What are the first-line antibiotics for Serratia (Serratia marcescens) infection?

From the Guidelines

For first-time treatment of Serratia infections, a carbapenem such as meropenem (1g IV every 8 hours) is typically recommended as initial therapy, given its broad-spectrum activity and effectiveness against Serratia species, as seen in the guidelines for the diagnosis and management of skin and soft tissue infections 1.

Key Considerations

• Serratia marcescens, the most common species causing human infections, naturally produces AmpC beta-lactamases, making it resistant to ampicillin and first-generation cephalosporins.
• It also frequently develops resistance to multiple antibiotics, so susceptibility testing is crucial to guide definitive therapy.
• For serious infections, combination therapy may be initially used until susceptibility results are available.
• Serratia commonly causes urinary tract infections, pneumonia, wound infections, and bloodstream infections, particularly in hospitalized or immunocompromised patients.

Treatment Options

• Carbapenems such as meropenem (1g IV every 8 hours) are effective options, especially for more severe infections.
• Treatment duration generally ranges from 7-14 days depending on infection severity and site.
• Other options like ciprofloxacin (400mg IV every 12 hours or 500-750mg orally twice daily) or a third-generation cephalosporin like ceftriaxone (1-2g IV daily) may be considered based on susceptibility results and clinical response.

Adjusting Treatment

• Treatment should be adjusted based on culture results, infection site, and clinical response.
• Colistin, for example, does not cover gram-positives or anaerobes, Proteus, Serratia, or Burkholderia, and thus may not be the best initial choice for Serratia infections 1.

Clinical Context

• The choice of antibiotic should consider the potential for resistance and the severity of the infection, as well as the patient's clinical condition and potential allergies or contraindications to certain antibiotics.
• In cases where the infection is severe or the patient is immunocompromised, hospitalization and empiric antibacterial therapy with vancomycin plus antipseudomonal antibiotics such as cefepime, a carbapenem, or piperacillin-tazobactam may be recommended 1.

From the FDA Drug Label

1.2 Lower Respiratory Tract Infections Tobramycin for Injection is indicated for the treatment of lower respiratory tract infections caused by susceptible isolates of P. aeruginosa, Klebsiella spp., Enterobacter spp., Serratia spp., E. coli, and S. aureus in adult and pediatric patients. 1.7 Complicated and Recurrent Urinary Tract Infections Tobramycin for Injection is indicated for the treatment of complicated urinary tract infections caused by susceptible isolates of P. aeruginosa, Proteus spp., (indole-positive and indole-negative), E. coli, Klebsiella spp., Enterobacter spp., Serratia spp., S. aureus, Providencia spp., and Citrobacter spp. in adult and pediatric patients

First-line antibiotics for Serratia may include Tobramycin, as it is indicated for the treatment of infections caused by susceptible isolates of Serratia spp. in various infections, including lower respiratory tract infections and complicated urinary tract infections 2.

From the Research

First-Line Antibiotics for Serratia

• Serratia marcescens is a type of bacteria that can cause various infections, and the choice of antibiotic is crucial for effective treatment.
• According to the studies, meropenem is a broad-spectrum carbapenem antibiotic that has shown excellent activity against Serratia marcescens 3, 4.
• Meropenem has been used to treat various infections, including complicated skin and soft tissue infections, intra-abdominal infections, and bacterial meningitis 5, 4, 6.
• In one study, meropenem was compared to imipenem/cilastatin in the treatment of skin and soft tissue infections, and both antibiotics showed similar efficacy and safety profiles 6.
• Another study reported the use of meropenem in a pediatric patient with Serratia marcescens ventriculitis, and the antibiotic was found to be effective in achieving a successful clinical outcome 3.
• Ceftazidime is another antibiotic that has been used to treat Serratia infections, but its effectiveness may be limited by the development of resistance 7.
• The choice of antibiotic for Serratia infections should be based on the severity of the infection, the susceptibility of the bacteria, and the patient's underlying medical conditions.

Antibiotic Resistance and Susceptibility

• Serratia marcescens can develop resistance to various antibiotics, including ceftazidime and cefotaxime 3, 7.
• Meropenem has been shown to be effective against Serratia marcescens, including strains that are resistant to other antibiotics 3, 4.
• The susceptibility of Serratia marcescens to meropenem and other antibiotics should be determined by laboratory testing to ensure effective treatment.

Treatment Outcomes

• The treatment outcomes for Serratia infections with meropenem and other antibiotics have been reported in various studies 5, 3, 4, 6.
• Meropenem has been found to be effective in achieving clinical and bacteriological responses in patients with Serratia infections 3, 6.
• The choice of antibiotic and the treatment outcome may depend on various factors, including the severity of the infection, the patient's underlying medical conditions, and the susceptibility of the bacteria to the antibiotic.