Treatment of Serratia marcescens Infections
The recommended first-line treatment for Serratia marcescens infections is a combination of a third-generation cephalosporin (ceftazidime, ceftriaxone, or cefotaxime) with an aminoglycoside (gentamicin or amikacin). 1
Treatment Options Based on Infection Site
Hospital-Acquired and Ventilator-Associated Pneumonia
- AVYCAZ (ceftazidime-avibactam) is FDA-approved for treatment of HABP/VABP caused by Serratia marcescens 2
- Clinical cure rates with AVYCAZ for S. marcescens pneumonia were 73.3% in clinical trials 2
- For pneumonia, treatment should continue for 7-14 days 1, 2
Intra-abdominal Infections
- For complicated intra-abdominal infections, a carbapenem-sparing regimen is preferred where possible 3
- Ceftolozane/tazobactam plus metronidazole may be valuable for treating infections caused by gram-negative MDROs to preserve carbapenems 3
- Treatment duration should be 5-14 days 2
Bloodstream Infections
- Blood cultures should be obtained if systemic symptoms are present 1
- For bacteremia, treatment with carbapenems (imipenem or meropenem) shows high efficacy with MIC90 of 1.0 μg/mL 4
- Ciprofloxacin also demonstrates good activity against S. marcescens with MIC90 of 0.19 μg/mL 4
Endocarditis
- For endocarditis caused by S. marcescens, cardiac surgery in combination with prolonged antibiotic therapy is recommended 1
- Valve replacement after 7-10 days of antibiotic therapy is recommended as mortality rates can reach 70% 1
- Therapy should be administered for a minimum of 6 weeks 1
Antibiotic Selection Based on Resistance Patterns
First-Line Options
- Cefotaxime and gentamicin show very low resistance rates (0.6%) and are suitable first-line options 5
- Amikacin shows excellent susceptibility with no resistance in some studies 6
Second-Line Options
- Carbapenems (imipenem, meropenem) have excellent activity against S. marcescens with virtually all isolates susceptible 4
- Ciprofloxacin demonstrates good in vitro activity against S. marcescens 4
Antibiotics to Avoid
- All isolates are typically resistant to ampicillin and cephalothin 4, 7
- High resistance rates to tetracycline (>90%) make it unsuitable 7
- Colistin is ineffective against S. marcescens 6
Important Considerations and Monitoring
- Resistance development during therapy is a concern, particularly with aminoglycosides 8
- For deep tissue infections, monitor for increasing resistance if infection fails to clear promptly 8
- Follow-up cultures should be obtained to document clearance of infection 1
- Antimicrobial therapy should be continued until further debridement is no longer necessary, the patient has improved clinically, and fever has been resolved for 48-72 hours 1
Treatment Duration
- For endocarditis and other serious infections: minimum 6 weeks 1
- For hospital-acquired pneumonia: 7-14 days 1, 2
- For complicated intra-abdominal infections: 5-14 days 2
- For complicated urinary tract infections: 7-14 days 2