Infection control measures for adult cardiac surgery in the UK—a survey of current practice

Journal of Hospital Infection (2003) 54, 174–178

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Infection control measures for adult cardiac surgery in the UK—a survey of current practice J.B. Kendall*, C.A. Hart, S.H. Pennefather, G.N. Russell Department of Anaesthesia, The Cardiothoracic Centre, Thomas Drive, Liverpool L14 3PE, UK Received 25 November 2002; accepted 12 March 2003

KEYWORDS Anaesthesia; Antibiotic prophylaxis; Cardiac surgery; Viruses; Screening; Questionnaire

Summary The aim of the study was to define current UK practice for antimicrobial prophylaxis and preoperative screening for bloodborne viruses and methicillinresistant Staphylococcus aureus (MRSA) before routine cardiac surgery. An e-mail survey was sent to the Association of Cardiothoracic Anaesthetists (ACTA) Linkmen in all 36 UK adult cardiac surgical units, during May 2001. Questions were asked regarding MRSA, hepatitis B, C and human immunodeficiency virus (HIV) screening. Regarding antimicrobial prophylaxis questions were asked regarding agent(s), dose, frequency and duration of use for coronary artery and value surgery. Responses were received from 29 units (response rate 81%). There was a wide variety of practices for all units surveyed. For MRSA screening, 19 units (65%) screened all patients before surgery, but two (7%) screened none, with the remaining eight units (28%) screening selected highrisk groups. Regarding screening for bloodborne viruses: eight units (28%) tested all patients routinely for hepatitis B, 11 units (39%) selectively tested only high-risk patients and transplant recipients. No units tested for hepatitis C and HIV infection routinely. All units used prophylactic antibiotics routinely, but the type and number of agents, along with dose and duration of therapy all varied widely. For coronary artery bypass graft (CABG) surgery, a single agent was used by 16 units (55%), two agents by 12 units (41%) and three agents by one unit (4%). There is a wide variation in infection control practice in adult cardiac units throughout the UK. Rationalization of preoperative screening and use of prophylactic antibiotics, by adopting nationally agreed practice guidelines, could significantly reduce costs and potentially reduce the incidence of resistant organisms. Q 2003 The Hospital Infection Society. Published by Elsevier Science Ltd. All rights reserved.

Introduction Prophylactic antimicrobials have been used routinely in cardiac surgery for many years to reduce the incidence of infection.1 However, the overuse of antibiotics is associated with additional cost *Corresponding author. Tel.: þ 44-151-228-1616; fax: þ 44151-220-8573. E-mail address: [email protected]

implications and the development of antimicrobial resistance. The choice of agents used and the duration of use has changed over time as new antibiotics have become available and understanding of microbiology has improved.2,3 This survey is the first to define current practice in UK adult cardiac centres since 1993.4 Our survey targeted the anaesthetist, who is usually the clinician responsible for administering antibiotics at the time of induction of anaesthesia.

0195-6701/03/$ - see front matter Q 2003 The Hospital Infection Society. Published by Elsevier Science Ltd. All rights reserved. doi:10.1016/S0195-6701(03)00134-8

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In addition, this survey is the first to investigate the practice of screening patients before cardiac surgery for methicillin-resistant Staphylococcus aureus (MRSA) and the bloodborne viruses hepatitis B, C and human immunodeficiency virus (HIV). There are significant cost implications involved in screening all patients before cardiac surgery. However in the absence of nationally defined practice, these decisions are often made locally.

Method An e-mail survey was sent to the Association of Cardiothoracic Anaesthetists (ACTA) Linkmen in all 36 UK adult cardiac surgery units (see Appendix 1), during May 2001. If after a follow-up e-mail, no response was received, a postal survey was then sent to that unit. The following questions were asked: 1. MRSA: Which patients are screened preoperatively? Which sites are sampled by swabbing? Are medical and nursing staff ever screened? How often are intensive care unit (ITU) patients screened? 2. Hepatitis B, C and HIV: Which patients are screened preoperatively? Is specific consent sought and are counselling services available? 3. Antibiotic use: Drug(s), dose, frequency and duration of use for both coronary artery and value surgery

Results Responses were received from 29 units (response rate 81%). There were a wide variety of practices for all units surveyed.

Figure 1 Patients screened for MRSA.

45% of units regularly screened long-term ITU patients from anywhere between daily and weekly.

