EMQ on bugs

Question 1

A 19-year-old man returns from holiday in Spain. Four weeks later, he develops a hot, swollen, painful red knee joint, with an effusion. The knee is tapped, and 20 ml of cloudy yellow fluid is withdrawn. Microbiology reveals Gram-negative intracellular diplococci.

What is the bug?

Answer 1

Neisseria gonorrhoea

Most common cause of septic arthritis in the young

Question 2

A 19-year-old student arrives in casualty, septic, pyrexial and confused with a pyrexia of 39oC. He has a stiff neck, and a lumbar puncture reveals Gram-negative intracellular diplococci

What is the bug?

Answer 2

Neisseria meningititis

Very aggressive, causes sepsis

Question 3

A 19-year-old student arrives in casualty, septic, pyrexial and confused with a pyrexia of 39oC and blood cultures grew Gram-positive diplococci.

What is the bug?

Answer 3

Streptococci pneumoniae

Question 4

A 19-year-old student arrives in casualty, septic, pyrexial and confused with a pyrexia of 39oC and blood cultures fail to culture any organisms. Cold agglutinins are positive.

Answer 4

Mycoplasma

COLD AGGLUTINS

Question 5

A 19-year-old student has a boil on his leg which is 2cm in diameter, and painful. It is drained and some of the pus sent to microbiology. Eventually it grows Gram-positive cocci in clusters.

Answer 5

Staph aureus

Treatment of choice: flucloxacillin

Question 6

A 19-year-old has a mild fever for several months, and no cause can be found. After 2 months, blood cultures come back positive for Gram-positive cocci.

1. Diagnosis? Signs?
2. What bug?

Answer 6

1. Diagnosis: Endocarditis

• Roth spots
• Splinter haemorrhages
• Osler’s nodes and Janeway lesions
• Clubbing
• Microscopic haematuria
• SPLENOMEGALY

2. Bug: Streptococcus viridans

Question 7

What is the cause of this appearance?

Answer 7

Left ventricle hypertrophy

Caused by hypertension and aortic stenosis

Question 8

What does this image show?

Answer 8

Sickle cell anaemia

Question 9

A 6 year old boy arrives in casualty, septic, pyrexial and confused with a pyrexia of 39oC. He has a stiff neck, and a LP reveals gram negative rods.

What is the bug?

Answer 9

Haemophilus influenzae

Only present in children who don’t recieve HIB

No E.coli in CSF

Question 10

What are the commonest bugs causing meningitis in the following age groups that appear in the CSF when a LP is done?

1. 0 years
2. 6 years (non-vaccinated)
3. 18-25
4. over 60

Answer 10

1. 0 years - E.coli
2. 6 years - Haemophilus influenzae
3. 18-25 years - Neisseria meningititis
4. Over 60 - pneumoncoccus

Question 11

1. what endocarditis do drug users get?
2. Where does strep viridans target?

Answer 11

1. Staph aureus endocarditis, right sided affecting the tricuspid valve
2. Streptococcus viridans is not as aggressive, lungs filter it out easily. It will not settle on a healthy non-damaged valves. Hence why they tend to settle on the aortic valve which deals with high pressures and is often damaged. This is also why people with rheumatic fever are at risk of endocarditis too, because the valve has been damaged.