Gram-Positive Bacilli Flashcards
Gram-positive bacilli are subdivided in which ways?
Spore and non-spore forming and based on need for anaerobic conditions for growth
Describe spore forming gram positive bacilli
Includes:
Aerobic bacillus
Anaerobic clostridium
Not many spore-forming organisms are of clinical significance
Describe non-spore forming gram positive bacilli
Many more of these are clinically significant
Corynebacterium Propionibacterium Listeria Lactobacilli Nocardia Actinomyces
What are the two types of toxins associated with bacteria, and why is this important when discussing gram positive bacilli?
Endotoxins: released upon cell death; highly present in
gram positive bacilli which can result in endotoxic shock
Exotoxins: released by living bacteria.
Clostridia species release exotoxins. They are responsible for illnesses like botulism, tetanus and food poisoning.
How do exotoxins move around the body?
released from a small infection, travel in the bloodstream to the gut
Are antitoxins effective on bound or unbound toxins?
Unbound (travelling around the body); toxins already bound to tissues cannot be treated by antitoxin.
An antitoxin can prevent further damage from toxin but not reverse damage already occured
What is an example of a modified exotoxin?
Toxoids, used in immunization.
Where can bacillus species be found?
Environmental
Skin flora
Often found in non-sterile environmental cultures
Often in the air
What are the two most relevant bacillus spp?
B. anthracis
B. cereus
Anthrax is caused by which organism?
B. anthracis; primarily in animals
very rare in N. america
Potential bioterrorism agent
Bacillus cereus is associated with which types of infections?
Blood stream
Food poisoning
What are the most significant clostridium species?
Clostridium botulinum
Clostridium tetani
Clostridium perfringens
Clostridioides difficile
Which organism is responsible for botulism?
Clostridium botulinum
anaerobic, gram-positive, spore-forming bacteria
Routine precautions (not person-to-person)
What is Botulism?
neuroparalytic disorder mediated by toxin production. Source is usually contaminated food
What is Tetanus?
Toxin mediated neurologic disease acquired mainly from contaminated wounds
Which organism is responsible for tetanus?
Clostridium tetani
Gram-positive bacilli, spore-forming, anaerobic
Routine precautions (not person-to-person)
What two syndromes can clostridium perfringens cause?
Food poisoning Gas gangrene (clostridial myonecrosis)
Summary of C. diff
anaerobic gram positive spore forming bacillus
Spores can survive long time in environment
Clinical disease mainly mediate by enterotoxins
Toxins A & B are most common toxins
No single test can be reliably used for Cdiff
Can be detected in asymptomatic pts
high rate of c diff colonization in children
Which bacteria is responsible for diphtheria
corynebacterium diphtheriae
Gram-positive bacilli, non-spore forming, aerobic
How does c. diphtheria appear on agar?
Using tellurite agar
Grows as a black colony
Sometimes diphtheroids and some staphylococci will appear black, but grow poorly
Differentiate between respiratory and cutaneous diphtheria
Respiratory: faucial (narrow pass from mouth to pharyx), nasal, laryngeal
Cutaneous: non-specific ulcers; usually no complication but myocarditis and neuritis possible
What are the possible outcomes of respiratory diphtheria?
1) full recovery
2) complications:
- airway obstruction (week 1)
- myocarditis (week 2)
- neuritis - cranial or peripheral (up to months later)
Who are typically affected by Listeria?
immunocompromised and newborns
Describe the listeria bacteria
non-spore forming
gram- negative
bacilli
