Microbio Exam 1 Flashcards
Pathogens that cause:
Otitis Media and Sinusitis
SMH pathogens
Strep PNA
M. Cat
H. Influenzae
Pathogens that cause:
Otitis Externa
Pseudomonas Aerug
Staph Auereus
Pathogen that causes Diptheria
Corynebacteriam diptheria
Pathogen that causes Whooping cough (pertussis)
Bordetella pertussis
Sx of Otitis externa
Otalgia (pain) and
Otorrhea (drainage)
fever greater than 38.3 indicated more than just localized involvement
Pseudomonas and Staph are Halophiles
meaning they can live on the salty skin
cause Otitis Externa
Pseudomonas Aeruginosa
Gram (-)
Pigment producer: Pyocanin (non fluorescent blue) and
Pyroverdin (fluorescent green)
Encapsulated
Otitis Externa
one cause is Pseudomonas Aeruginosa: blue and green
most strains produce Pyocyanin (blue) but nearly ALL produce pyoverdin (green!!)
Staph Aureus
another big cause of Otitis Externa
Gram (+) cocci in clusters
Coagulase (+)
B-hemolytic
Beta hemolytic
complete hemolysis, can see through
Tx of Otitis Externa
Topical: acidifying agent, topical corticosteroid, topical antimicrobial
Oral abx if fever is presnt or extension of dz
Systemic analgesics (pain)
Otitis Media and Sinusitis
SMH pathogens
Strep PNA: 50%
H. Influenza: 20%
M. Cat: 10%
Strep PNA
Gram (+) Lancet shaped diplococci Encapsulated A-hemolysis (incomplete, cannot see thru- yellow to grayish green on plate) Optochin sensitive
Strep PNA review
Gram (+) Lancet shaped diplocicci Encapsulated a-hemolysis Optochin sensitive
H Influenza
Gram (-) coccobacilli
M. Cat
Gram (-) Diplococci
Oxidase (+) !!!
B-lactamase producer
Otitis Media
Amoxicillin
Diptheria
Cutaneous (abscesses and sores) vs Respiratory
Diptheria
Gram (+) pleomorphic bacilli, often CLUB SHAPED with the “palisades” or V shaped appearance
and
Metachromatic (volutin) dark purple granules at the bottom point of the V
Toxigenic strains of Diptheria have a phage encoded exotoxin
Diptheria toxin
Exo meaning it is expelled from the pathogen
Diptheria toxin
A-B exotoxin
B: receptor binding
A: catalytic subunit
binds to heparin binding EGF receptor- exotoxin is endocyosed, vesicle acidifies, releasing A subunit and allowing it to go to cytosol
Then the A subunit inactivates EF-2 via ADP-ribosylation- halting protein synthesis
Cutaneous diptheria
most cases d/t nontoxigenic strains
Respiratory diphteria
pharyngeal colonoziation
sudden onset malaise, exudative throat, low grade fever, lymph
Formation of PSEUDOmembrane= fibrin, bacteria, WBC, and Necrotic epithelial cells
“Bullneck”
systemic comp
Pseudomembrane in Diptheria is what color:
thick grayish to black
Diptheria Pathogenesis
Adherence and prolif (2-6 days)
Localized damage d/t exotoxin- inh of protein synthesis and cell death
Leads to Local necrosis and edema OR continued exotoxin production –> Systemic toxicity (myocarditis and demyelination)
Diptheria is uncommon in developed countries
vaccinate
Cultures for Diptheria
Loeffler’s medium: supports growth and enhances formation of volutin granules (the v points)
Cysteine-tellurite agar: distinctive black to tellurite reduction (only supports growth of this pathogen)
Isolates tested for toxin production
Staining for Diptheria
Gram: club shaped gram (+) bacilli
Volutin: metachromatic (volutin) granules (the V poitn)
Diptheria Dx
Presumptive isolates should be tested for TOXIN PRODUCTION
Elek test
PCR
ELISA
Immunochromatographic strip assay- very sensitive
Tx/prevention of Diptheria
Neutralize exotoxin with Diptheria Antitoxin: the most important!!! bc exotoxin is most damaging
then,
Abx: Erythromycin
Isolate person to minimize spread
Vaccinate
Pertussis
aka whooping cough
small gram (-) coccobacilli
virulence factors: adhesins and exotoxins
Pertussis Adhesins
mediate attachment to integrins and help colonization in the respiratory epithelium
Four exotoxins in Pertussis
A-B exotoxin: inactivates Gialpha, inhibits phagocytic killing and monocytic migration: kills lymphocytes
Adenylate cyclase toxin
Dermonecrotic toxin: vasoconstriction and ishcmic necrosis
Tracheal cytotoxin: kills respiratory epithelial cells: sitmulates IL-2 release
overall, the toxins acting in Pertussus:
block the affects of the immune system
Pertussis pathogenesiss
inhalation
bacterial attachment to ciliated airway epithelium and production of toxins
bacterial multiplication, influx of neutrophils, damage to ciliated epith, mucus HYPERsecretion
effects of Pertussis
compromise small airway sesp of infants, predispose to atelectasis,c ough, cyanosis, PNA
Review graph for stages of pertusssis
draw
Pertussis Dx
Presumptive:serology
Definitive: Culture (Bordet-Gengou or Regan-Low agar)
PCR: highly sensitive!
Pertussis Tx
Erythromycin
Immunize
Loeffler’s medium (volutin granules)
Cysteine-tellurite agar (black)
Diptheria
Elek test, PCR, ELISA, and Immunochromatogaphic strip assay
Diptheria
Bordet-Geng and
Regan-Lowe agar
Pertussis
Presumptive dx: Serology
Definitive dx: Culture on enriched medium (Bordet-geng and Regan Lowe), and PCR- highly sensitive
Pertussis
Definitive dx for Pertussis
Culture on enriched
PCR
Gram (+) organisms
Staph Aureus
Strep PNA
Corny Diptheria
Gram (-) organisms
Pseudomonas
H. Influenza
M. Catt
Pertussis