Microbial Contamination Flashcards
What is the order for resistence to sterilisation?
- Multicellular organisms
- Vegetative bacteria and fungi, algae, protozoa, large viruses
- Fungal spores
- Small viruses
- Bacterial endospores
- Prions
Which type of bacteria have a thick layer of peptidoglycan?
Gram-positive
Which type of bacteria contain LPS?
Gram-negative
What are the stages in biofilm development?
Initial attachment Irreversible attachment Microcolony formation Maturation Dispersal
Why are biofilms such a problem?
More resistant to antibiotics and biocides
More difficult to phagocytose
What is bacterial sporulation?
Survival strategy when nutrients become exhausted
Which type of bacteria form spores?
Gram-positive (not all of them however)
Bacterial spores are very resistant to what?
Heat
Radiation
Chemical agents
Dessication
How long can bacterial spores survive for?
Years
Bacterial sporulation occurs during which phase?
Stationary phase
What are the 3 types of fungi?
Yeasts
Multicellular filamentous moulds
Macroscopic filamentous fungi
Features of yeasts
Reproduce by budding/fission
but can form spores
Features of Macroscopic filamentous fungi
Reproduce by formation of spores
Can viruses grow/replicate outside of the host?
No, they don’t acquire nutrients (obligate intracellular)
What type of product do viruses normally contaminate?
Blood-derived
Protozoa are what type of eukaryotes?
Animal-like (most are free-living)
TRUE/FALSE? Protozoa have cell walls
False (means they don’t survive drying very well)
TRUE/FALSE Prions are a type of organism
False (they are infectious agents)
How do prions cause infection?
Through PRPsc-templated conversion of PRPc proteins
What diseases are related to prions?
CJD and Kuru
Prions are resistant to what?
Chemical and heat sterilisation
preference for use of disposable items in patients with CJD
What are the most comment contaminants?
Bacteria and Fungi
