Introduction to Infection Flashcards
What is the definition of symbiosis?
Interaction between two different organisms living in close physical association, typically to the advantage of both.
What is a commensal symbiotic relationship?
A symbiotic relationship between two different species where one derives some benefit & the other is unaffected.
What is colonisation?
When a microbe grows on or in another organism without causing any disease.
List some host risk factors for infection.
- Extremes of age
- Stress & starvation
- Compromised barriers - Physical (skin), Biochemical
- Immunocompromised host
In which different ways can a host be immunocompromised?
- Primary immunodeficiency (from birth)
- Secondary immunodeficiency (acquired after birth)
- Immunosuppression (iatrogenic from immune suppressing treatment).
List 4 physical barriers which prevent most infectious agents from entering the body.
- Skin
- Mucus
- Respiratory cilia
- Commensal organisms
List 4 biochemical barriers which prevent most infectious agents from entering the body.
- Sebaceous secretions in skin
- Lysozyme in tears
- Spermine in sperm
- Gastric acid
Which investigations and signs can be used for diagnosing infections?
- Markers of inflammation in blood or other body fluids
- Microscopy, culture & sensitivity testing for bacteria
- Nucleic acid detection for viruses
- Antibody detection for viruses and unusual pathogens
- Antigen detection for unusual pathogens
- Imaging studies
What are the 8 steps which bacteria will need to follow to cause infection?
- Access - can they reach suitable site for adherence?
- Adherence - can they stick to suitable site for invasion?
- Invasion - can they penetrate the barriers to infection?
- Multiplication - can they replicate to cause infection?
- Evasion - can they evade the host immune system?
- Resistance - can they resist anti-microbial treatments?
- Damage - do they damage host cells (directly or indirectly)?
- Transmission - can they be released to infect other hosts?