Improved management of infrainguinal bypass graft infection with methicillin-resistant Staphylococcus aureus

Complex treatment of vascular prostheses infections

Infections after vascular reconstructions are very rare; however, when they occur, they are associated with a high risk of morbidity. In order to obtain the best results possible, the treatment needs to be initiated as early as possible, from the very first signs of infection, and it needs to be carried out in centers specializing in vascular surgery. The aim of the present study was to assess the incidence of infections in a single university center.This retrospective analysis over a 2-year period is based on the medical reports of hospitalized patients who were diagnosed with infection following revascularization.From 2013 to 2014, a number of 151 open reconstructive surgical procedures were performed. 15 patients suffered from infection (10%) of the vascular reconstruction. Of these patients, 40% have had an aorto-bifemoral bypass, 53%-a femoro-popliteal bypass, and 7% (n = 1)-an axillo-femoral bypass. According to the Samson classification, the patients were categorized as follows: group 2: 6 cases, group 3: 2 cases, group 4: 4 cases, and group 5: 3 cases. The most frequent bacteria found were methicillin-resistant Staphylococcus aureus (MRSA) (n = 6, 40%), followed by S aureus (n = 5, 33%). The treatment options were: application of antibiotics alone without any invasive treatment in 3 patients, local irrigation and debridement in 6 patients, complete explantation of the prosthesis with a new extra-anatomic bypass in 6 cases, and partial excision of the prosthesis, which was replaced and covered with muscle flap, in 3 cases. The amputation rate in our study was 18%, which corresponds to the rates published in the literature.The treatment of infections in vascular surgery needs to be complex and adapted to each individual patient, because infections being in a permanent dynamic state. The treatment needs to be performed in specialized centers that have large experience in vascular surgery, in order for the patient to have the best chances of survival and protection from amputation.

Early Transposition of the Sartorius Muscle for Exposed Patent Infrainguinal Bypass Grafts

The traditional approach for patent and exposed and infected infrainguinal bypass grafts in the groin has included wide operative debridement and secondary or delayed primary closure. However, this has been associated with significant risk of further contamination and length of stay. The authors reviewed their experience using the wide debridement, sartorius muscle flap transposition, and primary wound closure as an alternative. During the past 5 years, they have had 50 patients with major wound necrosis or infection in the groin or thigh with the graft or native artery being exposed after debridement. This group included 28 men; 74% of the patients had hypertension, 58% had diabetes, and 20% had renal failure. The grafts were split evenly between native vein and prosthetic material. After wide debridement, closure was performed by the vascular surgeon using the sartorius muscle flap. Postoperatively, there was an 8% major amputation rate and a 12% mortality rate in the first 30 days. One patient developed a pseudoaneurysm 5 weeks after placement of the flap. This patient underwent removal of the infected polytetrafluoroethylene graft with ligation of the common femoral artery. None of the procedures have resulted in further systemic or graft sepsis. None have resulted in arterial or graft blowout. Follow-up was for an average of 18 months. Closure of groin and thigh wounds with exposed bypass graft or native artery can be safely performed with the sartorius muscle flap with excellent results. The length of stay of these patients compared to historical controls is acceptable. Furthermore, the chance of infection of the native artery or bypass may be reduced. Familiarity with this simple technique can be a valuable tool for the vascular surgeon.

Salvage of Exposed Groin Vascular Grafts with Early Intervention Using Local Muscle Flaps

Background:

Peripheral vascular surgery may be complicated by wound infection and potential graft exposure in the groin area. Muscle flap coverage of the graft has been promoted to address these wound complications. The authors present their findings regarding graft salvage rates and patient outcomes using local muscle flaps to address vascular graft complications of the groin.

Methods:

Data were obtained by retrospective cohort study of patients who underwent a local muscle flap procedure by a single surgeon following vascular graft complication in the groin.

