ANAEROBIC SPORE-FORMING GRAM POSITIVE BACILLI Flashcards
Anaerobes, on the other hand, are particularly susceptible to these toxic derivatives of oxygen because they lack the protective enzymes_______ or______, or the enzymes are present in low concentrations.
superoxide dismutase and/or catalase
Clostridium causing Tetanus (Spasmic Paralysis)
CLOSTRIDIUM TETANI
CLOSTRIDIUM TETANI
Also known as…
Due to the location or position of its endospore (terminal or outer portion)
Racquet Bacillus
C tetani
• Endospores are….
(drumstick/ tennis racquet appearance)
Motility…
Round & Terminal
Motile by peritrichous flagella
is able to kill the C tetani spores within a few hours
It is a toxic substance for C. tetani
lodine (1%) in water
TOXIN/VIRULENCE FACTOR (Clostridium tetani)
TETANOSPASMIN
C tetani
• Neurotoxin and an essential pathogenic product
Toxic to humans and various animals when injected parenterally, but it is not toxic by the oral route
Causes increasing excitability of spinal cord neurons and muscle spasm
TETANOSPASMIN
T or F
Tetanospasmin
Toxic to humans and various animals when injected parenterally, but it is not toxic by the oral route
True
The neonate is displaying a bodily rigidity produced by Clostridium tetani exotoxin, called…
neonatal tetanus
Sir Charles Bell’s portrait of a soldier dying of tetanus.
The characteristic rigidity of the body is referred to as…
opisthotonos and risus sardonicus.
LABORATORY DIAGNOSIS (Clostridium tetani)
Specimen:
Wound exudates using capillary tube
is a good method for identifying Clostridium.
Gram stain
is a Gram-positive rod, motile with a round terminal spore giving a drumstick appearance.
The______’ location is not observed in a Gram stain.
C. tetani
spores
CULTURE (Clostridium tetani)
On____ agar and incubated anaerobically
Growth appears as a_____
blood
fine spreading film
Spore-forming, anaerobic, gram-positive bacilli
Causative agent of GAS GANGRENE
CLOSTRIDIUM PERFRINGENS
C perfringens
also known as…
Gas Gangrene Bacillus
Can also cause Food poisoning
Non- motile, Capsulated with Subterminal spores
C perfringens
SPORE LOCATION
B. anthracis
C. tetani
C. perfringens
Central
Terminal
Sub-terminal
TOXIN (Clostridium perfringens)
a-TOXIN
B-TOXIN
Enterotoxin
most important toxin
Lyses RBCs, platelets, leukocytes and endothelial cells
a-TOXIN
phospholipase C & lecithinase
Once these are being released by C. perfringens, there will be:
Increased vascular permeability with massive hemolysis and
a-TOXIN
• phospholipase C & lecithinase:
C. perfringens toxin
If not treated, then it results in Hepatic toxicity and myocardial dysfunction.
At some point, it will lead to death.
a-toxin
C perfringens toxin
Responsible for necrotic lesions in necrotizing enterocolitis
B-toxin
C perfringens toxin
• Heat-Labile toxin produced in the colon
• For food poisoning
ENTEROTOXIN
LABORATORY DIAGNOSIS (Clostridium perfringens)
Specimen:_____
Histological specimen transferred aseptically into a_____ & used immediately for microscopic examination & culture.
Histological specimen or wound exudate
sterile screw capped bottle
Specimens of exudates should be taken from the deeper areas of the wound where the infection seems to be most pronounced.
If wound exudates are not possible, then use wound aspirates.
