Microbiology Flashcards
Definition of pathogen.
Organism that causes or is capable of causing disease.
Definition of commensal.
Organism which colonies the host but causes no disease in normal circumstance.
Definition of opportunist pathogen.
Microbe that only causes disease if host defences are compromised.
Definition of pathogenicity.
The degree to which a given organism is pathogen/ any strategy to achieve this.
What colour does gram positive bacteria stain?
Purple.
What colour does gram negative bacteria stain?
Pink.
What acid-fast bacilli stains red with Ziehl-Neelsen Stain?
Mycobacteria e.g. TB.
What test is used to differentiate between staphylococci and streptococci?
Catalase test.
Is staphylococci positive or negative?
Positive.
Is streptococci positive or negative?
Negative.
What test is used to differentiate between staphylococcus aureus and staphylococcus. epidermis?
Coagulase test.
Characteristics of staphylococcus. aureus?
- Gram positive, B-haemolytic cocci in clusters.
- Skin infections, endocarditis, TSS and rapid onset food poisoning.
- MRSA.
Characteristics of staphylococcus. epidermis?
- Gram positive cocci in clusters.
- Infects prosthetic devices.
What are the three types of worms (helminths)?
Nematodes, Cestodes and Trematodes.
Define the pre-patent period?
The interval between acquiring infection and the appearance of eggs/larvae in the stool.
