Final answer:
The recommended treatment for a 22-year-old woman with frequent and painful urination and gram-negative rods cultured from her urine would likely be a course of antibiotics, such as fluoroquinolones, nitrofurantoin, cephalosporins, or a combination of trimethoprim and sulfamethoxazole.
Step-by-step explanation:
The most likely causative agent in this case is Escherichia coli, a gram-negative rod bacteria. Bacterial cystitis, which is commonly treated with antibiotics, is caused by gram-negative bacteria such as E. coli, as well as other pathogens like Proteus vulgaris, Pseudomonas aeruginosa, and Klebsiella pneumoniae. Treatment options for bacterial cystitis include fluoroquinolones, nitrofurantoin, cephalosporins, or a combination of trimethoprim and sulfamethoxazole.