Infectious Diseases

Question 1

Protozoal infection treatment (Trichomonas, Giardia, Amoeba)

Answer 1

Metronidazole

Question 2

Aspiration pneumonia treatment ?

Answer 2

Metronidazole (as it is caused by anaerobes)

Question 3

What does metronidazole cover?

Answer 3

Gram-negative anaerobes:
- Bacteroides fragilis (though some resistance is emerging)
- Fusobacterium species
- Prevotella species

✅ Gram-positive anaerobes:
- Clostridium difficile (though vancomycin is preferred)
- Clostridium perfringens
- Peptostreptococcus (limited coverage)

✅ Protozoa:
- Trichomonas vaginalis
- Giardia lamblia
- Entamoeba histolytica

Question 4

Pneumocystis jirovecii prophylactic medication + CD4 count threshold ?

Answer 4

Co-trimoxazole

Start when CD4 count is below 200

Question 5

Lyme disease treatment (early and late)

Answer 5

Early Lyme disease = oral doxycycline (14-24 days)

Late Lyme disease (CNS involvement) = IV ceftriaxone

Question 6

STD gram-negative diplococci + treatment

Answer 6

Gonorrhoea, IM ceftriaxone

Question 7

Commonest causative organism of malaria?

Answer 7

Plasmodium falciparum

Question 8

Deterioration in patient with hepatitis B ?

Answer 8

Hepatocellular carcinoma

Question 9

Syphilis treatment

Answer 9

Benzathine penicillin (Benzylpenicillin + benzathine)

Question 10

Animal bite - what to prescribe

(+ what to prescribe of penicillin allergic)

Answer 10

Co-amoxiclav

if penicillin-allergic, prescribe doxycycline and metronidazole

Question 11

TB treatment side effects:

Answer 11

RifamPEEcin - orange urine (Rifampicin is orange/red)
IsoNERVazid - Vitamin B6 deficiency
PyraLIVERmide - Hepatoxicity
EYEthambutol - Optic neuritis

Question 12

Which hepatitis carries most risk of hepatic failure in pregnancy?

Answer 12

Hepatitis E

Question 13

Traveller’s diarrhoea - most common causative organism ?

Answer 13

E. coli

Question 14

Bacterial vaginosis:
1. what organism causes it?
2. how does it present clinically?
3. what would you find on microscopy?

Answer 14

1. Gardnerella vaginalis
2. thin, greyish-white discharge with a characteristic ‘fishy’ odour
3. clue cells

Question 15

Disseminated gonococcal infection triad?

Answer 15

1. tenosynovitis
2. migratory polyarthritis
3. dermatitis

Question 16

Which organism can cause lactose intolerance and why?

Answer 16

Giardia lamblia

• decreases the expression of brush-border enzymes in the small intestines

Question 17

Hepatitis D treatment?

Answer 17

pegylated interferon alpha

• over 48 weeks
• not always effective

Question 18

Severe MRSA infection - what antibiotic?

Answer 18

IV vancomycin

Question 19

Prophylactic treatment for close contacts of patients with meningococcal meningitis?

Answer 19

Ciprofloxacin

Question 20

Which UTI antibiotics should be used/avoided in pregnancy?

Answer 20

1st line = Nitrofurantoin (avoid near term)
2nd line = amoxicillin or cefalaxine

DO NOT prescribe trimethoprim (teratogenic in first trimester and avoided during pregnancy)

Question 21

CAP in a penicillin-allergic patient ?

Answer 21

Clarithromycin/doxycycline