Flashcards in Infection Deck (188)
Ann invasion of hosts tissues by microorganisms
Causing disease by microbial multiplication, toxins or host response
Give some examples of pathogens using different routes of infection
Self - Escherichia coli - Uti
Direct contact - Herpes Simplex Virus - Cold sore
Vector - Plasmodium vivax - malaria
Faeco-oral (food and water) - Clostridium difficile - c diff
Droplet - Influenza - flu
Aerosol - Mycobacterium tuberculosis - TB
Blood - Hepatitis B - hep B
Vertical transmission - cytomegalovirus (placental), Chlamydia trachomatis (delivery)
Differentiate exo and endo toxins
Exo - released by the bacteria usually acting away from the site
Endo - structural components of bacteria
Which types of bacteria are more likely to express endotoxins?
What are the toxins released by c diff
type A create pores in enterocytes
type B are cytotoxic
What pathogen and host factors influence disease severity?
Virulence of pathogen
What are the two broad categories of investigations for infection?
Supportive (e.g. Cxr, fbc)
Specific (e.g. Micorscopy, culture)
What sorts of viruses are effected by alcohol?
Enveloped - disrupts their membrane
Examples of Non enveloped viruses (thus less effected by alcohol)
Paravirus 19 (fifths disease)
Hep A and E
Give some examples of DNA viruses
Counterstain in a gram stain?
Differentiate the types of fungi
Yeast - single cell (e.g. Candida, pneumocystis jiroveci)
Mould - multi cell (e.g. Aspergillus, tinia)
Give 3 examples of protazoa and their disease
Plasmodium - malaria
Giardia lamblia - giardiasis
Trypanosoma cruzi - chagas
Cause of bilharzia
What patient factors influence susceptibility to infection?
Age (Stis in teens and 20s, varied levels of immunity to meningococcal meningitis)
Gender (uti and anatomy, suppressed immunity in males)
Physiological state (preggers, puberty/menopause)
Pathological state (immunocompromised, low blood flow)
Drugs (PPIs, steroids)
Social (living cramped, damp)
Time (seasonal infections, incubation)
Place (current - e.g. Hospital, recent - e.g. Travel infections)
What are the two main categories of infection treatment? What can be done in each?
Specific - abx, surgery
Supportive - fluids, o2, pain relief, immunoglobulins, abx against proteins to reduce exotoxin production
What are the sirs criteria?
Give some examples of organ dysfunction seen in severe sepsis
Hypotension, confusion, decreased urine output, lactic acidosis
Why does sepsis alter coagulation?
What are the consequences
Cytokines initiate thrombin production and inhibit thrombolysis
Endothelial damage exposes TF and impairs prostacyclin production
DIC develops and clots can cause gangrene
What are the sepsis 6?
Within one hour:
Bloods for culture
IV fluids up
Urine output monitored
How is meningococcal meningitis subdivided?
What can we vaccinate against
Serogroups a,b, and c
Vaccines for a and c
What sort of a response does innate immunity provide to the body?
Fast and non specific
What are the first and second line defences of the innate immune system?
First - limits entry and growth
Second - contains and clears
What are the four categories of first line innate defences?
Physical - eg epithelial barrier, mucus membrane
Physiological - eg d/v coughing, sneezing
Chemical - eg stomach acid, vaginal acid, molecules (lysozymes, IgA, mucous, pepsin)
Biological - normal flora (compete, actively kill)
How does the stomach act as a chemical barrier to infection?
What is involved in second line innate defences?
What do phagocytes use to recognise pathogens?
Use pathogen recognition receptors (PRRs) to detect pathogen associated molecular patterns (PAMPs)
Examples of PAMPs with associated bacteria
Lipopolysaccerides (gram -ve)
Peptidoglycan (gram +ve)
Flagellin (flagella bacteria)
Mannose rich glycans (mycobacteria)
What can enhance recognition of bacteria by PRRs?
Opsinisation with C3b, C4b, IgG, CRP