C. Diff

Question 1

What is c. diff?

Answer 1

An organism first described in 1935
➢ It was isolated from feces of normal infants and
named Bacillus difficilis due to difficulty of isolation
➢ Recognized as a pathogen in 1970s
➢ Gram-positive, spore forming bacteria
➢ Anaerobic, motile. Show optimum growth on blood agar
Rod-shaped bacteria
➢ Under SEM, they appear as long, irregular
cells with a bulge at their terminal ends
➢ Present in 2–5% of the healthy adult population

Question 2

Under stress it produces

Answer 2

Under stress, C. difficile cells produce spores that
can resist extreme conditions that other bacteria
cannot tolerate

Question 3

How does it spread?

Answer 3

➢ Diarrhoea is an efficient method of spreading
spores of C. difficile

➢ Spores can be spread by hands that touch contaminated surfaces

Question 4

Risks of CDI

Answer 4

Previous hospitalisation
➢ Underlying disorder
➢ Age (>65 years)
➢ Use of antibiotics (+++)

Question 5

Pathogenesis of C. Diff

Two Toxins

Answer 5

Enterotoxin (Toxin A):

• Cytotoxin (Toxin B):

Question 6

What does cytotoxin do?

Answer 6

Aggravate inflammation

Question 7

What does enterotoxin do?

Answer 7

Toxin A binds to the brush border of the intestine
causing inflammation via recruitment of neutrophils.
This leads to the disruption of cell-cell junctions
resulting in watery Diarrhoea.

Question 8

Symptoms of C. Diff?

Answer 8

Watery smelling Diarrhoea, greater than 3 times per 24 hours, lower
abdominal pain, low grade fever, nausea…
* Inflammatory Diarrhoe

Pseudomembranous colitis: Fulminant colitis,
Diarrhoea, diffuse abdominal pain, fever, abdominal
distention, marked leucocytosis…
It is an invasive disease that can cause sepsis,
bowel perforation and toxic megacolon.

Question 9

Definition of CDI

Answer 9

A case definition of CDI should include the presence of clinical symptoms
(usually Diarrhoea) and a stool test result positive for C. difficile toxins, or
colonoscopy findings demonstrating pseudomembranous colitis

Question 10

Sequence of events leading to C. Diff?

Answer 10

Alteration of the normal gut flora
➢ Nosocomial infection by C. difficile
➢ Growth and production of toxins
➢ Tissue damage by toxin A, exacerbated by toxin B
➢ Diarrhoea and colitis

Question 11

How do we diagnose C. Diff?

Answer 11

Presence of toxins: Nucleic Acid Amplification Tests (NAATs) (such as
PCR)
➢ Glutamate Dehydrogenase (GDH) screening test for C. difficile (lower
sensitivity than NAATs)
➢ ELISA can be performed to reinforce results of the previous tests
➢ Visualisation of the pseudomembranes

Question 12

Management and Treatment of C-Diff

Answer 12

Infection control
Antimicrobrial therapy and surgery

Question 13

How do we provide infection control?

Answer 13

Rapid diagnostic testing
➢ Patient isolation
➢ Chlorine-releasing agents or a sporicidal product, gaseous hydrogen
peroxide and, more recently, UV decontamination!

Question 14

How do we provide antimicrobiral therapies/surgery?

Answer 14

Antimicrobial therapy and surgery
➢ In about 20 % of patients with CDI, infection resolves within 2-3 days
of discontinuing the antibiotic that the patient is taking.
➢ Metronidazole, Vancomycin
➢ Fidaxomicin
➢ Abdominal colectomy (Fulminant CDI)!!
➢ Faecal microbiota transplantation (FMTh

Question 15

What measures do we use to reduce incidences?

Answer 15

Accurate and rapid diagnosis
➢ Appropriate treatment option
➢ Implementation of enteric precautions for symptomatic patients
➢ Reinforcement of hand disinfection
➢ Reinforcement of environmental disinfection
➢ A restrictive antibiotic policy