What is clinical infection characterised by?
Pyrexia (raised body temperature)
Tachycardia (increased heartrate)
Rigors (sudden feeling of cold with shivers)
Increased white cell count
Increased C reactive protein (CRP)
What is pyrexia?
Raised body temperature
What is tachycardia?
What are rigors?
Sudden feeling of cold with shivers
What is a pathogen?
An organism that can cause disease
What is a commensal?
An organism which is part of normal flora
What are examples of commensals?
E coli in the gut
Staph aureus in the nose
What is a skin commensal?
When can coagulase-negative staphyloccii be pathogenic?
In the presence of foreign bodies (such as prosthetic heart valves)
What is Koch's postulates?
The criteria used to identify the agent of a particular disease
What are the principles of Koch's postulates?
Organism must be found in all cases of the disease
Able to be cultured outside the body for several generations
Should reproduce the disease on inoculation (vaccination)
What do non-sterile sites contain that sterile sites do not?
What do we need knowledge of to determine if something is a pathogen?
Normal flora for the site
What is pathogenicity?
Ability of an organism to cause disease
What is flora?
Collective bacteria and other microorganisms in an ecosystem
What does an organism need to be to cause an infection?
Infectivity (ability to become established)
Virulence (ability to cause harmful effects once established)
What is infectivity?
Ability to become established
What is virulence?
Ability to cause harmful effects once established
What are things that help infectivity?
Attachment (such as P-fimbriae on E coli)
Acid resistance (such as urease on helicobacter pylori)
What is an example of attachment helping infectivity?
P-fimbriae on E coli
What is an example of acid resistance helping infectivity?
Urease on helicobacter pylori
What is urease?
An enzyme that catalysis urea to ammonia and carbon dioxide
What is virulence supported by?
Evasion of immune system
What is virulence specific to?
Strains, not species
What is an example of invasiveness?
Streptococcus pyogenes causing:
Necrotising fascilitis (flesh eating disease)
Connective tissue breakdown
What is haemolysis?
The rupture or destruction of red blood cells
What are the 3 types of haemolysis?
Alpha haemolytic (partial haemolysis, turns blood agar green)
Beta haemolytic (complete haemolysis, turns blood agar clear)
What is alpha haemolytic?
What colour does alpha haemolytic turn blood agar?
What is beta haemolytic?