 (0.7%) 0/776 0.03
Adverse events
Nasal effect, discontinuation 0 1
CHX wipe skin event (rash/itch) 1.2% 1.5% 0.54
Any treatment symptom 8.9% 1.8% <0.0001
Patient perception
Rx important to reduce SSI 57% 60%
Application ‘unpleasant’ 38% 4% <0.0001
While it would seem sensible to apply the nasal preparation at least at the same start time as
any skin decontamination method, both the nasal solution papers on the meta-analysis only
used the nasal application the morning of surgery.15,16
We recommend: CHX starting the day before (twice a day) and the morning of surgery.
Nasal povidone-iodine to start the day before as well, with further application(s) morning of
surgery.
Mupirocin is an alternative nose agent. Triclosan wash is an alternative skin agent for
patients with CHX allergy.
Reasons to favour nasal povidone-iodine over nasal mupirocin:
New Zealand resistance rates to fusidic acid and mupirocin among local staphylococci
increased mupirocin resistance when it is used in ICU settings
no reported resistance to iodine
trial data showing positive effect for povidone-iodine with use limited to just the day of
surgery
most mupirocin data relates to use for many days, although some has been day before
and day of surgery
better patient acceptance in Phillips et al study15 (see above)
fewer overall side effect symptoms in Phillips et al study15 (see above)
cost
there is a current supply issue with mupirocin, which could occur in the future.
Anti-staphylococcal bundle to reduce SSIs in orthopaedic and cardiac surgery – Discussion paper page 21
Appendix 4: SSI bundle costing
Agent type Agent name Topical preparations
Pricing Estimate Comments
Nasal decolonisation agents
Mupirocin Ointment 2% (22 g)
$9.34 NB: Current shortage, section 29 of Medicines Act
Nasal ointment 2% (3 g)
Approved Price (AP)
$43.99 section 29 of Medicines Act
Povidone-iodine
Ointment 10% (25 g)
National Price (NP)
$3.27
Fusidic acid Ointment 2% (15 g)
NP $3.45
Cream 2% (15 g)
NP $2.52
Skin decolonisation agents
Chlorhexidine Cream 1% (50 g)
NP $1.21
M/Wash 0.2% (200 mL)
NP $2.57
Lotion 1% (200 mL)
NP $2.98
Solution 4% (50 mL)
NP $1.86
Solution 4% (500 mL)
Community NP
$3.98 Not listed HML*
Community use restricted to dialysis patients
Solution 5% (500mL)
NP $15.50
Wipes 2%
$184/carton
$3.83/pack
48 packs/carton. Four wipes a pack. One pack for whole body ‘wipe’.
Not listed HML.*
Scrub brush 4%
Triclosan Solution 1% (500 mL)
Community NP
$4.50 Not listed HML*
Community use restricted to MRSA decolonisation
* Hospital medicines list. We have initiated a request to get these onto the list so hospitals can access
them.
NB: At present there would be cost and availability issues for some possible bundle
components for scripts to be filled in the community. It will take some time for these to be
resolved with PHARMAC.
Anti-staphylococcal bundle to reduce SSIs in orthopaedic and cardiac surgery – Discussion paper page 22
In the meantime DHBs would be able to dispense the chosen bundle components, with clear
instructions, to patients while they are in the hospital – for example, at pre-admission clinic.
This would remove any cost as a barrier to patients and allow focused discussion with the
patient on how they can contribute to reducing their risk for SSI.
Anti-staphylococcal bundle to reduce SSIs in orthopaedic and cardiac surgery – Discussion paper page 23
Appendix 5: Back of envelope cost–benefit analysis of an anti-
staph bundle in New Zealand
Meta-analysis of observational studies showed ~50% reduction in ‘all cause’ SSIs (slides
10 and 12, Appendix 2).
Also showed ~50% reduction in S. aureus SSIs (slides 11 and 12, Appendix 2).
To March 2016: 28,768 orthopaedic procedures, 340 SSIs.
155 SSIs due to pure growths of staphylococci; 107 S. aureus, rest other staphylococci.
67 deep and organ space SSIs due to pure growth of S. aureus.
Excess cost of orthopaedic SSI = $40,000, excess length of stay (LOS) = 42 days.17
Cost of S. aureus screen likely to be at least $20.
