Snapshot A 76-year-old woman presents to the emergency department for altered mental status. She currently lives in a nursing home and was brought to seek treatment by her daughter. She was noted to be more confused over the course of a few days and developed a fever. Her temperature is 101°F (38.3°C), blood pressure is 133/99 mmHg, pulse is 101/min, and respirations are 20/min. Physical examination is notable for being alert and oriented to self but not time or place and suprapubic abdominal pain. A urinalysis is remarkable for being leukocyte-esterase positive. Urine culture grows Escherichia coli. Introduction Classification a gram-negative bacilli Epidemiology incidence the most common cause of UTI in women Microbiology reservoir gastrointestinal tract transmission fecal-oral urethral ascension catheter aspiration properties enterotoxins heat labile increases cAMP heat stable increases cGMP shiga-like toxin inhibits the 60s ribosomal subunit, impairing protein synthesis fimbriae K-antigen (capsule) H-antigen (flagella) Associated conditions enterotoxigenic (ETEC) enterohemorrhagic (EHEC) can result in hemolytic uremic syndrome enteroinvasive (EIEC) neonatal meningitis urinary tract infection (UTI) Presentation E. coli Clinical Presentation Condition Presentation Diagnostic Studies Treatment Enterotoxigenic (ETEC) Symptoms watery diarrhea that occurs after returning from a resource-limited area Clinical diagnosis and no diagnostic studies are required Supportive treatment Enterohemorrhagic (EHEC) Symptoms bloody diarrhea no fever Physical exam abdominal tenderness Hemolytic uremic syndrome (HUS) associated with the strain O157:H7 triad acute renal failure microangiopathic hemolytic anemia non-immune mediated thrombocytopenia Sorbitol-MacConkey agar O157:H7 does not ferment sorbitol Enzyme-linked immunosorbent assay (ELISA) Polymerase chain reaction (PCR) Supportive care Antibiotics are generally not beneficial and its use has been associated with the development of HUS Enteroinvasive (EIEC) Symptoms begins as watery diarrhea and can lead to bloody diarrhea with pus the organism invades the intestinal cells to multiply intracellularly and then invade adjacent intestinal cells Sereny test Supportive care Neonatal meningitis Symptoms irritability lethargy poor tone seizures Physical exam temperature instability fever or hypothermia bulging fontanelle Lumbar puncture Ampicillin Cefotaxime or ceftazidime in ampicillin-resistant strains Urinary tract infection (UTI) Symptoms dysuria urinary frequency and urgency Urinalysis and urine culture Trimethoprim-sulfamethoxazole Fosfomycin Nitrofurantoin Clinical diagnosis and no diagnostic studies are required Supportive care