Which oral option is appropriate to treat a urinary tract infection caused by persisting Enterococcus faecalis?

The appropriate oral option to treat a urinary tract infection caused by Enterococcus faecalis is amoxicillin. This bacterium is part of the normal flora but can cause infections, especially in certain conditions. Enterococcus faecalis is usually susceptible to penicillins, including amoxicillin, which makes it a viable option for treating infections caused by this organism.

Amoxicillin works well against Enterococcus faecalis due to its ability to inhibit bacterial cell wall synthesis, effectively treating the infection. In contrast, cephalexin and cefdinir are cephalosporins, which are generally less effective against Enterococcus species. Vancomycin, while effective against certain resistant strains, is typically reserved for more severe infections and is not the first choice for uncomplicated urinary infections unless there's a specific reason to suspect resistance or severe disease. Therefore, amoxicillin is the most appropriate choice in this scenario.