Results:

Seventeen patients undergoing local muscle flap coverage of a vascular graft were reviewed. Six men and 9 women, 51–80 years old, were included in the study. Wound complications in the groin occurred anywhere from 3 days to 3.5 years following graft placement. Graft exposure was the most common presenting complication (14 of 17 patients). Muscle flap coverage occurred within 15 days of complication presentation in all patients (average, 6.4 days). Seven of the 15 patients experienced postoperative complications within 6 months of the procedure, most commonly wound dehiscence. However, analysis demonstrated that vascular grafts were successfully salvaged in 10 of the 17 patients (59%) over the course of follow-up (range, 104–1748 days). Average time to muscle flap coverage was 4.2 days in patients who retained the graft and 9.6 days in patients who ultimately lost their vascular graft.

Conclusion:

The authors demonstrate improved vascular graft salvage rate when local muscle flap procedure is performed early after initial wound complication presentation.

Surgical and antimicrobial treatment of prosthetic vascular graft infections at different surgical sites: a retrospective study of treatment outcomes

Objective

Little is known about optimal management of prosthetic vascular graft infections, which are a rare but serious complication associated with graft implants. The goal of this study was to compare and characterize these infections with respect to the location of the graft and to identify factors associated with outcome.

Methods

This was a retrospective study over more than a decade at a tertiary care university hospital that has an established multidisciplinary approach to treating graft infections. Cases of possible prosthetic vascular graft infection were identified from the hospital's infectious diseases database and evaluated against strict diagnostic criteria. Patients were divided into groups according to the locations of their grafts: thoracic-aortic, abdominal-aortic, or peripheral-arterial. Statistical analyses included evaluation of patient and infection characteristics, time to treatment failure, and factors associated specifically with cure rates in aortic graft infections. The primary endpoint was cure at one year after diagnosis of the infection.

Results

Characterization of graft infections according to the graft location did show that these infections differ in terms of their characteristics and that the prognosis for treatment seems to be influenced by the location of the infection. Cure rate and all-cause mortality at one year were 87.5% and 12.5% in 24 patients with thoracic-aortic graft infections, 37.0% and 55.6% in 27 patients with abdominal-aortic graft infections, and 70.0% and 30.0% in 10 patients with peripheral-arterial graft infections. In uni- and multivariate analysis, the type of surgical intervention used in managing infections (graft retention versus graft replacement) did not affect primary outcome, whereas a rifampicin-based antimicrobial regimen was associated with a higher cure rate.

Conclusions

We recommend that future prospective studies differentiate prosthetic vascular graft infections according to the location of the grafts and that rifampicin-based antimicrobial regimens be evaluated in clinical trials involving vascular graft infections caused by staphylococci.

Factors predictive of treatment failure in staphylococcal prosthetic vascular graft infections: a prospective observational cohort study: impact of rifampin

BACKGROUND

There exists considerable debate concerning management of prosthetic vascular graft infection (PVGI), especially in terms of antimicrobial treatment. This report studies factors associated with treatment failure in a cohort of patients with staphylococcal PVGI, along with the impact of rifampin (RIF).

METHODS

All data on patients with PVGI between 2006 and 2010 were reviewed. Cure was defined as the absence of evidence of infection during the entire post-treatment follow-up for a minimum of one year. Failure was defined as any other outcome.

RESULTS

84 patients (72 M/12 F, median age 64.5 ± 11 y) with diabetes mellitus (n = 25), obesity (n = 48), coronary artery disease (n = 48), renal failure (n = 24) or COPD (n = 22) were treated for PVGI (median follow-up was 470 ± 469 d). PVGI was primarily intracavitary (n = 47). Staphylococcus aureus (n = 65; including 17 methicillin-resistant S. aureus) and coagulase-negative Staphylocococcus (n = 22) were identified. Surgical treatment was performed in 71 patients. In univariate analysis, significant risk factors associated with failure were renal failure (p = 0.04), aortic aneurysm (p = 0.03), fever (p = 0.009), aneurysm disruption (p = 0.02), septic shock in the peri-operative period (p = 0.005) and antibiotic treatment containing RIF (p = 0.03). In multivariate analysis, 2 variables were independently associated with failure:septic shock [OR 4.98: CI 95% 1.45-16.99; p=0.01] and antibiotic containing rifampin [OR: 0.32: CI95% 0.10-0.96; p=0.04].

