T14: Toxin Associated infections

Question 1

Differentiate between an exotoxin and an endotoxin

Answer 1

Endotoxin= not secreted. Exotoxin= Secreted

Question 2

List 4 examples of exotoxins

Answer 2

1. Enterotoxins
2. Neurotoxins
3. Cytotoxins
4. Superantigens (pyrogenic exotoxins)

Question 3

What do pyrogenic exotoxins do?

Answer 3

Massive stimulation of the immune system

Question 4

Describe 2 effects of exotoxins

Answer 4

1. Damage cell wall/ membrane

2. Affect intracellular processes/ structures

Question 5

A-B Toxins

• What type of toxins are these? (endo or Exo)
• What do A and B stand for?
• List 5 examples of A-B toxins

Answer 5

• Exotoxins
• A= active component, B= binding component
• Cholera, Diphtheria, Anthrax, Pertussis, Shigella, S. aureus

Question 6

State whether this refers to endo or exotoxin:

- component of Gram - cell wall

Answer 6

Endotoxin

Question 7

State whether this refers to endo or exotoxin:

- Gram + and Gram -

Answer 7

Exotoxin

Question 8

State whether this refers to endo or exotoxin:
- Lipid and polysaccharides (core or variable) are responsible for the toxic activity and causes systemic effects due to immune system stimulation

Answer 8

Endotoxin

Question 9

How do endotoxins work?

Answer 9

Endothelial damage» fibrinolysis» vascular permeability» vasodilation
DIC» septic shock

Question 10

DIPHTHERIA: Corynebacterium diphtheriae

• How is it spread? (airborne, contact, droplet, etc.)
• How is the diagnosis made?
• How do we manage it?

Answer 10

• Droplet spread
• Dx on culture
• Give anti-toxin (low access in SA), penicillin + supportive management

Question 11

Name the toxin that:

Has high affinity for heart and neurological structures

Answer 11

Diphtheria

Question 12

Name the toxin that:

Classically presents as Pharyngitis with grey-white membrane

Answer 12

Diphtheria

Question 13

What do we give to prevent Diphtheria at 6w, 10w, 14w

Answer 13

DTap/ IPV/Hib

Question 14

At which ages do we give Td (Diftavax) booster

Answer 14

6 + 12 years

Question 15

Anthrax (Bacillus anthracis) has a toxin complex consisting of 3 proteins- what are these and what of they do?

Answer 15

1. Protective antigen- bings to macrophage receptor
2. Oedema factor- blocks adenyl cyclase
3. Lethal factor- vascular permeability

Question 16

There are 3 types of anthrax presentations, depending on the mode of transmission. Explain these presentations

Answer 16

1. Respiratory anthrax- inhalation of spore/ wool fibers» causes pulmonary hemorrhage and hemodynamic collapse (resp failure)
2. GIT anthrax: ingestion of contaminated meat from animals that dies of anthrax» hemorrhagic diarrhea
3. Cutaneous anthrax» inoculation of skin» malignant pustule. 10% fatal- spread to the blood

Question 17

Describe the following pertaining anthrax

1. Dx
2. Rx
3. Prevention

Answer 17

1. Inform lab (contanimants)
2. Penicillin, doxycycline, ciprofloxacin
3. Vaccinate animals and give toxoid in high-risk occupations- vets/ leather or wool industry

Question 18

Name the species that cause gad gangrene

Answer 18

Clostridium perfrigens
Clostridium septicum
Clostridium histolyticum

Question 19

What is the source of clostridium spp. and how does it get to the body?

Answer 19

Soil, human and animal feces and it infects contaminated wounds with poor blood supply and severe tissue damage

Question 20

Name the clostridial toxins that are :

1. Cytotoxic
2. Cause tissue breakdown

Answer 20

1. Lecithinase

2. Hyaluronidase, collagase, proteinases

Question 21

Due to the rapid spread of infection in gas gangrene, how do patients present?

Answer 21

With acute pain

Question 22

Describe the sequelae of toxemia of clostridium (in gas gangrene) species

Answer 22

Toxemia» massive hemolysis» renal failure» death

Question 23

Describe the following pertaining to gas gangrene

1. Diagnosis
2. Treatment
3. Prevention

Answer 23

1. Culture of tissue/ exudate, blood culture
2. Resus, early surgical debridement, amputation? and A/B covering gram + and -
3. Clean wounds and debride early

Question 24

BOTULISM

1. Name the cause of botulism
2. What type of exotoxin is this and how does it work?
3. What is the source of the cause of botulism?
4. Describe transmission

Answer 24

1. Clostridium botulinim
2. Neurotoxin- prevents ACh release at the NMJ
3. Spores found in the soil, animals, environment
4. Ingestion of contaminated food, wound infection with spores (IVDU)

Question 25

BOTULISM- describe the following 1. Clinical presentation 2. Therapy 3. Prevention

Answer 25

1. Symmetrical descending flaccid paralysis 2. polyvalent antitoxin, ICU, ventilation 3. Heat sterilization of food when preserved/ canned (the toxin is heat-labile)

Question 26

TETANUS 1. Name the causative organism 2. Tetanus toxin is also a neurotoxin (like botulinum toxin): Name this toxin and explain how it works 3. How does tetanus get to humans? 4. Describe the clinical picture 5. True or false: diagnosis is made by culture

