What is the appropriate follow-up antibiotic for acute cystitis after treatment failure with Macrobid (Nitrofurantoin)?

From the Guidelines

For acute cystitis that has failed treatment with Macrobid (nitrofurantoin), the recommended follow-up antibiotic is typically trimethoprim-sulfamethoxazole (TMP-SMX, Bactrim) 160/800 mg twice daily for 3 days, as suggested by the most recent guidelines 1. This recommendation is based on the European Association of Urology guidelines on urological infections, which provide suggested antimicrobial therapy regimens for uncomplicated cystitis. The choice of follow-up antibiotic should consider local resistance patterns, patient allergies, and comorbidities. Some key points to consider when selecting a follow-up antibiotic include:

• Obtaining a urine culture to identify the causative organism and its antibiotic susceptibilities, as this will guide the most appropriate treatment 1.
• Considering alternative antibiotics such as fosfomycin 3 grams as a single dose, especially if local resistance patterns are a concern 1.
• Being aware of the potential for treatment failure due to resistant organisms, inadequate treatment duration, or because the infection involves the upper urinary tract (pyelonephritis) rather than just the bladder 1.
• If symptoms persist after a second antibiotic course, further evaluation with imaging studies may be necessary to rule out complications or anatomical abnormalities contributing to recurrent infections. It's also important to note that fluoroquinolones, such as ciprofloxacin, can be effective but should be reserved for cases where other UTI antimicrobials are not suitable due to concerns about promoting fluoroquinolone resistance and its association with increased rates of MRSA 1.

From the FDA Drug Label

CLINICAL STUDIES In controlled, double-blind studies of acute cystitis performed in the United States, a single-dose of fosfomycin was compared to three other oral antibiotics Treatment Arm Treatment Duration (days) Microbiologic Eradication Rate Clinical Success Rate Fosfomycin 1 630/771 (82%) 591/771 (77%) Ciprofloxacin 7 219/222 (98%) 219/222 (98%) Trimethoprim/sulfamethoxazole 10 194/197 (98%) 194/197 (98%) Nitrofurantoin 7 180/238 (76%) 180/238 (76%)

The follow-up antibiotic for acute cystitis after failure with Macrobid (nitrofurantoin) could be ciprofloxacin or trimethoprim/sulfamethoxazole, as they have shown higher microbiologic eradication rates and clinical success rates compared to fosfomycin and nitrofurantoin in the studies 2.

From the Research

Follow-up Antibiotic for Acute Cystitis after Failure with Macrobid

• The initial treatment for acute cystitis often involves antibiotics such as nitrofurantoin (Macrobid), trimethoprim-sulfamethoxazole, or fosfomycin 3.
• If the initial treatment with Macrobid fails, alternative antibiotics may be considered, including fluoroquinolones, although they are generally reserved for more invasive infections due to resistance concerns 3.
• A study comparing nitrofurantoin and trimethoprim-sulfamethoxazole for the treatment of acute uncomplicated cystitis found that a 5-day course of nitrofurantoin was equivalent to a 3-day course of trimethoprim-sulfamethoxazole 4.
• Another study evaluating empiric therapy for acute uncomplicated cystitis suggested that nitrofurantoin or first-generation cephalosporins could be effective alternatives for managing the condition, considering local resistance patterns 5.
• The effectiveness of nitrofurantoin, fosfomycin, and trimethoprim for treating cystitis can be influenced by renal function, with nitrofurantoin being less effective in patients with reduced renal function (eGFR <60 mL/min) compared to fosfomycin-trometamol 6.

Considerations for Alternative Antibiotics

• Fluoroquinolones, such as ciprofloxacin, may be considered as alternative antibiotics for acute cystitis, especially in cases where the initial treatment fails 7, 5.
• However, the use of fluoroquinolones should be judicious due to concerns about resistance and potential side effects 3, 7.
• The choice of alternative antibiotic should be guided by local resistance patterns, patient factors (such as renal function), and the specific characteristics of the infecting organism 3, 5, 6.