Corynebacterium, Listeria, and Bacillus Flashcards
Is Corynebacterium diphtheriae Gram positive or negative, environmental conditions and shape?
- Gram Positive
- strict Areobe (requires oxygen)
- Pleomorphic (club shaped)
How can you identify C. Diphtheriae?
- grows on Loeffler’s Medium
- Stain for polyphoshate granules (stain pink)
- cell stains blue
- Metachromatic
Growth on Tellurite agar
- reduction by bacteria
- tellurium precipitation
- Black Colonies
Schick skin test
What are the symptoms associated with C. Diphtheriae?
- Infection of the upper respiratory tract (pharynx,larynx,nose,skin)
- pseudomembrane
- choking
- bacteria do not spread systematically
- mucosal lesions marked with greyish patches with surrounding inflammation
- Bull Neck (characteristic feture)
Does C. Diphtheriae produce a Toxins?
Yes, C. Diphtheriae does produce an AB exotoxin in which the B subunit binds to the host cell and the A subunit inhibits protein synthesis. A characteristic of the toxin is that when ADP-ribose mou=iety (NADH) attaches it is able inhibit ELII.
If so what is a characteristic feature of the C. Diphtheriae toxin?
encoded by a bacteriophage tax gene
- not produced in the presence of iron
- iron-represor complex forms
- inhibits expression of the tax gene
What treatment is given to patients who acquire C. Diphtheria?
Patients must be treated with an antibiotic and an anti-toxin.
Can be given penicillin or erythromycin and the diphtheria anti-toxin . After infection is eliminated patient must be given an immunization with the toxoid in order to develop immunity.
Prevention of C. Diphtheria includes?
- DPT: Toxoid (+pertussis and Tetanus)
- Found on Normal Flora
What are the Characteristics of Listeria monocytogenes?
- Gram positive (rod shapes smaller than E. colli)
- Motile (dishtiguishable from Corynebacterium)
- Catalase-positive (unlike streptococcus)
- grows in 1-45ºC
Referidgerator temp.
What are the clinical manifestations and of L. monocytogenes?
- Meningitis (swelling of membranes surrounding the brain)
- Encephalitis (swelling of the actual brain)
- Bacteremic infection in pregnant women can cause abortion,stillbirth,or premature birth
- Neonatal meningitis,bacteremia, or both which can occur though transplacental infection or vaginal delivery.
What are the most important epidemiological facts are associated with L. monocytogenes?
- Foodborne transmission and intrauterine transmission
- Intestinal colonization of the human reservoir
- periodic outbreaks associated with dairy products.
What abilities of specific abilities allows for pathogenesis of L. monocytogenes?
1) Penetrate host cells of the epithelial lining
2) produces lysteriolysin
3) produces phospholipases
What are the 5 steps associated with the colonization of cultured cells and intracellular spread of L.monocytogenes?
- Phagocytosis by a macrophage or invasion of non- phagocytic cells mediated by L. monocytogenes membrane protein “internalin.”
- Escape from membrane-bound vacuole into host cell cytosol mediated by LLO.
- Multiplication of the bacterium in the host cell.
- Movement through the host cell cytosol mediated
by actin polymerization. - Penetration of neighboring host cell membranes.
Entry into cytosol possibly mediated by
phospholipase.
When is someone Diagnosed with L. monocytogenes
-monocytes seen in the peripheral blood and spinal fluid.
• Hemolysin is important marker, but not definitive.
• Characteristic tumbling motility at 25C.
• Can multiply at low temperatures (enriched
in contaminated food in refrigerator).
What is the treatment given to patients diagnosed with L. monocytogenes?
- Penicillin G
- Ampicillin
Which populations are susceptible to L. Monocytogenes?
Increased frequency of listeriosis in people with compromised cellular immune function due to disease (AIDS), immunosuppressive therapy, age, or pregnancy.
