Use of rifampin-soaked gelatin-sealed polyester grafts for in situ treatment of primary aortic and vascular prosthetic infections

BACKGROUND: In situ treatment of artery/graft infection has distinct advantages compared to vessel excision and extra-anatomic bypass procedures. Based on animal studies of a rifampin-soaked, gelatin-impregnated polyester graft that demonstrated prolonged in vivo antibacterial activity, this antibiotic-bonded graft was used selectively in patients for in situ treatment of low-grade Gram-positive prosthetic graft infections or primary aortic infections not amenable to excision and ex situ bypass. METHODS: In a 5-year period (1995-1999), 27 patients with prosthetic graft infection (aortofemoral, n = 18, femorofemoral, n = 3; axillofemoral, n = 1) or primary aortic infection (mycotic aneurysm, n = 3; infected AAA, n = 2) underwent excision of the infected vessel and in situ replacement with a rifampin soaked (45-60 mg/ml for 15 min) gelatin-impregnated polyester graft. All prosthetic graft infections were low grade in nature, caused Gram-positive bacteria (Staphylococcus epidermidis, 16; Staphylococcus aureus, 5; Streptococcus, 1), and were treated electively. Patients with mycotic aortic aneurysm presented with sepsis and underwent urgent or emergent surgery. RESULTS: Two (8%) patients died-1 as a result of a ruptured Salmonella mycotic aortic aneurysm and the other from methicillin-resistant S. aureus infection following deep vein replacement of an in situ replaced femorofemoral graft. No amputations or late deaths as the result of vascular infection occurred in the 25 surviving patients. Two patients developed recurrent infection caused by a rifampin-resistant S. epidermidis in a replaced aortofemoral graft limb and were successfully treated with graft excision and in situ autogenous vein replacement. Eighteen patients remain alive and clinically free of infection after a mean follow-up interval of 17 months. CONCLUSIONS: In situ replacement treatment using a rifampin-bonded prosthetic graft for low-grade staphylococcal arterial infection was safe, durable, and associated with eradication of clinical signs of infection. Failure of this therapy was the result of virulent and antibiotic-resistant bacterial strains.     

Antibiotic therapy of aortic graft infection: treatment and prevention recommendations

Surgical site infection (SSI) after aortic intervention, an uncommon but serious vascular condition, requires patient-specific antibiotic therapy. Effective treatment and prevention requires the vascular surgeon to be cognizant of changing SSI microbiology, advances in antibiotic delivery, and patient characteristics. The majority of aortic graft infections are caused by Gram-positive bacteria, with methicillin-resistant Staphylococcus aureus now the prevalent pathogen. Nasal carriage of methicillin-sensitive or methicillin-resistant S aureus strains, diabetes mellitus, recent hospitalization, a failed arterial reconstruction, and the presence of a groin incision are important SSI risk factors. Overall, the aortic SSI rate is higher than predicted by the Centers for Disease Control and Prevention's National Nosocomial Infections Surveillance risk category system; ranging from 5% after open or endovascular aortic interventions to as high as 10% to 15% after aortofemoral bypass or uni-aortoiliac grafting with femorofemoral bypass. Perioperative measures to reduce S aureus nares and skin colonization, administration of antibiotic prophylaxis, meticulous wound closure/care, and therapy directed to optimize patient host defense regulation mechanisms (eg, temperature, oxygenation, blood sugar) can minimize SSI occurrence. Antibiotic therapy for aortic graft infection should utilize bactericidal drugs that penetrate bacteria biofilms and can be delivered to the surgical site both parenterally and locally in the form of antibiotic-impregnated beads or prosthetic grafts.     

Antibiotics-why so many and when should we use them?

Antibiotic prophylaxis in vascular surgery has been proven beneficial to reduce surgical site infections after reconstruction of the aorta, procedures on the leg that involve a groin incision, any procedure that implants a vascular prosthesis or endoluminal stent, and lower extremity amputation for ischemia. Bactericidal antibiotics administered before induction-cefazolin or cefuroxime for 1 to 2 days alone or in combination with vancomycin if a hospital wound surveillance program indicates a high incidence of methicillin-resistant Staphylococcus aureus infection-is recommended. If a patient is felt to be at increased risk for infection and require prosthetic grafting, the use of a rifampin-soaked (1 mg/mL) gelatin- or collagen-impregnated graft may decrease the incidence of wound and graft infection. Antibiotic treatment of established vascular graft infections should begin with broad-spectrum coverage for expected pathogens (S aureus, Staphylococcus epidermidis, Gram-negative bacteria) followed by culture-specific therapy based on antibiotic susceptibility testing. Specific antibiotic usage involves a decision regarding efficacy to expected or isolated pathogens versus its potential side effects and the drug costs. New applications for antibiotics in vascular surgery include the use of specific tetracyclines (doxycycline, azithromycin) as an inhibitor of matrix metalloproteinases to retard aortic aneurysm growth or for their antiinflammatory properties to retard atherogenesis related to Chylamydia pneumoniae.     