CONCLUSION

Results of the present study suggest that fever, septic shock and non-use of antibiotic treatment containing RIF are associated with poor outcome.

Magnetic Drug Targeting as New Therapeutic Option for the Treatment of Biomaterial Infections

Implant-associated infections are a challenging problem in surgery. Bacteria in biofilms are difficult to treat as they are less susceptible to antibiotics or antiseptics which require high drug concentrations at the site of infection. We present a novel strategy to concentrate high antibiotic doses systemically at the target site using newly developed antibiotic-functionalized nanoparticles directed by a magnetic drug-targeting system. The important and effective antibiotic gentamicin served as antimicrobial substance and was ionically or covalently attached to magnetic nanoparticles. Subsequently, the particles were characterized thoroughly. Anti-infective properties with regard to Staphylococcus aureus and the degree of cytotoxicity concerning human umbilical vein endothelial cells were determined. The enrichment of the magnetic nanoparticles at the surface of model tubes in circulatory experiments was investigated. We describe a promising technique for the loading of magnetic nanoparticles to treat systemic infections. Gentamicin-coated magnetic nanoparticles reduced bacterial growth even beyond pathologically relevant concentrations within 24 h. Excellent concentration independent biocompatibility was found for the nanoparticles themselves and we demonstrate that the magnetic nanoparticles can be navigated and concentrated on surfaces of model implants using a permanent magnetic field.

Successful Surgical Treatment of Methicillin-Resistant Staphylococcus Aureus (MRSA) Vascular Graft Infection

A 54-year-old man was referred to our hospital because of a false aneurysm in his right groin following Aortobifemoral and femoropopliteal bypass surgery. He underwent false aneurysm repair and infrainguinal arterial reconstruction. He then developed MRSA sepsis in the right groin. The patient underwent a number of operations to remove the infected grafts and distal revascularization to allow limb salvage. His last operation was an iliofemoral bypass via extra-anatomical route, from just below the iliac crest into the popliteal artery using an 8 mm-ringed polyester gelatin polypropylene tube graft, with complete debridement of a groin infection. Postoperative duplex scan and 3-dimentional CT angiography revealed a patent prosthetic graft and the patient made uneventful postoperative recovery. We conclude that this extra-anatomical bypass is a safe technique and a good option for patients with an infected vascular prosthetic graft in the groin after previous revascularization.

Should vascular surgery patients be screened preoperatively for methicillin-resistant Staphylococcus aureus?

BACKGROUND

Methicillin-resistant Staphylococcus aureus (MRSA) can cause severe infection in patients who are undergoing vascular surgical operations. Testing all vascular surgery patients preoperatively for MRSA and attempting to decolonize those who have positive results may be a strategy to prevent MRSA infection. The economic value of such a strategy has not yet been determined.

METHODS

We developed a decision-analytic computer simulation model to determine the economic value of using such a strategy before all vascular surgical procedures from the societal and third-party payer perspectives at different MRSA prevalence and decolonization success rates.

RESULTS

The model showed preoperative MRSA testing to be cost-effective (incremental cost-effectiveness ratio, <$50,000 per quality-adjusted life year) when the MRSA prevalence is > or = 0.01 and the decolonization success rate is > or = 0.25. In fact, this strategy was dominant (ie, less costly and more effective) at the following thresholds: MRSA prevalence > or = 0.01 and decolonization success rate > or = 0.5, and MRSA prevalence > or = 0.025 and decolonization success rate > or = 0.25.

CONCLUSION

Testing and decolonizing patients for MRSA before vascular surgery may be a cost-effective strategy over a wide range of MRSA prevalence and decolonization success rates.

