Chapter 139: Urinary Tract Infections

KEY CONCEPTS

• Urinary tract infections (UTIs) can be classified as uncomplicated and complicated. Uncomplicated refers to an infection in an otherwise healthy, premenopausal female who lacks structural or functional abnormalities of the urinary tract. Most often complicated infections are associated with a predisposing lesion of the urinary tract; however, the term may be used to refer to all other infections, except for those in the otherwise healthy, premenopausal adult female.

• Recurrent UTIs are considered either reinfections or relapses. Reinfection usually happens more than 2 weeks after the last UTI and is treated as a new uncomplicated UTI. Relapse usually happens within 2 weeks of the original infection and is a relapse of the original infection because of unsuccessful treatment of the original infection, a resistant organism, or anatomical abnormalities.

• The majority (75%-90%) of uncomplicated UTIs are caused by Escherichia coli and the remainder are caused primarily by Staphylococcus saprophyticus, Proteus spp., and Klebsiella spp. Complicated infections may be associated with other gram-negative organisms and Enterococcus faecalis.

• Symptoms of lower UTIs include dysuria, urgency, frequency, nocturia, and suprapubic heaviness, whereas upper UTIs involve more systemic symptoms such as fever, nausea, vomiting, and flank pain.

• Significant bacteriuria has been defined as bacterial counts of greater than 10⁵ organisms (colony-forming unit [CFU])/mL (10⁸ CFU/L) of a midstream clean catch urine. However, this is too general and significant bacteriuria in patients with symptoms of UTI may be defined as greater than 10² organisms (CFU)/mL (10⁵ CFU/L).

• The goals of treatment of UTIs are to eradicate the invading organism(s), prevent or treat systemic consequences of infections, prevent the recurrence of infection, and prevent antimicrobial resistance.

• Uncomplicated UTIs can be managed most effectively with short-course therapy (3 days) with either trimethoprim–sulfamethoxazole, one dose of fosfomycin, or 5 days of nitrofurantoin. Fluoroquinolones should be reserved for suspected pyelonephritis or complicated infections.

• When choosing appropriate antibiotic therapy, practitioners need to be cognizant of antibiotic resistance patterns, particularly to E. coli. Trimethoprim–sulfamethoxazole has diminished activity against E. coli in some areas of the country, with reported resistance in some areas greater than 20%.

• Acute bacterial prostatitis can be managed with many agents that have activity against the causative organism. Chronic prostatitis requires prolonged therapy with an agent that penetrates the prostatic tissue and secretions. Therapy with fluoroquinolone or trimethoprim–sulfamethoxazole is preferred for up to 6 weeks.

BEYOND THE BOOK

EY, a 28-year-old pregnant female presents to her OB clinic for a routine week 18 appointment. Her past medical history is unremarkable except for seasonal allergies. In the clinic, she is hemodynamically stable with a BP 130/72 mm Hg, HR 78 BPM, RR 16, and temperature 97.5°F (36.4°C). Her home medications ...