Treatment of UTIs Sensitive to Aztreonam
For urinary tract infections sensitive to aztreonam, the recommended treatment is 500 mg to 1 g intravenously every 8 to 12 hours for moderately severe infections, with therapy continuing for at least 48 hours after the patient becomes asymptomatic. 1
Dosing Considerations
Aztreonam Dosing
- For uncomplicated UTIs: 500 mg IV every 8-12 hours
- For complicated UTIs: 1 g IV every 8-12 hours
- For severe systemic infections: 2 g IV every 6-8 hours 1
Duration of Therapy
- Generally 7-14 days for complicated UTIs 2
- Continue treatment for at least 48 hours after symptom resolution 1
- For men, 14 days when prostatitis cannot be excluded 2
- A shorter duration (7 days) may be considered when the patient has been afebrile for at least 48 hours 2
Dosage Adjustments
- For renal impairment (CrCl 10-30 mL/min): Halve the dose after initial loading dose 1
- For severe renal failure (CrCl <10 mL/min): Give maintenance dose of one-fourth the usual initial dose 1
- For elderly patients: Consider renal function assessment and appropriate dosage modifications 1
Clinical Considerations
Indications for Aztreonam
- Particularly valuable for gram-negative infections, including those caused by:
- Escherichia coli
- Klebsiella pneumoniae
- Proteus mirabilis
- Pseudomonas aeruginosa
- Enterobacter species
- Serratia marcescens 1
Complicated UTI Management
Consider underlying factors that may complicate treatment:
- Urinary tract obstruction
- Foreign bodies
- Incomplete voiding
- Vesicoureteral reflux
- Recent instrumentation
- ESBL-producing organisms
- Multidrug-resistant organisms 2
For complicated UTIs with systemic symptoms, other recommended options include:
- Amoxicillin plus an aminoglycoside
- A second-generation cephalosporin plus an aminoglycoside
- An intravenous third-generation cephalosporin 2
Catheter-Associated UTIs
- Remove indwelling catheters if present 3
- Catheterization duration is the most important risk factor for developing catheter-associated UTIs 2
- Signs of catheter-associated UTI include new onset of fever, altered mental status, flank pain, and pelvic discomfort 2
Important Caveats
- Aztreonam has no activity against gram-positive or anaerobic organisms 1
- For suspected mixed infections, combine aztreonam with agents active against gram-positive or anaerobic bacteria 1
- Concurrent therapy with other antimicrobials is recommended before the causative organism is known in seriously ill patients 1
- Avoid concurrent use with beta-lactamase-inducing antibiotics (e.g., cefoxitin, imipenem) due to potential antagonism 1
- Fluoroquinolones should not be used for empirical treatment of complicated UTIs in patients from urology departments or when patients have used fluoroquinolones in the last 6 months 2
Follow-up
- Clinical response should be assessed within 48-72 hours 3
- If symptoms persist or recur within 2 weeks, perform a repeat urine culture and select a different antibiotic class 3
- For recurrent infections, consider underlying structural abnormalities 3
Aztreonam has demonstrated high efficacy in treating UTIs caused by multidrug-resistant gram-negative bacteria, with bacteriologic cure rates of 96-98% reported in clinical studies 4.