C perfringens
C perfringens
→ blackening of meat will be observed with the production of____ and ____
Robertson’s cooked meat medium
H2S and NH3
Exhibit Double zone of hemolysis (two zone of beta hemolysis)
It ferments many carbohydrates with acid & gas
C perfringens
Nagler reaction (+)
It acidified litmus milk with stormy clot production
C perfringens
This test is done to detect the lecithinase activity
Nangler reaction
Inoculated on the medium containing human serum or egg yolk (contains lecithin)
Nagler reaction
In Nagler Reaction test
Colonies of Cl. perfringens are surrounded by _______ due to_____ activity and the effect is specifically inhibited if Cl. perfringens antiserum containing antitoxin is present on the medium.
zones of turbidity
lecithinase
C perfringens
Litmus milk
In a culture medium that contains lactose, if there is a fermentation, then it produces acid and a litmus indicator will turn the medium’s color into_____.
pink
C perfringens
Litmus milk
In a basic reaction, from Casein, if digestion occurs, then it produces alkaline amines.
If the environment is already alkaline, the litmus indicator present in the culture medium will turn into_____.
blue
REVERSE CAMP TEST for C. perfringens
_______ is streaked in SBA &______ is streaked perpendicular to it.
CAMP positive S. agalactiae (Group B Streptococcus)
C. perfringens
Reverse CAMP Test
(+) “arrowhead” (enhanced) hemolysis is seen in between
= C. perfringens
CLOSTRIDIUM BOTULINUM
causes…
BOTULISM (Flaccid Paralysis)
C botulinum
______ neurotoxic subtypes - labeled____
Seven
A-G
C botulinum
First recognized and isolated in_____ by_____
1896
Van Ermengem
is a neuroparalytic disease
Affects the nervous system
Botulism
• Once released into the bloodstream it irreversibly binds to the acetylcholine receptors in the neuromuscular junction
C botulinum
It alters the mechanism for acetylcholine release, making the neuron unresponsive to action potentials
It alters the mechanism for acetylcholine release, making the neuron unresponsive to action potentials
C botulinum
C botulinum
Most common form
Afflicts babies from 1 week - 1 year
Antigenic variation types A/B
Floppy Baby Syndrome
Floppy Baby Syndrome
CAUSED BY:
• Ingesting contaminated foodstuff
• Untreated natural honey and corn syrup
• Household dust containing C. botulinum spores
MANAGEMENT (Clostridium botulinum)
•________ must be administered intravenously (recovery takes several weeks)
• Mechanical respirator is administered if necessary.
Support of the on-going treatment
(Trivalent (A,B,E) antitoxin
LABORATORY DIAGNOSIS (Clostridium botulinum)
•_____ found in serum, leftover food.
• In infants, found in____.
• Mice injected with toxins____
• spores are____, location?
• Lipase (+)
Toxins
stool
DIE RAPIDLY
Oval
Subterminal
• A common cause of nosocomial antibiotic associated diarrhea (AAD) & antibiotic (Clindamycin)
-associated pseudomembranous colitis
CLOSTRIDIUM DIFFICILE
• The only nosocomial organism that is anaerobic and forms spores (survive _____and hard to destroy)
• Pathogenesis is mainly due to toxin production: Infective dose is____
CLOSTRIDIUM DIFFICILE
> 5 months
< 10 spores
LABORATORY DIAGNOSIS (Clostridium difficile)
• Specimen:
• Cultured on _________= (+) colonies with______
Stool
Cycloserine-Cefoxitin Fructose Agar
Yellow Halo
Best Strategy for C. difficile testing
• For clinical use: two-step testing uses initially___________detection screening followed by_______ or toxigenic culture for confirmation
ElA (Enzyme Immunoassay)
cytotoxicity assay
Best Strategy for C. difficile testing
• Gold standard is _______followed by TOXIGENIC CULTURE ASSAY
STOOL CULTURE
• Among the 4 medically significant Clostridium spp.
We only have_______ as nonmotile and the rest are motile.
C. perfringens
• For the LECITHINASE TEST, only ______is positive and the rest are negative.
C. perfringens
• For the LIPASE TEST, only _____ is positive while the rest are negative.
C. botulinum
• For the LACTOSE TEST, only______ is positive while the rest are negative.
C. perfringens
• For the GLUCOSE FERMENTATION TEST, all are able to break down glucose except_____
C. tetani.
