Infectious diseases

Question 1

Fever on alternating days, think

Answer 1

Fever on alternating days, think Malaria

Question 2

CT head showing temporal lobe changes - think

Answer 2

CT head showing temporal lobe changes - think herpes simplex encephalitis

Question 3

Herpes simplex encephalitis presentation

Answer 3

fever, headache, psychiatric symptoms, seizures, vomiting
focal features e.g. aphasia
peripheral lesions (e.g. cold sores) have no relation to the presence of HSV encephalitis

Question 4

Atypical lymphocytes can indicate which infection?

Answer 4

Atypical lymphocytes - ?glandular fever

Question 5

Campylobacter infection antibiotic of choice

Answer 5

Campylobacter infection is often self-limiting but if severe then treatment with clarithromycin may be indicated

Question 6

Infective endocarditis in intravenous drug users most commonly affects which valve?

Answer 6

tricuspid valve

Question 7

the most common cause of travellers’ diarrhoea

Answer 7

E.coli

Question 8

C. difficile antigen positivity but C diffcile toxin negative. what does thi indicate?

Answer 8

C. difficile antigen positivity only shows exposure to the bacteria, rather than current infection

Shows C.difficile colonisation

Question 9

What is used as prophylaxis for contacts of patients with meningococcal meningitis

Answer 9

Oral ciprofloxacin or rifampicin is used as prophylaxis for contacts of patients with meningococcal meningitis

Question 10

commonest type of malaria

Answer 10

Falciparum malaria is the commonest type of malaria and most severe

Question 11

falciparum malaria classic triad of symptoms

Answer 11

• flu-like illness
• classical triad of symptoms includes paroxysms of fever, chills, and sweating.
• These symptoms may occur every 48 hours corresponding to the erythrocytic cycle of the Plasmodium falciparum parasite.
• Fever is often high, intermittent, and may be accompanied by rigors.
• Initial manifestations can be non-specific and include malaise, headache, and myalgia, which might be mistaken for a viral syndrome.

Question 12

falciparum malaria general features and severe features

Answer 12

Question 13

falciparum malaria complications

Answer 13

• cerebral malaria: seizures, coma
• acute renal failure: blackwater fever, secondary to intravascular haemolysis, mechanism unknown
• acute respiratory distress syndrome (ARDS)
• hypoglycaemia
• disseminated intravascular coagulation (DIC)

Question 14

management of falciparum malaria

Answer 14

Question 15

Suspected bacterial meningitis: an LP should be done before IV antibiotics, unless:

Answer 15

• cannot be done within 1 hour
• signs of severe sepsis or a rapidly evolving rash
• significant bleeding risk
• signs of raised intracranial pressure

Question 16

Giardiasis is caused by
It is spread by

Answer 16

Giardiasis is caused by the flagellate protozoan Giardia lamblia. It is spread by the faeco-oral route.

Question 17

Giardiasis risk factors

Answer 17

foreign travel
swimming/drinking water from a river or lake
male-male sexual contact

Question 18

Giardiasis features

Answer 18

• often asymptomatic
• non-bloody diarrhoea
• steatorrhoea
• bloating, abdominal pain
• lethargy
• flatulence
• weight loss
• malabsorption and lactose intolerance can occur

Question 19

Giardiasis investigations and treatment

Answer 19

Investigations
* stool microscopy for trophozoite and cysts: sensitivity of around 65%
* stool antigen detection assay: greater sensitivity and faster turn-around time than conventional stool microscopy methods
* PCR assays are also being developed

Treatment is with metronidazole.