Chapter 20: Infectious Diseases Affecting the Gastrointestinal Tract- Part 2 Flashcards
Shigellosis classic symptom
Dysentery (bloody diarrhea)
Other symptoms of shigellosis
Headache Vomiting Fever Stiff neck Convulsions Joint pain
Shigellosis is commonly ___ for infants in developing countries
Fatal
Causative agent (s) of shigellosis
Four species of Shigella S. flexnuri S. boydii S. sonnei S. dysenterriae (All cause shigellosis)
S. dysenteriae is ____ encountered in the US
Rarely
S. dysenteriae produces..
Potent A-B toxin
Shiga toxin
The shiga toxin acts much like a ______ toxin and is associated with…
Cholera
Fatal hemolytic uremic syndrome
What accounts for the blood in diarrhea in shigellosis?
Inflammatory response
First step in shigellosis pathogenesis
Shigellas are taken up by M cells and transported beneath epithelium. Macrophages take up shigella, die and release the bacteria
Second step in shigellosis pathogenesis
The bacteria enter the inferior and lateral aspects of the epithelial cells by inducing endocytosis. The endoscopes are quickly lysed, leaving the shigella free in the cytoplasm
Third step in shigellosis pathogenesis
Actin filaments quickly form a tail, pushing the shigella into the next cell
Fourth step in shigellosis pathogenesis
Shigellas multiply in the cytoplasm and the infection extends to the next cell
Last step in shigellosis pathogenesis
Infected cells die and slough off. Intense response of acute inflammatory cells (neutrophils), bleeding and abscess formation
Shigellosis source of transmission
Human, Fecal-oral
Are shigellosis bacteria easily killed by stomach acid?
No so they have a low infecting dose, as few as 20 organisms!
Transmission of shigellosis occurs most often as a result of..
Overcrowding
- Also daycares and homosexual men
- Contaminated water
Shigellosis is controlled by..
Sanitary measures and surveillance of food handlers and water supplies
Is there a vaccine for shigellosis?
No
Most important treatment of shigellosis is….
Fluid and electrolyte replacement
_________ are often used to shorten duration of symptoms of shigellosis
Antimicrobials
Antimicrobials can also be used to..
Shorten time that bacteria is discharged in feces
___ % of Shigella species are resistant to antibiotics of choice
20
________ used to be the drug of choice for shigellosis but now it is…
Ampicillin
Newer penicillins or Ciprofloxacin
Clostridium Difficile signs and symptoms
Diarrhea commencing in late antibiotic therapy or even after therapy has stopped
Severe cases of C diff exhibit..
Abdominal cramps, fever and leukocytosis
With C diff, the colon is inflamed and gradually..
Sloughs off loose, membrane like patches called pseudomembranes
If c diff is not stopped…
Perforation of the cecum and death can result
C diff causative agent
Clostridium difficile (gram-positive endospore forming rod)
C diff is able to superinfection the large intestine when…
Drugs hace interrupted the normal biota
C diff produces _ and _ enterotoxins
A
B
A and B enterotoxins cause..
Necrosis in the large intestine
C diff are now known to cause a condition called…
Pseudomembranous colitis
C diff is a major cause of diarrhea in…
Hospitals (community - acquired infections)
Uncomplicated cases of C diff respond to…
Withdrawal of antibiotics and replacement therapy for lost fluids and electrolytes
More severe cases of C diff are..
Treated antibiotics for several weeks until the intestinal biota return to normal
Vancomycin
Fidaxomciin
New treatment techniques of C diff
Vaccination (toxoid, not approved yet)
Probiotics
Fecal transplant
Restoration of normal biota by ingestion of a mixed culture of lactobacilli and yeasts
Vancomycin
Cell wall synthesis inhibitor for gram +
Fidaxomicin
Nucleic acid synthesis inhibitor especially effective for clostridium
