Effect of extended perioperative antibiotic prophylaxis on intravascular catheter colonization and infection in cardiothoracic surgery patients

J. A. T. Sandoe1,*, B. Kumar2, B. Stoddart1, R. Milton2, J. Dave1, U. R. Nair2 and M. H. Wilcox1

Departments of 1 Microbiology and 2 Cardiothoracic Surgery, Leeds Teaching Hospitals and University of Leeds, Leeds, UK

Received 4 November 2002; returned 31 December 2002, revised 4 February 2003; accepted 13 August 2003


    Abstract
 Top
 Abstract
 Introduction
 Patients and methods
 Results
 Discussion
 References
 
Intravascular catheter-related infections (CRI) account for one third of nosocomial bloodstream infections in England. UK Department of Health guidelines state that antibiotic prophylaxis is not required during placement, or use of, central venous catheters, to prevent CRI. However, some clinicians continue to use antibiotics in an attempt to prevent CRI. We investigated the effect of extended routine perioperative antibiotic prophylaxis in cardiothoracic patients on rates of intravascular catheter (IVC) colonization and infection. Investigations were undertaken in patients undergoing uncomplicated cardiothoracic surgery during July 2001–February 2002. Patients who received three doses of cefuroxime as perioperative prophylaxis were compared with those who received extended cefuroxime prophylaxis until the IVC was removed. Patients were not randomized into groups, but received the different prophylaxis regimens according to the usual practice of the consultant cardiothoracic surgeon. A roll tip method was used to determine IVC colonization. Of 191 patients who fulfilled the inclusion criteria, 12 were excluded because data were incomplete. One hundred and forty-six patients received routine prophylaxis, and 33 prophylaxis until the IVC was removed. Twenty-three out of 146 (16%) IVCs in the ‘routine’ group and four out of 33 (12%) in the ‘extended’ group became colonized; no IVC-related bloodstream infections occurred during the survey. The duration of IVC placement and the types of operation performed in the two groups were not significantly different (P > 0.05). In routine cardiothoracic surgery patients, extending routine perioperative antibiotic prophylaxis until all IVCs have been removed does not influence rates of IVC colonization.

Keywords: intravascular catheters, antibiotic prophylaxis, coronary artery bypass, valve replacement, infections


    Introduction
 Top
 Abstract
 Introduction
 Patients and methods
 Results
 Discussion
 References
 
Bloodstream infection is one of the most serious complications of intravascular catheter (IVC) placement.1,2 In cardiothoracic patients, particularly those undergoing heart valve surgery, intravascular catheter-related bloodstream infection (CRBSI) can be devastating because of the risk of seeding a newly repaired or implanted valve, causing endocarditis. In the past, antibiotics have been used in an attempt to prevent infection arising from IVCs.3 UK Department of Health guidelines do not advocate the use of antibiotics during IVC placement to prevent infection,3 however, the evidence supporting these guidelines was inconclusive, and was derived entirely from studies in oncology patients and neonates. In The General Infirmary at Leeds, routine perioperative antibiotic prophylaxis, aimed primarily at reducing wound infection rates, comprises three doses of cefuroxime. Because cardiothoracic patients represent a patient population with risk factors different from those used to develop UK Department of Health guidelines, some cardiac surgeons extend perioperative antibiotic prophylaxis until all IVCs have been removed, in an attempt to prevent CRBSI. In the absence of definitive evidence to support or refute such practice, we compared the incidence of catheter colonization and CRBSI in cardiothoracic patients receiving short or extended perioperative prophylactic cefuroxime to determine any impact on infection.


    Patients and methods
 Top
 Abstract
 Introduction
 Patients and methods
 Results
 Discussion
 References
 
In the period July 2001–February 2002, the cohort of patients eligible for inclusion were those in whom an IVC had been placed during cardiothoracic surgery, and who had received cefuroxime perioperative prophylaxis. Patients were excluded if they were treated with any other antibiotic at any time during the period in which the IVC was in situ. Patients were not randomized into groups, but received routine short-course perioperative antibiotic prophylaxis or extended antibiotic prophylaxis, according to the usual practice of the consultant cardiothoracic surgeon. Ethical committee approval was not sought because this was a survey of usual clinical practice. Data were collected on the type and date of operation, type of IVC and date of removal, results of IVC tip and blood cultures and duration of cefuroxime prophylaxis. ‘IVC’ included all types of central venous and pulmonary artery catheters, but no antibiotic-impregnated IVCs were included. Short-course perioperative antibiotic prophylaxis was defined as up to three doses of cefuroxime; extended antibiotic prophylaxis continued until IVCs were removed.

