What is the recommended treatment for Serratia marcescens infections?

Treatment of Serratia marcescens Infections

For Serratia marcescens infections, an extended-spectrum penicillin (e.g., piperacillin/tazobactam) or an extended-spectrum cephalosporin (e.g., ceftazidime, ceftriaxone, or cefotaxime) together with an aminoglycoside is recommended for a minimum of 6 weeks of therapy. 1

First-Line Treatment Options

• Imipenem is indicated for the treatment of lower respiratory tract infections, urinary tract infections, intra-abdominal infections, gynecologic infections, bacterial septicemia, bone and joint infections, skin and skin structure infections, and endocarditis caused by susceptible strains of Serratia marcescens 2
• For Gram-negative bacteria including Serratia marcescens, a combination of an extended-spectrum penicillin (e.g., piperacillin/tazobactam) or an extended-spectrum cephalosporin (e.g., ceftazidime, ceftriaxone, or cefotaxime) together with an aminoglycoside is recommended 1
• Levofloxacin is indicated for the treatment of nosocomial pneumonia due to Serratia marcescens and may be considered as an alternative agent 3

Treatment Based on Infection Site

Endocarditis

• For endocarditis caused by Serratia marcescens, cardiac surgery in combination with prolonged courses of combined antibiotic therapy is a cornerstone of treatment 1
• Valve replacement after 7-10 days of antibiotic therapy has been recommended for these difficult infections, as mortality rates can reach 70% 1
• A combination of a third-generation cephalosporin and an aminoglycoside (either gentamicin or amikacin) is recommended for Gram-negative bacillary endocarditis 1

Skin and Soft Tissue Infections

• For necrotizing soft tissue infections caused by Gram-negative bacteria including Serratia marcescens, broad-spectrum coverage should be urgently commenced 1
• Carbapenems, administered in adequate dosage, including meropenem, imipenem-cilastatin, or doripenem may be used in settings with high local prevalence of ESBL-producing Enterobacteriaceae 1

Antibiotic Susceptibility Considerations

• Recent studies show that Serratia marcescens clinical isolates have the lowest resistance rates to cefotaxime and gentamicin (0.6%), making these potentially suitable antibiotics for treatment 4
• Ciprofloxacin and imipenem have demonstrated good activities against S. marcescens in studies measuring minimum inhibitory concentrations 5
• Due to increasing multidrug resistance, choosing appropriate antimicrobial agents such as moxalactam, imipenem, and ciprofloxacin should be highly recommended for the treatment of S. marcescens infections 5

Treatment Duration

• For endocarditis and other serious infections caused by Serratia marcescens, therapy should be administered for a minimum of 6 weeks 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
• Procalcitonin monitoring may be useful to guide antimicrobial discontinuation in cases of necrotizing infections 1

Special Considerations

• For pediatric patients with Serratia marcescens ventriculitis, continuous-infusion meropenem has been used successfully when other treatments failed 6
• The combination of fosfomycin plus gentamicin has shown synergism in vitro on isolated Serratia strains and has been effective in treating Serratia marcescens septicemia in children 7
• For multidrug-resistant strains, susceptibility testing is crucial to guide therapy, as resistance patterns can vary significantly between medical centers 8

Monitoring and Follow-up

• Blood cultures should be obtained if systemic symptoms are present to rule out concurrent bacteremia, which would require more aggressive management 9
• Follow-up cultures should be obtained to document clearance of infection, especially in cases of persistent or recurrent infections 9