Gram Positive/Negative Anaerobes Flashcards
Clostridium perfringens diseases
- Gas gangrene
- Food poisoning
- Intra-abdominal infection
Clostridium tetani diseases
Tetanus
Clostridium botulinum diseases
Botulism
Clostridium difficile diseases
Nosocomial GI infection
Propionobacterium acnes diseases
Acne
Infection of prosthetics
Actinomyces diseases
Abscess formation
Peptostreptococcus diseases
Mixed contiguous infections
What are the spore forming Gram positive anaerobes?
Clostridium
What are the non-spore forming Gram positive anaerobes?
P. acnes
Actinomyces
Peptostreptococcus
What are the Gram negative anaerobes?
Bacteriodes
Fusobacterium
Prevotella
Porphyromonas
Bacteroides fragilis diseases
Abscess formation with mixed infection
Fusobacterium nucleatum diseases
Pneumonia or lung abscess with potent endotoxin
Liver abscess
Fusobacterium necrophorum diseases
Metastatic infection that is due to high virulence because of its endotoxin
Prevotella diseases
Female GU tract infections
Oral and GI tract infections
Often causes mixed infections
Porphyromonas diseases
Oral and periodontal infections
What anaerobes cause mixed infections?
Bacteroides fragilis
Prevotella
C. perfringens
Peptostreptococcus
What is the best antibiotic for anaerobic Bacteroides infection?
Metronidazole
What is the main toxin of C. perfringens and what is its function?
Alpha Toxin.
It lyses inflammatory cells and protects C. perfringens
from attack by WBCs which leads to gas gangrene where no live WBCs can be found in the blisters.
What is the onset of gas gangrene?
Rapid onset
How does C. perfringens cause gas gangrene?
Effects of the exotoxins released: – necrosis of muscle and skin – tense edema – bullae formation – gas formation
How does C. perfringens cause food poisoning?
Spores contaminate food which is ingested and enterotoxin produced following germination of large numbers of organisms leads to disease 8-24 hrs later
How is C. tetani spread?
– puncture wounds
– burns
How does C. tetani cause tetanus?
Releases tetanospasmin, a neurotoxin that blocks postsynaptic inhibition spinal motor reflexes (GABA) leading to spasmotic contractions
What does C. tetani look like under the Gram stain?
Tennis rackets
What is the manifestation of C. tetani infection?
Axonal transport of toxin with variable manifestations that develops into generalized tetanus preceded most commonly by trismus
What is a frequent source of C. botulinum infection?
Home canning of fruits/vegetables/fish
What causes botulism?
Preformed toxin with spore contamination.
It does not require spore germination.
What are some manifestations of botulism?
Descending paralysis (flaccid) - 1st symptoms are lack of eye movement
What is the major mechanism for C. difficile infection?
Patients in hospitals on antibiotics
What is megacolon?
Megacolon - colon can enlarge and dilate leading to
perforation that could kill patient
How does C. difficile cause its disease?
It produces and enterotoxin and a cytotoxin
What does C. septicum cause?
Nontraumatic myonecrosis and bacteremia
What does C. sordellii cause?
Fatal toxic shock syndrome following medical
abortions and natural child birth
What infection is Actinomyces associated with?
Slow growing- abscess forming in cervicofacial, thoracic, pelvic, intraabominal locations
What infection is Propionobacterium acnes associated with?
Acne
Prosthetic Devices
What is Peptostreptococcus associated with?
Often found among mixed infections like brain, intraabdominal, lung
What is the hallmark of B. fragilis infection?
Abscess formation
– Inflammatory response to infection
– Encapsulated “pus”
What are the main virulence factors of B. fragilis?
- Polysaccharide Capsule
- O2 Tolerance
What is the function of the B. fragilis toxin?
Nothing. It is defective.
How does B. fragilis infection normally occur?
Stool infection of a wound
What are the characteristics of Prevotella?
– Non-motile
– Non-encapsulated
– Strict anaerobe
What infections do P. bivia and P. disiens cause?
Female genital tract infections
What infections does P. melaninogenica cause?
Oralcavity, urogenital, GI tract
What is the best antibiotic for Fusobacterium infection?
Metronidazole
What is the best antibiotic for Peptostreptococcus infection?
Penicillin
What infections does Porphyromonas cause?
Mixed or single oral, periodontal infections
What infections does Fusobacterium nucleatum cause?
- aspiration pneumonia, lung abscess, empyema, chronic otitis media, sinusitis, brain abscess
- liver abscess
What is the main virulence factor of Fusobacterium?
High virulence toxin
What infections does Fusobacterium necrophorum cause?
- Lemierre’s syndrome/ post anginal sepsis
* widespread metastatic infection
