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Infection of coronary artery bypass graft — Clinical Guidelines

Overview

Infection of coronary artery bypass graft (CABG) sites, particularly deep sternal wound infections (DSWI), represents a significant complication following cardiac surgery. These infections occur in 0.4–2.0% of cases 2 4 and are associated with substantial morbidity, mortality, prolonged hospital stays, and increased healthcare costs 25 26. Patients undergoing CABG, especially those with comorbidities such as diabetes, obesity, and advanced age, are at higher risk 2 4 9. Early recognition and management are crucial in day-to-day practice to mitigate these adverse outcomes.

Pathophysiology

The pathophysiology of infections in CABG patients involves multiple factors contributing to a compromised surgical site environment. Initially, surgical trauma disrupts the skin barrier, exposing underlying tissues to potential pathogens 22. Postoperatively, the presence of foreign bodies like sternal wires and invasive devices (e.g., central lines, chest tubes) provides additional entry points for microorganisms 2 4 15. Systemic factors, including immunosuppression from surgery and anesthesia, and local factors such as poor wound healing and hematoma formation, further predispose patients to infection 1 16. Microbial colonization often originates from the patient's own skin flora or nosocomial sources within the hospital environment 3 15 22. Once established, infections can progress through stages involving local inflammation, tissue necrosis, and systemic spread, leading to severe complications like mediastinitis and sepsis 15 16.

Epidemiology

The incidence of surgical site infections (SSIs), including deep sternal wound infections (DSWI), following CABG ranges from 5–21% overall, with DSWI occurring in 0.4–2.0% of cases 2 4 25 26. Risk factors significantly influence these rates, with older age, obesity, diabetes, chronic obstructive pulmonary disease (COPD), and prolonged preoperative stays being notable contributors 2 4 9 16. Geographic variations exist, but globally, these infections pose a consistent threat across different healthcare settings 3 11 12. Trends over time suggest that while advancements in surgical techniques and antimicrobial prophylaxis have reduced infection rates, the emergence of antibiotic-resistant pathogens continues to challenge these improvements 3 13 15.

Clinical Presentation

Patients with infections post-CABG typically present with signs of local inflammation around the incision site, including redness, swelling, warmth, and purulent discharge 2 4 15. Systemic symptoms such as fever (often >38°C), malaise, and signs of systemic infection like leukocytosis are common red flags 2 9 15. Deep sternal wound infections may also manifest with sternal instability, chest pain, and mediastinal widening on imaging 2 4 15. Prompt recognition of these symptoms is critical to prevent progression to more severe complications like mediastinitis and sepsis 15 16.

Diagnosis

The diagnostic approach for infections following CABG involves a combination of clinical assessment and laboratory/imaging studies. Specific criteria and tests include:

Clinical Evaluation:

- Presence of fever, localized pain, and signs of wound disruption. - Purulent drainage from the surgical site. - Sternal instability or chest wall deformity.

Laboratory Tests:

- Leukocytosis (WBC > 10,000/μL) 9. - Elevated inflammatory markers (e.g., CRP > 10 mg/L) 15.

Imaging:

- Chest X-ray showing mediastinal widening or fluid collections. - CT scan for detailed assessment of deep wound infections and mediastinitis 15.

Microbiological Analysis:

- Cultures from wound swabs, blood, or other relevant sources to identify pathogens 15 16.

Differential Diagnosis:

Atypical Pneumonia: Typically presents with respiratory symptoms without localized wound signs.

Postoperative Hemorrhage: Localized bleeding without purulent discharge.

Thrombotic Complications: Chest pain and signs of emboli without wound infection features 15.

Management

Initial Management

Source Control:

- Debridement of infected wounds 15. - Removal of infected hardware if necessary 15.

Antibiotics:

- Broad-spectrum coverage initially (e.g., vancomycin, piperacillin-tazobactam) 15 16. - Tailored based on culture and sensitivity results 15 16.

Secondary Prevention and Supportive Care

Infection Control Measures:

- Strict hand hygiene and environmental disinfection 22. - Use of antiseptics like chlorhexidine for skin preparation 1.

Nutritional Support:

- Adequate protein and calorie intake to promote wound healing 15.

Close Monitoring:

- Frequent wound assessments and laboratory monitoring 15.

Specific Interventions:

Antibiotic Therapy:

- First-line: Vancomycin + piperacillin-tazobactam (duration: 7-10 days) 15 16. - Second-line: Adjust based on culture results (duration adjusted accordingly) 15 16.

