Microbiology Flashcards
What are commensals
Good bacteria that live on our skins - exist on body parts exposed to the external environment
Benefits of normal flora
Prevents pathogen colonisation
Antagonises other bacteria
Gut microbes make vitamins - k2
How do pathogenic microorganisms spread
Droplets, skin contact, sexual transmission, direct inoculation, vertical transmission, contaminated food
Two types of DNA in bacteria cell
Genomic DNA
Plasmid - can spread information from one microbe to another directly
How does gram staining work
Crystal violet dye
Gram +ve has thick peptidoglycan wall and dye will bind to this - stains positive
Gram -ve has thin peptidoglycan wall and extra layer on outside (LPS), dye will not reach peptidoglycan wall therefore stain negative
Morphology of bacteria
Bacilli - bacilli, vibrio, fusiform
Spirocheates - corkscrew shaped
Cocci - spherical shaped, diplomatic, strep, staph
What is an obligate aerobes
Bacteria can only survive with oxygen - can only survive in that condition
What is a facultative aerobes
Can switch between aerobic and anaerobic respiration but prefers aerobic conditions
What is aerotolerant anaerobes
They prefer anaerobic environments but they can also tolerate oxygen
Oxygen detoxifying enzymes
Superoxide dismustase - detoxified O2 radicals
Catalse - Detoxifies H2O2
What is E. coli
Gram -ve, bacilli, obligate anaerobe
What s. mutans
Gram +ve, coccus, facultative anaerobe
What is helicobacter pylori
Gram -ve, helical bacillus, microaerophile
What is a biofilm
An aggregate of interactive bacteria attached to a solid surface or to each other, encased in an extracellular polysaccharide matrix
How much of biofilm is extracellular polymeric substance
30%