Microbiological methods

During the survey period, IVC tips were collected from patients when catheters were considered no longer clinically necessary, and were cultured by the roll tip method. The exit site was routinely cleansed with povidone iodine or Betadine solutions prior to IVC removal. Significant IVD colonization was defined as growth of >15 cfu4 from the removed tip. Isolates were identified using standard microbiological techniques. Blood cultures were incubated in a continuous monitoring system (Vital 800, BioMerieux, Marcy l’Étoile, France). CRBSI was defined as a positive blood culture when the IVC was in situ, with significant colonization of the device tip by the same microorganism. Antibiotic susceptibility testing was carried out using a disc-diffusion method.


    Results
 Top
 Abstract
 Introduction
 Patients and methods
 Results
 Discussion
 References
 
Three hundred and eighty-nine IVC tips were submitted from eligible patients during the survey. These patients represented ~50% of the total cohort that underwent cardiac surgery during the survey period. Of the 389 patients, 191 fulfilled the inclusion criteria, but 12 were excluded because data were incomplete. Of the remaining 179, 146 patients received short-course cefuroxime perioperative prophylaxis, and 33 had extended prophylaxis. The IVCs comprised 175 central venous catheters and four pulmonary artery catheters. One hundred and thirty-one patients had coronary artery bypass graft (CABG) surgery alone, 46 had valve surgery with or without CABG and the remainder had miscellaneous procedures such as pericardectomy. The type of operation did not differ significantly in the two antibiotic groups, and duration of IVC placement was similar in the surgery groups. IVCs remained in place in the short-course prophylaxis group for a median of 4 days (range 1–14), versus a median of 4 days (range 1–20) in the extended prophylaxis group. The risk of IVC colonization increased with duration in situ (Figure 1).



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Figure 1. Effect of duration of placement on risk of IVC colonization in coronary artery bypass patients.

 
Twenty-three of 146 (16%) IVC in short-course patients and four of 33 (12%) in the extended prophylaxis group became colonized, but there were no episodes of CRBSI in either group. There was no significant difference in the risk of IVC colonization between the two groups (risk ratio 1.043, 95% confidence intervals 0.85–1.26). In the subgroup of patients who had valve surgery, duration of antibiotic prophylaxis did not affect the risk of IVC colonization (risk ratio 1.101, 95% confidence intervals 0.79–1.27).

The microorganisms causing IVC colonization are shown in Table 1, with the most common being coagulase-negative staphylococci. Twenty-nine isolates were recovered from 29 IVC tips, of which two provided a mixed growth. For 69% of the tip isolates, cefuroxime was not considered appropriate therapy either because of previous local surveillance data (coagulase-negative staphylococci), inherent resistance (enterococci, yeasts) or on the basis of resistance on susceptibility testing. The patients administered extended antibiotic prophylaxis (n = 33) received 145 more days of cefuroxime than the short-course (routine) prophylaxis group. This amounted to an estimated extra £2000 (145 x 3 x £5.05 = £2196.75) in drug costs.5


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Table 1. Organisms causing IVC colonization in patients receiving short-course and extended perioperative antibiotic prophylaxis
 

    Discussion
 Top
 Abstract
 Introduction
 Patients and methods
 Results
 Discussion
 References
 
IVCs are the source of ~30% of nosocomial bloodstream infections in England and Wales.6 Perioperative bloodstream infection in patients undergoing cardiac surgery, particularly heart valve surgery, is of concern because of the potentially serious sequelae. Prevention of perioperative bacteraemia in such patients is therefore of paramount importance. Placement of central venous catheters and arterial catheters is a routine part of the perioperative management of patients undergoing cardiac surgery, and is usually carried out in the anaesthetic room prior to operation. Although current UK Department of Health guidelines do not advocate use of antibiotics during IVC placement to prevent infection,3 not all clinicians are convinced that the lack of evidence to support antimicrobial prophylaxis during use of IVCs equates to a lack of effectiveness. To this end, some surgeons continue routine perioperative antibiotic prophylaxis until all central venous catheters have been removed. The aim of this survey was to investigate the value of extended routine perioperative cefuroxime prophylaxis for the prevention of IVC-related infection.