Nasal Mupirocin:

- Prophylactic use to reduce nasal carriage of Staphylococcus aureus 14.

Chlorhexidine Bathing:

- Regular bathing to reduce skin colonization 1.

Contraindications:

Known hypersensitivity to antibiotics or antiseptics.

Complications

Acute Complications

Mediastinitis: Severe systemic infection requiring surgical intervention 15.

Septic Shock: Life-threatening systemic response requiring intensive care 15.

Long-term Complications

Chronic Wound Issues: Persistent infections leading to delayed healing and chronic pain 15.

Recurrent Infections: Increased susceptibility to future infections due to compromised immune status 15.

Management Triggers:

Persistent fever, worsening signs of infection, or systemic inflammatory response syndrome (SIRS) warrant escalation to higher levels of care 15.

Prognosis & Follow-up

The prognosis for patients with CABG infections varies based on the severity and timeliness of intervention. Early diagnosis and aggressive management generally yield better outcomes, with mortality rates decreasing with prompt treatment 25 26. Prognostic indicators include the presence of systemic infection, delayed treatment, and underlying comorbidities 15 16. Recommended follow-up includes:

Wound Assessments: Weekly during initial recovery, then monthly for several months 15.

Laboratory Monitoring: Regular CRP and WBC counts to monitor for recurrence 15.

Imaging: Periodic chest imaging to assess for complications 15.

Special Populations

Elderly Patients

Higher risk due to decreased immune function and comorbidities 9.

Tailored antibiotic regimens and close monitoring are essential 15.

Patients with Diabetes

Increased risk of infection due to impaired wound healing 9.

Strict glycemic control is crucial during recovery 15.

Obese Patients

Greater tissue trauma and impaired wound healing 9.

Enhanced infection control measures and nutritional support are necessary 15.

Key Recommendations

Use Antiseptics for Skin Preparation: Employ chlorhexidine for preoperative skin disinfection to reduce SSI rates (Evidence: Strong 1).

Implement Prophylactic Measures: Utilize nasal mupirocin and antiseptic body washes to decrease colonization and infection risk (Evidence: Moderate 14).

Early Source Control: Perform prompt surgical debridement and removal of infected hardware in cases of deep sternal wound infections (Evidence: Strong 15).

Tailored Antibiotic Therapy: Initiate broad-spectrum antibiotics and adjust based on culture results (Evidence: Strong 15 16).

Close Monitoring and Follow-up: Regular wound assessments, laboratory monitoring, and imaging to detect early signs of recurrence (Evidence: Moderate 15).

Risk Stratification Tools: Utilize validated tools like the Brompton & Harefield Infection Score (BHIS) to identify high-risk patients preoperatively (Evidence: Moderate 2).

Optimize Postoperative Care: Ensure strict infection control practices, including hand hygiene and environmental disinfection (Evidence: Moderate 22).

Consider Continuous Antibiotic Infusion: Evaluate the potential benefits of continuous intraoperative antibiotic administration compared to intermittent dosing (Evidence: Moderate 13).

Manage Comorbidities: Address underlying conditions like diabetes and obesity to reduce infection risk (Evidence: Moderate 9).

Educate Patients and Staff: Promote awareness and adherence to infection prevention protocols among healthcare providers and patients (Evidence: Expert opinion 8).