Bloodborne virus screening A total of 29% of units tested all patients routinely for hepatitis B carriage, but 32% tested none. The remaining 39% of units selectively tested only highrisk patients and transplant recipients. No units tested for hepatitis C and HIV infection routinely, but 45 and 38% of units tested high-risk patients and transplant recipients for hepatitis C and HIV, respectively. Counselling or consent before testing were routine practice in 81% of units involved in viral screening. However 19% of units neither took consent nor had counselling services available for these procedures.

Prophylactic antibiotics All units used prophylactic antibiotics routinely, but the type and number of agents, along with dose and duration of therapy all varied widely. In all, 89% of units had standard departmental guidelines, which are followed routinely.

MRSA screening Sixty-five percent of units screened all patients before surgery, but 7% screened none, with the remaining 28% screening selected high-risk groups (Figure 1). The numbers of sites from which swabs were taken varied from one to five, with four sites being the most common (Figure 2). The nose was the commonest swab site, used by 90% of units. Screening of medical and nursing staff was carried out by 66% of units during outbreaks only. The remainder carried out no staff screening. Overall

Figure 2 Number of sites swabbed for MRSA.

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Antimicrobials The most common types of antimicrobials included as part of regimens were cephalosporins (61%) followed by penicillins (45%), then aminoglycosides (39%). Single antimicrobials were used by 55% of units for coronary artery surgery, two agents by 41.5% and three agents by one unit (3.5%). The cephalosporins were most commonly used as monotherapy (48%). The agents most commonly used in combination were gentamicin and flucloxacillin (24%). Twenty-four of units changed their practice for valve surgery, with 62% of units using two or more agents in combination. The most commonly added additional agents were vancomycin (10.5%) and teicoplanin (10.5%). These data are shown in Table I. Doses and duration For coronary artery surgery only 10% of units used a single dose regimen. Forty-five percent of units discontinued therapy at 24 h. Twenty-eight percent of units discontinued therapy at 48 h, and only 17% of units continued treatment beyond this (Figure 3). Treatment was typically longer for valve surgery, with 48% of units continuing therapy for more than 24 h. The doses of agents used also varied widely. Gentamicin was given in seven different doses ranging from 80 mg up to 400 mg. Some units used flucloxacillin at a dose of 500 mg while others used 1 g, similarly some units used 750 mg cefuroxime while others used 1.5 g.

Discussion No previously published studies have examined the practice of preoperative screening before cardiac surgery for either MRSA or bloodborne viruses. Any screening programme is only useful if it provides

J.B. Kendall et al.

Figure 3 Duration of antibiotic use after CABG surgery.

reliable information, leading to an intervention, which subsequently changes an outcome. In this survey we did not enquire about subsequent interventions or outcomes, but focused our attention towards defining current practice and use of resources. There was a surprisingly wide variety of practices in all areas surveyed. MRSA screening has been shown to be a costeffective intervention for screening high-risk patients on admission to hospital.5 However no study has shown this to be the case for all patient admissions. The number of swabs needed to provide a high sensitivity is difficult to quantify, but unnecessary swabs can add to the cost of a screening programme.6 The current cost per swab is approximately £10 and the mean number of swabs per patient before cardiac surgery in the UK currently is 1.84. Subsequent clearance of skin and nasal carriage of MRSA by topical antibiotics has been shown to reduce surgical wound infection rates.7,8 Screening for bloodborne viruses has no immediate benefit to patients but is primarily used to alert staff to the potential risk of contamination. However, it may also alter recipients’ transplant

Table I Antibiotic prophylaxis combinations used for coronary artery bypass graft and valvular surgery Agent combination

Coronary artery bypass graft (%)

Valve (%)

Cephalosporin Flucloxacillin Vancomycin

14 (48) 2 (7) 0

7 (24) 2 (7) 2 (7)

Flucloxacillin þ gentamicin Flucloxacillin þ netilmicin Cephalosporin þ gentamicin Cephalosporin þ vancomycin Cephalosporin þ teicoplanin Benzylpenicillin þ flucloxacillin

7 (24) 1 (3.5) 2 (7) 0 1 (3.5) 1 (3.5)

7 (24) 1 (3.5) 2 (7) 3 (10) 3 (10) 1 (3.5)

Cephalosporin þ gentamicin þ flucloxacillin

1 (3.5)

1 (3.5)

Total

29 (100)

29 (100)

