Diptheria, Listeria, Bacillus Flashcards
Diptheria shape
CLUB SHAPED….”chinese letters” or V and L palisades
Diptheria gram positive or negative?
Positive. But may be Gram variable in smears from respiratory specimens
Diptheria granules
THEY HAVE NONE. they do have metachromatic granules though
What are some good mediums to isolate diptheria?
Loeffler coagulated serum medum, tellurite agar
must tell the lab that you are looking for it (since it’s so rare)
Pathogenesis of diptheria
Respiratory and cutaneous transmission…spread occurs via droplets or direct contact with skin abrasions….very fast infection (incubation 2-4 days = very contagious)
many people can carry it. multiply on mucous membranes (tonsilspharynx)..DOES NOT INVADE deep tissues/blood
What is a virulence factor of diptheria?
DIPTHERIA EXOTOXIN. lysogenic bacteriophage carries toxin gene
How does diptheria toxin kill?
By inhibiting protein synthesis, toxin can travel through blood (althoug bacteria can’t) and can affect heart (cardiac arrest)
Presentation of diptheria
Sore throat, low grade fever, pseudomembrane of necrotic epithelium = suffocation, toxic effects of heart (myocarditis)
BULL NECK (lymphadenopathy and edma)
can also cause paralysis (neuropathy)
Once you determine that you have diptheria…what next?
PROMPT Tx!
antitoxin (DAT), antibiotics, cleansing of lesion in cutaneous diptheria)….and VACCINATION DUHHHHH (DTaP, Tdap, Td all defend against diptheria)
How does one get listeria?
FOOD BORNE (BLUE BELL OMGGGGG, cheeses, coldcuts, hot dogs, CANALOOP biiiig outbreak)
Who gets listeria?
Not many people (immune system can usually defend against it)
But…elderly or AIDS patients (immunocompromised), can infect pregnant women and fetus (perinatal listeriosis)
Shape of listeria
club shaped bacillus, can move
Listeria gram negative or positive?
Positive
Other characteristics of listeria?
Resistant to high salt and bile, weakly hemolytic in plate, teullurite resistant, catalase positive (unlike strep), can multiply at 4 degrees celcius..in your fridge)
Transmission of listeria?
contaminated food products, common in dairy cattle
How does listeria invade?
Invades epithelial cells, released by invasin/interlain and release from phagosome via listeriolysin O….can multiply when T-cell dependent immune system is compromised
What immune components do you need to get rid of listeria?
NO VACCINE.
You need activated macrophages and cytotxic T cells, gamma interferon
Most common presentations of listeria?
Sepsis and meningitis
How to treat listeria?
Sensitive to antibiotics (BUT NOT CEPHALOSPORINS), must use drug that can penetrate eukarytoci cells (i.e. ampicillin/rifampin)
Properties of bacillus
- gram positive
- produce SPORES, grows in end to end chains
- non motile
- grows on simple carbon and nitrogen sources
How is bacillus anthrasis (anthrax) transmitted?
Zoonotic (human contact with sheep, cattle, horses, etc) hair, bristles, hide, wool.
Can have cutaneous, intestinal, or pulmonary inoculation (no person-to-person transmission)
What does anthrax look like in skin?
dark, necrotic scar….eschar formation
What happens to mediastinum in pulmonary/inhalational anthrax?
it widens
How does anthrax cause disease?
SPORES are phagocytosed by macrophages then germinate…death due to septicemia, toxemia, and shock
