upper respiratory tract infections

Question 1

upper RT

Answer 1

nasal cavity
nasopharynx
mouth 
divided from lower at the level of the vocal chords
continuum with lymph nodes
eyes, ears, nose, throat

Question 2

host defences of upper airway

Answer 2

air filtration, warm, hair, mucous
cough
epiglottic reflex
musocillilary clearance

Question 3

defences impaired by

Answer 3

alcohol prevents epiglottic reflex 
tracheotomy - artificial airway 
tumour 
ventilator
cystic fibrosis

Question 4

causes

Answer 4

mostly viral

major bacteria: Pertussis, Haemophilis influenza

Question 5

acute pharyngitis

Answer 5

sore throat and tonsilitis (lymphoid tissue)
15-30% infections caused by group A strep
chlamydophile and mycoplasma pneumoniae in children
neisseria gonorrheae
corynebacterium disptheria

Question 6

strep sore throat

Answer 6

requires antibiotic treatment - penicillin and macrolides
consequence of untreated infection: non infectious sequele
1) post streptococcal glomerulonephritis
circulating immune complexes become trapped in glomerule in kidneys
2) rheumatic fever
type 2 hypersensitivity, molecular protein
M protein on capsule of strep - antibodies raised against
antibodies recognise cardiac tissue and destroy

Question 7

diagnosis of strep sore throat

Answer 7

clinic: scoring approaches
feverPAIN
score of >3, antibiotics given
diagnostic lab: dry swab, most microbes dry out but gram positive strep wont - selective
grow on blood agar - B haemolysis - clear zone
antibody testing
serology: streptolysin O is highly immunogenic look for anti-strep antibodies
mycoplasma - NAATs

Question 8

Diptheria

Answer 8

corynebacterium diptheria - gram positive bacilli
pseudomembrane forms - layer of pus and dead tissue over airway
production of endotoxin - inhibits protein synthesis
virulence gene delivered by bacteriophage
pleomorphic
damage to nerve endings, adrenal glands
bull neck - swollen lymph nodes
children vaccinated

Question 9

diptheria toxin

Answer 9

encoded by a phage gene 'Tox'
AB toxin 
requires low extracellular iron
uptake by endocytosis 
A ribosylates EF2- no protein synthesis - cell death

Question 10

diagnosis of diptheria

Answer 10

clinical: pseudomembrane 
treat with anti toxin then antibiotics
throat swab 
blood tellurate agar
black colonies
resistant to phosphomycin
toxin detection: ELEK test - precipitation with antitoxin

Question 11

epiglottis

Answer 11

prevents food from entering the trachea 
haemophilis influenzae type B 
vaccine in UK
swelling - blockage 
seen in young children `

Question 12

otitis media

Answer 12

middle ear infection
inflammation and pus behind ear drum
extreme pain
S pneumonia 
H influenzae 
S pyogenes

Question 13

sinusitis

Answer 13

strep pneumonia 
Haemphilis infuenzae 
staphylococci biofilm
inflammation of mucus lining the sinusis
viruses main cause
fluid build up