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.     

Gradual Hunterian ligation for infected prosthetic bypass.

OBJECTIVE: To review gradual snare occlusion for the management of complex or recurrent graft infection. PATIENTS AND METHODS: Medical records of patients treated with gradual snare occlusion following graft infection were reviewed for indication for operation, type of bypass and graft material used. In addition, infecting organism, grade of infection (Szilágyi) and outcome were recorded. RESULTS: Four femoropopliteal, two extra-anatomic (axillofemoral) and aortobifemoral bypasses were included in this study. All had chronic infection (Szilágyi grade III) with onset of 4 to 24 months and two of which were recurrent. The causative organisms were coagulase-negative staphylococci, Staphylococcus epidermidis and methicillin-resistant Staphylococcus aureus in three patients, with no organism isolated in the remaining cases. There was no loss of limb following gradual snare occlusion but there was only one death due to aortic stump rupture 2 weeks later. CONCLUSION: Gradual snare occlusion is an alternative for the management of chronic or recurrent graft infection.     

Successful treatment of MRSA mediastinitis after aortic arch replacement.

An aortic arch graft replacement was successfully performed for a true aneurysm on the distal aortic arch. However, Methicillin-resistant Staphylococcus aureus (MRSA) mediastinitis occurred after surgery. Following reoperation for debridement and irrigation of the mediastinal space, antibiotics were administered and continuous irrigation of mediastinal space with saline containing appropriate antibiotics and intermittently short duration irrigation with a large quantity of saline containing popidone-iodine were carried out with good results. This paper presents the successful treatment of mediastinitis after replacement of the aortic arch without removing the graft, followed by a brief review of the literature regarding infection of prostetic grafts for the thoracic aorta.     

Microbial pathogenesis of bacterial biofilms: a causative factor of vascular surgical site infection

Vascular surgical site infection (SSI) is caused by pathogenic bacterial strains whose preferred mode of growth is within a surface biofilm. Bacterial biofilm formation can develop within hours to days in a wound and produces a recalcitrant infectious process especially in the presence of a prosthetic graft. The initial steps of biofilm formation are bacterial adhesion to biologic or inert surgical site structures followed by organism production of exopolysaccaride matrix which encases developing bacteria colonies to produce a protective microenvironment. As the biofilm matures, a dynamic process of organism cell-to-cell signaling occurs with varying growth modes of sessile bacteria within the biofilm and the release of planktonic bacteria with the potential to spread and expand the biofilm-mediated infection. The prevalence of staphyloccocal strains causing vascular SSI is best understood when viewed as a biofilm-mediated infection with virulence factors related to specific cell surface adhesion proteins and bacteria-derived matrix production. Nonhealing surgical sites following lower limb revascularization, the late appearance of prosthetic graft infection caused by Staphylococcus epidermidis, and the development of groin site tracts after aortofemoral bypass grafting are clinical examples of a biofilm-mediated SSI. A mature biofilm within a wound or coating a prosthetic device exhibits resistance to host defenses and selected antibiotics, impairs wound healing, and is a perpetual irritant to that host by inciting a chronic inflammatory process. By understanding the microbial pathogenesis of biofilm formation, strategies to treat and prevent biofilm-mediated infection can be developed and utilized to reduce vascular SSIs.     

Methicillin-resistant Staphylococcus aureus infection in a cardiac surgical unit.

