Used primarily to treat uncomplicated urinary tract infections (UTIs), especially those caused by Gram-negative bacteria like Escherichia coli. It is effective due to its stability against many beta-lactamases, making it a valuable option in areas with high antibiotic resistance. Pivmecillinam hydrochloride is a prodrug that converts to mecillinam in the body, targeting bacterial cell wall synthesis. It is commonly prescribed for cystitis in women and children, offering a narrow-spectrum alternative that helps preserve broader antibiotics for more severe infections.