Gram-Positive Rods Flashcards
What are the 5 medically important gram-positive rods?
Bacillus, clostridium, Corynebacterium, listeria, gardnerella
What are the spore-forming gram positive rods?
Bacillus and clostridium
What are the medically important bacillus pathogens?
Anthracis and cereus
How does b.antracis cause infection?
It produces two endotoxins: lethal factor and edema factor
Edema factor is an adenylate cyclase, which increases the intracellular levels of AMP, leading to high extracellular fluid levels
Lethal factor inhibits the MAPK pathway, which is a signal transduction pathway important for cell growth
What are treatments for b.antracis?
Ciprofloxacin (Fluoroquinolone) is the drug of choice. Doxycycline (tetracycline) can also be used
What spore forming, gram-positive rods would cause food poisoning?
B. Cereus (Enterotoxin similar to staph aureus enterotoxin and an adenylyl cyclase stimulating toxin)
C. Perfringes (enterotoxin similar to staph aureus enterotoxin)
What are the medically relevant pathogens of clostridium?
C.difficle
C.botulinum
C.tetanus
C.perfringis
What pathogen is responsible for gas gangrene? What other disease can it cause?
Clostridium perfringes causes gas gangrene. It can also cause food poisoning
What treatment is used for clostridium perfringes? Through what mechanism does it cause it’s skin disease?
Penicillin G
Alpha toxin, which degrades cell membranes
How does c.difficle cause disease?
When antibiotics destroy gut sensitive members of the flora, it is able to multiply and produce endotoxin A and B, which kill enterocytes
What disease is caused by c.difficle?
Pseudomembrane colitis (leading cause of infectious GI deaths in the US)
What are the treatments for c.difficle?
Stop the current antibiotic regimen
Fidaxomicin
What are the three non-spore forming, gram positive rods?
Gardnerella, Listeria, corynebacterium
What is diphtheria? What mechanisms are responsible?
Diphtheria is a serious nose and throat infection caused by Corynebacterium diphtheriae
Diphtheria toxin inhibits protein synthesis by ADP-ribosylation of elongation factor 2 EF-2
Why is listeria monocytogenes medically relevant?
It can cause meningitis and sepsis in newborns, pregnant women and the immunocompromised