BACKGROUND: Increased antibiotic resistance of common bacteria is attributed in part to the widespread use of various antibiotic agents. Prophylactic and therapeutic antibiotic treatments are routinely used in cardiac surgical units, and it is no surprise that methicillin-resistant Staphylococcus aureus infection is becoming a major cause of surgical infections in cardiac patients. METHODS: We reviewed our experience with patients who underwent cardiac surgery and experienced infection caused by methicillin-resistant Staphylococcus aureus. Between 1992 and 2000 at the Montreal Heart Institute, 39 patients had methicillin-resistant Staphylococcus aureus surgical infections, and 13,199 patients underwent cardiac surgery. The yearly incidence of methicillin-resistant Staphylococcus aureus infection, the relative risk of acute mediastinitis and of superficial wound infections or other types of methicillin-resistant Staphylococcus aureus infection episodes, and the effect of preventive measures were analyzed. RESULTS: The annual incidence of methicillin-resistant Staphylococcus aureus acute mediastinitis decreased from 0.37% (5/1321) of cardiac patients in 1992 and 0.44% (6/1355) in 1993 to 0% between 1994 and 1997, 0.13% (2/1528) in 1999, and 0% (0/1700) in 2000. The total incidence of methicillin-resistant Staphylococcus aureus infection, including mediastinitis, superficial and deep sternal and leg wound infection, and all systemic infection episodes ranged from 0.68% of patients in 1992 and 0.96% of patients in 1993 to 0.46% of patients in 1999 and 0.53% of patients in 2000. The relative risk of severe mediastinal methicillin-resistant Staphylococcus aureus infection to all other methicillin-resistant Staphylococcus aureus infection episodes decreased from 1.65 in 1992 to 0.41 in 1999 and 0 in 2000. Beginning in 1993, all patients given a diagnosis methicillin-resistant Staphylococcus aureus infection and all nasal carriers of methicillin-resistant Staphylococcus aureus were strictly isolated on the surgical unit, and vancomycin was used as the prophylactic antibiotic agent for cardiac surgery in these patients. Moreover, since 1998, all patients admitted in the hospital were screened, and nasal carriers were isolated and treated with topical antibiotic ointment. CONCLUSION: Mediastinal and other infections caused by methicillin-resistant Staphylococcus aureus have a significant morbidity in cardiac surgical patients. After an outbreak of methicillin-resistant Staphylococcus aureus mediastinal infections, several preventive measures to control methicillin-resistant Staphylococcus aureus contamination of surgical patients were implemented (nasal screening, preventive isolation, application of mupirocin, prophylaxis with vancomycin and alcohol gels) and were effective in decreasing the incidence of methicillin-resistant Staphylococcus aureus infection and mediastinitis after cardiac surgery.     

Vulnerability of an equine pericardial roll graft to Gram-positive cocci after graft replacement for a ruptured infected abdominal aorta

We describe the influence of methicillin-resistant Staphylococcus aureus (MRSA) bacteremia on histopathological alteration of a glutaraldehyde-fixed equine pericardial roll (EPR) graft in a 77-year-old male who underwent in-situ EPR replacement of a ruptured infected abdominal aorta with concomitant repair of the perforated duodenum. The patient died of circulatory failure after septic shock due to MRSA infection and gastrointestinal bleeding on postoperative day (POD) 23. The autopsy revealed no perforation of the EPR graft or anastomotic disruption between the native abdominal aorta and EPR graft. Histological examination revealed that the inner layer of the EPR graft was colonized and damaged by Gram-positive cocci (MRSA suspected). We therefore suggest that the infection-resistant property of EPR grafts may be uncertain in patients with postoperative sustained MRSA bacteremia when these grafts are used for arterial reconstruction.     

Postoperative mediastinitis following hemiarch replacement

Although various strategies have been advocated for mediastinitis following cardiac operations, surgical results for this complication remain a significant concern. The condition would be more complicated with replacement of the ascending aorta using a prosthetic graft. We present the case of a 50-year-old female patient with acute aortic dissection who underwent hemiarch replacement using a prosthetic graft and concomitant coronary artery bypass grafting, and developed periprosthetic purulent collection 2 months later. Successful treatment involved debridement of infected tissues and omental flap transposition. Postoperative chest computed tomography revealed no sign of perigraft infection. Omental flap transposition can be effective for treating mediastinitis following prosthetic graft replacement of the ascending aorta. The patient has remained in good health for 1 year, with no signs of recurrent graft infection or pseudoaneurysm formation.     

