Theme 3 Lecture 15: Infection tests

Question 1

What are some system specific symptoms of infections and which system do they relate too?

Answer 1

• cough (respiratory)
• neck stiffness (CNS)
• bony pain (orthopaedic)
• skin pain/redness (SST)
• dysuria (urinary)

Question 2

What are some non specific system symptoms of infections and which system do they relate too?

Answer 2

• fever
• shaking episodes/chills
• sweating/night sweats
• feeling muddled/confused

Question 3

What information in the history would you want to ask a patient who is presenting with symptoms of infection?

Answer 3

• travel
• occupation
• animal contact (which animals/nature of contact)
• hobbies
• sexual history

Question 4

What is a fever?

Answer 4

• a sign of inflammation and can be a symptom/ sign of infection
• temperature > 38 degrees

Question 5

On examination of a patient with suspected infection, what might you expect to find?

Answer 5

• lung crackles
• meningism
• bony tenderness
• skin erythema
• loin tenderness
• pyrexia
• rigor/chills
• sweating
• confusion

Question 6

What are the different diagnostic tests for infection?

Answer 6

• haemaglobin
• white blood cell count
• inflammatory markers e.g C-reactive protein, procalcitonin
• Chest X-ray

Question 7

How can we determine how severe a case of pneumonia is?

Answer 7

CURB-65:
Confusion
Urea
Respiratory rate
BP
Age > 65

Question 8

What is the most common bacterial cause?

Answer 8

streptococcus pneumoniae

Question 9

What are the 5 steps in blood culture sampling?

Answer 9

1. patient sampling
2. sample handling
3. specimen transport
4. incubation
5. growth detection

Question 10

How do we incubate blood cultures?

Answer 10

• 35-37 degrees
• 5-7 days
• microbial growth is usually detected by constant automatic monitoring of CO2

Question 11

What is gram stain?

Answer 11

chemical process that distinguishes between bacterial cell walls that retain crystal violet, and those that do not, when stained and washed with acetone

Question 12

How is the sensitivity of an antibiotic measured?

Answer 12

1. agar plate covered in bacteria of interest
2. add filter paper discs (brown) - each letter represents a different antibiotic which then diffuse into the medium
3. after incubation the bacteria grow
4. where there is no growth, it shows the antibiotic is having a killing effect on the bacteria
5. lab measures zone of inhibition

Question 13

What is a titre?

Answer 13

1/greatest dilution at which an antibody is detectable

Question 14

When should culture tests be taken?

Answer 14

before antibiotics are given

Question 15

Microbiological diagnosis relies on what 3 modalities?

Answer 15

1. direct detection
2. culture
3. immunological tests