Clostridium Genus

Question 1

Clostridium Genus General Info

Answer 1

• Gram Positive
• Rods
• Spore forming (deform shape)
• Obligate Anaerobes
• Soil, Intestines, Surface water

Question 2

Clostridium Tetani

Answer 2

• Gram positive rod
• Spores bulge out
• Obligate anaerobe

Question 3

C. Tetani Cultivation

Answer 3

• Dextrose-blood agar show grey colonies with no hemolysis
• Meat boullion (holman), no meat breakdown, no gas produced (vs gas gangrene)

Question 4

C. Tetani Virulence Factors

Answer 4

Neurotoxins
- Tetanospasmin: heat-labile, blocks release of inh gaba/glycine = muscle spasms & spastic paralysis (A/B)
- Tetanolysin: hemolysis & cardiotoxic effects
- Spore formation, toxin travels retrograde from axon to CNS

Question 5

C. Tetani Diseases

Answer 5

Tetanus
- Generalized
- Localized
- Cephalic (stroke-like)
- Neonatal
- Maternal

Question 6

Generalized Tetanus:

Answer 6

• Trismus/Lockjaw
• Risor Sardonicus (smile)
• Opisthotonus (back arch)
• Dysphagia
• Stiff neck, Apnea, Cardiac arrhythmia

Question 7

C. Tetani Treatment

Answer 7

• Human Tetanus Ig (HTIG) Antitoxin
• Vaccine: Tetanus Toxoid in DTaP

Question 8

Types of Gas gangrene Clostridia

Answer 8

• C. Perfringens
• C. Septicum (20%)
• C. Histolyticum (10-20%)
• C. Novyi A (40%)
• C. Sordelii

Question 9

C. Perfringens General

Answer 9

• Exogenous source from soil, wounds, deep necrotic wounds
• Endogenous from gut or SSI

Question 10

C. Perfringens Morphology

Answer 10

• Gram Positive
• Rod
• Obligate Anaerobe
• Encapsulated
• Double a/B-Hemolysis

Question 11

C. Perfringens Virulence Factors

Answer 11

• Toxin production (a-Toxin)
• Collagenase, Hyaluronidase, DNase, Lipases, Proteases

Question 12

C. Perfringens Toxin

Answer 12

Classified into 5 strains A-E, all producing a-Toxin
- B-Toxin (pore forming)
- ε-Toxin (trypsin act., permeability of GI wall)
- Iota-Toxin (vascular perm, necrotic)
- C. Perferingens Enterotoxin (CPE) induces electrolyte loss & is superantigen (type A)

Question 13

C. Perfringens Diseases

Answer 13

• Gas Gangrene = Clostridial Myonecrosis
• Anaerobic Cellulitis
• Necrotizing Fasciitis
• Food poisoning (CPE, A)
• Necrotizing Enteritis (B-toxin, C strains)

Question 14

C. Perfringens Treatment

Answer 14

• Removal of necrotic tissue & amputation
• Clindamycin & B-Lactam (piperacillin or tazobactam)
• Hyperbarix O2 therapy

Question 15

C. Botulinum General Info

Answer 15

• Spreads via ingestion of contaminated food with pre-formed toxin (canned)
• Infants can ingest from spores in Honey, which germinate in infant’s intestine due to unformed microbiota

Question 16

C. Botulinum Morphology

Answer 16

• Gram Positive
• Rod
• Spore forming (deforming)
• Obligate Anaerobe

Question 17

C. Botulinum Virulence Factors

Answer 17

• Botulinum toxin (A/B toxin)
• Spore formation

Question 18

Botulinum Toxin

Answer 18

Groups
- I: A, B, F
- II: B, E, F
- III: C, D
- IV: G
Group A is a Neurotoxin inh release of ACh at NMJ, Flaccid paralysis, SNARE protease, heat labile

Question 19

C. Botulinum Diseases

Answer 19

• Botulism (flaccid paralysis)
• Foodborn, Infant, Wound, Inhalation (bioweapon)

Question 20

C. Botulinum Treatment

Answer 20

• Heptavalent / Polyvalent Antitoxin
• Mechanical Ventilation

Question 21

C. Botulinum Microbiological Diagnosis

Answer 21

• Animal Inoculation
• ELISA
• Anaerobic cultivation

Question 22

C. Difficile General Info

Answer 22

• Part of Normal GI flora
• Disruption of normal flora can cause infection (clindamycin)
• Nosocomial Pathogen

Question 23

C. Difficile Morphology

Answer 23

• Gram Positive
• Spore forming
• Obligate Anaerobe

Question 24

C. Difficile Virulence Factors

Answer 24

• Toxin A (diarrhea, brush border)
• Toxin B (actin depol, pseudomembrane)
• Binary Toxin (enhances attachment)
• Spore formation

Question 25

C. Difficile Diseases

Answer 25

C. Difficile infection (CDI) - Severe Diarrhea (watery, mucoid yellow) - Pseudomembranous Colitis (sever inf. of inner colon) - Toxic Megacolon (toxins leak into blood)

Question 26

C. Difficile Treatment

Answer 26

- Discontinue previous antibiotic if possible - Oral Vancomycin cause doesnt absorb from gut - Metronidazole - Fidaxomicin (C. Difficile specific, NA synth inh.) - Fecal microbiota transplantation

Question 27

C. Difficile Microbiological Diagnosis

Answer 27

- Detection of C. Difficile in stool is not proof of infection - Detection of Toxins (A/B/Binary) from stool shows infection - GDH antigen test of stool or PCR