MICR_041813 Leg_Coryne_Myco Flashcards
What are some characteristics of legionella pneumophilia?
gram (-) pleiomorphic rod, intracellular growth, fastidious
Where is legionella pneumophilia normally found?
water of cooling towards, growing within AMOEBAS or BIOFILMS
Who is at risk for legionella pneumophilia?
elderly, immune-compromised or immuno-suppressed patients
What symptoms does legionella pneumophilia cause?
ATYPICAL PNEUMONIA, fevers, chills, productive cough, muscle aches, headaches, loss of appetite, diarrhea
Infections with legionella pneumophilia can be severe or mild. What characterizes either form?
MILD: “pontiac disease” W.O pneumonia. SEVERE: can disseminate from the lungs and cause systemic damage due to LPS
What’s the difference between atypical and typical pneumonia?
ATYPICAL: diffuse infection in the lungs; does not respond to penicillin or sulfonamide. TYPICAL: lobar, localized infection in the lungs.
What pathogens ause atypical pneumonia? Typical pneumonia?
ATYPICAL: legionella, mycoplasma, chylamdia. TYPICAL: Haemophilus influenza, Moraxella catarrhalis, Streptococcus pneumonia
How is legionella pneumophilia usually acquired?
airborne from environemental contamination, NOT from infected people.
What is the pathogenicity mechanism of legionella pneumophilia?
1) acquired via airborne route, 2) incubation period 2-10d, 3) EARLY stage: apoptosis of macrophage and alveolar epithelial cells, 4) LATE stage: necrosis, 5) SEVERE: dissemination from lungs -> systemic disease
How is legionella pneumophilia diagnosed? (4)
1) since it’s fastidious, grow on charcoal yeast extract with iron/cysteine. 2) fluorescent antibody test to ID organism in sputum. 3) detect antigens in urine sample, 4) detect antibody levels in blood
How do you prevent legionella pneumophilia?
proper water handling
What does mycoplasma pneumoniae cause?
infection of the respiratory tract in humans only
What is a cool fact about mycoplasma pneumoniae?
it’s the smallest replicating bacteria!
What are some characteristics of mycoplasma pneumoniae?
no cell wall, gram variable, pleiomorphic shape, colonies have a fried egg appearance, one serotype
What does mycoplasma pneumoniae require for growth?
cholesterol - its usually obtained from the host or supplemented in the growth medium. Provides membrane rigidity.
What enables mycoplasma pneumoniae to evade the immune response?
various lipoproteins
Which age group is most susceptible to mycoplasma pneumoniae?
school age kids - young adults; severity of infection is correlated with age
T/F Infection with mycoplasma pneumoniae provides life-long immunity.
False. Immunity is NOT lifelong
What is the frequency of mycoplasma pneumoniae outbreaks?
4-8 year intervals
What are hthe symptoms of mycoplasma pneumoniae?
ATYPICAL PNEUMONIA - gradual onset of non-productive cough -> sputum with small amounts of blood -> weakness, fever, cough, headache, diffuse changes on chest xray
What are some complications that can arise from mycoplasma pneumoniae infection?
extrapulmonary infections in CNS with additional symptoms (arthritis, autoimmune disease)
What is the mechanism of pathogenesis of mycoplasma pneumoniae?
1) aerosol droplet transmission, 2) attaches to epithelium via P1 adhesin, 3) production of H2O2 and superoxide, which causes oxidative damage to the cell, 4) inflammation, 5) disease
What are the 3 virulence factors of mycoplasma pneumoniae?
1) P1 adhesin, 2) H2O2, 3) superoxide
How do you diagnose mycoplasma pneumoniae? (4)
1) sputum gram stain 2) throat swab and culture, 3) PCR, 4) cold agglutination test
What is cold agglutination? What organism is this test used to detect?
auto-agglutination of RBC at low temps due to the presence of auto-immune antibodies against RBCs
How do you treat mycoplasma pneumoniae?
macrolides (erythromycin), tetracycline
T/F The vaccine for mycoplasma pneumoniae is a live-attenuated one.
No such thing. There is no vaccine for mycoplasma pneumoniae!!
What are some charcteristics of cornynebacterium diphtheriae?
gram (+), pleiomorphic, aerobe, does not form spores
What are the two groups of cornynebacterium diphtheriae?
1) cornynebacterium diphtheriae - cause of diphtheriae 2) diphtheroids (all others) - normal commensal bacteria
Where is cornynebacterium diphtheriae most prevalent?
developing countries with inadequate pediatric immunizations/medical care
T/F Infection with cornynebacterium diphtheriae provides life-long immunity.
False. Immunity is NOT lifelong
What is the mechanism of pathogenesis of cornynebacterium diphtheriae?
1) aerosol droplet transmission, 2) attaches to epithelium in the throat or skin. THROAT: fever, sore throat, pseudomembrane formation. SKIN: necrotizing skin
What is the pseudomembrane made of? What bacteria produces it?
produced by cornynebacterium diphtheriae. Made of fibrin, necrotic epithelium, WBC
T/F cornynebacterium diphtheriae can cause systemic disease.
False. It is confined to the initial infection site (throat/skin)
If cornynebacterium diphtheriae is confined to the initial infection site, what causes the systemic symptoms observed?
Diphtheria toxin (produced by cornynebacterium diphtheriae in the throat)
What does diphtheria toxin do?
it’s lethal to cells of the heart, kidneys, and nervous system. BLOCKS PROTEIN SYNTHESIS by inactivating elongation factor 2 (EF2) - an enzyme involved in peptide bond formation on ribosomes
How do you diagnose cornynebacterium diphtheriae? (5)
1) presence of pseudomembrane, 2) grow on special media (tellurite agar, tinsdale medium, loeffler media) and look for metachromatic granules, 3) PCR, 4) Immunoassay, 5) Elek Test
What is the Elek test? What is it used to diagnose?
used to determine if the suspected strain of cornynebacterium diphtheriae is toxigenic – if it is, a toxin/anti-toxin band is observed
How do you treat cornynebacterium diphtheriae? (2).
antitoxin for horse (neutralizes the free toxin) and penicillin
How do you treat people who’s been in contact with patients infected with cornynebacterium diphtheriae?
reimmunization + penicillin
What vaccine is available for cornynebacterium diphtheriae?
formaldehyde-treated diphtheria toxin = TOXOID, which is coupled with pertussis + tetanus vaccine (DTaP)