Assume a conservative treatment bundle cost – that is, nasal mupirocin (~ $9) and CHX
body wash (0.5L = ~$6). Total = $15.
Table 1 below assumes increasingly conservative clinical benefit of a bundle.
No allowance made for reduction in deaths related to SSIs.
M = $1,000,000.
Px = prophylaxis bundle.
Screening cost: 28,768 × $20 = $0.576M.
Treatment cost, all patients: 28,768 × $15 = $0.432M.
Treatment cost after screening, assume ~30% positive: 28,768 × 0.3 × $15 = $0.130M.
‘Screen and treat’ bundle cost = $0.576M + $0.130M = $0.706M.
Cost difference between ‘screen and Px’ vs. ‘universal Px’ = $0.274M.
Additional cost only calculated for first assumption in table.
Assuming 40–50% reduction in all-cause SSIs predicts the most saving, ~$5–6M.
Assuming 40–50% reduction in only staphylococcal SSIs there is still considerable saving,
~$2–2.6M.
Assuming 30–40% reduction in S. aureus SSIs only, saving $0.8–1.2M.
17
Gow N, McGuinness C, Morris AJ, et al. 2016. Excess cost associated with primary hip and knee joint arthroplasty surgical site infection: a driver to support investment in quality improvement strategies to reduce infection rates. New Zealand Medical Journal 129(1432): 51–8. URL: https://www.nzma.org.nz/journal/read-the-journal/all-issues/2010-2019/2016/vol-129-no-1432-1-april-2016/6848 (accessed 26 September 2016).
Anti-staphylococcal bundle to reduce SSIs in orthopaedic and cardiac surgery – Discussion paper page 24
Table 1: Cost–benefit analysis of bundle based on increasingly conservative
assumptions
Assumption, bundle prevents
Total SSIs
SSIs prevented
Cost saved
Bundle Cost of bundle
Saving Bed days saved
50% all SSIs 340 170 $6.7M Screen and Px if positive
$0.706 $5.994M 7098
50% all SSIs 340 170 $6.7M No screen, universal Px
$0.432 $6.268M 7098
50% all staph SSIs 155 77 $3.08M No screen, universal Px
$0.432 $2.648M 3234
40% all SSIs 340 136 $5.4M No screen, universal Px
$0.432 $4.968 5670
40% all staph SSIs 155 62 $2.44M No screen, universal Px
$0.432 $2.008M 2562
40% S. aureus SSIs only
107 42 $1.68M No screen, universal Px
$0.432 $1.248M 1764
40% S. aureus deep and organ space SSIs only
68 27 $1.08M No screen, universal Px
$0.432 $0.648M 1134
30% S. aureus SSIs
107 32 $1.28M No screen, universal Px
$0.432 $0.848M 1344
30% S. aureus SSIs deep and organ space only
68 20 $0.8M No screen, universal Px
$0.432 $0.368M 840
20% S. aureus SSIs deep and organ space only
68 13 $0.52M No screen, universal Px
$0.432 $0.088M 546
Px = prophylaxis bundle
Anti-staphylococcal bundle to reduce SSIs in orthopaedic and cardiac surgery – Discussion paper page 25
Appendix 6: Issues relating to screening for S. aureus carriage
While several studies included in the meta-analysis performed screening and either applied
the bundle to carriers or stopped the bundle if cultures were negative, there are several
logistical and theoretical issues that need to be considered.
A single nose swab does not detect all carriers. People may have carriage at other sites
or ‘low count’ colonisation in the nose. That said, the risk of developing S. aureus
infection may be lower in those that are ‘missed’ in a single nasal swab.
Decisions would need to be made if swabbing was undertaken in the patient pathway.
For example:
– Swab collected at outpatients or pre-admission clinic?
– Self-swab or staff collect?
– Timing in relation to operation date to allow testing and reporting before admission.
– Which laboratory does swab go to?
– What method (plate/broth/polymerase chain reaction (PCR)) is used in the laboratory
to detect carriage?
– Screening could be a significant increase in specimen processing (plating or PCR)
for the lab.
– Who pays for swab? For many laboratory contracts this would need to be negotiated
with the laboratory service provider.
– Where does the result go to get actioned – ward/clinic/GP/surgeon?
– How is theatre (preoperative holding area) notified if positive for MRSA to ensure
vancomycin is added to prophylaxis with increased administration time?
– Who responds to positive screen results?
