Infection Model Flashcards
(21 cards)
What is the infection model?
Pathogen + Patient (Mechanism of infection) ->
Infection ->
Management ->
Outcome
Separate the microbial kingdoms into eukaryotes and prokaryotes
Prokaryotes - bacteria
Eukaryotes - Fungi (yeast and Moulds), parasites (protozoa and helminths)
Virus not contained in either
Describe how age affects the likelihood of infection with meningitis as an example
Neonates/infants - group B strep meningitis or E. coli meningitis
Children - neisseria meningitidis or strep pneumoniae
Adults - neisseria meningitidis or strep pneumoniae
Elderly - listeria monocytogenes
At what ages are people most vulnerable to infection and why?
Post 6 months - immature adaptive immune system and no longer breast fed so no maternal Abs from placenta or breast feeding
Elderly - increased risk of comorbidity and gradual immunosuppression
Give an example of how sex can influence a risk of infection
Females more likely to contract urinary tract infections due to proximity or urethral opening to anus
What is the link between infection and pregnancy?
Pregnant women are more susceptible to infection from usually non-pathogenic microbes and infections are usually more severe.
Result from changes in hormone levels and immune suppression
What is the link between infection and the menstrual cycle?
The menstrual cycle affects the likelihood of infection because the environment of the uterus and vagina change, with fluctuations in pH
How does the time of year influence the likelihood of infection?
Many microbial diseases have annular peaks in occurrence eg. flu and norovirus (winter vomiting virus) due to temperature and humidity allowing better survival as particulates and replication in extremities eg nasal cavity
Describe the contiguous spread mechanism of infection
Contiguous spread is when microbiota spread in the same plane. Eg entering open wound from skin, entering peritoneum from ulcer
Describe the inoculation mechanism of infection
The introduction of a microbe to a tissue via contact or transmission of fluid eg. Medical interventions
Describe the haematogenous mechanism of infection
Introduction of microbe to secondary infection sites via the circulation. Eg endocarditis in people with poor dental hygiene (tend to affect heart due to turbulent flow around valves helping transmission)
Describe the ingestion mechanism of infection
Swallowing microbe infected material. Most commonly faeco-oral transmission
Describe the inhalation mechanism of infection
Breathing in microbes that can be expelled from other sources via coughing/sneezing etc. with microbes remaining in the air in aerosols/nuclei droplets
Describe the vector mechanism of infection
The transmission of an infection via a secondary carrier eg. Malaria, zika virus, Lyme disease
Describe the vertical transmission mechanism of infection
Transfer of microbes from maternal source eg. Intrauterine, vaginal during birth (HIV), via placenta, via breast feeding
Why would non-bacteriocidal medications be preferable in some infections?
Prevents release of endotoxins (only released when organism degenerates e.g. Lipoproteins in cell wall) that can be potentially damaging
What are the 3 main parts of diagnosing an infection?
What are the 2 main things we need to identify?
History
Examination
Investigations
Causative agent
Location
Treatment can be separated into 2 main types, what are they?
Describe the 2 subcategories for each
Specific - antimocrobials and surgery
Supportive - symptom relief and physiological restoration
Give an example of a symptom relief treatment and what it does
Antipyretics (eg NSAIDs) - reduce fever/calor
Give an example of a physiological restoration treatment and when it would be used
Fluid replacement eg. Diarrhoea, sepsis
Surgical treatments for infection can be categorised as 3 main types, what are these?
Drainage
Debridement
Dead space removal