Limitations in the use of rifampicin-gelatin grafts against virulent organisms

OBJECTIVE: Efficacy and duration of antibacterial activity of rifampicin-gelatin grafts against virulent organisms were evaluated in an animal model.Materials And Methods: Rifampicin-gelatin grafts were prepared with impregnation of Gelseal (Vascutek Ltd, Scotland) graft in 1 mg/mL rifampicin solution. Rifampicin-gelatin grafts (6 cm long; n = 24) and plain Gelseal grafts as controls (n = 4) were implanted into the canine abdominal aorta with inoculation of Staphylococcus epidermidis, Escherichia coli, or methicillin-resistant Staphylococcus aureus (MRSA), and the rifampicin-gelatin grafts were retrieved after 1 to 4 weeks. Disks cut from the retrieved rifampicin-gelatin grafts were placed on agar plates streaked with one of the organisms, and the graft antibacterial activity was assessed with the width of the inhibition zone. RESULTS: In in vitro tests, initial inhibition zones (inhibition zone of 24 hours after incubation) of rifampicin-gelatin grafts against S epidermidis, MRSA, and E coli were 40.0 +/- 0.3 mm, 36.0 +/- 0.2 mm, and 11.8 +/- 0.1 mm, respectively. In the implantation, S epidermidis -inoculated rifampicin-gelatin grafts had no findings of graft infection, and no colony growth was recognized on the plates streaked with the perigraft fluids. Initial inhibition zones of S epidermidis -inoculated rifampicin-gelatin grafts retrieved at 1 or 2 weeks were 20.1 +/- 1.1 mm and 7.6 +/- 1.0 mm, respectively. In E coli -inoculated and MRSA-inoculated rifampicin-gelatin grafts, all of the eight animals had perigraft abscess, and blood culture test results probed septicemia in five animals with patent grafts at death. Inhibition zones against E coli or MRSA were not formed on the plates streaked with the same organism, whereas initial inhibition zones of E coli -inoculated and MRSA-inoculated rifampicin-gelatin grafts on S epidermidis -streaked plates were 8.0 +/- 0.2 mm and 18.5 +/- 0.5 mm, respectively. In the MRSA group, however, recolonization of high minimal inhibitory concentration strains developed within the inhibition zones as early as 24 hours. Histologically, neither organisms nor inflammatory cells were found in S epidermidis -inoculated rifampicin-gelatin grafts and tissue ingrowth was recognized at 2 to 4 weeks, whereas E coli -inoculated and MRSA-inoculated rifampicin-gelatin grafts had aggressive neutrophil infiltration into the graft interstices, revealing establishment of uncontrollable graft infection. CONCLUSION: These results suggested that rifampicin-gelatin grafts are clearly valid for S epidermidis infection, whereas no efficacy was recognized against either MRSA or E coli graft infection because of early development of high minimal inhibitory concentration MRSA strains or poor susceptibility.     

Inhibition of vascular prosthetic graft infection using a photocrosslinkable chitosan hydrogel

BACKGROUND: Despite improvements in surgical techniques and antimicrobial therapies, prosthetic aortic graft infections remain a clinical problem. It is well known that chitosan has strong antibacterial activities to a wide variety of bacteria including Staphylococcus aureus, epidermidis and Escherichia coli (E. coli). The antibacterial activity by adhering a photocrosslinkable chitosan hydrogel to Dacron grafts was investigated in vitro and in vivo using a rabbit model. MATERIALS AND METHODS: The photocrosslinkable chitosan hydrogel (50microl) coated grafts (3 x 2mm fragments) were evaluated on a resistance against E. coliin vitro. The graft infections in vivo were also initiated through implantation of a Dacron graft fragment into the infrarenal aorta of a rabbit, followed by a topical inoculation with 10(6) colony-forming units of E. coli. The graft infection was allowed to develop over the following 1 week. RESULTS: The photocrosslinkable chitosan hydrogel-coated grafts exhibited a resistance against E. coliin vitro. Furthermore, application of 0.1ml photocrosslinkable chitosan hydrogel on the Dacron implant in vivo substantially inhibited graft infection with E. coli. CONCLUSIONS: These preliminary results suggested the potential use of a photocrosslinkable chitosan hydrogel in directing graft infection prophylaxis.     

The effect of G-CSF in an experimental MRSA graft infection in mice.