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status. But with the use of universal precautions, and immunization programmes for hepatitis B for medical staff, is screening necessary for nontransplant patients? A study of patients undergoing cardiac surgery in the Baltimore, MD, USA in the 1980s found an incidence of undiagnosed hepatitis C of 2.4% over a two-year period.9 Another study of patients undergoing elective orthopaedic procedures in the same hospital between 1989 – 1995 found an incidence of undiagnosed HIV of 0.15%.10 Whenever testing for a serious communicable disease is undertaken, the General Medical Council recommends consent be sought before testing and counselling services should be available.11 In 19% of centres where testing for bloodborne viruses was undertaken, we found this advice was not being followed. The current cost per hepatitis B test is approximately £25. The use of antibiotic prophylaxis for patients undergoing cardiac surgery is associated with a reduced incidence of wound infection,12 and hence has been adopted universally. Antibiotic prophylaxis should be targeted towards the most likely pathogen and there should be adequate tissue and blood concentrations at the wound site during the time of peak potential for contamination, i.e. intraoperatively. The organisms implicated in surgical site infections (SSIs) following coronary artery surgery during 1997 – 1999 have been identified by the UK Nosocomial Infection National Surveillance Scheme (NINSS).13 These are, in order of frequency, S. aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa and coliforms. NINSS found the incidence of SSI for coronary artery surgery to vary from 2 to 12% between centres. NINSS highlighted MRSA as being the most common staphylococcal pathogen in general and orthopaedic surgery, but MRSA only accounts for approximately 20% of SSIs following coronary artery surgery. Approximately 20% of the SSIs caused by staphylococci were due to coagulase–negative staphylococci. Multiple antibiotic resistance is common in these groups, hence monotherapy may be inadequate for some of these potential pathogenic combinations and combination treatment will be necessary. However, widespread use of multiple agents may encourage emergence of highly resistant organisms and therefore cannot currently be recommended for routine use. Tissue concentrations of antibiotics can be affected by dilution and perfusion changes during cardiopulmonary bypass (CPB). Antibiotic concentrations should remain consistently above minimum inhibitory concentrations. There is evidence from a small-scale study that single doses of cefuroxime or vancomycin provide adequate serum concentrations for the duration of surgery up to 8 h, and

177 that additional doses for CPB are not necessary.14 Generally there are little pharmacokinetic data for antibiotic concentrations during cardiac surgery. However, large-scale, prospective, randomized controlled trials of nearly 2000 patients at one centre have shown that the use of single agents, in single dose regimens do not result in increased infection rates and are associated with reduced cost.15,16 Furthermore, there is no demonstrable difference in effectiveness of first, second or third-generation cephalosporins.17 We found in this survey nearly half of the units in the UK using multiple agents for more than 24 h despite evidence that this is unnecessary, may cause toxicity, encourage bacterial resistance and is less cost-effective. These factors are often difficult to quantify. We have calculated the annual cost of the antibiotic regimens currently used by respondents to this survey as accurately as possible, using prices as listed in the British National Formulary and activity levels as listed in the National Adult Cardiac Surgery Database. This cost is approximately £7 million per annum. If this trend were extrapolated to all UK cardiac surgical cases it would give an estimated cost of over £9 million per annum as the annual NHS expenditure for antibiotic prophylaxis for cardiac surgery the in the UK. This cost may actually be less than estimated due to locally negotiated price reductions, but by comparison if a single dose cephalosporin was used, this cost could be cut to less than £200 000 per annum for the entire NHS. The precise regimen for prophylaxis should be based on local information about pathogens and their susceptibility to antimicrobial drugs. The policy should be developed and audited jointly by surgeons, microbiologists and infection control teams. In addition to antibiotic prophylaxis, prevention of infection requires close attention to other factors such as treatable risk factors in the patient, good surgical technique, strict theatre discipline and scrupulous standards of infection control by all staff. In conclusion, there is a wide variation in infection control practice in adult cardiac units throughout the UK. Rationalization of preoperative screening and use of prophylactic antibiotics, by adopting nationally agreed practice guidelines, could significantly reduce costs and potentially reduce the incidence of resistant organisms.

Acknowledgements We thank all the ACTA members who completed this survey.

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Appendix 1. UK cardiac units 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. 36.

Aberdeen Belfast Birmingham (Queen Elizabeth) Blackpool Brighton Bristol Cambridge (Papworth) Cardiff Coventry (Walsgrave) Edinburgh Glasgow (HCI) Glasgow (Royal) Glasgow (Western) Hull Leeds Leicester Liverpool London (Brompton & Harefield) London (Chest & Barts) London (Guys & St Thomas’) London (King’s) London (Middlesex) London (Royal Free) London (St George’s) London (St Mary’s) Manchester (MRI) Manchester (Wythenshawe) Newcastle (Freeman) Nottingham Oxford Plymouth Sheffield South Cleveland Southampton Stoke (North Staffordshire) Swansea

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