Infectious Diseases - Cases

Question 1

What are the common caustive organisms in

1. Erysipelas
2. Cellulitis

Answer 1

1. beta haemolytic Group A Streptococci e.g. strep pyogenes
2. Staph Aureus

Question 2

What is first line antibiotic for mammal bites?

Answer 2

Co-amoxiclav

Question 3

Which 2 anitibiotics could you use in MRSA?

Answer 3

Doxycycline (mild/mod) and Vancomycin (severe)

Question 4

What is a worrying sign of deep soft tissue infection?

Answer 4

Pain that is out of proportion with clinical signs

Question 5

What is necrotizing fasciitis?

Answer 5

• a medical emergency.
• In the media it is often referred to as “flesh eating disease”.
• The hall-mark of this disease is rapid progression and tissue necrosis, often following trauma or surgery.
• Infection has spread along the fascial planes and systemic illness is the norm.
• The patient will need emergency surgical debridement of all necrotic tissue and antibiotics to cover Gram negative, Gram positive and anearobic bacteria.
• Infection is often polymicrobial and the most commonly isolated bacteria are Group A Streptococcus, Staphylococcus aureus and anaerobes.
• Even with prompt therapy, mortality is around 10-30%.

Question 6

What is the most common group A strep?

Answer 6

Strep pyogenes

Question 7

This is caused by gas-forming bacteria especially Clostridium perfringens. It is an emergency

Answer 7

gas-gangrene

Question 8

Who are at risk for cellulitis?

Answer 8

People with venous stasis or lymphoedema are at higher risk of cellulitis in the legs,

1. for example patients who have pedal oedema secondary to congestive cardiac failure
2. patients who are obese and have excess adipose tissue on their limbs and trunk.
3. Diabetes is another common risk factor.

Question 9

What looks like cellulitis but isn’t?

Answer 9

1. deep vein thrombosis
2. lymphedema
3. venous insufficiency
4. venous eczema

Question 10

What is the difference between MSSA and MRSA?

Answer 10

MRSA is is more difficult to treat because of resistance to antibiotics

MRSA and MSSA have similar virulence, it is just that MRSA is resistant to all penillins, cephalosporins and many other antibiotics. It is particularly associated with hospital-acquired infection but does exist in the community.

Question 11

What organism is gas gangrene caused by?

Answer 11

Clostridium perfringens

Question 12

Why can you get sick from Flu twice in one year?

Answer 12

2 different strains - genetic drift

Question 13

What is antigenic shift?

Answer 13

two or more strains combine to form a new subtype with surface antigens that humans have not encountered previously.

Question 14

When are flu patients most infectious?

Answer 14

24-48hrs before they display symptoms

Question 15

Which is the more serious strain of influenza virus?

Answer 15

Influenza A

Question 16

What kind of drug is used as an antiviral against influenza?

Answer 16

Neuraminidase inhibitors - end in -amivir

Question 17

How long can the “shedding” period after flu be?

Answer 17

Up to 14 days

Question 18

What are the common causes of CAP in regular pts?

Answer 18

1. Streptococcus pneumoniae,
2. Haemophilus influenzae,
3. Influenza,
4. Legionella pneumophila,
5. Mycoplasma pneumoniae

Question 19

What are the contraindications to flu vaccination?

Answer 19

1. immunocompromised
2. aged < 2 years
3. current febrile illness or blocked nose/rhinorrhoea
4. current wheeze (e.g. ongoing viral-induced wheeze/asthma) or history of severe asthma (BTS step 4)
5. egg allergy
6. pregnancy/breastfeeding
7. if the child is taking aspirin (e.g. for Kawasaki disease) due to a risk of Reye’s syndrome

Question 20

What test is used to diagnose systemic mould (Aspergillus) infections?

Answer 20

Serum galactomannan (GM) test

Question 21

Which viruses can cause diarrhoea?

Answer 21

1. Rotavirus
2. Norovirus
3. In the immunocompromised, CMV

Question 22

What is the treatment for CMV?

Answer 22

Ganciclovir