Evolving Microbiology and Treatment of Extracavitary Prosthetic Graft Infections

The authors report the microbiology and outcomes following an individualized treatment algorithm for extracavitary (EC) prosthetic graft infection, including the use of graft preservation and in situ graft replacement techniques. A retrospective 8-year review of 87 patients treated for EC prosthetic graft infections was carried out. The treatment algorithm included culture-specific antibiotic therapy, surgical site debridement with antibiotic bead placement, selected graft preservation with muscle flap coverage, or graft excision with in situ conduit replacement. Outcomes measured included death, limb loss, and recurrent infection. It was found that present-day management of EC prosthetic graft infections is associated with lower mortality and morbidity despite changes in microbiology and the increased application of graft preservation and in situ grafting treatments.

Managing extracavitary prosthetic vascular graft infections: a pathway to success

Prosthetic vascular graft infections portend grave consequences if not treated expediently. Despite the low incidence of infection, the potential for limb loss or death greatly magnifies this complication. The surgical management of prosthetic graft infections has evolved over the last 2 decades. With the myriad therapeutic options now available, an algorithm is necessary to provide the optimal surgical treatment of Samson groups 1 through 5 extracavitary infected vascular prostheses. An extensive review of the literature was undertaken to evaluate the most effective management schemes. The authors found that 3 factors--Samson classification, bacteriology, and patient vascular anatomy--are vital to the surgical strategy. These 3 criteria were examined, and an algorithm was developed based on successful clinical and experimental results. This review provides a step-by-step rationale for the surgical management of extracavitary prosthetic graft infections according to the most successful reported outcomes.

Does the timing of reoperation influence the risk of graft infection?

OBJECTIVE

This study compared the incidence and characteristics of graft infection in patients who underwent early vs late revisional surgery of lower extremity arterial bypass grafts.

METHODS

Between 1992 and July 2005, 500 revisional procedures were performed on 198 lower extremity bypass grafts. Patients whose revisions were performed <30 days after the primary bypass were in the early revision (ER) group (n = 99), and those done >30 days after bypass were in the late revision (LR) group (n = 99). Infection was defined as cellulitis with graft exposure or purulence in continuity with a graft that required antibiotics and operation for infection control. Mean follow-up was 60 months (range, 2 to 60 months). Groups were compared using Student's t test.

RESULTS

The ER group included 66 autogenous and 33 prosthetic grafts. The LR group consisted of 53 autogenous and 46 prosthetic grafts. Of the 500 revisional procedures performed, 17 graft infections occurred (3.4%). Twelve (70.6%) were prosthetic grafts and five (29.4%) were autogenous grafts (P = .004). Defining the infection rate per graft rather than per revisional procedure, the ER group had a significantly higher graft infection rate at 11% (11/99) compared with 6.1% in the LR group (6/99; P = .012). The risk of infection for prosthetic grafts was significantly higher within the ER group at 27.3% (9/33) compared with autogenous grafts at 3.1% (2/66; P = .0001). Infection developed in three vein grafts and three prosthetic grafts in the LR group (P = NS). For prosthetic graft revisions only, infection risk was 27.3% (9/33) in the ER group and 6.5% (3/46) in the LR group (P = .005). The most common cultured pathogen was methicillin resistant Staphylococcus aureus (ER, 6/11 vs LR, 3/6; P = NS). Within the ER group, the prevalence of Pseudomonas aeruginosa was significantly higher at 27.3% (3/11) compared with 0% (0/6) in the LR group (P = .04).

CONCLUSIONS

Early revision of lower extremity arterial bypass grafts has a significantly higher risk of graft infection compared with revision >1 month after surgery. Infection will develop in approximately 25% (9/33) of prosthetic grafts that are reoperated on early. If feasible, reoperation should be delayed >1 month for prosthetic grafts needing revision. Endovascular or extra-anatomic interventions should be considered if early revision is mandated in this group.

