Complicated urinary tract infections.

The distinction between complicated and uncomplicated urinary tract infections is usually based on the presence or absence of some abnormality in the path of urine flow. Other differences include characteristic patient profiles, usual setting, likely pathogens and their antimicrobial susceptibility, and treatment options. Complicated infections are most common in older patients, usually men with prostatic enlargement. Gram-negative bacilli are the most frequent pathogens, but Escherichia coli plays a less dominant role. Isolates from patients with complicated infections are more likely to be resistant to older antibiotics, and therapy is usually parenteral. Many complicated urinary tract infections are hospital-acquired, and are often due to indwelling urinary catheters. Resistance to antimicrobials among isolates is common in this setting. Nosocomial urinary tract infections contribute substantially to morbidity, mortality, and health care costs. Numerous effective treatment options are available for uncomplicated infections. The types of patients, predisposing factors, and organisms limit antimicrobial choices for complicated infections. Although new antibiotics offer certain advantages, final therapeutic success usually depends on resolving the disorder that predisposes the patient to infection.