Bacterial Infections, Part 3 (Enteropathogenic, Pulmonary GramNeg) Flashcards
A 32-year-old man presents with a 2-day history of fever, myalgias, headache, and multiple watery stools (5-10 per day) that contain some blood. A stool smear shows leukocytes and Gram-negative curved bacilli. The patient reports drinking raw milk 7 days ago.
Campylobacter jejuni -most common cause of bacterial diarrhea in developed world; also a major cause of childhood mortality and common cause of travelers’ diarrhea (but not as common as ETEC) - curved Gram(-) rod
A man develops a sudden onset of fever, chills, non-productive cough, and chest pain. He reports that a number of cases have occurred recently in the building where he works.
Legionnaires disease (Legionellosis) Legionella pneumophila -cooling towers, water heaters, humidifiers, ventilation systems -acute onset
Sudden onset, rapidly progressive pneumonia with a characteristic thick mucoid sputum….
Klebsiella or Enterobacter -represent 10% of all nosocomial infections -GramNeg bacilli
You’re shadowing in the ER this weekend and a patient presents with fever, diarrhea, and abdominal pain in the right lower quadrant. The ER doc, thinking this might be a case that you can accurately diagnose, asks for your opinion. It’s appendicitis, but since you’ve been studying so much infectious disease, you incorrectly diagnose it as….
Yersinia Yersinia enterocolitica Fail. Yersinia features a “painful diarrhea.” The pain is often in the RLQ due to proliferation of the organism in the ileum.
A 35-year-old man presents with sudden-onset, crampy abdominal pain and watery diarrhea. He also has low-grade fever with chills, nausea, and vomiting. He ate partially cooked eggs 24 hours prior to onset.
Salmonella (Salmonella enterocolitis) Key feature is onset at 12-48 hours post-ingestion. (Compared to Staphylococcal food poisoning, which is caused by a preformed toxin and begins at 1-6 hours post-ingestion.)
A 20-year-old male, who has just returned from a trip to India, complains of fatigue and severe, unremitting, watery diarrhea which as a “rice water” appearance.
Vibrio cholerae Cholera -rice water appearance -cholera toxin binds to intestinal epithelial cells, causes increased cAMP, which leads to water secretion -labs may show hypernatremia, hypokalemia
A patient presents with diarrhea. She tells you that it started two days ago as a watery diarrhea, but is now “bloody and mucus-y.”
Shigellosis -starts as watery, but within 1-2 days the stools become small-volume with gross blood, sloughed pseudomembranes, and mucus. Pathogenesis Review Shigella are endocytosed into small bowel enterocytes. Replicating shigellae kill infected cells then spread spread to adjacent cells. Shigellae also produce Shiga toxin (exotoxin) that interferes with ribosomes, blocking fluid absorption and causing watery diarrhea.
An aggressive pneumonia associated with hospital environments, burns, urinary catheterization, cystic fibrosis, antibiotic use, diabetes, neutropenia…
Pseudonomas aeruginosa
A 50-year-old woman becomes ill about 10 days after returning from a trip to a country with questionable food handling practices, where she consumed a lot of milk and shellfish – hopefully not simultaneously. She has a variety of systemic symptoms. Pathological findings include hypertrophy of Peyer patches and ulcers oriented along the longitudinal axis of the bowel.
Salmonella (Typhoid Fever) Salmonella typhii Incubation is 10-14 days Invasion is most prominent in ileum, in areas overlying Peyers patches. Ulcers have longitudinal orientation.
You’re visiting Mexico. You start getting watery diarrhea. Uh oh. Whaddya got?
Enterotoxigenic E. coli (ETEC) ETEC adheres to intestinal mucosa, elaborates enterotoxin(s) that cause secretory dysfunction of the small bowel.
A 23-year-old student develops fever, abdominal pain, and bloody diarrhea 1-2 days after eating Taco Bell’s new Fiery Doritos Locos Taco. The patient develops oliguria, and labs show elevated serum levels of BUN and creatinine.
Enterohemorrhagic E. coli The key feature is hemolytic-uremic syndrome. Signs and symptoms include hemolytic anemia and acute kidney failure, manifested by oliguria, elevated creatinine & BUN, thrombocytopenia, purpuric skin rash.
During your Peds rotation, a hospitalized infant develops diarrhea. Your attending, Dr. Rubin, gives you a clue, saying “this organism is not invasive, and causes disease by adhering to and deforming the microvilli of intestinal epithelial cells.” What is the organism?
Enteropathogenic E. coli -major cause of pediatric diarrhea in poor tropical areas -causes sporadic outbreaks among hospitalized infants younger than 2 years
