Infection and immunity

Question 1

Give ONE HIV-associated example of each of the following :

(i) A central nervous system infection.
(ii) A respiratory infection.
iii) A gastrointestinal infection.
(iv) A malignancy.
(v) non-malignant skin diseases
(vi) ocular infection

Answer 1

CNS: cerebral toxoplasmosis, cryptococcal meningitis, HIV encephalopathy, peripheral neuropathy

Resp: pneumocystis jirovecii pneumonia, TB

GI: Oesophageal candiasis

Malignancy: Kaposi’s sarcoma, non-hodgkin’s lymphoma

Skin: chronic HSV, sebarrhoeic dermatitis. recurrent shingles, oral hairy leukoplakia, molluscum contagiosum, mucocutaneous candiadiasis, pityriasis versicolor

Eye: CMV retinitis

Question 2

Name the antibiotics used to treat the following conditions:

syphilis
tonsilitis
cellulitis
HAP
CAP

Answer 2

syphilis - pencillin
tonsilitis - penicillin
cellulitis - flucloxacillin
HAP - piperacillin-tazobactam 
CAP - amoxacillin, clarithromycin

Question 3

meningitis
osteomyelitis
gonorrhoea
gastroenteritis
chlamydia

Answer 3

meningitis - ceftriaxone
osteomyelitis - ceftriaxone
gonorrhoea - ceftriaxone 
gastroenteritis - erithromycin, ciprofloxacin
chlamydia - doxacycline

Question 4

pertussis
nec fasc
endocarditis
opthalmic infection
acne
abcesses

Answer 4

pertussis - clindamycin
nec fasc - clindamycin
endocarditis - gentamicin
opthalmic infection - gentamicin
acne - doxacycline
abcesses - metronidazole

Question 5

bacterial vaginosis
MRSA
simple UTI
complex UTI
TB
H Pylori

Answer 5

bacterial vaginosis - metronidazole
MRSA - ciprofloxacin, vancomycin
simple UTI - nitrofurantoin, trimethoprim
complex UTI - ertapenem, gentamicin
TB - 4: rifampicin, isoniazid, pyrazinamide, ethambutol
H Pylori - triple: amoxacillin, clarithromycin/metronidazole, PPI

Question 6

what is hypersensitivity

Answer 6

inappropriate immunological reaction to an external antigen

Question 7

what are class I-IV hypersensitivity reactions, what mediates them, and give examples

Answer 7

I - mediator is IgE which coat mast cells which then degranulate, examples are allergies, anaphylaxis, atopy, asthma

II - mediator is igM/igG, examples are AI haemolytic anaemia, goodpastures, MG, graves

III - mediator is immune complexes, examples are EAA, RA, SLE

IV - mediator is CD4 Th cells, examples are contact dermatitis, MS, transplant rejection

Question 8

What are the 3 key symptoms of meningitis?

Answer 8

headache, fever, neck stiffness

Question 9

list 4 bacterial causes of meningitis

Answer 9

neisseria meningitidis
streptococcus pneumonia
group B strep
haemophilus influenzae

Question 10

what are four mechanisms of antibiotic resistance?

Answer 10

1. prevent entry of drug / eject it
2. use different metabolic pathway
3. alter target binding site
4. break down drug

Question 11

what is the pathogenesis of influenza?

Answer 11

host cell entry - bind to receptors in resp tract

cytopathy - lysis of ciliated and mucus epithelial cells

host protective response and immunopathology

Question 12

what is the pathogenesis of varicella?

Answer 12

host cell entry

stability - infects T cells which deliver virus to skin

cytopathy - syncytia form in epithelia

host protective response and immunopathology

latent infection in neurons (dorsal root and cranial ganglia)

Question 13

4 broad methods of investigating viral infection?

Answer 13

antigen detection
nucleic acid detection
igM for acute
igG for immunity

Question 14

what are the Sx of anaphylaxis?

how do you treat anaphylaxis?

Answer 14

bronchospasm, facial/laryngeal oedema, hypotension

Adrenaline IM 0.5mg
Chlorphenamine IV 10mg
Hydrocortisone IV 200mg
and repeat after 5 minutes if no improvement