Treatment Failure of First-Line Therapy for Acute Cystitis
If first-line antibiotic therapy for acute cystitis fails, obtain a urine culture with antimicrobial susceptibility testing and retreat with a 7-day course of a different antibiotic class based on culture results. 1
Defining Treatment Failure
Treatment failure occurs when symptoms do not resolve by the end of the initial antibiotic course or recur within 2 weeks after completing treatment. 1 There is no universally agreed-upon definition, but failure may result from clinical persistence of symptoms, microbiological persistence of bacteria, or both. 2
Immediate Steps When First-Line Therapy Fails
1. Obtain Urine Culture and Susceptibility Testing
- Always perform urine culture with antimicrobial susceptibility testing before initiating second-line therapy in patients whose symptoms persist or recur within 2-4 weeks. 2, 1
- This is critical for identifying resistant organisms and guiding appropriate antibiotic selection. 2
- Continued documentation of cultures during symptomatic periods helps establish a baseline and allows for tailoring therapy based on bacterial sensitivities. 2
2. Retreat with Culture-Directed Therapy
- Use a 7-day course of a different antibiotic class based on susceptibility results, rather than the shorter 3-5 day courses used for initial uncomplicated cystitis. 1
- The longer duration (7 days versus 3-5 days) is recommended specifically for treatment failures. 1
Second-Line Antibiotic Options
If Culture Shows Susceptibility:
Fluoroquinolones (if not used initially):
- Ciprofloxacin 500 mg twice daily for 7 days 3
- Levofloxacin or ofloxacin are alternatives 4
- Reserve fluoroquinolones for situations where first-line agents cannot be used due to resistance or allergy. 4
Oral β-lactams (if susceptible):
- Amoxicillin-clavulanate, cefdinir, cefaclor, or cefpodoxime-proxetil for 7 days 3, 4
- These have generally inferior efficacy compared to first-line agents but may be necessary based on susceptibility patterns. 4
Cephalosporins:
- Cefadroxil 500 mg twice daily or cephalexin can be used if local E. coli resistance is <20%. 1
If Culture Shows Multidrug Resistance:
For oral antibiotic-resistant organisms:
- Consider culture-directed parenteral antibiotics for as short a course as reasonable, generally no longer than 7 days. 2
- Options include ceftriaxone, aminoglycosides, or other parenteral agents based on susceptibility. 5, 6
Special Considerations
Risk Factors for Treatment Failure:
While you should not routinely adjust treatment based on these factors alone, be aware that the following increase risk of failure: 2
- Older age
- Diabetes mellitus
- Immunosuppression
- Pregnancy
Consider Alternative Diagnoses:
- If there is lack of correlation between microbiological data and symptomatic episodes, diligently consider alternative or comorbid diagnoses. 2
- Persistent symptoms despite appropriate antibiotic therapy may indicate conditions other than bacterial cystitis.
Treatment Algorithm for First-Line Failure
- Obtain urine culture with susceptibility testing 1
- Assess for complications (fever, flank pain suggesting pyelonephritis; consider imaging if recurrent failures) 2
- Select second-line agent based on culture results:
- Ensure 7-day duration (not the shorter 3-5 day courses used initially) 1
Common Pitfalls to Avoid
- Do not empirically retreat with the same antibiotic class that failed initially without culture guidance. 1
- Do not use shorter 3-5 day courses for treatment failures; extend to 7 days. 1
- Do not delay obtaining urine culture in patients with treatment failure, as this is essential for guiding appropriate therapy. 2, 1
- Do not assume treatment failure is always due to resistance; consider alternative diagnoses if cultures do not correlate with symptoms. 2
- Avoid using fluoroquinolones as routine first-line therapy to preserve them for treatment failures and more serious infections. 4