B3.030 - Upper Respiratory Infections Flashcards
Describe where S. pyogenes is on the tree
Gram +
Catalase -
Aerobic +
Beta hemolytic
Describe where Corynebacterium are on the tree
Gram + Bacilli
Aerobic +
Describe where Moraxella are on the tree
Gram - Cocci
Describe where Bordatella are on the tree
Gram - bacilli
Growth on McConkey -
Oxygen tolerance +
What are the primary host of GAS
humans
How is S. pyogenes transmitted
respiratory droplets
How does S. pyogenes infect
Low inoculum, invaves mucous membranes
What diseases does GAS cause in the respiratory tract
Strep
Pharyngitis
What does GAS cause in the skin
Impetigo
Erysipelas/Cellulitis
Necrotizing fasciitis
What does GAS cause systemically
Bacteremia
Rheumatic fever
Acute glomerulonephritis
Strep Toxic Shock Syndrome
What is the most common bacterial infection of the throat
Acute streptococcal pharyngitis
Strep pharyngitis is hard to differentiate from what
viral pharyngtitis
How long does Strep pyogens persist without treatment
1-4 weeks
How is strep pharyngitis treated
penicillins
What is scarlet fever a complication of
GAS pharyngitis
What produces scarlet fever
Spe A and SpeC
Describe the chest rash caused by scarlet fever
sand paper like
what are symptoms of scarlet fever
Diffuse rash on chest
Raw strawberry tongue
Circumoral pallor
What are GAS virulence factors that help it early in disease process
Adhesins (M protein) >160 serotypes
Hyalonuric acid capsule prevents phagocytosis
What are later GAS virulence factors
SLO
Hyaluronidase
Spe
Streptokinases
What is SLO
pore forming toxin that lyses target cells
What is Spe
Key in superantigen infections
Scarlet fever
Toxic shock syndrome
What do streptokinases do
activate plasminogen to dissolve clots
how is Strep pyogenes treated
Penicillins
How is the strep throat treated
amoxacillin
How is the cellulitis treated
Penicillin with ceftriaxone
How is bacteremia due to GAS treated
Penecillin and clindomycin (suppresses toxin production
Recurrent disease/ treatment failure of GAS is due to
Reinfection
Colonization with different bacteria that produce beta lactamase
How is strep diagnosed
RADT detecting Group A capsule antigen
Culture if RADT is negative bc its more sensitive
Describe Corynebacterium diptheriae
Gram + rod non motile aerobic Club shaped V and L shaped arrangments
How is are the club shaped granules visualized
using Loffler medium
describe the diphtheria toxin
A-B exotoxin
The B subunit targets what
Upper respiratory tract
Heart
Nerve cells
What causes a shutdown of protein synthesis in diptheria
a subunit ADP ribosylates elongation factor
What is the inactive form of toxin called and what is it used for
toxoid, for DTaP vaccine
What is caused in the throat by diphtheria
psuedomembranous pharyngitis
What is the <1 week activity of diphtheria toxin
incubation and colonization of pharyngeal epithelial cells
What happens upon diphtheria toxin release
sudden onset of malaise, sore throat, low grade fever, exudative pharyngitis
What is characteristic of pseudomembranous pharyngitis
grayish pseudomembrane
what are is the grayish pseudomembrane made of in diphtheria
bacteria lymphocytes plasma cells fibirn dead cells
what are complications of the grayish pseudomembrane caused by diphtheria
asphyxiation
hard to dislodge without bleeding
what is bull neck associated with
diphtheria causing cervical adenitis and edema
what are more serious complications of respiratory diphtheria
myocarditis
neuropathies
What is cutaneous diphtheria
papule –> non healing ulcer with grayish membrane –> systemic disease due to toxin spread
how is diphtheria diagnosed
Tellurite containing differential
Chocolate agar
Elek test
PCR by CDC
What is the chocolate agar used for
inhibits other respiratory tract bacteria, is reduced causing black pigment
what is an elek test
demostration of toxin by agar diffusion with antitoxin
What is the toxin treated with in DTap
Formalin
when is the DTap and Tdap vaccine reccommended
2,4.6.15.18mo, 4-6 years
Boosters every 10 years
how is diptheria treated
immediate administration of antitoxin
DOC:
Erythromycin or penecillin
does a diphtheria infection create antibodies to it
no
Where is moraxella commesal to
nasopharynx
clinical presentation of moraxella
otitis media
sinusitis
laryngitis
Clinical presentation of moraxella with underlying chronic lung disease
bronchitis
pneumonia
describe moraxella
gram - small coccobacilli
Dipmococcus
describe the transmission of moraxella
direct contact with contaminated secretions
respiratory droplets
what do the pili and fimbriae of moraxella help with
adhesion
what endotoxin does moraxella have
LPS
What are the more serious clinical presentations of moraxella
endocarditis
how is moraxella diagnosed
look like neisseria on gram stain
pink brown coloration of colonies on chocolate agar, not apparent on blood agar
why is moraxella asaccharolytic
does not produce acid from glucose, maltose, lactose or sucrose
what is the treatment of moraxella
penecillin with beta lactamase inhibitor
moraxella are universally susceptible to what
all other antibiotics used for respiratory therapy
describe bordetella
strictly aerobic non fermenting
small gram - bacilli/coccobacilli
what does bordetella cause
whooping cough
what adhesins does bordetella use
Fha
Pertactin
promote binding to ciliated epithelial cells, PMNs
What is the bordetella toxin
AB5
B subunits bind ot glycolipidson cilliated respiratrory cells or phagocytes
what does the A subunit of the bordetella toxin do
ADP ribosylates Gi to increase cAMP levels
what are the 3 stages of bordetella
- catarrhal - highly infectious
- paroxymal 0 1-6 wks whooping cough v exhausting
- convalescent 0 susceptible to other resp infections
how is bordetella transmitted
respiratory droplets
what is the DTap Vaccine cotained of
purified proteins Pertussus toxoid Fha fimbriae pertactin
what do the letters in Tdap stand for
Tetanus toxoid
reduced diphtheria
acellular pertussis
what are the current Tdap recommendations
DTap: 2,4,5,15-18 mo, 4-5 years Single does of Tdap therafter 7-10 years if not fully vaccinated 11-18 years if not immunized 19-65 years if not already immunized
treatment of pertussis
macrolides in early stages
prophylaxis macrolides as well
supportive measure after paroxysmal stage
how is pertussis diagnosed
culture in special transport medium nasopharingeal swab/aspirate during catarrhal stage speacial growth on Regan-Lowe DFA PCR serology for paroxixmal/convalescent
