What is the recommended antibiotic treatment for a diabetic patient with an uncomplicated urinary tract infection (UTI) caused by Enterobacter cloacae that is susceptible to Macrobid (nitrofurantoin)?

Treatment of UTI from Enterobacter cloacae with Nitrofurantoin in Diabetic Patients

Nitrofurantoin (Macrobid) 100 mg twice daily for 5 days is the recommended treatment for a diabetic patient with uncomplicated UTI caused by Enterobacter cloacae that is susceptible to nitrofurantoin. 1

Rationale for Nitrofurantoin Selection

Nitrofurantoin is an appropriate choice for this patient for several reasons:

• It is effective against Enterobacter cloacae when susceptibility is confirmed, as in this case
• The American College of Physicians recommends nitrofurantoin as a first-line treatment option for uncomplicated UTIs 1
• The World Health Organization endorses nitrofurantoin as a first-choice antibiotic for lower UTIs due to excellent efficacy and lower risk of resistance development 1
• Recent research shows nitrofurantoin maintains high susceptibility rates (95.6%) against common uropathogens, with only 2.3% resistance rates, significantly better than fluoroquinolones and trimethoprim-sulfamethoxazole 2

Dosing and Duration for Diabetic Patients

• Recommended dose: 100 mg twice daily 1
• Duration: 5 days is appropriate for uncomplicated UTIs in diabetic patients 3
  • A retrospective cohort study comparing 5 vs 7 days of nitrofurantoin in diabetic women with UTIs found no clinically significant difference in treatment failure rates (adjusted risk difference 1.4%, 95% CI -0.6 to 3.4) 3
  • The 5-day regimen helps reduce cumulative nitrofurantoin exposure in diabetic patients 3

Important Considerations for Diabetic Patients

1. Confirm renal function: Only use nitrofurantoin if GFR >30 mL/min 1
2. Monitor glycemic control: UTIs can worsen glycemic control in diabetic patients
3. Follow-up urine culture: Consider follow-up culture after treatment to confirm eradication, especially important in diabetic patients who are at higher risk for complicated infections
4. Watch for recurrence: Diabetic patients have higher rates of recurrent UTIs and may require longer follow-up

Alternative Options if Nitrofurantoin Cannot Be Used

If nitrofurantoin is contraindicated (e.g., poor renal function):

1. Fosfomycin: 3g single dose - effective for uncomplicated UTIs and shows good activity against Enterobacter species 1, 4

   • Research shows fosfomycin may be associated with fewer recurrences of UTI in diabetic patients compared to nitrofurantoin 4

2. Trimethoprim-sulfamethoxazole: 160/800 mg twice daily for 3 days - only if susceptibility is confirmed 1

Pitfalls and Caveats

• Do not treat asymptomatic bacteriuria in diabetic patients, as this does not improve outcomes and contributes to antibiotic resistance 1
• Avoid fluoroquinolones as first-line therapy due to increasing resistance rates (approximately 24%) and risk of adverse effects 2
• Check drug interactions: Nitrofurantoin may interact with antidiabetic medications
• Monitor for adverse effects: Nitrofurantoin can cause pulmonary and hepatic toxicity, though these serious adverse events are rare (0.001% and 0.0003%, respectively) 5
• Consider specialist consultation for complex cases with resistant Enterobacter infections if the patient does not respond to initial therapy 1

Prevention of Recurrent UTIs in Diabetic Patients

For diabetic patients with recurrent UTIs:

• Increase fluid intake
• Avoid prolonged urine retention
• Consider prophylactic antibiotics if recurrences are frequent 5, 1
• Optimize glycemic control to reduce UTI risk