bacterial upper respiratory tract infections Flashcards Preview

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Flashcards in bacterial upper respiratory tract infections Deck (25)
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1

strep pyogenes

gram + cocci, chains
catalase - (no bubbling)
beta hemolytic
bacitracin sensitive, PYR +

2

staphylococci

catalase + (bubbling)
tells apart from strep pyogenes

3

how strep presents

pharyngitis, pyoderma, impetigo, erysipelas, cellulitis, necrotizing fasciitis, strep toxic shock

4

30% of sore throats in kids is caused by

group A strep - pharyngitis

5

signs of strep pharyngitis

petechiae in soft palate
inflammation in oropharynx

symptoms can inlude: nausea, vomiting, abdominal pan

6

strep pyogenes and rheumatic heart disease

M protein, antiphagocytic on outer surface of group A strep --> triggers anti-cardiac Ab responsible for leaflet thickening and deposits and RHD
MOLECULAR MIMICRY

7

haemophilus influenzae

gram - coccobacilli
curved ends on round rods
requires X AND V growth factors (both present in chocolate agar)
oxidase +

8

what are the growth requirements of haemophilus influenzae

requires X AND V growth factors (both present in chocolate agar)
x is hemin/heat stable; V is Nad or nadp/heat labile
grows best in 5-10% co2

9

types of h influenzae

6 capsular types a-f
type b are responsible for human diseases (primarily children)
nonencapsulated are normal flora in URT

10

which type of h influenzae causes disease in humans?

type b capsular
polyribose-ribitol phosphate (PRP or Hib) capsule is antiphagocytic

11

what protects from type b h influenzae?

antibody against PRP (polyribose ribitol phosphate) capsule

12

type b h infuenzae diseases

mostly affects nonvaccinated children
meningitis
epiglottitis
pneumonia

13

nonencapsulated h influenzae infections

acute atitis media and sinusitis------second to s pneumoniae
exaccerbations of COPD
conjunctivitis (daycare centers)
bacteremia/invasive infections in adults with underlying conditions

14

type b h influenzae usually infects who in the developed world?

nonvaccinated young children or elderly

15

how do anti-capsular antibodies protect humans?

they act as opsonins and mediate complement-dependent phagocytosis of the bacteria
Ab + complement can lead to bacterial lysis

16

how to treat h influenzae infections?

cephalosporin or ampicillin
Hib vaccinations for kids

17

what causes diptheria?

corynebacterium diphtheriae

18

cornuebacterium jeikeium causes

infections in immunosuppressed and is frequently resistant to many antibiotics

19

signs of diphtheria

incubation period 2-5 days
involves mucus membranes
classified by site (anterior nasal, tonsillar, laryngeal, ocular, genital, etc...)

20

how diphtheria progresses

enters URT
colonizes mucosa
makes diphtheria toxin --> toxin gene inhibits protein synthesis
can cause myocarditis, neuritis, or necrosis
creates pseudomembrane after necrosis and then death by obstruction

21

treatment for diphtheria

antitoxin - horse origin
antibiotic - kills bacteria BUT does not prevent intoxication
immunize with toxoid

22

what bacteria has M protein virulence factor

group a streptococci pyogenes

23

gram + rods that form chinese letters, non motile, non spore forming
catalase +

c diphtheriae

24

how does c diphtheriae toxin work?

A-B single chain toxin that ADP-ribosylates EF-2 and stops protein synthesis
cytotoxic to cells

25

prp conjugate vaccine is to prevent what bacteria

haemophilus influenzae