What is the recommended treatment for a urinary tract infection caused by Pseudomonas aeruginosa and Klebsiella pneumoniae with a urine culture showing greater than 100,000 CFU/mL of each organism?

From the Guidelines

For a urinary tract infection caused by both Pseudomonas aeruginosa and Klebsiella pneumoniae with high bacterial counts (>100,000 CFU/mL each), the recommended treatment is a carbapenem such as meropenem 1 gram intravenously every 8 hours for 7-14 days, depending on severity, as supported by the most recent guidelines 1.

Treatment Options

• Meropenem 1 gram intravenously every 8 hours for 7-14 days
• Alternatively, piperacillin-tazobactam 4.5 grams intravenously every 6-8 hours can be effective
• For less severe infections, oral ciprofloxacin 500 mg twice daily for 7-10 days may be appropriate if susceptibility testing confirms sensitivity, as seen in the provided antimicrobial susceptibility testing results

Rationale

• Both Pseudomonas aeruginosa and Klebsiella pneumoniae are gram-negative bacteria with potential resistance mechanisms, requiring broad-spectrum antibiotics
• Pseudomonas particularly requires specific antibiotic coverage and is intrinsically resistant to many antibiotics
• Treatment should be adjusted based on culture susceptibility results when available, such as the provided results showing susceptibility to meropenem, piperacillin-tazobactam, and ciprofloxacin

Additional Considerations

• Patients should complete the full course of antibiotics even if symptoms improve
• Patients should drink plenty of fluids and follow up with repeat urine cultures after treatment to ensure complete resolution
• If symptoms worsen or don't improve within 48-72 hours, reevaluation is necessary as these organisms can cause complicated infections requiring longer treatment or different antibiotic combinations, as discussed in the guidelines 1

From the FDA Drug Label

1. 10 Complicated Urinary Tract Infections: 10 Day Treatment Regimen Levofloxacin tablets are indicated for the treatment of complicated urinary tract infections (mild to moderate) due to Enterococcus faecalis, Enterobacter cloacae, Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, or Pseudomonas aeruginosa [see Clinical Studies (14.8)].

The recommended treatment for a urinary tract infection caused by Pseudomonas aeruginosa and Klebsiella pneumoniae is levofloxacin.

• Levofloxacin is indicated for the treatment of complicated urinary tract infections due to Pseudomonas aeruginosa and Klebsiella pneumoniae.
• The MIC values for levofloxacin against Pseudomonas aeruginosa and Klebsiella pneumoniae are 0.5 and <=0.12 respectively, indicating susceptibility to levofloxacin 2.
• Combination therapy with an anti-pseudomonal β-lactam may be recommended for the treatment of Pseudomonas aeruginosa infections 2.
• It is essential to note that the treatment should be guided by the results of culture and susceptibility testing, and the patient's clinical condition should be closely monitored during therapy 2.

From the Research

Treatment Options for Urinary Tract Infections

• The urine culture shows greater than 100,000 CFU/mL of Pseudomonas aeruginosa and Klebsiella pneumoniae, indicating a complicated urinary tract infection.
• According to the provided antibiotic susceptibility test results, Pseudomonas aeruginosa is susceptible to amikacin, cefepime, ceftazidime, ciprofloxacin, gentamicin, imipenem, levofloxacin, meropenem, and piperacillin/tazobactam.
• Klebsiella pneumoniae is susceptible to amikacin, amox/clavulanic acid, amp/sulbactam, cefepime, ceftazidime, ciprofloxacin, gentamicin, imipenem, levofloxacin, meropenem, and piperacillin/tazobactam.

Recommended Treatment

• Based on the study by 3, imipenem/relebactam has potent in vitro activity against Pseudomonas aeruginosa and Klebsiella pneumoniae, including against resistant subsets.
• The study by 4 suggests that colistin is the most active antibiotic in vitro against Pseudomonas aeruginosa.
• However, the study by 5 found that piperacillin-tazobactam was not noninferior to meropenem for the treatment of bloodstream infections caused by Escherichia coli or Klebsiella pneumoniae with ceftriaxone resistance.
• The study by 6 found that the 2020 EUCAST update contributed to an increase in carbapenem prescriptions for the treatment of urinary tract infections caused by Pseudomonas aeruginosa.

Considerations

• The choice of antibiotic should be based on the susceptibility test results and the severity of the infection.
• The study by 7 highlights the need for more research on the pathogenesis of urinary tract infections caused by Pseudomonas aeruginosa.
• The treatment of urinary tract infections caused by Pseudomonas aeruginosa and Klebsiella pneumoniae requires careful consideration of the antibiotic susceptibility test results and the potential for resistance development.