Micro Test 3: Anaerobes I & II
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3 Categories of Anaerobes: What are they and what do the include?
- 1. Gram-P Spore Forming Anaerobes: Clostridium dificille, Clostridium perfringens, Clostridium tetani, Clostridium botulism
- 2. Gram-P Non-spore Forming Anaerobes: Actinomyces
- 3. Gram-N Anaerobes:
What Gram-P spore forming anaerobe causes antibiotic-induced diarrhea, and severe colitis?
During anaerobic growth, energy is generated through (2 ways)
- 1) Fermentation (uses various molecules as end product- substrate level phosphorylation)
- 2) Anaerobic respiration: oxidative phosphorylation
In fermentation, what can be used to identify molecules?
- End products
- (Streptococci/lactoccoi --> lactic acid)
- (Clostrydia -> hydrogen, butyric acid)
With anaerobic respiration, during transport of e- to their terminal acceptor, protons are concomitantly pumped ___ the cell. The resulting proton and voltage gradient can then be used to do work.
True or False: Anaerobic bacteira outnumber aerobic bacteria in the mouth.
What has a major role in creating anaerobic environments?
- Tissue damage
- (tissue damage --> limited blood supply --> limited oxygen supply --> growth)
Simultaneous infection with an anaerobic and a facultative anaerobic bacteria cause
What is a polymicrobial infection?
- Simultaneous infection by an anaerobe and a facultative anaerobe.
- (any O2 in the tissue --> facultative anaerobes deplete it --> growth)
Hints for diagnosing Anaerobic Infections:
Adjacent to _________
________ lesion or discharge
Necrotic tissue, abscesses, "gangrenous"- promotes anoxi conditions
- Adjacent to mucosal surfaces
Perisitent infection after administration of antibiotics is characteristic of?
Anaerobic bacteria are most susceptible to what antibiotics? The exception is?
Metronidazole and penicillins; Bacteroides fragilis
Are anaerobic bacteria transmisible? What is the exception?
Usually NOT transmissible. C. dificle is the exception
What is the differential medium that is used to determine oxygen relationships of bacteria.
- Anaerobic= colorless
- Aerobic= greenish-blue
What 2 bacteria produce spores?
Clostridium & Bacillus
Process of spore production
Spore within the bacterial cell
What triggers sporulation?
Development of dormant spores into a metabolically active vegetative cell.
3) Aerobic/ Anaerobic
- 1) Gram-P
- 2) Rods (club-shaped due to endospore production)
- 3) Anaerobic
- 4) Motile (except C. perfringens which is nonmotile)
- 5) Peritrichous
- 6) Ubiquitous
Which type of Clostridium is non-motile but appears motile on agar plates?
How does Clostridium conven virulence?
Primarily through toxin production
What Clostridium produce diarrhea and colitis?
C. dificile, C. perfringens
What produces intestinal damage?
Clostridium dificile disease is a 2 step process. What are the steps?
- 1) acquire toxin-producing strain
- 2) Disruption of other normal flora (via antibiotic)
Clostridium dificile has toxins A & B in most strains. These toxins:
1) Inactivates host ________
2) Achieve cytotoxic levels when C. dificile predominates
Which C. dificile toxin is an enterotoxin that is chemotactic for neutrophils and disrupts cell-cell junctions?
Which C. dificile toxin is a cytotoxin that kills intestinal epithelial cells?
C. dificile toxin B kills ________
intestinal epithelial cells
Which component of the C. dificile binary toxin (present in new epidemic strains) BINDS receptor and determines which cells are affected?
Which component of the C. dificile binary toxin (present in new epidemic strains) Activates the enzyme and does the damage?
C. dificile _____ aid in binding to the intestinal epithelia and concentrating toxin?
Surface layer proteins (SLPs)
Name 2 C. dificile infetions (CDIs)
- Antibiotic-induced diarrhea
- Pseudomembranous colitis
What are inciting agents for C. difile infections?