Wound infection after prosthetic material implantation is a troublesome complication with an incidence of 2% to 10%. The effect of granulocyte colony-stimulating factor (G-CSF) was studied in an experimental methicillin-resistant Staphylococcus aureus (MRSA) graft infection model. Eighty adult mice were used. Under general anesthesia an abdominal incision of 2 cm in length was performed. A subcutaneous cavity of 2 x 2 cm in size was created. Polypropylene mesh pieces of 2 x 1 cm and MRSA solution of 0.1ml of 10(8) CFU/mL were used. G-CSF was applied systemically or locally in a dosage of 0.02 MU/30 g body weight. There were 8 groups: group I, wound + MRSA; group II, wound + mesh + MRSA; group III, wound + mesh + MRSA + G-CSF (ip, 48 h before operation); group IV, wound + mesh + MRSA + G-CSF (ip, 24 h before operation); group V, wound + mesh + MRSA + G-CSF (locally, into the cavity); group VI, wound + mesh (incubated in G-CSF solution for 4 h) + MRSA; group VII, wound + mesh + MRSA + G-CSF, ip, 24 h from operation; and group VIII (positive control group), wound + mesh + MRSA + Teicoplanin (0.03 mg/30 g body weight, ip, 1/2 h before operation). Three days after, animals were killed and incisions were examined for possible infection or abscess formation and wound failure. Meshes were removed; after vortexing and dilution, samples were incubated with 5% agar media. Results of bacterial incubation were evaluated 24 h and 48 h later. There were symptoms of wound infection and abscess formation in all groups except group VIII. In group VIII, MRSA was isolated in 7 events with a colony count below 10(3). Bacterial counts were above 10(6) (10(6)-10(8)) in all other groups. Thus, it was observed that wound infection could be created with this model, but G-CSF could not prevent the development of wound infection, whether it was administered systemically or locally. Teicoplanin decreased the number of colony-forming units of MRSA, and prevents wound infection in this MRSA wound infection model.     

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.     

Pectoralis major muscle flaps for closure of the infected median sternotomy wound

A case of post-sternotomy mediastinitis due to methicillin-resistant Staphylococcus aureus after aortocoronary bypass procedure was treated with debridement, open clean packing, and delayed wound closure by the technique of pectoral muscle flap mobilization. The cosmetic and functional results were excellent. This technique seems to be a very effective method of treatment for the serious complication of deep sternal infection with mediastinitis after cardiac operation.     

The Effect of G-CSF in an Experimental MRSA Graft Infection in Mice

Wound infection after prosthetic material implantation is a troublesome complication with an incidence of 2% to 10%. The effect of granulocyte colony-stimulating factor (G-CSF) was studied in an experimental methicillin-resistant Staphylococcus aureus (MRSA) graft infection model. Eighty adult mice were used. Under general anesthesia an abdominal incision of 2 cm in length was performed. A subcutaneous cavity of 2 × 2 cm in size was created. Polypropylene mesh pieces of 2 × 1 cm and MRSA solution of 0.1ml of 10⁸ CFU/mL were used. G-CSF was applied systemically or locally in a dosage of 0.02 MU/30 g body weight. There were 8 groups: group I, wound + MRSA; group II, wound + mesh + MRSA; group III, wound + mesh + MRSA + G-CSF (ip, 48 h before operation); group IV, wound + mesh + MRSA + G-CSF (ip, 24 h before operation); group V, wound + mesh + MRSA + G-CSF (locally, into the cavity); group VI, wound + mesh (incubated in G-CSF solution for 4 h) + MRSA; group VII, wound + mesh + MRSA + G-CSF, ip, 24 h from operation; and group VIII (positive control group), wound + mesh + MRSA + Teicoplanin (0.03 mg/30 g body weight, ip, 1/2 h before operation). Three days after, animals were killed and incisions were examined for possible infection or abscess formation and wound failure. Meshes were removed; after vortexing and dilution, samples were incubated with 5% agar media. Results of bacterial incubation were evaluated 24 h and 48 h later. There were symptoms of wound infection and abscess formation in all groups except group VIII. In group VIII, MRSA was isolated in 7 events with a colony count below 10³. Bacterial counts were above 10⁶ (10⁶–10⁸) in all other groups. Thus, it was observed that wound infection could be created with this model, but G-CSF could not prevent the development of wound infection, whether it was administered systemically or locally. Teicoplanin decreased the number of colony-forming units of MRSA, and prevents wound infection in this MRSA wound infection model.     

