Diagnostic Microbiology

Question 1

define infection vs colonisation

Answer 1

infection is inflammation due to a microbe. May be an inappropriate immune response to a relatively non-serious pathogen

colonisation is the presence of a microbe in the human body without an inflammatory response

Question 2

bacteraemia vs sepsis

Answer 2

Bacteraemia is the presence of viable bacteria in the blood

Sepsis is the dysregulated host response to infection

Question 3

gram stains

Answer 3

Gram positive cells stain blue/purple
Gram negative cells stain pink/red.

Question 4

define clinical breakpoint and MIC

Answer 4

A clinical breakpoint is a measure of how much antibiotic needs to be in a tissue in order to work. The clinical breakpoint describes the likelihood that this level will be met with the prescribing guidelines (ex taking into account patient’s liver function etc). This can guide prescribing.

The clinical breakpoint is determined using MIC.
The minimum inhibitory concentration (MIC) is the lowest concentration of a chemical, usually an antibiotic or drug, that stops the visible growth of bacteria or fungi in a laboratory setting

Question 5

what is the most common pathogen in ulcer infections; gram; treatment

Answer 5

Staph aureus! Gram positive –> flucloxacillin
If resistant (MRSA) –> vancomycin