– How would script or ‘bundle package’ be sent to patients?
– How is use of bundle explained to patient?
– How is compliance measured on admission?
– For confirmed positive MRSA carriers, would there be a recommendation of delaying
procedure if decolonisation could not be completed prior to scheduled surgery date?
– Surgery may be delayed, so what is an acceptable time between screening and
having the procedure performed (eg, weeks or months)?
Screening would detect MRSA carriage and allow vancomycin to be added to surgical
prophylaxis – ~10% of S. aureus in New Zealand is MRSA.
It is possible that any bundle aimed at S. aureus may also have a beneficial effect on
reducing SSIs due to coagulase-negative staphylococci. Applying the bundle to only
S. aureus carriers would prevent any beneficial effect on other staphylococci.
The cost of a screen is likely to be in the order of $20–25.
On balance it is recommended that screening should not be part of any anti-staph
patient care bundle.
Anti-staphylococcal bundle to reduce SSIs in orthopaedic and cardiac surgery – Discussion paper page 26
Appendix 7: Susceptibility of staphylococci in New Zealand
Local resistance patterns are relevant when making choices/recommendations for
components in an ‘anti-staph’ bundle.
The best reference for New Zealand-wide data is the recent Institute of Environmental
Science and Research (ESR) report on susceptibility of S. aureus in New Zealand.20
For Table 2, the resistant (R) percentage does not include intermediate strains.
Table 2: Staphylococcal resistance rates for fusidic acid and mupirocin in New
Zealand
MRSA MSSA S. epidermidis Coag-neg
staphs
Where Year % R
fusidic acid
% R
mupirocin
% R
fusidic acid
% R
mupirocin
% R
fusidic acid
% R
fusidic acid
Auckland
LabPlus18
2015 49%
(n=573)
8%
(n=573)
19%
(n=3758)
8%
(n=3758)
60%
(n=533)
19%
(n=313)
Auckland
Labtests Auckland
19
2015 50%
(n=3988)
8%
(n=3988)
26%
(n=27,559)
12%
(n=27,559)
National20
(weighted data)
2014 58%
(n=123)
4%
(n=123)
22%
(n=1255)
9%
(n=1255)
We are unaware of mupirocin susceptibility data for coagulase-negative staphylococci in
New Zealand.
Reduced susceptibility to chlorhexidine is known to occur. The most common and studied
mechanism of reduced susceptibility is the presence of efflux-pump(s), encoded by qac
genes (qacA/B, etc). Approximately 7% of isolates in the ESR survey20 were qacA/B positive
18
LabPLUS, Auckland City Hospital. 2016. Summary of antimicrobial susceptibility test results: 2015. URL: http://www.labplus.co.nz/assets/Uploads/2015-Gram-positive-antimicrobial-report.pdf (accessed 26 September 2016). 19
Labtests Auckland. 2016. Cumulative antimicrobial susceptibility report – Auckland 2015. URL: http://www.labtests.co.nz/images/Referrers/Information/AST-2015-Table.pdf (accessed 26 September 2016). 20
Heffernan H, Bakker S, Woodhouse R, et al. 2016. Demographics, antimicrobial susceptibility and molecular epidemiology of Staphylococcus aureus in New Zealand. URL: https://surv.esr.cri.nz/PDF_surveillance/Antimicrobial/Staph/2014Saureussurveyreport.pdf (accessed 26 September 2016).
Anti-staphylococcal bundle to reduce SSIs in orthopaedic and cardiac surgery – Discussion paper page 27
(Dr D. Williamson, personal communication). The relationship between qac gene carriage,
phenotypic reduced susceptibility and clinical efficacy is not clear.21
Resistance to iodine-containing preparations is not known to occur.
Based on susceptibility data, fusidic acid should not be used as part of an anti-staph bundle.
Mupirocin resistance is not rare, and its use may reduce the efficacy of any bundle which
includes it.
We recommend that a povidone-iodine preparation be used as the nasal component of an
anti-staph bundle. Mupirocin is an alternative agent and should be used if there is a concern
about allergy to iodine.
21
Horner C, Mawer D, Wilcox M. 2012. Reduced susceptibility to chlorhexidine in staphylococci: is it increasing and does it matter? Journal of Antimicrobial Chemotherapy 67(11): 2547–59. DOI:10.1093/jac/dks284.