Clinical meaning
UTI pathogenesis involves uropathogenic E. coli (80% of uncomplicated UTIs) with P-fimbriae and type 1 pili adhesins. Uncomplicated cystitis: nitrofurantoin 100mg BID x5 days or TMP-SMX x3 days (if resistance <20%). Pyelonephritis: fluoroquinolone x7 days or IV ceftriaxone. Complicated UTI: IV antibiotics with imaging to rule out obstruction/abscess. CAUTI: remove/replace catheter + antibiotics based on culture.
Diagnosis & workup
Diagnostics & workup: - CRP and ESR for inflammatory response quantification - CBC with differential (left shift, leukocytosis, lymphopenia) - Wound/tissue/fluid cultures with Gram stain - Blood cultures x2 sets (before antibiotics) from separate sites - Procalcitonin for bacterial infection likelihood - Nucleic acid amplification testing (NAAT) for STIs, TB, viral loads - Lumbar puncture for CNS infection (meningitis, encephalitis)
Risk factors: - Broad-spectrum antibiotic exposure (C. diff risk factor) - Diabetes mellitus with impaired neutrophil function - Age extremes (<2 and >65 years with immature/declining immunity) - Immunocompromised state (HIV CD4 <200, transplant, chemotherapy) - Indwelling medical devices (central lines, urinary catheters, prosthetic joints) - Chronic liver disease with impaired immune function - Crowded living conditions (TB, meningococcal disease)