Prunuske- C. Diff Case Study Flashcards
1
Q
What is the prevalence of c. diff?
A
- 500,000 Americans a year die from C. difficile infections (CDI)–many are acquired while in the hospital
- C. diff- transmitted fecal-oral route and hospital workers and devices (fomite) may be intermediaries (nosocomial infection)
- Acquired through the ingestion of endospores
- Increase in incidence and severity possibly due to the emergence of more virulent strains like B1/NAP1/027, which produce more toxin as well as binary toxin
2
Q
What are the risk factors for CDI?
A
- Carriers: 5-15% of adults, 84% of infants, and 57% of individuals in long term care facilities
- Taking an antimicrobial or antineoplastic (anti-cancer drug–kill rapidly growing cells, bacteria fall into that category) in the last 2 months: disease has been reported following 1 dose of antibiotics. **Virtually every antibiotic is associated but broad spectrum are a particular concern.
- Antibiotics diminish healthy bacteria allowing C. diff to multiply and begin producing toxins
- Gastric acid suppression- proton pump inhibitor (Reduce stomach acid level, more likely to develop infections b/c acidic environment helps to sterilize what’s coming in)
- Hospitalization (one of most common nosocomial infection)
- Immunocompromised or elderly individuals
**Diminish healthy bacteria, which allows C. diff to multiply and become toxic
3
Q
Why do c. diff infections frequently reoccur?
A
- Disruption of normal flora
- Acquisition of c. Diff –>some people are just colonized but don’t become infected
- Others get diarrhea
- Some people resolve
- Additional antibiotics make it worse
4
Q
What are the symptoms associated with C. Diff?
A
- Mild disease: Present with fever, abdominal pain, watery diarrhea, and dehydration
- Diarrhea is a key clinical feature- 3 or more loose stools for 1-2 days with no blood present, watery
5
Q
What is Pseudomembranous colitis?
A
- Severe complications include perforation of colon, dehydration, death
- Sepsis- inflammation leading to decrease in blood volume, interferes with organ function and can cause shock/death
- Toxic megacolon becomes so swollen creating pressure on lungs making breathing difficult, colon relaxes, becomes so swollen makes breathing difficult
6
Q
What are differential diagnosis?
A
- Diarrhea can be side effect from many antibiotics
- Watery diarrhea is often caused by viruses (rotavirus, Norovirus) Bacteria (E. coli 157:H7, Vibrio cholerae, Campylobacter, Salmonella, Shigella, Yersinia, and Clostridium difficile)
Protozoan (Giardia, Cryptosporidium, and Cyclospora) - Most of these infections are self-limiting and not life-threatening, but knowing cause is critical for choosing the correct antimicrobial
7
Q
What are the signs for a positive c. diff diagnosis?
A
- Positive stool test for toxin (usually 3 samples)
- Increased WBC>15,000 cells/mm3
- Direct visualization by sigmoidoscopy of pseudomembranous colitis
8
Q
What is ELISA?
A
- (enzyme-linked immunosorbent assay) to test for Toxin A and B, some strains are A-negative, B-positive
- If target substance is present in immobilized sample then peroxidase enzyme
generates purple color or can use fluorescence to detect toxin—only stable for 2hrs - ELISA has low sensitivity (60-80%) so recommending using nucleic acid amplification tests for toxin genes (NAA)–PCR primers specific to toxin used to amplify for toxin
**GDH is more sensitive but less specific, other organisms may give a positive result
9
Q
What are the components of pseudomembranous colitis?
A
Neutrophils, dead epithelial cells, and inflammatory debris
10
Q
What type of bacteria is c. diff?
A
Anaerobic, gram-positive rod, difficult to culture RECOGNIZE IMAGE
11
Q
What allows for the stability of c. diff (spore life cycle)?
A
- Clostridium form endospores–allows for stability outside of the host in the soil.
- Assymetrical cell division, forms sporangium, sporangium forms forespore, produces dense coat surrounding endospore. Creates free spore. Germination converts spore back to vegetative cell.
- Produces more toxins than any other bacterial genius.
12
Q
What is the pathology of c. diff?
A
- Normal microbiome suppresses C.diff growth
- If microbiome is killed C. diff activated, toxins expressed
- Both exotoxin A and exotoxin B bind receptors SPECIFICALLY in the colon walls and are glucosyltransferases that glucosylate RhoGTPase leading to the depolymerization of actin and death of enterocytes.
- Toxin A (enterotoxin) activates the inflammatory cascade and disrupts the intercellular tight junctions causing fluid secretion, mucosal injury, edema, and inflammation.
- Toxin B (cytotoxin) disrupts the cytoskeleton, leading to mucosal injury and activation of the inflammatory cascade.
- Inflammation results in fever, watery diarrhea, increase in white blood cells
13
Q
How do you prevent the spread of c. diff?
A
- Some of the EPA approved hospital disinfectants do not kill C. diff spores even though they said they did on the labels
- Alcohol-based disinfectants are not effective against spore forming bacteria.
14
Q
What is decontamination?
A
Occurs prior to sterilization doesn’t remove microbes but removes chemicals, radioactivity to make safe to handle
15
Q
What is sterilization?
A
DESTROYS all living organisms, viruses, and endospores so they are no longer able to reproduce
