Bacterial Infections, Part 2 (Clostridial, Animal Vectors) Flashcards
An unvaccinated teenager complains of fatigue and muscle weakness since returning from summer camp three weeks ago. He came to see you today because his face “looks funny”. Physical exam reveals spastic rigidity of facial muscles with “rises sardonicus”. What pathogen is likely responsible for his symptoms?
Clostridium tetani
–rises sardonicus is the name for the fixed grin caused by spastic rigidity of facial muscles; it’s why tetanus is sometimes called “lockjaw”
A patient presents with a one day history of abdominal cramping and severe watery diarrhea. Her symptoms started yesterday afternoon, and now, almost 24 hrs later, seem to be completely improved. She denies antibiotic use or consumption of anything undercooked or unpasturized, but admits to leaving a roast on the counter to cool for several hours the day before her symptoms started. What illness does she most likely have, and how did she acquire it?
Clostridial food poisoning
–C. perfringens spores survive cooking temperatures, and proliferate when food is not refrigerated. Meats, gravies and sauces are common substrates for growth.
Besides clostridial food poisoning, what other GI illness can Clostridium perfringens cause? What accounts for the difference in pathology and symptoms?
Necrotizing enteritis, caused by C. perfringens type C, which has a different enterotoxin.
A young man presents with a wound in his leg. He states that is happened two days ago, but all of a sudden this morning it became increasingly painful, smelly, and the skin started to darken and swell. Microscopic examination shows necrosis, dissolution of cells, almost no neutrophils, and gram pos rods. What is your diagnosis?
Gas gangrene
You’re doing a surgery rotation. A patient who had abdominal surgery the previous day has developed diarrhea, fever and abdominal pain. The surgeon says he has pseudomembranous colitis. What pathogen is likely responsible?
C. difficile
A patient presents to your rural family practice clinic complaining of blurred vision, photophobia, dry mouth, difficulty swallowing, and muscle weakness especially of the neck. Your physical exam finds evidence of cranial nerve paralysis. Last time this patient came for an exam, she brought you homemade canned peaches. What illness are you worried about, and how would it cause your patient’s neurological symptoms?
Botulism
C. botulinum spores are resistant to drying and boiling, and can grow in improperly canned food. They produce a neurotoxin which causes descending paralysis (affects the cranial nerves first).
A patient, who has no medical history but recently returned from a trip to visit family in Peru, presents with fever and skeletal pain. He insists that he has “Oroya fever”. Lab work shows acute hemolytic anemia. What type of infection do you suspect, and how does it progress if untreated?
Bartonellosis (transmitted by sandflies)
Presents in a biphasic pattern, with acute hemolytic anemia (Oroya fever), followed by a dermal eruptive phase (verruga peruana)
A veterinarian presents with a two month history of recurrent fever, joint and bone pain, and other constitutional symptoms. Because of his occupation and undulant fever, you suspect what illness?
Brucellosis
You are working in a small hospital in Arizona. A man is admitted for septic shock. You notice that he has enlarged lymph nodes, especially in his groin, and remember that your Rubin’s textbook called them buboes. Examination and staining of blood samples show gram neg rods that stain more heavily at the ends. Because you studied Rubin’s so much, you know this patient could have a rare illness seen only 30-40 times per year in the US. What do you suspect, and how else could it present clinically?
Bubonic plague. Can present as bubonic plague, septicemic plague, or pneumonic plague.
