Lecture 2 & 3 Flashcards
What are the three circumstances under which normal flora may cause pathology in an animal?
Superinfection
Persistent antibiotic use selecting for resistant bacteria
Secondary invasion
What is superinfection?
A minor flora species overgrows when part of the normal flora is removed - becomes problematic when at higher numbers.
What is secondary invasion?
A lesion, immunocompromise or change in local microenvironment caused by an invading pathogen leads to conditions being favorable for excessive replication/invasion of a normal flora species e.g viral URT infection followed by bacterial pneumonia
Name three bacterial genera commensal to the oral cavity.
Staphylococci, streptococci, Actinomyces
Name three bacterial genera commensal to the large intestine.
Enterobacteria, Clostridia, Enterococci
Name three microbe genera commensal to the vulva/prepuce.
Diptheroids, micrococci, yeasts
Name three microbe genera commensal to the vagina
Streptococci, coliforms, proteus
Name three bacterial genera commensal to the skin
Staphylococci, Micrococci, Diptheroids
Where is the best location in the body to obtain a post-mortem sample if you are searching for a causative bacteria?
Medulla of long bones - this is the last site invaded by commensal organisms post death
How many different levels of biological safety cabinets are there?
Three.
How many different levels of microbiological containment are there?
Four.
Define sterilisation
The elimination of all viable micro-organisms from a material including spores
Define disinfection
Removal of potential infectivity by chemical treatments but not necessarily destruction of all viable organisms
Define antisepsis
Application of chemicals to a body surface to kill or inhibit pathogens
Why is autoclaving more effective at sterilising than dry heat?
Presence of water forms H-bonds with the dissociated proteins of organisms and helps to dissociate them further