Answer 26

1. Clostridium tetani 2. Toxospasmin- It blocks the normal inhibition of UMN over LMN>> causing increased tone and spastic paralysis 3. Contamination of wounds with spores from the environment (dust/ soil) >> spores germinate in the wounds with poor blood supply (anaerobic) 4. Lockjaw, muscle spasms. Sympathetic nerves: tachycardia, fluctuating Bp 5. False= culture is impossible. Dx= clinical

Question 27

TETANUS 1. Describe the management of a patient presenting with tetanus 2. What preventative measures are there in place for tetanus? 3. Name 2 types of tetanus prophylaxis 4. Describe tetanus prophylaxis for clean, minor wounds vs dirty wounds.

Answer 27

1. ICU support, give antitoxin (Ig), metronidazole, and wound debridement 2. Give TT (tetanus toxoid) to pregnant women in LEDCs, Td given at 6 + 12 yo to boost immunity. Hygienic birth practices and daily disinfection of umbilical stump 3. TIG (tetanus antitoxin) and TT (tetanus toxoid) 4. Clean, minor wounds= No TIG. TT is always given except if completed TT course and booster at 6+ 12 within the past 5 years. Dirty wounds= TIG + TT- Except if completed a course of TT and booster within the 5 past years

Question 28

TOXIC SHOCK SYNDROME 1. What kind of exotoxins are these? 2. Name the 2 causative organisms and where they work 3. What is the mechanism of these toxins? 4. And with that said - describe the clinical presentation 5. Describe the management of these patients

Answer 28

1. Pyrogenic exotoxins 2. S. aureus (enterotoxin) and Staphylococcus pyogenes (Erythrogenic toxin) 3. They are potent stimulators of T-lymphocytes >> uncontrolled cytokine release 4. Fever, conjunctivitis, headache, sore throat, vomiting and diarrhea, strawberry tongue, erythematous skin rash, hypotension, multiorgan failure, shock (Bacteraemia is rare) 5. IV fluids, supportive, removal of infected focus, antimicrobial Rx

Question 29

SCARLET FEVER 1. What is the causative organism? 2. Describe the clinical presentation 3. What treatment do you give for scarlet fever? 4. What are the complications of scarlet fever?

Answer 29

1. Group B beta-streptococcus 2. Pharyngitis and erythematous skin rash (Erythrogenic toxin) 3. Give penicillin or a macrolide 4. Peritonsillar abscess, otitis media, septicemia, myocarditis, rheumatic fever, glomerulonephritis

Question 30

CLOSTRIDIUM DIFFICILE 1. Classify this bacteria (Gram and shape) 2. In terms of clinical presentation, there is a whole range of presentations. Describe the following - Mild - Moderate - Severe - Fulminant 3. True or false- Toxin A and B independently cause disease

Answer 30

1. Gram + spore-forming bacillus 2. Mild- Diarrhea and no colitis; Moderate- Diarrhoea and colitis; Severe: moderate plus high WCC, serum Cr, Fever, hypoalbumin; fulminant: toxic megacolon 3. True

Question 31

CLOSTRIDIUM DIFFICILE 1. List 3 risk factors for clostridium difficile 2. How is C. difficile diagnosed? 3. How is C. difficile treated? 4. Describe the prevention of C. difficile

Answer 31

1. Hospitalisation; Antibiotic use (cephalosporines, fluoroquinolones, clindamycin) and old age 2. Detection of toxin and NAAT (nucleic acid detection) 3. Rx= metronidazole and if severe, vancomycin 4. Antibiotic stewardship, hand hygiene, clean environment, more clinical awareness

Question 32

WHOOPING COUGH - Name the toxins involved here - Name the causative orgnism - If a patient has whooping cough, what are your differentials? - Explain how you would go about proving the diagnosis objectively - Describe the management

Answer 32

- Tracheal cytotoxin and pertussis cytotoxin - Bordetella pertussis - Viral: adenovirus, parainfluenza, RSV, mycoplasma pneumonia - I would need to inform labs about Bodertella (special media) after taking a nasopharyngeal swab. Some labs do PCR - Oxygen, ventilation, IV rehydration, and 14 days of erythromycin (or azithromycin or clarithromycin) It is a notifiable disease

Question 33

BORDETELLA PERTUSSIS - What are the complications of Bordetella pertussis - What precautions do you take for pertussis? - Explain how PEP is given in: asymptomatic vs coughing contacts - When are we at the highest risk for pertussis? - Explain prevention - What does DTap-IPV/Hib protect against?

Answer 33

- Bordetella pneumonia, hypoxia encephalopathy, seizures, secondary bacterial infections (OM, pneumonia). Pressure effects (pneumothorax, epistaxis, subconjunctival hemorrhage, subdural hematoma) - Droplet and standard precautions - If asymptomatic- no Rx. If symptomatic= give Rx for pertussis and investigate other causes - When pt is coughing, talking, sneezing, and during procedures: suctioning, nebulization - DTap-IPV/ Hib. Immunization is not lifelong (wanes 4-8 years later) - Diphtheria, Tetanus, acellular pertussis, inactivated polio vaccine, Hib