Otitis, Sinusitis, Diptheria, Pertussis Flashcards
What causitive agent produces pyoverdin? What does pyoverdin do?
Pseudomonas aeruginosa, sequesters iron
What are the two most common causes of otitis externa?
Pseudomonas aeruginosa and staph aureus
What helps you distinguish staph aureus?
beta hemolysis, coagulase positive
What are the three most common causes of AOM and sinusitis, starting with the most common?
Strep pneumo, haemophilis influenzae, moraxella catarrhalis
What helps you distinguish strep pneumo?
alpha hemolysis, encapsulated (virulent only), optochin sensitive
Which AOM agent is a gram negative coccobacilli?
Haemophilus influenzae
Which AOM agent is a gram negative diplococci, oxidase +, beta-lactamase producer?
Moraxella catarrhalis
Which agent is a gram + pleomorphic bacilli that grows best on blood agar?
Corynebacterium (“Chinese letters”)
What type of toxin is the diptheria toxin and what is its goal?
A-B exotoxin, to halt protein synthesis
What is the clinical presentation of diptheria? What is the sign of the most severe case?
sudden onset of malaise, exudative pharyngitis, lymphadenopathy, low-grade fever
- Formation of pseudomembrane of fibrin+bacteria+WBCs+necrotic epithelial cells
- “Bull neck” is the sign of the most severe case
How is a diagnosis of diptheria made?
primarily clinical due to the severe nature, bull neck and black pseudomembrane
How is diptheria dx confirmed in culture and agar?
Loeffler’s medium checks for growth of volutin granules, cysteine tellurite agar checks for the exotoxin
What 4 tests are run on presumptive isolates of diptheria to check for the exotoxin?
Elek Test, PCR for the tox gene, ELISA, and the immunochromatographic strip assay (this one is the most sensitive for the diptheria toxin)
What causitive agent is defined as a small, aerobic, gram negative coccobacilli?
Bordatella Pertussis
What are the two main virulence factors for B. Pertussis?
Adhesins and exotoxins
What are the adhesins that participate in virulence in B. Pertussis?
filamentous hemagglutinin and pertacin and agglutinogens
What are the four exotoxins that participate in virulence in B. Pertussis and what do they do?
Pertussis A-B exotoxin= lymphocytosis
Dermatonecrotic toxin= vasoconstriction and ischemic necrosis
adenylate cyclase toxin= decreased chemotaxis
tracheal cytotoxin= kills ciliated epithelial cells, stimulates IL-1 release
Which stage of pertussis is the highly contagious one? How long does it last and what does it look like?
Catarrhal, 1-2 weeks as a nonspecific URI
What other test, besides agar, is used to make a definitive diagnosis of pertussis?
PCR
What two agars are used for a definitive diagnosis of pertussis?
Bordet-Gengou, Regan-Lowe
What is used for a presumptive diagnosis of pertussis?
ELISA
What is the DOC for Diptheria and pertussis?
Erythromycin, or another macrolide for Pertussis
