Micro V Flashcards
What is the morphology of clostridium tetani?
Gram positive rods
Is clostridium tetani an aerobe or an anaerobe?
Anaerobic
What is the reservoir for clostridium?
Soil
What is the MOA of tetanus toxin?
Toxin blocks release of inhibitory neurotransmitters (Glycine and GABA) Spastic
paralysis
Cleavage of synaptobrevin
What is the tetanus vaccine?
Toxoid
What is the most common scenario for acquiring
tetanus?
Rusty nail stick
What virus ascends in a retrograde manner to the
CNS?
Rabies
What is the treatment for tetanus?
Hyperimmune IVIG + benzos for spasms
What are the s/sx of tetanus? (3)
Trismus
Sardonic smile
Arched back
What are the top three cases requiring passive and active immunization?
- Tetanus
- Rabies
- HBV (needle stick or mothers)
What are the EM findings of Rabies?
Negri bodies
What is opisthotonus?
arched back 2/2 tetanus
Why are benzos useful for treating tetanus?
Potentiates GABA (which is blocked by tetanus)
What is another common scenarios for getting tetanus in developing countries?
Umbilical stump of newborn infants
What is the morphology of clostridium botulinum?
Gram positive rods
Is clostridium botulinum aerobic or anaerobic?
Anaerobic
What is the reservoir for clostridium botulinum?
Spores in the soil =
What is the treatment for clostridium botulinum?
antitoxin
What is the pathogenesis of clostridium botulinum?
Botulinum toxin inhibits neurotransmitter release from
presynaptic nerve endings by selectively proteolysing
(inhibiting) the synaptic protein synaptobrevin, which
plays a role in calcium-dependent exocytosis of
acetylcholine.
What are the foods associated with infant botulism?
Canned food or honey
Do adults get infected with clostridium botulinum through spores?
No–only infants whose immune system is not mature
What are the s/sx of botulinum?
- Fixed, dilated pupils
- Diplopia
- Dysphagia
What is the most common source of botulism in
adults?
The most common source of botulism in adults is canned beans; and in
particular yellow beans
What is the most common source of botulism in
babies?
• The common source of botulism in babies is honey.
Botulinum toxin is transferred by blood. Tetanus is
transmitted by what?
Botulinum toxin is transferred by blood. Tetanus is transmitted by nerves.
What is the morphology of clostridium perfringens? Aerobic?
Gram positive rod
Anaerobic
What is the virulence factor for clostridium perfringens?
Lectinthiase
What is the pathogenesis of clostridium perfringens?
Lecithinase and sphingomyelinase released from vegetative bacteria, degrade components in cell membranes
What is the management strategey of clostridium perfringens?
Debridement of the wound
Palpation of the wound infected with clostridium perfringens reveals what?
Crepitus
What is the treatment for clostridium perfringens? (3)
PCN
Clindamycin
Metronidazole
Does C. perfringens produce exotoxin?
perfringens produces an exotoxin, but it is not virulent in gas
gangrene. The toxin is virulent in C. perfringens enteritis.
What is the older name for C. Perfringens?
The older name for C. Perfringens is C. welchii.
What is claimed to be the third most common
cause of food poisoning in the USA and United
Kingdom?
Clostridium perfringens enterotoxicity is claimed to be the third most
common food poisoning!
What strain of C. perfringens cause gas gangrene?
Strains A and C cause enterotoxicity in humans.
What is the name of the toxin that causes gas
gangrene
The toxin involved in gas gangrene is known as -toxin, which has
Lecithinase and sphingomyelinase.
All members of the genus clostridia are motile
except what?
Strain A causes both gas gangrene and enterotoxicity!
What is the most common way for getting C. perfringens food poisoning?
C. perfringens food poisoning is commonly acquired by eating improperly
cooked beef or pork meat that is soiled with the clostridial spores.
What is the mechanism of C. Perfringens cause?
The enterotoxin forms a complex protein that forms pores in the cells of
the intestine and allow potassium ions and fluids to leak out.
What is the morphology of C. diff? Aerobic?
Gram positive rod
Anaerobe
What is the reservoir for C. diff?
Colon
What is the pathogenesis for C. Diff?
Clindamycin and ampicillin decrease normal flora
What is the treatment for C. diff?
Metronidazole
Vancomycin
What is the function of exotoxin B of C. diff?
Kills mucosa and forms pseudomembranes
Clostridium perfringens that causes myonecrosis,
and cellulitis associated with wound infections, is
most likely responsive to what antibiotic?
Treatment of choice for gas gangrene of C. perfringens includes
penicillin and/or clindamycin.
What are the three major indications for vanco?
MRSA
C. Diff
Staph Epidermidis
What is the CCFA media for c. diff culturing
Cycloserine (kills gram -)
Cefoxitin
Fructose
Agar
What is the morphology of Corynebacterium diphtheriae?
Gram positive rods that form chinese characters
What is the agar used for corynebacterium?
Tellurite agar
What is the pathogenesis for Corynebacterium diphtheriae?
Gray pseudomembranes formed from inhibition of ADP ribosylating eIF-2
What are the major complications of Corynebacterium diphtheriae?
Myocardial damage
Neuropathy
What are the s/sx of Corynebacterium diphtheriae infection? (3)
- Gray pseudomembranes
- Laryngeal nerve spasms
- CHF
What is the treatment for Corynebacterium diphtheriae infection?
Passive immunoglobulins
PCN or erythromycin
What other bacteria produces a toxin similar to
diphtheria and blocks the elongation factor
(unzipping effect)?
Pseudomonas
What two gram-positive rods are known as
Chinese letter bugs?
Listeria and diphtheria are known as Chinese letter bugs.
Diphtheria toxin has tropism for what two organs?
Diphtheria toxin has tropism for: (1) nerves, causing neuritis and lysis of
myelin sheath neuritis (e.g. it causes laryngeal nerve spasm); and (2) for
myocardium, causing necrosis and degeneration of the myocytes.
What are the morphological characteristics of listeria monocytogenes? Hemolysis pattern?
Gram positive rods that grow as “chinese letters” on blood agar, with beta hemolysis
What are the most important sources for listeria monocytogenes?
- Unpasteurized milk
- Prepackaged meats
What is the major diseases caused by listeria monocytogenes?
Meningitis in infants and the elderly
What test distinguishes Listeria from B strep?
Catalase test distinguishes the two from each other. Listeria is catalasepositive.
The top two DOCs of Listeria are?
Ampicillin and
The second DOC of listeria is TMP/SMX
What is Infanti septic granulomatosis?
Infantiseptica is abortion or stillbirth fetus infected with Listeriosis and it is
characterized with granuloma and abscesses
Listeria is the second most common cause
meningitis in neonates. What are the first and
third common causes?
The first cause, group B streptococcus; and the 3rd cause, E coli (K1)
What four situation after establishing and clinical d of disease warrant administration of passive immunization?
1 Tetanus
- Botulinum
- CMV
- Diphtheria
What type of immunity plays an important role in
Listeriosis?
Cell-mediated immunity.
Doe pseudomonas ferment lactose
Nah dawg
What is the pigment that pseudomonas produces? Smell?
Blue-green pigment
Grape smell
What is the treatment for pseudomonas? (3)
Piperacillin
Cipro
Gentamicin