Infection Intro Flashcards
What is an infection?
Invasion of hosts tissues by micro-organisms
How is disease caused
Microbial multiplication
Toxins
Host response (how we react symptoms)
What is microbiota
AKA commensals - normally carried by hosts and do not usually cause harm unless transferred to other sites
How do people get infections via intermediary/source
From physical contact (STI)
Airborne (chicken pox)
Vector (malaria)
How can we get infection from environment
Water, food, air, surfaces (surgical instruments)
Horizontal transmission
Contact (either direct or indirect or via vector)
Inhalation (droplets or aerosols)
Ingestion (faecal-oral)
Verticals transmission
From mother to child (before birth in uterus or after)
Virulence factors
Enhance survival in host and cause damage to host
Virulence factors examples
Exotoxins (cytolytic, AB toxins, superantigens, enzymes)
Endotoxins
How to microorganisms cause disease
Exposure, adherence, invasion, multiplication, dissemination
What determines body’s response to disease
Pathogen (virulence factors, inoculum size, anti microbial resistance)
Patient (site of infection and co morbidities)
How do we know if patients have an infection
History (symptoms - focal? Severity? Duration?)
Examination
Investigations (specific or supportive)
Supportive investigations examples
Full blood count (neutrophils and leukocytes)
CRP (c reactive protein to show inflammation response)
Kidney function test
Imaging
Histopathology
GIVE NO IDENTIFICATION OF SPECIE CAUSING DISEASE
Bacteriology
Specimen (swab/fluid/tissue)
MCS:
Microscopy (bacteria or cerebrospinal fluid)
Culture (using agar and sheep blood)
Antibiotic susceptibility (see which kills bacteria)
Antigen detection
Nucleic acid detection
Virology
ELISA TEST: Antigen detection (the virus) Antibody detection (the patients response) Not elisa: Detecting nucleic acid (DNA/RNA)
