What are the appropriate antibiotics for a urinary tract infection caused by Gram-negative rods?

From the Guidelines

For a urinary tract infection caused by gram-negative rods, empiric treatment with fluoroquinolones like ciprofloxacin 250-500 mg twice daily for 7 days is recommended, as supported by the most recent guidelines 1.

Key Considerations

• The choice of antibiotic should be guided by local resistance patterns and adjusted based on culture results.
• Gram-negative rods in urine commonly include E. coli, Klebsiella, Proteus, and Pseudomonas species, which possess an outer membrane that makes them resistant to certain antibiotics.
• Ensure adequate hydration during treatment and complete the full course of antibiotics even if symptoms resolve quickly to prevent recurrence and resistance development.

Treatment Options

• For uncomplicated cases, trimethoprim-sulfamethoxazole (TMP-SMX) 160/800 mg twice daily for 3-5 days or nitrofurantoin 100 mg four times daily for 5-7 days can be considered, but fluoroquinolones are generally preferred due to their broader coverage 1.
• For complicated UTIs or pyelonephritis, consider broader coverage with ciprofloxacin 500 mg twice daily for 7-14 days or ceftriaxone 1-2 g daily.

Duration of Treatment

• A treatment duration of 7 days is recommended for gram-negative bacteremia from a urinary source when source control has been addressed, as supported by recent guidelines 1.
• Shorter durations may also be effective, but have not been studied, and longer durations may be necessary in certain cases, such as complicated UTIs or pyelonephritis.

From the FDA Drug Label

Levofloxacin tablets are indicated for the treatment of complicated urinary tract infections due to Escherichia coli, Klebsiella pneumoniae, or Proteus mirabilis 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 Levofloxacin tablets are indicated for the treatment of uncomplicated urinary tract infections (mild to moderate) due to Escherichia coli, Klebsiella pneumoniae, or Staphylococcus saprophyticus

The appropriate antibiotics for a urinary tract infection caused by Gram-negative rods are:

• Levofloxacin for infections due to Escherichia coli, Klebsiella pneumoniae, or Proteus mirabilis
• Levofloxacin for infections due to Enterobacter cloacae, Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, or Pseudomonas aeruginosa 2

From the Research

Treatment Options for Urinary Tract Infections Caused by Gram-Negative Rods

• The recommended first-line empiric therapies for acute uncomplicated bacterial cystitis in otherwise healthy adult nonpregnant females include a 5-day course of nitrofurantoin or a 3-g single dose of fosfomycin tromethamine 3, 4.
• Second-line options include fluoroquinolones and β-lactams, such as amoxicillin-clavulanate 3, 4.
• Current treatment options for UTIs due to AmpC- β -lactamase-producing organisms include fosfomycin, nitrofurantoin, fluoroquinolones, cefepime, piperacillin-tazobactam, and carbapenems 3, 4.
• Treatment options for UTIs due to ESBLs-producing Enterobacteriaceae include nitrofurantoin, fosfomycin, fluoroquinolones, cefoxitin, piperacillin-tazobactam, carbapenems, ceftazidime-avibactam, ceftolozane-tazobactam, and aminoglycosides 3, 4.
• For UTIs caused by carbapenem-resistant Enterobacteriaceae (CRE), treatment options include ceftazidime-avibactam, colistin, polymixin B, fosfomycin, aztreonam, aminoglycosides, and tigecycline 3, 4, 5.
• For UTIs caused by multidrug-resistant (MDR)-Pseudomonas spp., treatment options include fluoroquinolones, ceftazidime, cefepime, piperacillin-tazobactam, carbapenems, aminoglycosides, colistin, ceftazidime-avibactam, and ceftolozane-tazobactam 3, 4, 5.

Considerations for Treatment

• The use of fluoroquinolones for empiric treatment of UTIs should be restricted due to increased rates of resistance 3, 4.
• Aminoglycosides, colistin, and tigecycline are considered alternatives in the setting of MDR Gram-negative infections in patients with limited therapeutic options 3, 4, 5.
• An interdisciplinary approach, including urologists, microbiologists, and infectious disease physicians, is strongly advised to ensure prudent use and to avoid the development of resistance to novel anti-infective substances 5.