Broad spectrum antibiotics: clindamycin, pencillins, cephalosporins, quinolones
What is the primary defense against C. dificile toxins?
Antibodies (High Ab titier = less disease, less risk of recurrence)
Pseudomembraneous colitis occurs in ________ and into ____
lower reaches of ileum and into colon
What disease causes small white/yellow plaques on the intestine?
Pseudomembraneous colitis (C. dificile)
Pseudomembraneous colitis (PMC) leads to _____
To diagnose C. dificle, use immunoassays to detect __________________
enterotoxin or cytotoxin in stool specimen
(Isolation of organism in feces denotes colonization, but not necessarily disease)
What bacteria will lead to a thickened colon wall seen on CT scans?
Is C. dificile acquired from exogenous source or from endogenous flora? (Slide 25)
Evidence is leading towards exogenously acquired due to Nosocomial acquisition and epidemic strain transmission
C. dificile treatment:
- Discontinuatin of inciting antibiotic
- Relapses are very common, spores are resistant to antibiotics
- Antidiarrhea drugs worsen outcome (increases toxin retention)
Loss of what regulatory proteins leads to higher virulence of C. dificile due to unregulation of its toxins?
Triangle of Bad Disease:
S. aureus (clindamycin)--> C. dificile (vancomycin) -> E. faecalis/faecium (horizontal gene transfer of van genes) --> S. aureus
Which type of Clostridium perfriengens causes most humain infections in USA
USA= Type A
Which type of C. perfringens causes necrotizing enteritis?
Which type of C. perfringens is present in human intestinal tract and soil?
Types B-E do NOT survive in soil, only present in humans and anima
Which strain of bacteria has a double zone (alpha and beta hemolysis)?
What is the basis for the type designation of C. perfringens?
Four "lethal toxins"
(alpha, Beta, epsilon, iota)
Which C. perfringens toxin has lecithinase (phospholipase C) lyses RBCs, WBCs & platelets; mediates massive hemolysis and bleeding.
Which C. perfringens toxin has necrotic activity, intestinal stasis, loss of mucosa, and formation of necrotic lesions?
Which C. perfringens toxin has protoxin (activated by trypsin, that increases vascular permeability of intestinal wall?
Which C. perfringens toxin has necrotic activity, increases vascular permeability, and is produced by Type E strains?
Which type strain of C. perfringens releases enterotoxin. Under what conditions?
- Type A
- Released w/ spores during sporulation (alk. conditions of small intestines stimulate sporulation)
Name 2 types of diseases C. perfringens causes.
- Soft tissue infections- cellulitis, fasciitis/suppurative myositis, gas gangrene/myonecrosis
- Gastroenteritis- food poisoning (3rd most common cause in USA), necrotizing enteritis
Which C. perfringes toxin is associated with necrotizing enteritis?
The enterotoxin of C. perfringes is heat-labile so best way to prevent food poinsoning with it is by ____
Localized edema and erythema
Generally not painful
Can progress to fascitis
Cellulitis (C. perfringens)
Spread of C. perfringens ot underlying muscle
Accumulation of pus in muscle planes
No muscle necrosis or systemic symptoms
Prominent in limbs following trauma
Rapid, extensive muscle destruction, systemic spread
Intens pain, death within 2 days of onset
Toxins causes extensive hemolysis, bleeding
Myonecrosis/gas gangrene (C. perfringens)
Which strain and which toxin of C. perfringens produces food poisoning?
How do you prevent this toxin?
Is Ab to toxin protective?
- Enterotoxin of type A strain
- Rapid refrigeration of food after preparation or re-heating to destroy heat-labile enterotoxin prevents disease
- Ab to toxin is NOT protective
Caused by __________ in the _________
C. perfringens in the jejunum
What type bacteria, strain and toxin cause necrotizing enteritis?
C. perfringens, Type C strain, beta toxin
What are the four symptoms of necrotizing enteritis?
