Lecture 1 Flashcards
How do you get infections?
Source Intermediary -physical contact -airborne -vector may be necessary (mosquito) -ingestion of contaminated food/water -inhalation of air contaminated by environmental organisms -contact with contaminated surfaces (medical devices)
What are the types of transmission?
Horizontal:
- contact (direct/indirect/vectors)
- inhalation (droplets/aerosols-remain suspended in air for ages, whereas droplets don’t) (chicken pox is transmitted by airborne aerosols)(vent used on wards to remove the aerosols)
- ingestion (faecal-oral transmission)
Vertical:
-Mother to child before birth (infected in uterus/at time of birth)
How do microorganisms cause diease?
Exposure Adherence Invasion Multiplication Dissemination (spreading-wide)
Name some virulence factors:
Exotoxins
- cytolytic
- AB toxins (destroy tissue)
- superantigens (defences that divert immune system)
- enzymes
Endotoxins (host recognises these e.g. high levels of LPS-sepsis)
What are disease determinants?
Patient & Pathogen
Pathogen
- virulence factors
- inoculum size (amount of pathogen-differs from pathogen to pathogen)
- antimicrobial resistance
Patient
- site of infection
- co-morbidities (e.g. chronic conditions- diabetes, COPD, cancer)
How do you know patients have an infection?
Symptoms/potential exposure e.g. location (History)
Examination
Investigation (supportive/specific-know the pathogen)
What are supportive investigations?
E.g.
blood count (neutrophils/lymphocytes)
C-reactive protein (CRP-elevation/lack of)
Liver/kidney function tests (may have to alter treatment if these organs aren’t functioning properly)
Imaging
Histopathology (take a piece of tissue)
What is bacteriology?
Identification of the bacteria
Microscopy: staining
-
What is virology?
Don’t do viral culture anymore
Instead
- antigen detection
- antibody detection
- detecting viral nucleic acid
