A 78-year-old male patient with CHF develops a bacterial UTI from an indwelling foley catheter. He has a known allergy to PCN and sulfonamides. What is the appropriate choice for antimicrobial therapy?

In this case, the appropriate choice for antimicrobial therapy is ciprofloxacin. Ciprofloxacin is a fluoroquinolone antibiotic that is effective against a variety of bacterial infections, including those caused by gram-negative organisms commonly associated with urinary tract infections (UTIs). Given the patient’s age and his chronic heart failure (CHF) status, ciprofloxacin is also advantageous because it has good oral bioavailability and can be dosed once or twice daily, which may help with patient compliance.

The patient's known allergy to penicillin and sulfonamides rules out amoxicillin and any related medications. While levofloxacin is another fluoroquinolone option and also effective for UTIs, the choice of ciprofloxacin may be favored based on its specific spectrum of activity, ease of administration, and established efficacy in similar cases.

Doxycycline, while it may be effective against some urinary pathogens, is not typically the first-line treatment for UTIs, especially in the context of a patient who has a high likelihood of gram-negative infections associated with catheter use. Therefore, ciprofloxacin stands out as the most suitable option in this clinical scenario.