A case report of poststernotomy mediastinitis treated with the pectoralis major muscle flap after protracted wound irrigation]

A 8-year-old boy developed mediastinitis after direct closure of atrial septal defect. Methicillin-resistant Staphylococcus aureus (MRSA) was detected from the wound. Intermittent wound irrigation with povidone-iodine solution and vancomycin solution was protracted for two months. After the remission of MRSA infection, implantation of pectoralis major muscle flap was performed. Without recurrence of infection the wound was healed completely. Although pectoralis major muscle flap is an effective method of choice for mediastinitis, an appropriate timing of enforcing this method should be investigated hereafter.     

Active infective endocarditis due to methicillin-resistant Staphylococcus aureus in the acute phase of infectious mononucleosis

A 26-year-old male was treated for acute hepatitis due to Epstein-Barr virus and infectious mononucleosis in our hospital. At 2 weeks after admission, there was relapse with high fever. A blood culture detected methicillin-resistant Staphylococcus aureus. A two-dimensional echocardiogram revealed severe aortic regurgitation and vegetation on the left coronary cusp of the aortic valve. The diagnosis was active infective endocarditis due to methicillin-resistant Staphylococcus aureus in the acute phase of infectious mononucleosis. Following preoperative administration of vancomycin, the aortic valve was replaced with a Carbomedics prosthetic valve. The aortic valve was bicuspid, and the right cusp and non-coronary cusp were conjoined. As the focus of infection was localized to the left coronary cusp, the infected tissue was fully removed with resection of all the cusps. Although fever persisted long after the operation, the blood culture became negative for methicillin-resistant Staphylococcus aureus, and repeated echocardiograms including transesophageal echocardiogram showed no prosthetic valve infection. Vancomycin was administered until the C-reactive protein became negative at 45 days after the operation.     

Mediastinitis with an infection of methicillin-resistantStaphylococcus aureus treated by an omental transfer following CABG using a right gastroepiploic arterial graft: Report of a case

We report a case of severe mediastinitis infected by methicillin-resistantStaphylococcus aureus (MRSA) after a coronary arterial bypass using the internal thoracic arteries and the right gastroepiploic artery (RGEA) in which mediastinitis was treated by an omental transfer. The patient was a 60-year-old man diagnosed as having an acute myocardial infarction of the left anterior wall. There was severe coronary stenosis of three vessels involving the left main trunk. The patient underwent a coronary arterial bypass with four grafts using the internal thoracic arteries, the RGEA, and the saphenous vein. Postoperative heart failure led to wound infection, resulting in mediastinitis infected by MRSA. Debridement and immediate closure with omental drainage was successfully performed without irrigation. After the establishment of the RGEA graft, the omentum is still viable and usable for mediastinal drainage.     

Methicillin-resistant Staphylococcus aureus infection in vascular surgical patients.

BACKGROUND: Methicillin-resistant Staphylococcus aureus (MRSA) infection is emerging as a major problem in vascular surgical practice. The aim of this study was to review the management of patients with MRSA infection complicating vascular surgical operations. METHODS: Data were obtained from the vascular audit, case notes, intensive therapy unit (ITU) notes, high dependency unit (HDU) notes and microbiological records of patients who underwent either arterial reconstruction (n = 464) or limb amputation (n = 110) between April 1994 and October 1998. RESULTS: Forty-nine vascular surgical patients developed clinical MRSA infection (9%). Clinical MRSA infection in patients who had undergone aorto-iliac reconstruction (n = 18) was associated with a 56% mortality (n = 10) and the most common infections were bacteraemia (55%) and pneumonia (50%). MRSA infection occurred in 17 patients who had undergone infra-inguinal bypass and was associated with a 29% mortality (n = 5). The most common site of MRSA infection was the groin wound (76%) leading to anastomotic dehiscence and death in one patient (11%) and necessitating wound debridement in 4 patients (22%). MRSA infection of the groin wound in the presence of a prosthetic graft (n = 3) led to anastomotic dehiscence in 2 patients, and graft excision in 2 patients. Similar complications were not observed in the presence of an underlying autogeneous long saphenous vein graft (n = 16). MRSA infection following major lower limb amputation (n = 14) was associated with death in 5 patients (36%). Wound infection in 10 amputees (71%) led to revision of the amputation to a higher level in 2 (14%) and wound debridement in 2 (14%). CONCLUSIONS: MRSA infection has a high mortality in vascular surgical patients in general, and following aorto-iliac reconstruction in particular. Autogeneous vein may confer some protection against local complications following groin wound infection. Strategies aimed at reducing the incidence of infection, including strict adherence to infection control procedures, may reduce the severity of this problem.