Term
| What are three characteristics of anaerobic organisms? |
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Definition
1. Lacks certain enzymes in the CP450 system to metabolize O2.
2. Can't detox ROS 3.
Require a low Eh to function. |
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Term
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Definition
Eh is the electric potential needed to transfer electrons from one compound to another.
Healthy human tissue = +150mV
Human bowels (w/anaerobes) = -250mV
Abscess/Necrotic Tissue = Low Eh |
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Term
| What type of anaerobes cause most of the anaerobic infections in humans? |
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Definition
| "Moderately obligate anaerobes" |
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Term
| List some characteristics of anaerobic infections. |
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Definition
1. Found in all anatomic sites
2. Infections are usually polymicrobial
3. *Infections usually occur when there is a mucosal or normal flora disruption of a normally sterile site.
4. Gm- anaerobe --> abscess formation |
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Term
| Your patient is former US President, George W. Bush. He presents with a suspected anerobic infection. What are some signs you would expect to see? |
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Definition
| Putrid discharge, polymicrobial flora on gram stain, aerobic cultures will be negative and you may find gas in the tissues (production of CO2 and H2) |
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Term
| Pierce Brosnan comes to your office and he says "Doc I feel like I might have an anerobic infection, can you tell me what it is? He says its probably intra-abdominal, drug resistant, resistant to bile and a gm- slender rod or coccobacilli. You tell him, "007, I think I already know that your infection is caused by..." |
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Definition
Bacteroides fragilis.
The major virulence factor of this bug is the polysaccharide capsule. the LPS endotoxin doesn't do much. It also produces neuraminidae, protease, pili, and hemagglutins. |
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Term
| Your patient arrives experiencing diplopia and difficulty swallowing. She said she ate some home-canned food for dinner the previous night. She was also beginning to experience flaccid paralysis. What bug caused this and what are some characteristics of it? |
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Definition
Clostridium botulinum.
Symptoms caused by a neurotoxin which blocks Ach release.
Antitoxin and supportive case are the standard treatments. |
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Term
A worried parent brings in an infant who looks like a "floppy baby". The infant is 15 weeks old and has a feeble cry with weak suckling reflexes. The mother said the last thing the baby ate yesterday was a little bit of honey.
What caused this? |
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Definition
Infant botulism.
Supportive treatment leads to a favorable outcome.
Recall that the symptoms are caused by the ORGANISM and not the toxin. |
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Term
| A drunk fisherman hooks himself with an old fishing hook and gets sick sometime later. He experiences trismus which then lead to tonic seizures. What was the toxin that causes this and how does it act? |
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Definition
Tetanospasmin is the major toxin released by Clostridium tetani.
It inhibits neurotransmitter release and normal inhibitory input leading to spastic paralysis. |
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Term
| What is the toxin produced by Clostridium perfringens? |
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Definition
Alpha-toxin lecithinase.
It damages cell membranes and causes gas gangrene. |
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Term
| How does Lecithiniase cause cell death in eukaryotic cells? |
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Definition
It hydrolyzes phosphatidylcholien and sphingomyelin. This leads to membrane damamge.
Remember, Alpha Toxin = lecithinase = PLC |
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Term
| How do patients die of C. perfringens specifically? |
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Definition
| Patients die from shock and renal failure within a few days of onset. |
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Term
| What are the most effective treatments for C.perfringens? |
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Definition
| Surgical removal of the involved tissue. Hyperbaric O2 may also be effective. |
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Term
| A clinical case study you're reading describes a situation with food poisoning. The patient had severe diarrhea about 18 hour after ingestion of food. Patient was afebrile and denied any vomiting. The patient recovered on their own about 1-2 days later. What is the microbe responsible? |
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Definition
C.perfringens.
Some strains produce a powerful enterotoxin which can give you the runs.
Recall if you see blood in the diarrhea that it may be O157:H7 EHEC |
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Term
| What is the most common cause of nosocomial diarrhea? |
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Definition
C. difficile.
It releases toxin A which is an enterotoxin and toxin B which is a cytotoxin. They inactivate cytoskeleton maintenance and disrupt intracellular tight junctions. |
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Term
| For which anerobic bacteria can one look for toxins in stool. |
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Definition
C. Difficile
C. botulinum may also be detected in infants stool if they ingested honey. |
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