What are the inpatient antibiotics for Proteus (Proteus mirabilis) infections?

From the Guidelines

For inpatient treatment of Proteus infections, I recommend a combination of a penicillin, such as ampicillin (2 g IV every 4 hours), or a broad-spectrum cephalosporin with an aminoglycoside, usually gentamicin (1.7 mg/kg every 8 hours), as first-line options. This recommendation is based on the American Heart Association guidelines for the treatment of infective endocarditis caused by Gram-negative bacilli, including Proteus mirabilis 1.

Key Considerations

• The choice of antibiotic should be guided by culture and sensitivity results, with consideration of the patient's renal function and potential for nephrotoxicity with aminoglycosides.
• Third-generation cephalosporins, such as ceftriaxone, have shown promise in experimental models of E coli endocarditis and may be considered as alternative options 1.
• The specific aminoglycoside used is a critical variable, and determinations of tube-dilution MBC often are necessary to guide therapy 1.

Treatment Duration and Monitoring

• Treatment duration typically ranges from 7-14 days depending on infection severity, site, and clinical response.
• Close monitoring of the patient's clinical response, renal function, and antibiotic levels (for aminoglycosides) is essential to ensure effective treatment and minimize adverse effects.

Resistance and De-escalation

• Proteus species have increasing resistance to ampicillin and first-generation cephalosporins, making broader-spectrum antibiotics necessary.
• De-escalation to narrower-spectrum antibiotics should be considered when possible to reduce resistance development and adverse effects.

From the FDA Drug Label

Meropenem for injection is indicated for the treatment of complicated skin and skin structure infections (cSSSI) due to ... Proteus mirabilis, ...

The clinical efficacy rates by pathogen are provided in Table 8

MICROORGANISMS1Meropenem for Injection n 2/N 3(%) 4 ... Proteus mirabilis11/13 (85)

Meropenem is effective against Proteus mirabilis with a clinical efficacy rate of 85% 2.

• The recommended dose of meropenem for complicated skin and skin structure infections is 500 mg given every 8 hours.
• Meropenem should be administered by intravenous infusion over approximately 15 minutes to 30 minutes.
• The use of meropenem in patients with renal impairment requires dosage adjustment based on creatinine clearance.

From the Research

Inpatient Antibiotics for Proteus

• The choice of inpatient antibiotics for Proteus infections depends on various factors, including the severity of the infection, the susceptibility of the bacteria, and the patient's medical history 3, 4, 5, 6, 7.
• Carbapenems, such as meropenem, ertapenem, and doripenem, have been shown to be effective against extended-spectrum β-lactamase (ESBL)-producing Proteus mirabilis 3.
• Piperacillin/tazobactam is also effective against Proteus infections, but its efficacy may be lower than that of carbapenems, especially against isolates with higher minimum inhibitory concentrations (MICs) 3, 5, 6.
• Meropenem has been shown to have a broad spectrum of activity against Gram-positive and Gram-negative pathogens, including ESBL-producing Enterobacteriaceae 4.
• The pharmacodynamic modeling of imipenem-cilastatin, meropenem, and piperacillin-tazobactam has been studied, and the results suggest that these antibiotics can achieve bactericidal exposures against a range of pathogens, including Proteus species 5.

Treatment Options

• Meropenem is a suitable option for the treatment of serious bacterial infections, including those caused by Proteus species 4, 7.
• Piperacillin/tazobactam is also a viable option, especially for infections caused by isolates with lower MICs 3, 5, 6.
• The choice of antibiotic should be based on the susceptibility of the bacteria, the severity of the infection, and the patient's medical history 3, 4, 5, 6, 7.

Clinical Trials

• The MERINO trial is a randomized controlled trial that aims to compare the efficacy of meropenem and piperacillin-tazobactam for the treatment of bloodstream infections caused by ESBL-producing Escherichia coli and Klebsiella spp. 7.
• The results of this trial may provide valuable information on the effectiveness of these antibiotics for the treatment of Proteus infections 7.