What considerations are necessary for a patient admitted with Corynebacterium diphtheriae bacteria and infective endocarditis?

Management of Corynebacterium diphtheriae Infective Endocarditis

Complete device and lead removal is mandatory for all patients with Corynebacterium diphtheriae infective endocarditis, along with appropriate antibiotic therapy and consideration of early surgical intervention, especially for those with prosthetic valves. 1, 2

Diagnostic Considerations

• Obtain at least 3 sets of blood cultures before initiating antimicrobial therapy 1, 3
• Perform transthoracic echocardiography (TTE) as first-line imaging 1, 3
• Progress to transesophageal echocardiography (TEE) for:
  • Negative/non-diagnostic TTE with high clinical suspicion
  • Presence of prosthetic valve or intracardiac device
  • Evaluation of left-sided heart valves, even if TTE shows lead-adherent masses 1
• Consider additional imaging if needed:
  • Intracardiac echocardiography in cases with negative TEE but high suspicion 1
  • Radiolabeled leukocyte scintigraphy or 18F-FDG PET/CT as additive tools 1

Antimicrobial Management

• Choice of antimicrobial therapy should be based on identification and susceptibility results of the infecting pathogen 1
• For C. diphtheriae specifically:
  • Penicillin-based regimens are typically effective (penicillin G or amoxicillin) 4, 5
  • Consider combination therapy with an aminoglycoside (preferably tobramycin) for synergistic effect 4, 5
  • For penicillin-allergic patients, vancomycin is the recommended alternative 4, 6
• Duration of antimicrobial therapy:
  • At least 4-6 weeks for complicated infection (endocarditis) 1
  • Continue antibiotics after device removal 1

Device Management

• Complete device and lead removal is mandatory for all patients with definite CIED infection 1
• Percutaneous extraction is recommended in most patients, even those with vegetations >10mm 1
• Surgical extraction should be considered if:
  • Percutaneous extraction is incomplete or impossible
  • Associated severe destructive tricuspid valve endocarditis exists
  • Large vegetations (>20mm) are present 1

Surgical Considerations

• Early surgical intervention is strongly recommended for:
  • Patients with prosthetic valves infected with C. diphtheriae 2, 7
  • Severe valve regurgitation or obstruction causing heart failure 1
  • Locally uncontrolled infection (abscess, false aneurysm, fistula) 1
  • Persistent vegetations >10mm after embolic episodes despite appropriate antibiotic therapy 1
• Native valve endocarditis with C. diphtheriae may be managed medically with careful monitoring, but surgery should be immediately available if clinical deterioration occurs 2

Device Reimplantation

• Reassess the need for reimplantation after device extraction 1
• If reimplantation is necessary:
  • Postpone definite reimplantation to allow several days or weeks of antibiotic therapy 1
  • Avoid immediate reimplantation due to risk of new infection 1
  • Ensure blood cultures are negative for at least 72 hours before placement of new device 1
  • Reimplant on the contralateral side to the extraction site 1
  • Consider temporary pacing with active fixation leads as a bridge for pacing-dependent patients 1

Additional Considerations

• Monitor for complications:
  • Repeat echocardiography if new complications are suspected (new murmur, embolism, persistent fever) 1
  • Watch for signs of septic pulmonary emboli, even after surgical intervention 3
• Consider referral to specialized centers:
  • Patients with complicated IE should be evaluated and managed at a reference center with immediate surgical facilities and a multidisciplinary Endocarditis Team 1
  • Early and regular communication with reference centers for patients managed elsewhere 1

Pitfalls to Avoid

• Do not dismiss Corynebacterium species as contaminants in blood cultures, especially in patients with prosthetic valves 6
• Avoid percutaneous aspiration of generator pocket as part of diagnostic evaluation 1
• Do not delay complete hardware removal, as infection relapse rates due to retained hardware are high 1
• Be aware of increasing antibiotic resistance among Corynebacterium species; vancomycin remains active against most isolates when penicillin resistance is present 6

Corynebacterium diphtheriae endocarditis is a serious condition with potentially high mortality rates. Early diagnosis, appropriate antimicrobial therapy, complete device removal when indicated, and timely surgical intervention when necessary are essential components of successful management.