Snapshot A 27-year-old man presents to the urgent care clinic for diarrhea. His symptoms began approximately 2 days ago. His symptoms are associated with abdominal pain, malaise, and fatigue. He denies the presence of blood or pus in the stool. He states he returned to the United States 1 week ago from his trip to Ecuador. Physical examination is notable for mild abdominal tenderness upon palpation but there is no appreciable hepatosplenomegaly or skin changes. He is recommended symptomatic treatment. (Traveler's diarrhea by ETEC) Introduction Classification gram-negative bacteria Escherichia coli Klebsiella Proteus mirabilis Enterobacter Serratia Shigella Salmonella Enterobacteriaceae Enterobacteriaceae Organism Microbiology Associated Conditions Treatment E. coli Reservoir gastrointestinal and urinary tract Transmission fecal-oral urethral ascension catheter aspiration Labs lactose fermenting β-hemolytic Properties enterotoxins heat labile, which increases cAMP heat stable, which increases cGMP fimbriae K-antigen (capsule) H-antigen (flagella) Diarrhea enterotoxigenic (ETEC) causes traveler's diarrhea, which is a watery diarrhea enterohemorrhagic (EHEC) causes bloody diarrhea secretes Shiga-like toxin, which can lead to hemorrhagic colitis hemolytic uremic syndrome associated with E. coli O157:H7 enteroinvasive (EIEC) causes bloody diarrhea (with pus and fever) Newborn meningitis irritability bulging fontanelle Urinary tract infection (UTI) dysuria, urinary frequency, and urinary urgency Diarrhea ETEC supportive treatment EHEC supportive treatment monitoring of hemolytic uremic syndrome, which is also managed with supportive treatment EIEC supportive Newborn meningitis ampicillin third-generation cephalosporin with gentamicin in ampicillin-resistant strains Urinary tract infection fluoroquinolone, trimethoprim/sulfamethoxazole (TMP-SMX), or nitrofurantoin K. pneumoniae Labs lactose fermenter Properties has a capsule and is nonmotile Pneumonia currant-jelly sputum typically seen in patients with underlying lung disease or alcohol use disorder UTI dysuria, urinary frequency, and urinary urgency typically hospital-acquired Typically with a 3rd generation cephalosporin P. mirabilis Labs splits urea into NH3 and CO2 indole negative non-lactose fermenting Properties urease positive motile UTI dysuria, urinary frequency, and urinary urgency urine pH is basic (elevated) due to producing NH3 Sepsis TMP-SMX Ampicillin S. dysenteriae Reservoir humans Transmission fecal-oral Labs non-H2S producing non-lactose fermenting never a part of the normal intestinal flora Properties non-motile invades the small intestine but not the lamina propria produces Shiga toxin acts on the 60s ribosomal subunit of the intestinal epithelia, impairing protein synthesis and causing intestinal damage Diarrhea bloody with blood and pus (similar to EHEC) Fluoroquinolones Azithromycin Ceftriaxone S. typhi Reservoir humans Transmission fecal-oral Labs H2S non-lactose fermenting Properties motile capsule patients with an absent or non-functioning spleen are at high risk of infection facultative intracellular can live in macrophages and in the gallbladder Typhoid fever fever hepatosplenomegaly rose abdominal spots abdominal pain Osteomyelitis seen in patients with sickle cell disease Ceftriaxone Meropenem Fluoroquinolone TMP-SMX Ampicillin