- Acute abdominal pain
- Bloody diarrhea
- Ulceration of intestinal wall
Necrotizing enteritis is most common in what country and is caused by what?
New Guinea; caused by eating undercooked, contaminated meat w/ sweet potatoes (trypsin inhibitor that prevents inactivation of toxin)
What disease can lead to perforations in the intestinal wall?
Which bacteria presents with gram-P rods w/ absent leukocytes (lysed by toxins)?
What else does it have?
Double zone of hemolysis on blood agar from alpha and theta? toxins
C. perfringens treatment:
1) Soft tissue infections must be treated aggressively! (surgical debridement, high-dose ______)
2) Food poisoning is self-limiting
3) Can treat myonecrosis/gas gangrene with?
- 1) high-dose penicillin
- 2) Hyperbaric oxygen therapy
C. perfringens vs. C. tetani: Which one is motile?
C. tetani is motile (although C. perfringens can appear to be motile on agar plate, but it is not)
Which bacteria has a terminal spore and drumstick shape?
Which bacteria forms a film, rather than colonies on a plate?
Why is it difficult to cultivate on plate?
Very susceptible to oxygen
Ubiquitous in soil, transient colonizer of human and animal GI tract.
What toxins does C. tetani produce?
Tetanolysin is inhibited by _______
Which C. tetani toxin is a neurotoxin, and classic AB toxin?
Which C. tetani toxin causes the clinical manifestation of tetanus? Is this reversible?
- tetanospasmin, irreversible
- (produced during stationary phase when cells lyse)
3 Types of Tetanus: What type has no systemic signs, just spasm and increased muscle tone around the wound? What is the exception?
Exception= Cephalic tetanus (follows head trauma, presents with cranial nerve palsies)
3 Types of Tetanus: What type is systemic and produces trismus/lock jaw, risus sardonicus (rigid smile), opisthotonos (arched back)?
What type of tetanus is the most common type in adults?
What 3 things can be seen in generalized tetanus?
- Risus Sardonicus (rigid smile)
- Opithotonos (arched back)
3 Types of Tetanus: Begins as infection of umbilical stump, progresses to generalized tetanus.
3 types of tetanus
What is the spatula test? What is it useful for diagnosing?
Touch posterior pharyngeal wall with sterile soft-tipped instrument induces jaw contraction (positive) or gag reflex (negative). Useful for diagnosing C. tetani
In C. tetani, why is tetanospamin antibody not detectable?
The toxin rapidly binds to motor neurons and is internalized. Not enough time for Ab resistance.
What two antibiotics can you used to treat C. tetani? Why can't you use penicillin?
- Metronidazole, tetracycline
- Can't use penicillin because it also inhibits GABA
C. botulinum has ____ distinct neurotoxins. Which ones causes human disease?
C. botulinum is found in _______ and has a _____ spore
soil and aquatic sediments; terminal spore
These two bacteria closely mimic C. botulinum and produce neurotoxins.
- C. butyricum (Type E)
- C. baratil (Type F)
Botulinum toxin is a _______ toxin.
B binds: ________
- AB toxin
- sialic acid receptor and glycoproteins on motor neurons (different targets than tetanospasmin)
Inactivates proteins that regulate release of ACh --> flaccid paralysis
Botulinum toxin ultimately results in
How does Botulinum toxin reach nerves? Is it heat labile?
- Hematogenous spread.
- Heat labile, but spores are not
______ toxin remains at neuromuscular junction, unlike _____ toxin which has retrograde transport
- C. botulinum= NMJ
- C. tetani= retrograde transport to spinal cord
What bacteria gives you spastic/rigid paralysis?
How does C. botulinum travel through the digestive tract?
Complexed w/ non-toxic proteins tha tprotect it
1) Travels to _______
2) Inhibits release of _____ and _____
3) Inactivates _______ neurons
5) What type of paralysis?
