Infectious diseases

Question 1

What is Lemierre’s syndrome?

Answer 1

Jugular vein suppurative thrombophlebitis

Think in bacteraemia with Hx of pharyngitis and unremitting fever

Question 2

Which organism often causes infection following fresh water exposure?

Answer 2

Pseudomonas aeruginosa

Question 3

What does a positive HBsAg suggest?

Answer 3

Hepatitis B surface antigen

Suggests active infection, acute or chronic

Question 4

What does a positive anti-HBs suggest?

Answer 4

Hepatitis B surface antibody

Suggests life-long immunity, either resolved infection or vaccination

Question 5

What does positive anti-HBc IgM suggest?

Answer 5

Current infection

Positive 4-8 months after infection

Question 6

What does a positive anti-HBc IgG suggest?

Answer 6

Resolution of acute infection

OR chronic infection (does not confer immunity)

Question 7

How do HBsAg levels change over time?

Answer 7

Positive: 2-10 weeks after infection

Negative: 4-6 months after infection (positive anti-HBc may be the only marker of acute infection)

Positive: > 6 months after infection (signals chronic infection)

Question 8

What does HBeAg reflect?

Answer 8

Marker of viral replication

Marker of infectibility/transmission

Question 9

An abrupt onset of fever + rash + severe arthralgia and myalgia is characteristic of which disease?

Answer 9

Dengue fever

Question 10

How is dengue fever transmitted?

Answer 10

Mosquitos

Most commonly in the tropics and subtropics

Question 11

Fever + bradycardia + jaundice + bleeding is characteristic of which condition?

Answer 11

Yellow fever

Question 12

What occurs once yellow fever progresses to severe disease?

Answer 12

Jaundice

Renal failure

Hepatic failure

Haemorrhagic complications

Question 13

How is syphilis diagnosed?

Answer 13

1. Non-treponemal test (non-specific anticardiolipin antibodies)
2. Followed by confirmation with a treponemal test (detects treponemal antibodies)

OR

Direct detection of the pathogen (dark field microscopy, PCR)

Question 14

What are two examples of a non-treponemal test?

Answer 14

Rapid plasma reagin (RPR)

Venereal disease research laboratory (VDRL)

Screening tool, can evaluate disease activity, monitoring response to treatment

Question 15

What is an example of a treponemal test used for the diagnosis of syphilis?

Answer 15

Treponema pallidum particle agglutination (TPPA)

Fluorescent treponemal antibody absorption test (FTA-ABS)

Question 16

When is direct detection of the pathogen by either dark field microscopy or PCR used for syphilis diagnosis?

Answer 16

When a sample can be obtained e.g., exudative chancre, condyloma

May be the only positive test in early primary syphilis

Question 17

Which drugs are used for active TB?

Answer 17

2 months of daily

1. Rifampicin
2. Isoniazid
3. Pyrazinamide
4. Ethambutol

Followed by 4 months of daily

1. Rifampicin
2. Isoniazid

Question 18

How is latent TB treated?

Answer 18

Isoniazid for 6-9 months

Decreases risk of progression

Eliminates risk of transmission

Question 19

How is a diagnosis of clostridium difficile confirmed?

Answer 19

Detection of toxins in stool (enzyme immunoassay)

Or PCR OR EIA for C. difficile glutamate dehydrogenase antigen

Question 20

From what species of parasite is malaria contracted?

Answer 20

Plasmodium

Question 21

What type of mosquito carries malaria?

Answer 21

Anopheles

Question 22

Which parasite causes the most severe form of malaria?

Answer 22

Plasmodium falciparum

Question 23

Which medications are used to treat malaria?

Answer 23

Artemether + lumefantrine