What is the recommended treatment for Methicillin-Sensitive Staphylococcus Aureus (MSSA) and Klebsiella Urinary Tract Infections (UTI)?

From the Guidelines

For MSSA and Klebsiella UTIs, the recommended treatment is a combination of amoxicillin plus an aminoglycoside or a second-generation cephalosporin plus an aminoglycoside, with consideration of local resistance rates and patient-specific factors. When considering the treatment of complicated UTIs, including those caused by MSSA and Klebsiella, the European Association of Urology guidelines from 2024 provide strong recommendations 1. The guidelines suggest the use of a combination of antibiotics, such as amoxicillin plus an aminoglycoside or a second-generation cephalosporin plus an aminoglycoside, for the treatment of complicated UTIs. Some key points to consider when treating MSSA and Klebsiella UTIs include:

• The use of ciprofloxacin is only recommended if the local resistance rate is <10% and the patient does not require hospitalization 1.
• The management of any urological abnormality and/or underlying complicating factors is crucial for effective treatment 1.
• The selection of antibiotics should be guided by culture and sensitivity results, as well as local resistance patterns.
• Treatment duration and the need for initial intravenous therapy should be determined based on the severity of the infection and patient-specific factors. In general, the treatment of MSSA and Klebsiella UTIs requires careful consideration of the causative organism, local resistance patterns, and patient-specific factors, with the goal of achieving optimal outcomes in terms of morbidity, mortality, and quality of life.

From the FDA Drug Label

1.3 Uncomplicated and Complicated Urinary Tract Infections (including pyelonephritis) Cefepime Injection is indicated for uncomplicated and complicated urinary tract infections (including pyelonephritis) caused by Escherichia coli or Klebsiella pneumoniae, when the infection is severe, or caused by Escherichia coli, Klebsiella pneumoniae, or Proteus mirabilis, when the infection is mild to moderate, including cases associated with concurrent bacteremia with these microorganisms. 1.4 Uncomplicated Skin and Skin Structure Infections Cefepime Injection is indicated for uncomplicated skin and skin structure infections caused by Staphylococcus aureus (methicillin-susceptible isolates only) or Streptococcus pyogenes.

The recommended treatment for MSSA and Klebsiella UTI is:

• For MSSA UTI: No specific recommendation is provided in the label.
• For Klebsiella UTI:
  • Mild to Moderate: 0.5-1 g IV every 12 hours for 7-10 days 2
  • Severe: 2 g IV every 12 hours for 10 days 2 Note that the label does not provide a direct recommendation for MSSA UTI, but it does provide recommendations for Klebsiella UTI.

From the Research

Treatment for MSSA and Klebsiella UTI

• The recommended treatment for Methicillin-Sensitive Staphylococcus Aureus (MSSA) infections is a β-lactam antibiotic, such as cefazolin or an antistaphylococcal penicillin 3, 4, 5.
• Cefazolin is a suitable option for the treatment of MSSA infections, with studies showing a lower risk of mortality compared to nafcillin or oxacillin 5.
• For Klebsiella UTIs, the treatment options are more limited, and the use of new antibiotic drugs such as cefiderocol, meropenem-vaborbactam, ceftazidim-avibactam, and imipenem-relebactam may be considered 6.
• However, there is currently no clear guideline on the most appropriate treatment for Klebsiella UTIs, and the choice of antibiotic should be based on individual patient factors and susceptibility testing.

Antibiotic Options

• Cefazolin is a recommended antibiotic for MSSA infections, with a lower risk of mortality compared to other β-lactam antibiotics 5.
• Antistaphylococcal penicillins, such as nafcillin or oxacillin, are also effective against MSSA infections, but may have a higher risk of mortality compared to cefazolin 5.
• For Klebsiella UTIs, the use of carbapenem-based antibiotics such as meropenem-vaborbactam or imipenem-relebactam may be considered, but the choice of antibiotic should be based on individual patient factors and susceptibility testing 6.

Treatment Duration and Frequency

• The treatment duration and frequency for MSSA and Klebsiella UTIs will depend on the individual patient factors and the severity of the infection.
• Once-daily treatment options for MSSA bacteremia are not currently recommended, due to insufficient evidence to support their use 7.
• Traditional treatment regimens for MSSA infections typically involve multiple daily doses of an anti-staphylococcal β-lactam antibiotic.