Introduction

Question 0

Explain how an infection develops

Answer 0

Commensal microbiota --> other sites
Physical contact (STIs) 
Airborne 
Via a vector 
Fecal-oral 
Air contamination 
Contaminated surfaces 
Horizontal transmission - contact, inhalation, ingestion
Vertical transmission - mother to baby

Question 1

Define the term ‘infection’

Answer 1

Invasion of a host’s tissues by microorganisms and disease caused by microbial multiplication, toxins or host response

Question 2

How do microorganisms cause disease?

Answer 2

Exposure
Adherence
Invasion
Multiplication
Dissemination 
Depends on virulence factors and host cellular damage

Question 3

Describe some disease determinants

Answer 3

Pathogen - virulence, inoculum size, antimicrobial resistance
Patient - site of infection, co-morbidities
Practise - standards, hand washing
Place - nightingale wards, isolation, carpeting

Question 4

How would you identify that a patient had an infection?

Answer 4

History - symptoms, exposure
Examination
Investigation - specific, supportive

Question 5

Describe the main Antimicrobial classes and their mechanism of action

Answer 5

B-lactams (penicillin, co-amoxiclav), glycopeptides (vancomycin), cephalosporins - inhibit peptidoglycan cross linkages
Aminoglycosides (streptomycin) - prevent translation
Macrolides (erythromycin), tetracyclines - interfere/inhibit protein synthesis

Question 6

Explain the principles of choosing antimicrobials for particular infections

Answer 6

Antibiotics, antifungals, antivirals

Antibiotics - affect different classes (e.g Gram +ve)