An Audit Demonstrating a Reduction in MRSA Infection in a Specialised Vascular Unit Resulting from a Change in Infection Control Protocol

INTRODUCTION

In 2003, 18% of all admissions to our vascular ward were colonised by MRSA, with an MRSA infection rate of 10.6%. Standard practice was to segregate patients with proven MRSA from the rest of the patient pool. After a prospective audit, regression analysis was used to identify factors that could stratify patients into high and low risk for MRSA colonisation. A change in isolation policy was introduced that segregated patients according to their risk of MRSA acquisition, and isolated all patients undergoing prosthetic vascular reconstruction. Antibiotic policy was also altered. This audit reports the impact of these changes on MRSA colonisation and infection rates.

METHODS

The MRSA status of patients during 777 in-patient episodes was prospectively recorded during three time spans; period 1 (November 2002-April 2003) before the change in isolation and antibiotic policy and, periods 2 (August-December 2003) and 3 (October 2004-January 2005) after the change in policy.

RESULTS

Hospital acquired MRSA colonisation was reduced from 10.6% in period 1, to 1.1 and 1.4% in periods 2 and 3, respectively (p<0.001). Similarly, MRSA infection rates fell from 10.6 to 2.9 and 0.9% over the same time frame (p<0.001). The most dramatic changes in MRSA infection rates occurred in patients undergoing aneurysm repair (MRSA infection 30.1% in period 1 vs. 3.9 and 2.9% in periods 2 and 3) and lower limb revascularization (31 vs. 0 vs. 4.2%). Stepwise regression analysis revealed that the system of isolation was a significant factor reducing MRSA infection and colonisation rates (p<0.001).

CONCLUSIONS

These data demonstrate that a change in infection control policy can significantly reduce MRSA infection in a vascular unit.

Infra-inguinal revascularization surgical site infections: Australasian benchmark

BACKGROUND

Infra-inguinal revascularization surgery remains one of the most commonly performed major vascular procedures in contemporary practice. Surgical site infections (SSI) are a common cause of morbidity in this patient cohort and generate high rates of limb loss and mortality when vascular graft involvement occurs. An overall reduction in North American SSI has been attributed to the establishment of national benchmarks. A comparable Australasian benchmark does not exist. The purpose of the present study was to assess the methods used by Australasian vascular units to determine SSI rates and to instigate the development of an acceptable benchmark.

METHODS

A structured questionnaire pertaining to SSI after infra-inguinal revascularization surgery was sent to 26 Australasian vascular units. Data requested included the number and type of lower extremity revascularization procedures performed. Units were also asked to report the methods employed for defining and detecting wound infections and to document their SSI rate. The incidence of SSI causation by methicillin-resistant Staphylococcus aureus (MRSA) was also sought.

RESULTS

The total number of revascularizations performed annually varied from 28 to 179 between units. The SSI rates ranged from 0 to 38%. The incidence of MRSA involvement varied from <1% to 56%. The SSI surveillance methodology varied considerably between units.

CONCLUSIONS

The present study confirms the significant incidence of SSI after infra-inguinal revascularization surgery in contemporary vascular practice. Standardized definitions and surveillance protocols are required to facilitate inter- and intrahospital comparisons. A possible benchmark infection rate may be 10-20%.

Methicillin-Resistant Staphylococcus aureus Infections in Vascular Surgery: Increasing Prevalence

BACKGROUND

Methicillin-resistant Staphylococcus aureus (MRSA) is a virulent organism that causes substantial infection-related morbidity and mortality in hospitalized patients. For example, MRSA infection of prosthetic vascular grafts can be limb- and life-threatening in surgical patients. We investigated the incidence of MRSA infection in vascular surgical patients who developed postoperative infectious complications.

METHODS

Prospective data (including procedure, nature of complication, and outcome) were collected on all vascular surgery patients (n = 772) over a two-year period from January, 2000, to December, 2001. The study cohort included all patients who developed postoperative complications (n = 119, 15.4%), including infection, unplanned or prolonged intubation, metabolic abnormalities, and myocardial ischemia. Bacteriologic data of all clinical cultures were reviewed and infection-related outcomes were examined.

