Treatment of Septic Pulmonary Embolism from Serratia from Port
Remove the infected port immediately and initiate targeted antimicrobial therapy against Serratia marcescens for 4-6 weeks, as catheter-related bloodstream infections with gram-negative organisms causing septic pulmonary emboli require both source control and extended antibiotic treatment to prevent mortality and metastatic complications.
Immediate Source Control
The infected port must be removed urgently 1. The European Society of Cardiology guidelines explicitly state that infected indwelling catheters are a recognized risk factor for septic embolism, and the ESMO guidelines mandate catheter removal for severe sepsis, suppurative thrombophlebitis, or bloodstream infection continuing despite 48-72 hours of adequate antimicrobial coverage 1.
Do not attempt catheter salvage with antibiotic lock therapy in this scenario, as septic pulmonary emboli represent a severe complication indicating systemic dissemination 1, 2.
Antimicrobial Therapy Selection
Initiate imipenem-cilastatin as first-line therapy for Serratia marcescens septic pulmonary embolism:
Imipenem-cilastatin is FDA-approved for treating bacterial septicemia and lower respiratory tract infections caused by Serratia marcescens 3. The FDA label specifically lists Serratia as a susceptible pathogen for both indications 3.
Administer 500 mg IV over 20-30 minutes every 6 hours, or 1000 mg IV over 40-60 minutes every 6-8 hours depending on severity (maximum 4 g/day) 3.
Alternative regimens include fourth-generation cephalosporins, carbapenems, or β-lactam/β-lactamase combinations based on institutional antibiogram data 1. The ESMO guidelines recommend empirical anti-gram-negative coverage with these agents in severe cases 1.
Adjust dosing based on renal function, as dose reduction is required for creatinine clearance <90 mL/min 3.
Treatment Duration
Administer antimicrobials for 4-6 weeks minimum:
The IDSA guidelines recommend 4-6 weeks of treatment for catheter-related bloodstream infections with persistent bacteremia (>72 hours after catheter removal) or when complications such as septic pulmonary emboli are present 1, 4.
For gram-negative rod CRBSI with persistent bacteremia or severe sepsis, treatment duration must extend beyond the standard 7-14 days when metastatic infection (such as septic pulmonary emboli) is present 1, 4.
A case report of Serratia marcescens Portacath-related sepsis with cerebral and pulmonary emboli documented that prolonged antimicrobial treatment according to culture sensitivities led to resolution 5.
Diagnostic Evaluation
Obtain blood cultures before initiating antibiotics, but do not delay treatment:
Draw at least two sets of blood cultures (preferably from the catheter and peripheral vein) before starting antimicrobials 1.
Chest CT will demonstrate multiple peripheral nodular lesions, possibly cavitated, which are pathognomonic for septic pulmonary embolism 1, 2.
Consider transesophageal echocardiography (TEE) to evaluate for right-sided endocarditis, as this is a common source of septic pulmonary emboli in patients with indwelling catheters 1, 6. The ESMO guidelines recommend TEE if signs of endocarditis are present, prolonged bacteremia occurs (>72 hours), or radiographic evidence of septic pulmonary emboli exists 1.
Monitoring and Follow-up
Obtain follow-up blood cultures 72 hours after catheter removal and antibiotic initiation 1.
If bacteremia persists beyond 72 hours despite appropriate therapy and source control, extend treatment to 4-6 weeks and evaluate for undrained metastatic foci or endocarditis 1, 4.
Monitor for complications including pulmonary abscess, empyema, bronchopleural fistula, and hemodynamic instability 7, 8.
Anticoagulation Considerations
The role of anticoagulation in septic thrombophlebitis and septic pulmonary embolism remains undefined, with no clear evidence supporting routine use 2.
Unlike thrombotic pulmonary embolism, septic pulmonary embolism requires specific antimicrobial treatment rather than anticoagulation as primary therapy 1.
Common Pitfalls to Avoid
Do not attempt catheter salvage when septic pulmonary emboli are present—this represents failed conservative management and mandates immediate removal 1, 2.
Do not use standard 7-14 day treatment courses for uncomplicated CRBSI when metastatic complications exist; this will lead to treatment failure and relapse 1, 4.
Do not delay source control while waiting for antibiotic response, as mortality in septic pulmonary embolism ranges up to 20% in published series 2.
Do not overlook right-sided endocarditis, which occurs in 25-32% of catheter-related Staphylococcus aureus infections and can also occur with gram-negative organisms like Serratia 1, 6.