1) Stays at ____
2) Inhibits release of ___
3) Inhibits _________
5) What type of paralysis?
- 1) motor neuron soma
- 2) glycine & GABA
- 3) inactivates inhibitory neurons
- 4) Overreactive
- 5) Spastic/rigid paralysis
- 1) NMJ
- 2) ACh
- 3) neurotransmission
- 4) inactive
- 5) flaccid
Symmetrical cranial nerve palsies (blurred vision, dilated pupils, slurred speech, droopy eyelids, difficulty speaking) with descending symmetric flaccid paralysis of voluntary muslces are the symptoms of?
What types of botulism can be ingested and lead to foodborn botulism?
What two types of botulinum toxin causes infant botulism? Why can't this colonize adults?
- Can't colonize adults due to competition with normal flora
What is the most common form of botulism in the US?
Wound botulism is caused by what type toxin?
Adult intestinal botulism resembles infant botulism except it is type ____ toxin as opposed to Types A & B toxin.
What two types of botulism are caused by Type C toxin?
- Wound Botulism
- Adult Intestinal Botulism
What two antibiotics can be used to eliminate C. botulinum toxin from the GI tract?
Metronidazole or penicillin
Causes pneumonia, endocarditis, arthritis, peritonitis, severe tachycardia, and myonecrosis (bacteremia and sepsis occur rarely). Can colonize vagina.
Cause of necrotizing fascitis and nontraumatic myonecrosis or spontaneous gas gangrene.
C. spticum colonizes individuals with _____
Sulfur granules are clumps of cells bound by ______ that are present in the colonies of what bacteria?
- calcium phosphate
Which gram-p bacteria is filamentous?
Is it acid-fast?
Chronic, granulomatous infections of face and neck, "lumpy jaw"
Actinomycosis (caused by Actinomyces)
These Gram-N anaerobes cause opportunistic infections by endogenous spread to normally sterile sites.
A healthy 24-year-old male mountain climber fell and injured his leg. It took him 2 days to return to his car and he did not seek immediate medical treatment. Several days later he had intense pain in his leg and went to the hospital emergency room, where he was diagnosed with myonecrosis. A gram-positive rod-shaped bacterium was recovered from the debrided tissue. Which of the following is LEAST characteristic of this bacterium and disease?
A. The rapidly dividing bacteria in the tissue produce gas as a metabolic by-product
B.The vegetative form of the bacterium is an obligate anaerobe
C.The spore form is often present in soil
D. The AB type toxin blocks release of neurotransmitters for inhibitory synapses
E. The toxins include hemolysins and a phospholipase
Answer: D, refers to C. tetani (The man was infected with C. perfringens...traumatic injury)
Which of the following statements concerning clostridia is LEAST correct?
A. Pathogenic clostridia are found both in the soil and as part of the normal flora of the colon
B. Antibiotic-induced diarrhea and pseudomembranous colitis are due to toxins produced by Clostridium difficile
C. Tetanus toxin blocks the release of acetylcholine, leading to flaccid paralysis
D. Tetanus can result from infection of the umbilical stump
E. Most pathogenic clostridia are strict anaerobes, and the vegetative cells are
readily killed by oxygen
Answer. C, refers to C. botulinum
Specific antitoxin is an important part of treatment for:
A. necrotizing enteritis
B. Pseudomembranous colitis
D. thoracic actinomycosis
An inciting agent for pseudomembranous colitis is
B. old age
c. young age
Why are anaerobic infections often treated empirically?
Select all that apply.
A.Because of the slow growth of anaerobes, antimicrobial susceptibility data that would assist therapeutic decisions are often delayed.
B. Antimicrobial resistance is rare among anaerobes so most agents are useful.
C.All anaerobes are susceptible to penicillin.
D.Most anaerobic infections are polymicrobial,
which requires use of broad spectrum antimicrobials.
Answer: A, D
Which anaerobes are notably penicillin resistant?
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