RESULTS

Hospital-acquired infection occurred in 79 (66.4%) of 119 patients who developed postoperative complications. Review of microbiology data (total, 197 bacterial isolates) confirmed that gram-positive organisms were the leading cause of infections, with 120 gram-positive isolates (60.9%). Of the gram-positive isolates, S. aureus was the most common pathogen, isolated in 73 (60.8%) cultures. The single most prevalent organism was MRSA, identified in 42 of 73 (57.5%) of cultures. The site of MRSA infection was confirmed to be the surgical site (54.8%), sputum (17.0%), blood (14.3%), urine (9.5%), peritoneal fluid (2.4%), or catheter insertion site (2.4%). Only four patients had prior MRSA infection or colonization. Prosthetic vascular grafts were placed in 51 (42.9%) of the 119 vascular patients, and 26 patients (51.6%) acquired MRSA infection. Graft removal was required in three patients due to infection (MRSA infection in two patients, Pseudomonas aeruginosa in one patient). Forty percent of patients with MRSA infection required an amputation as their surgical procedure. No patient died of MRSA bacteremia during the study period. Mean hospital length of stay (LOS) was longer in patients with MRSA infection (29.6 d vs. 22.7 days, range 2-174 days, p < 0.05) compared to the total study cohort of vascular patients with postoperative infections.

CONCLUSIONS

Methicillin-resistant S. aureus has emerged as the leading cause of postoperative infection in vascular surgery patients, and is associated with substantial morbidity, increased hospital LOS, and higher incidences of amputation and graft removal. Greater emphasis on preoperative screening protocols for MRSA colonization is warranted, in conjunction with aggressive infection control measures, alteration of preoperative prophylactic antimicrobial use in MRSA-colonized patients, and meticulous postoperative surveillance for MRSA infection. Furthermore, antimicrobial treatment of postoperative infectious complications in vascular surgery patients should include empiric coverage for MRSA in institutions where MRSA is endemic.

Vascularised muscular flaps and arterial graft infection in the groin

The groin is the commonest site for graft infections in vascular surgery. This is a potentially catastrophic situation as limb loss or even death occurs in a large percentage of cases. Standard teaching for treatment of infected vascular grafts is removal and extra anatomical bypass grafting whilst commencing appropriate antibiotics. This review article suggests careful scrutiny of the wound, debridement and coverage of the graft with a vascularised muscular flap is appropriate in certain situations.

Control and the prevention of methicillin-resistant Staphylococcus aureus in hospitals in Ireland: North/South Study of MRSA in Ireland 1999

As part of an all-island survey of methicillin-resistant Staphylococcus aureus (MRSA) in the Republic of Ireland (the South), where there is a mixed public and private healthcare system, and Northern Ireland (the North), where the healthcare system is part of the UK National Health Service, a questionnaire was circulated to all participating hospitals on measures routinely taken to control MRSA. Response rates were 100% in the North and 89% in the South. Over 70% of hospitals screened particular groups of patients on admission to hospital. Ninety-five percent of hospitals in the North and 88% in the South attempted to eradicate MRSA from carriage sites. Most hospitals attempted to isolate or cohort positive patients. About a quarter of hospitals in both parts of Ireland screened new healthcare workers for the presence of MRSA. Terminal decontamination of the environment after the discharge of a patient positive for MRSA was the norm in over 90% of hospitals, however, 6% of hospitals in the South used inappropriate disinfectants for MRSA. All hospitals in the North, but a minority (41%) in the South, had written antibiotic prescribing policies, but only 65% of hospitals in the South had access to an infection control committee, acute hospitals having greater access than district hospitals. The prevention and control of spread of MRSA remains a major challenge in the North and in the South. Although most hospitals in the North and in the South implemented current recommended guidelines on the control of MRSA in hospitals, there was some variability that may be resource related. Policies need to be reviewed in the light of the changing epidemiology of MRSA.

The acquisition of methicillin-resistant Staphylococcus aureus (MRSA) in vascular patients

OBJECTIVE

the aim of this study was to establish at which point during a hospital admission MRSA acquisition occurs in vascular patients.

