Clostridia Flashcards by janai oneal

shape

gram + rods

How well did you know this?

Not at all

Perfectly

oxygen requirement

strict anaerobe

How well did you know this?

Not at all

Perfectly

spore formation?

yes

How well did you know this?

Not at all

Perfectly

list the species of clostridium

dificile
perfringens
botulinum
tetani

How well did you know this?

Not at all

Perfectly

how does clostridium cause disease symptoms?

produce and release proteinaceous toxin

How well did you know this?

Not at all

Perfectly

what induces spore formation?

unfavorable conditions (ie nutrient depletion)

How well did you know this?

Not at all

Perfectly

when do spores germinate?

when conditions become favorable for vegetative growth

How well did you know this?

Not at all

Perfectly

Pseudomembranous colitis (PMC) is caused by what strain of clostridium?

C. diff

How well did you know this?

Not at all

Perfectly

PMC is characterized by:

yellow plaques filled with fibrin and cellular debris in ulcers of colonic mucosa

How well did you know this?

Not at all

Perfectly

what is leading cause of nosocomial diarrhea?

C. diff

How well did you know this?

Not at all

Perfectly

C. dificile mode of transmission

endospore (hands of healthcare workers)

How well did you know this?

Not at all

Perfectly

disease state of C. diff is usually associated with:

use of antimicrobial drugs (cephalosporins, ampicillin, clindamycin)

How well did you know this?

Not at all

Perfectly

true or false? C. diff is harbored in a dormant state in the small intestine of a small % of healthy people

false; harbored in large intestine

How well did you know this?

Not at all

Perfectly

how do C. diff spores react to antibiotics?

resistant ; antibiotics kill the normal flora

How well did you know this?

Not at all

Perfectly

what causes diarrhea in C. diff?

vegetative spores begin to produce toxin = diarrhea

How well did you know this?

Not at all

Perfectly

does C. diff invade the bowel wall?

no, just like E. coli and V. cholera

How well did you know this?

Not at all

Perfectly

what are the toxins of C. diff?

Toxin A

Toxin B

How well did you know this?

Not at all

Perfectly

which C. diff toxin is the enterotoxin?

Toxin A

How well did you know this?

Not at all

Perfectly

what damage does an enterotoxin do?

fluid production and damage to mucosa

How well did you know this?

Not at all

Perfectly

which C. diff toxin is the cytotoxin?

Toxin B

How well did you know this?

Not at all

Perfectly

what does a cytotoxin do?

rounding of tissue-culture cells

How well did you know this?

Not at all

Perfectly

where do C. diff toxins act?

cytoplasm of host cell

How well did you know this?

Not at all

Perfectly

how do C. diff toxins act?

glycosylate GTP-binding proteins (Rho, Rac)

How well did you know this?

Not at all

Perfectly

what happens when GTP-binding proteins are glycosylated by C. diff toxins?

cells lose cytoskeletal structure and die

How well did you know this?

Not at all

Perfectly

what is standard diagnostic for toxin A of C. diff?

ELISA

Where is C. perfringens found?

soil and intestinal tract of animals

where is C. perfringens NOT found?

Sahara desert sand

what is the major pathogen of wound infections, especially war wounds?

C. perfringens

true or false? C. perfringens causes local damage only

false, causes local AND systemic damage because of its invasive properties and toxin production

true or false? C. perfringens produces a toxin?

true

C. perfringens tissue infections caused when:

severe trauma introduces spores from environment

in C. perfringens, after a severe trauma, environmental spores germinate under what conditions:

anaerobic compromised blood supply Ca++ ions Availability of peptides and AAs

C. perfringens toxins typically cause:

cellulitis

cellulitis caused by C. perfringens toxins can lead to:

gas gangrene

what is gas gangrene:

necrotizing gas-forming systemic signs of shock

how many toxins does C. perfringens produce?

12 toxins

C. perfringens Alpha-toxin (lecithinase) does what?

damages cell membranes | causes gas gangrene

how does C. perfringens Alpha-toxin cause its damage?

Phospholipase Type C

What is Phospholipase Type C and what does it do?

produced by Alpha-toxin of C. perfringens | Hydrolyzes phosphatidylcholine and sphingomyelin = cell death

what is myonecrosis? symptoms?

destruction of muscle tissue reddish-blue to black in color gas bubbles present

How do you treat a C. perfringens infection?

surgery to remove infected muscle antibiotics for control but still amputation Antitoxin from horses High O2 Prompt care to restore arterial blood supply

C. perfringens food poisoning results when:

sporulating C. perfringens produces enterotoxin in intestine after eating contaminated food

At what point is diarrhea is typically seen in C. perfringens food poisoning?

12-24 hours

True or false? C. perfringens food poisoning is self limiting:

true - disappears on its own in 1-3 days

C. botulinum is found where?

soil and marine sediments

C. botulinum spores are unique because they:

heat resistant - survive food processing | germinate and grow under anaerobic conditions (cans)

causative agent of botulism

intoxication by ingestion of preformed toxin | *organism does not need to be present

C. botulinum produces how many toxins and what kind?

8 neurotoxin (BoNT) serotypes A-G among most poisonous substances known pose a bioweapon and bioterrorism threat

what are most common BoNT serotypes in humans?

A, B, E

Purified BoNT is produced as a:

900 kDa protein complex with a 150-750 kDa toxic/nontoxic ration connected by disulfide bridge

What is the MOA of C. botulinum neurotoxin?

prevents release of acetylcholine NT | zinc metalloprotease

C. botulinum neurotoxin prevents release of ACh which leads to:

impaired neurotransmission at peripheral cholinergic synapses

zinc metalloprotease does what?

cleaves proteins involved in NT vesicle docking

Symptoms of C. botulinum toxin poisoing

Flaccid paralysis in 12-36 hours Cranial nerves affected first - double vision, difficulty swalling Paralysis descends = respiratory failure

What are the 3 types of botulism?

Food-borne Infant Wound

what causes infant botulism

intestinal colonization of organisms in babies <1 | honey

is infant botulism slow or fast onset?

slow

infant botulism is characterized by:

hypotonic (floppy) baby

wound botulism

most rare | systemic spread of toxin produced by organisms in wound

causes of wound botulism

trauma, surgery subQ heroin injection sinusitis caused by intranasal cocaine

what should be administered immediately to treat C. botulinum?

trivalent antitoxin isolated from horses

C. tetani is found where?

ubiquitous in human and animal GI tracts | soil samples

True or false? C. tetani spores are susceptible to the environment

false- they are resistant to the environment

C. tetani infection is usually associated with:

traumatic wounds

what is the major toxin of C. tetani:

tetanospasmin - responsible for all symptoms

size of tetanospasmin:

150 kDa

Describe makeup of tetanospasmin

150 kDa protein | Heavy and light chain (A-B) connected by disulfide bridge)

True or false? Individual chains of tetanospasmin are extremely toxic

false, individual chains are not toxic

tetanospasmin MOA

attached to peripheral nerves near wound, transmitted to cranial nerve nuclei inhibits GABA release and normal inhibitory input

result of tetanospasmin actions

reflex spasms and spastic paralysis

What is trismus?

lockjaw | tetanic spasm of masseter mm. that prevent open mouth

effects of generalized tetanus

trismus (lockjaw) descends to neck & back = rigid abdomen & stiff extremities tonic seizures respiratory failure (chest mm. paralysis)

how to prevent tetanus?

``` DPT vaccine tetanus toxoid (inactivated antigenic toxin) ```

treatment of tetanus?

human globulin as passive immunization in tetanus prone wounds immediate antitoxin administration + penicillin G to prevent further paralysis surgical wound debridement