Are antibiotics recommended for patients with an open chest after cardiac surgery (delayed sternal closure)?

Antibiotic Prophylaxis for Open Chest After Cardiac Surgery

Yes, prophylactic antibiotics are recommended for patients with delayed sternal closure after cardiac surgery, and should be continued until the time of chest closure using standard first- or second-generation cephalosporins (cefazolin) rather than broad-spectrum agents. 1, 2

Recommended Antibiotic Regimen

First-Line Prophylaxis

• Cefazolin remains the antibiotic of choice for delayed sternal closure, administered as 2g IV with redosing of 1g every 4 hours during prolonged open chest management 1
• Alternative first-line options include cefamandole or cefuroxime 1.5g IV, with redosing of 0.75g every 2 hours 1
• Standard prophylactic regimens (first- or second-generation cephalosporins) are as effective as broad-spectrum antibiotics and avoid unnecessary antimicrobial resistance 2, 3

Alternative Regimens for Special Circumstances

• For patients with beta-lactam allergy: vancomycin 30 mg/kg over 120 minutes 1
• For documented MRSA colonization or recent reoperation in MRSA-endemic units: add vancomycin to cefazolin 1, 4
• Clindamycin 900 mg IV is another alternative for penicillin-allergic patients 1

Duration of Prophylaxis

Critical Timing Principles

• Continue prophylactic antibiotics until the time of sternal closure, not beyond 1, 2
• Maximum duration should not exceed 24 hours after chest closure 1
• Abbreviated courses (stopping before closure) showed 0% infection rate in one study, though sample size was small 2
• Extending antibiotics past the time of sternal closure does not reduce infection rates and may increase adverse effects 2

Evidence on Duration

The evidence shows substantial practice variation but clear outcomes: patients receiving antibiotics only until chest closure had 1.9% infection rates, while those continued past closure had 7.7% infection rates (though not statistically significant, p=0.352) 2. This suggests no benefit—and potential harm—from extended prophylaxis 2.

Key Evidence and Nuances

Adult Cardiac Surgery Data

• In 167 adult patients with delayed sternal closure, routine antibiotic prophylaxis (78.4% of patients) resulted in 4.6% sternal SSI, compared to 8.3% in those switched to broad-spectrum agents (p=0.407) 2
• Broad-spectrum antimicrobials showed no benefit and may increase adverse effects 2
• Standard cephalosporin prophylaxis is supported by ACC/AHA guidelines for all cardiac surgery patients 5

Pediatric Cardiac Surgery Considerations

There is conflicting evidence in pediatric populations: one study suggested vancomycin + meropenem reduced combined bloodstream and surgical site infections (31% vs 67% with cefazolin alone, adjusted OR 0.09, p=0.003) 4. However, a systematic review of 2,203 pediatric patients found that "non-standard" broad-spectrum strategies had higher SSI rates (8.8%) compared to standard cephalosporin regimens (6.8%, p=0.001) 3. The systematic review's larger sample size and meta-analytic approach provides stronger evidence favoring standard prophylaxis even in pediatrics 3.

Microbiological Considerations

• Standard cephalosporins provide adequate coverage against the most common pathogens: Staphylococcus aureus and coagulase-negative staphylococci 6
• When broad-spectrum agents are used, there is a shift toward more Gram-negative infections without overall reduction in SSI rates 7
• Beta-lactams with Gram-negative activity showed lower postoperative pneumonia and mortality in general cardiac surgery, but this does not translate to benefit in delayed sternal closure specifically 5, 1

Common Pitfalls to Avoid

Do Not:

• Switch to broad-spectrum antibiotics (e.g., vancomycin + meropenem, piperacillin-tazobactam) without specific indication such as documented MRSA or established infection 2, 3
• Continue prophylaxis beyond chest closure as this provides no additional benefit and increases resistance risk 1, 2
• Confuse prophylaxis with treatment: if infection develops, switch to therapeutic regimens appropriate for the site and suspected pathogens 6, 8

Do:

• Maintain standard cefazolin prophylaxis throughout the open chest period 1, 2, 3
• Redose cefazolin every 4 hours during prolonged open chest management 1, 9
• Discontinue prophylaxis within 24 hours of chest closure 1
• Consider adding vancomycin only for documented MRSA colonization or high-risk scenarios 1, 4

Clinical Algorithm

1. At initial surgery: Administer cefazolin 2g IV within 60 minutes before incision 1, 9
2. If chest left open: Continue cefazolin 1g IV every 4 hours 1
3. Special populations:
   • Beta-lactam allergy → vancomycin 30 mg/kg over 120 minutes, then every 12 hours 1
   • Known MRSA colonization → add vancomycin to cefazolin 1, 4
4. At delayed sternal closure: Give final prophylactic dose at time of closure 1, 2
5. Postoperatively: Discontinue within 24 hours of closure 1

The presence of chest tubes or drainage is not an indication to extend prophylaxis duration 1. If infection is suspected, transition to therapeutic antibiotics based on culture data and clinical presentation 6, 8.