Microbiology 5 Flashcards
what are the environmental control measures used to reduce risk of microbial contamination?
- clean room
- laminar flow cabinets
- isolaters
- air/water controls
what are the personnel control measures used to reduce risk of microbial contamination?
- PPE
- hand hygiene (antisepsis)
what are the other ways used to reduce risk of microbial contamination?
disinfection/antisepsis
- cleaning/disinfection of working enviro/personnel
sterilisation
- destruction of potential contaminants before release
preservation
- reduces risk of longer term contamination and spoilage
how can the risk of contamination be reduced?
use
- bunsen burner
- biosafety cabinets
- laminar flow cabinets
- glovebox/isolator
what is a bunsen burner used for?
heat sterilising metal and glass tools on lab bench
give examples of how under normal conditions, working area will be constantly contaminated with microorganisms?
- free floating/ carried on dust particles
- personnel
grades and C and D?
clean areas for carrying out less critical stages in manufacture of sterile products
grade B?
in case of aseptic prep and filling, background enviro for grade A zone
grade A?
local zone for high risk operations e.g. filling zone, open ampoules & vials, making aseptic connections
which grade is more and less stringent?
grades C and D = less stringent
grade A = more stringent
high efficiency particulate air (HEPA) filtration
removal of at least 99.97% of 0.3 micrometers diameter airborne particles
what are the 2 standards for water in pharmaceutical manufacturing?
- purified
- water for injection
purified water
non-sterile applications
- media prep
- basic prep e.g. cough syrup
water for injection (WFI)
sterile applications
- stricter quality guidelines than purified water
- endotoxin levels
how long can droplets remain in the air?
up to 2 hours
what is the advantage of hand washing?
- reduces risk of transmission of contaminants between hands & products
- reduces risk of transmission to sterile gloves
- alcohol hand gel reduces bacteria number further
give examples of protective equipment?
- gloves
- hairnets
- overshoes
products sampling/clinical samples
- filtration
- direct inoculation
—> broth/agar
environmental sampling
- surface swabbing
- contact plates
- air sampling
- liquid sampling
—> broth/agar
serial dilution and plate counts
- only shows viable cells (CFU)
3 diff methods
- pour plate
- spread plate
- drop count
optical density (OD) / turbidity
- counts everything
- inaccurate at high and low OD
direct microscopy
total number of cells in defined area
flow cytometry
uses fluorescence
what does total microbial count use?
haemocytometer
what does the total microbial coins enable?
counting of bacterial cells in known area
- need multiple fields of viewing
VERY TIME CONSUMING
what does the total microbial count show? and what is it good for?
- intact bacterial cells
- good for difficult to culture and polymicrobial
- doesn’t show anything about viability
what is the total viable count used for?
bacteria, yeasts and moulds
- can see individual
- count CFU
for viruses, you don’t see colonies
what do you count instead?
plaque forming units (PFU)
- absence of growth (plaques)
what percentage of human microbiota can be cultures?
1-5%
formula to calculate CFU/mL?
number of colonies X (dilution in tubes X no. of aliquots in 1mL)
what is the British pharmacopoeia?
- official standards for UK medicinal products & pharmaceutical substances
- specifies acceptable limits for microbial contamination of non-sterile products
what do sterile products have to contain?
no microbial contaminants
what is spoilage?
chemical and physiochemical deterioration
what will the rate of breakdown depend on?
- molecular structure
- environmental conditions
- type and number of microbial contaminant
give example of inactivation of a product?
penicillin breakdown by beta-lactamase
give example of breakdown of thickening/suspending agents?
starch breakdown by amylase
synthetic packing materials (e.g. nylon) are more … than naturally derived materials (e.g. cellophane)
resistant
what can you add to resist spoilage?
preservatives
the serious responses are from what?
injected products/ immunocompromised patients
most serious effects are from contaminated injectable products.
what can this lead to?
- general bacteraemic shock
- death