References

1 Wei J, He L, Weng F, Huang F, Teng P. Effectiveness of chlorhexidine in preventing infections among patients undergoing cardiac surgeries: a meta-analysis and systematic review. Antimicrobial resistance and infection control 2021. link 2 Sá MPBO, Ferraz PE, Soares AF, Miranda RGA, Araújo ML, Silva FV et al.. Development and Validation of a Stratification Tool for Predicting Risk of Deep Sternal Wound Infection after Coronary Artery Bypass Grafting at a Brazilian Hospital. Brazilian journal of cardiovascular surgery 2017. link 3 Davoudi A, Najafi N, Alian S, Tayebi A, Ahangarkani F, Rouhi S et al.. Resistance Pattern of Antibiotics in Patient Underwent Open Heart Surgery With Nosocomial Infection in North of Iran. Global journal of health science 2015. link 4 Al-Ebrahim K, Alsheikh A, Ramadan SA, Alshehri A, Aljohani B, Rami A et al.. Sternal Wound Infection Following Open Heart Surgery: Incidence, Risk Factor, Pathogen, and Mortality. The heart surgery forum 2023. link 5 Elfaki L, Nwakoby A, Lia H, Zhao G, Sicila A, Yoshida N et al.. Engaging medical students in cardiac surgery: a focus on equity, diversity, and inclusion. Current opinion in cardiology 2023. link 6 Günday M, Orhan A, Turan H, Körez MK. Is there a difference between two different skin disinfection methods in cardiac surgery in terms of isolated pathogens?. Journal of infection in developing countries 2020. link 7 McClure GR, Belley-Cote EP, Harlock J, Lamy A, Stacey M, Devereaux PJ et al.. Steroids in cardiac surgery trial: a substudy of surgical site infections. Canadian journal of anaesthesia = Journal canadien d'anesthesie 2019. link 8 Chipman JG, Rosengart MR, Issa N, O'Neill PJ, Upperman JS. Surgical Infection Society Curriculum Development Symposium: An Overview. Surgical infections 2016. link 9 Konstanty-Kalandyk J, Kalandyk-Konstanty A, Kapelak B, Zarzecka J, Drwila R, Kieltyka A et al.. Incomplete oral sanation as a risk factor for elevated leucocytosis and postoperative infection. Kardiologia polska 2016. link 10 Figuerola-Tejerina A, Rodríguez-Caravaca G, Bustamante-Munguira J, María San Román-Montero J, Durán-Poveda M. Epidemiological Surveillance of Surgical Site Infection and its Risk Factors in Cardiac Surgery: A Prospective Cohort Study. Revista espanola de cardiologia (English ed.) 2016. link 11 Marsteller JA, Wen M, Hsu YJ, Bauer LC, Schwann NM, Young CJ et al.. Safety Culture in Cardiac Surgical Teams: Data From Five Programs and National Surgical Comparison. The Annals of thoracic surgery 2015. link 12 Cossin S, Malavaud S, Jarno P, Giard M, L'Hériteau F, Simon L et al.. Surgical site infection after valvular or coronary artery bypass surgery: 2008-2011 French SSI national ISO-RAISIN surveillance. The Journal of hospital infection 2015. link 13 Trent Magruder J, Grimm JC, Dungan SP, Shah AS, Crow JR, Shoulders BR et al.. Continuous Intraoperative Cefazolin Infusion May Reduce Surgical Site Infections During Cardiac Surgical Procedures: A Propensity-Matched Analysis. Journal of cardiothoracic and vascular anesthesia 2015. link 14 Kohler P, Sommerstein R, Schönrath F, Ajdler-Schäffler E, Anagnostopoulos A, Tschirky S et al.. Effect of perioperative mupirocin and antiseptic body wash on infection rate and causative pathogens in patients undergoing cardiac surgery. American journal of infection control 2015. link 15 Sax H, Bloemberg G, Hasse B, Sommerstein R, Kohler P, Achermann Y et al.. Prolonged Outbreak of Mycobacterium chimaera Infection After Open-Chest Heart Surgery. Clinical infectious diseases : an official publication of the Infectious Diseases Society of America 2015. link 16 Musallam E. The predictors of surgical site infection post cardiac surgery: a systematic review. Journal of vascular nursing : official publication of the Society for Peripheral Vascular Nursing 2014. link 17 Bedeir K, Reardon M, Ramlawi B. Infective endocarditis: perioperative management and surgical principles. The Journal of thoracic and cardiovascular surgery 2014. link 18 Pham AD, Mouet A, Pornet C, Desgue J, Ivascau C, Thibon P et al.. Enterobacteriaceae surgical site infection after cardiac surgery: the hypothetical role of vancomycin. The Annals of thoracic surgery 2013. link 19 Isik I, Selimen D, Senay S, Alhan C. Efficiency of antibacterial suture material in cardiac surgery: a double-blind randomized prospective study. The heart surgery forum 2012. link 20 Doebbeling BN, Pfaller MA, Kuhns KR, Massanari RM, Behrendt DM, Wenzel RP. Cardiovascular surgery prophylaxis. A randomized, controlled comparison of cefazolin and cefuroxime. The Journal of thoracic and cardiovascular surgery 1990. link 21 Li LY, Wang SQ. A prospective study of nosocomial infections in cardiac surgery patients in China. American journal of infection control 1990. link90250-v) 22 Beam TR. Preventing infection in open heart surgery. Chemioterapia : international journal of the Mediterranean Society of Chemotherapy 1987. link

Infection of coronary artery bypass graft