What is the antibiotic choice for Serratia marcescens infection?

From the Guidelines

For Serratia marcescens infections, carbapenems such as meropenem (1g IV every 8 hours) are the preferred treatment option, especially for severe infections or if resistance is suspected, due to their broad range of in vitro activity and effectiveness against gram-negative bacilli that produce extended-spectrum beta-lactamases 1. Third-generation cephalosporins like ceftriaxone (1-2g IV every 24 hours) or ceftazidime (1-2g IV every 8 hours) can also be considered as first-line treatments. Some key points to consider when treating Serratia marcescens infections include:

• Serratia marcescens naturally resists several antibiotics including ampicillin, amoxicillin, first-generation cephalosporins, and colistin due to chromosomal AmpC beta-lactamases and efflux pumps.
• Antibiotic susceptibility testing is crucial as resistance patterns vary.
• For empiric therapy before culture results, combination therapy with an aminoglycoside (like amikacin 15mg/kg/day) plus a carbapenem or third-generation cephalosporin may be appropriate for severe infections to ensure adequate coverage.
• Treatment duration is typically 7-14 days depending on infection severity and site. It's also important to note that fluoroquinolones like ciprofloxacin (400mg IV every 12 hours or 500-750mg orally twice daily) can also be effective, but their use should be guided by antibiotic susceptibility testing 1.

From the FDA Drug Label

Tobramycin has been shown to be active against most isolates of the following bacteria both in vitro and in clinical infections: Gram-positive bacteria Staphylococcus aureus Gram-negative bacteria Citrobacter species Enterobacter species Escherichia coli Klebsiella species Morganella morganii Pseudomonas aeruginosa Proteus mirabilis Proteus vulgaris Providencia species Serratia species

Tobramycin is an option for treating Serratia marcescens infections, as it has been shown to be active against Serratia species 2. However, it is essential to perform susceptibility testing to confirm the effectiveness of tobramycin against the specific Serratia marcescens isolate.

• Key points:
  • Tobramycin is active against Serratia species
  • Susceptibility testing is necessary to confirm effectiveness
  • Tobramycin can be used to treat various infections, including those caused by Serratia marcescens 2 2

From the Research

Antibiotic Choice for Serratia marcescens

• The choice of antibiotic for Serratia marcescens infections is challenging due to increasing resistance to various antibiotics 3.
• According to a study published in 2019, cefotaxime and gentamicin are the most suitable antibiotics for treatment, with low resistance rates of 0.6% 3.
• A systematic review published in 2023 recommends the use of carbapenems or aminoglycosides in combination with third-generation (and eventually fourth-generation) cephalosporin for the treatment of Serratia marcescens infections 4.
• Meropenem has been shown to be effective in treating Serratia marcescens meningitis and ventriculitis, particularly when administered as a prolonged infusion or continuous infusion 5, 6.
• For carbapenem-resistant, SME-producing Serratia marcescens, meropenem-vaborbactam may be a potential treatment option 7.
• The following antibiotics have been reported to have activity against Serratia marcescens:
  • Cefotaxime
  • Gentamicin
  • Meropenem
  • Meropenem-vaborbactam
  • Ceftazidime-avibactam
• It is essential to note that antibiotic resistance patterns can vary depending on the region and hospital, and antibiotic susceptibility testing should be performed to guide treatment decisions 3, 4.