METHOD

a consecutive series of 100 patients undergoing arterial surgery were screened for MRSA carriage on admission to hospital, on exit from theatre, on discharge from ITU, weekly whilst an inpatient and on hospital discharge. Screening was with moistened swabs from nose, throat, perineum and open wounds that were pooled for microbiological culture.

RESULTS

four patients (4%) screened positive for MRSA on admission to hospital. Of the remaining 96, 16 (17%) acquired MRSA during their hospital stay as follows: exit from theatre, one; exit from ITU, six; on the ward postoperatively, nine. Comparing MRSA acquisition (n=16) with non acquisition (n = 80) the following characteristics were noted, length of stay 16 (4-66) vs 7 (2-50) days (Mann-Whitney p < 0.001); admission to ITU 13/16 vs 46/80 (Fishers chi-squared p = 0.10); length of ITU stay 3 (1-20) vs 3 (1-14) days (Mann-Whitney p = 0.41). Frequent hospital attendance, age, emergency admission, diabetes or renal failure were not commoner in those with MRSA acquisition.

CONCLUSIONS

these data indicate that 4% of patients undergoing arterial surgery are pre-existing carriers of MRSA. Length of hospital stay is the single most important determinant of MRSA acquisition.

Methicillin-resistant Staphylococcus aureus: vascular surgeons should fight back

Methicillin-resistant Staphylococcus aureus (MRSA) is now the commonest cause of serious vascular wound and graft infection in the U.K., and vascular departments in many other countries are similarly affected. There are no randomised trials that provide information about how to deal with this epidemic. There are, however, a number of clinical series that provide data that can be used to mount a logical and coherent response to the problem of preventing and managing MRSA infection. The risks and problems are different in every hospital and co-operation with local microbiologists is essential in creating individual protocols. Stratifying the risk to each patient is the first step; established antiseptic and surgical procedures are usually adequate as primary prevention. Studies into the role of targeted antibiotic therapy and isolation techniques are needed.

The impact of MRSA on vascular surgery

OBJECTIVES

To investigate the prevalence of MRSA infection in patients treated in a major vascular unit and examine its consequences.

DESIGN AND METHODS

A retrospective case-note review was performed.

RESULTS

During the period 1993 to 2000, a total of 172 patients (4.4% of total) were positive for MRSA. Of these 97 were colonised and 75 were infected by MRSA. The proportion of wound or graft infections caused by MRSA has increased (4% in 1994 to 63% in 2000). Three patients developed native artery infection (one following aortic stent insertion and 2 following embolectomy). All patients with aortic graft infection died. All patients with infected prosthetic infrainguinal bypass ended up with an amputation.

CONCLUSION

The prevalence of MRSA infection is increasing. Infection of aortic grafts appears to be uniformly fatal and lower limb graft infection is associated with high limb loss.

A Prospective Audit of Complex Wound and Graft Infections in Great Britain and Ireland: the Emergence of MRSA

BACKGROUND

a number of studies have examined the outcome of complex wound and graft infections, but most include small numbers of patients collected over a prolonged period of time. To date, there is little information on the clinical outcome of infections involving methicillin-resistant Staphylococcus aureus (MRSA).

METHODS

between February 1998 and January 1999, two prospective multi-centre audits were performed in order to examine the current outcomes following (1) complex vascular wound infections and (2) graft infections in Britain and Ireland with particular reference to outcome associated with MRSA infection.

RESULTS

seventy-five complex wound infections (Szylagyi II and III) were reported, with the commonest single organism being MRSA. Type II infections were associated with a 5% risk of death and/or amputation as opposed to 75% in those with a type III infection. Fifty-five graft infections were reported, with the commonest single organism being MRSA. Overall, 30 (55%) died or underwent amputation. MRSA wound and graft infections were associated with a significantly higher risk of amputation and prolonged hospital stay (but not of death) as compared with MRSA negative patients.

CONCLUSIONS

in this audit, MRSA was the commonest single organism cultured in patients with complex wound and graft infections after vascular surgery. This represents a major change in the spectrum of causative organisms relative to other, older published series. MRSA infections contribute towards an increased risk of adverse outcome and prolonged hospital stay.