No significant difference in the risk of IVC colonization was found when short-course perioperative prophylaxis was compared with extended prophylaxis to the point where all IVCs had been removed. This remained true even when heart valve and coronary artery bypass graft operations were analysed separately. CRBSI, one of the primary outcome measures, did not occur in any patient who fulfilled the inclusion criteria. This may have been because cases treated with another antibiotic during catheter placement were excluded from the survey, thus removing patients who had been started on empirical therapy for suspected CRBSI prior to line removal. CRBSI associated with central venous catheters has a reported incidence of 4%–14%, the wide range reflecting, at least in part, problems with the accuracy of laboratory diagnostic methods.7 Using these incidence rates we would have expected to see 7–25 cases of CRBSI in the 179 patients examined, assuming that all such potential episodes were appropriately investigated. Some CRBSI episodes that occurred during the survey may have been missed. However, of all the 389 IVC tips examined initially, the overall risk of colonization did not differ significantly between the short and extended prophylaxis groups (risk ratio 1.28, 95% confidence intervals 1.00–1.62) regardless of concurrent antimicrobial therapy.

In the absence of any CRBSI episodes in the survey population, IVC colonization is still potentially an important outcome measure. Since catheter colonization is a prerequisite for CRBSI, we believe that it is reasonable to assume that a reduction in the rate of IVC colonization would result in a reduction in CRBSIs.8 The roll tip method was used to determine IVC tip colonization. This method has relatively good sensitivity, but poor specificity;9,10 nevertheless, it remains the most commonly used diagnostic technique to detect catheter colonization. Consistent with previous findings, the risk of catheter colonization increased with duration in situ,11 and notably was not affected by duration of antibiotic use. We acknowledge that this is not a randomized study and that there are limitations with this kind of survey, but it does provide preliminary evidence that the extension of routine perioperative cefuroxime prophylaxis does not reduce rates of IVC colonization. In an era where antibiotic prescribing patterns should be reviewed to minimize unnecessary pressure towards the development of resistance, we found that extended antibiotic prophylaxis increased cost without discernible benefit to the patient. Following the introduction of daily clinical microbiology liaison in the cardiothoracic surgery unit, extended antibiotic prophylaxis has been ceased pending further analysis.


    Footnotes
 
* Correspondence address. Department of Microbiology, Leeds General Infirmary and University of Leeds, Old Medical School, Leeds LS1 3EX, UK. Tel: +44-113-392-6818; Fax: +44-113-343-5649; E-mail: J.Sandoe{at}leeds.ac.uk Back


    References
 Top
 Abstract
 Introduction
 Patients and methods
 Results
 Discussion
 References
 
1 . Maki, D. G. (1989). Pathogenesis, prevention and management of infections due to intravascular devices used for infusion therapy. In Infections Associated with Indwelling Medical Devices (Bisno, A. L. & Waldvogel, F. A., Eds), pp. 161–77. ASM Press, Washington, DC, USA.

2 . Mermel, L. A., Farr, B. M., Sherertz, R. J. et al. (2001). Guidelines for the management of intravascular catheter-related infections. Infection Control and Hospital Epidemiology 22, 222–42.[ISI][Medline]

3 . Pratt, R. J., Pellowe, C., Loveday, H. P. et al. (2001). The epic project: developing national evidence-based guidelines for preventing healthcare associated infections. Phase I: Guidelines for preventing hospital-acquired infections. Department of Health (England). Journal of Hospital Infection 47, Suppl., S3–82.[CrossRef]

4 . Maki, D. G., Weise, C. E. & Sarafin, H. W. (1977). A semiquantitative culture method for identifying intravenous-catheter-related infection. New England Journal of Medicine 296, 1305–9.[Abstract]

5 . Anonymous. (2002). Monthly pricelist, July. Chemist and Druggist 43. CMP Information Ltd., Tonbridge, Kent, UK.

6 . Anonymous. (2000). Surveillance of hospital acquired bacteraemia in English hospitals 1997–1999, pp. 1–11. Public Health Laboratory Service (PHLS), London, UK.

7 . Dobbins, B. M., Kite, P. & Wilcox, M. H. (1999). Diagnosis of central venous catheter related sepsis–a critical look inside. Journal of Clinical Pathology 52, 165–72.[Free Full Text]

8 . Darouiche, R. O. (2001). Device-associated infections: a macroproblem that starts with microadherence. Clinical Infectious Diseases 33, 1567–72.[CrossRef][ISI][Medline]

9 . Sitges-Serra, A. & Linares, J. (1988). Limitations of semiquantitative method for catheter culture. Journal of Clinical Microbiology 26, 1074–6.[ISI][Medline]

10 . Kite, P., Dobbins, B. M., Wilcox, M. H. et al. (1997). Evaluation of a novel endoluminal brush method for in situ diagnosis of catheter related sepsis. Journal of Clinical Pathology 50, 278–82.[Abstract]

11 . Richet, H., Hubert, B., Nitemberg, G. et al. (1990). Prospective multicenter study of vascular-catheter-related complications and risk factors for positive central-catheter cultures in intensive care unit patients. Journal of Clinical Microbiology 28, 2520–5.[ISI][Medline]





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