Which agent should be avoided in the treatment of a urinary tract infection caused by E. coli?

In the treatment of urinary tract infections (UTIs) caused by E. coli, selecting the appropriate antibiotic is crucial. Moxifloxacin, which is the correct choice to avoid, is primarily used for respiratory infections and does not achieve effective concentrations in the urine. This limits its utility for treating UTIs, where high urinary concentrations of the antibiotic are necessary to effectively eliminate the infection-causing bacteria.

Levofloxacin and Cotrimoxazole are both well-established options for treating UTIs, as they are effective against E. coli and are able to concentrate in the urine. Nitrofurantoin, while also effective for uncomplicated UTIs, is specifically indicated for conditions where its unique mechanism can be beneficial, making it a valid choice for E. coli infections as well.

Therefore, moxifloxacin's pharmacokinetic properties render it unsuitable for this specific indication, underscoring why it should be avoided in the treatment of UTIs caused by E. coli.