Contamination Control Flashcards
Why do microorganisms pose a problem to pharmacists?
- small
- abundant and can grow in the most unlikely situations
- may cause disease - pathogenic
- some form spores, which are resistant to killing by heat, chemical, radiation or drying
Describe bacteria.
- 0.7-4mcm
- unicellular
- rod shaped or spherical
- gram +/-
- nutrients: C, H, N, O, S, P, water
- aerobic/anaerobic
Describe bacterial spores.
- undergo a rpofound biochemical change
- lead to formation of spore
- highly resistant to adverse environemtn
Describe viruses.
- 20-250nm
- most pass through bacteria proof filters
- destruction by heat
- most inactivated at 60°C for 30 mins
- all killed by boiling water
- most chemical disinfectants have minimal virucidal activity
Describe fungi.
- single or multicellular
- single - 5-10mcm in diameter
- commonly form spores
- yeasts, moulds and mushrooms
Describe the air supply in aseptic areas.
areas have to be supplied and continuously flushed with air of suitable quality and at a positive pressure
achieved through High Efficiency Particulate Air (HEPA) filters of appropriate efficiency
Describe the cleanroom specifications.
- air wuality standards in aseptic processing areas must meet both US and European requirements
European standards:
- Grades A, B, C and D classifications, instead of 100,1000
- use particle and microbial limits per cubic metre, instead of cubic foot
- require particle measurements at 5 microns in addition to 0.5 microns in grade A and B areas
- differentiate area cleanliness dynamically “in operation” and ‘at rest’
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How can you measure aerial contamination?
- settle plates
- Slit Samplers
Describe the use of settle plates.
- nutrient plates which collects aerial contamination >100mcm which settle by gravity
- important hazard in aseptic work
- small particles not represented
- unaware of volume of air introduced
Describe the use of Slit Samplers.
- air drawn through a slit or number of small holes
- beneath which rotates a “nutrient” agar plate
- deposition of particles depends on the rate of air flow, slit width, or dimensions of holes and distance between slit/holes and plate
- 99% efficiency of particle - 1mcm
- can count number of organisms associated with particles in a known volume of air drawn through the device
What needs to be monitored in aseptic areas?
- particulate contamination
- temp & humidity
- air velocity and pressure
What is required from those who work in aspetic areas?
- high standards of personal hygiene and cleanliness
- any medical condition (colds, skin infections) should be reported
- min. number of people should be present when work in progress
- adequate training
- gowning up
What happens when viable cells are exposed to a lethal agent?
constant proportion, not a constant number of organisms are killed per unit time
plotted as:
- log number of viable cells
- log % viable cells against time
Steriling conditions should produce what probability level?
a probability level of one in one million units being non-sterile (based on linear death kinetics)
What is the sterility assurance and what does it mean?
10-6
degree of assurance with which the process in question renders a population of items sterile
SAL 10-6 = probability of not more than one viable organism in 1 x 106 sterilised items of final product
What is a D value?
decimal reduction value
value of a parameter of sterilisation (duration or absorbed dose) required to reduce the number of viable organisms by 90% or 1 log cycle
What is inactivation factor and how do you calculate it?
reduction in the number of viable organisms produced by sterilising process
10t/D
t = exposure time
D = D value
Describe the two approaches to sterilisation.
- overkill method
- sterilisation cycles based on inactivation of a greater N of organisms of greater resistance than the natural bioburden of the product
- minimum SAL set for cycle
- basis of traditional BP methods of heat sterilisation
- with recomended combinations of time and temp
- bioburden method
- requires knowledge of bioburden, D value and most resistant organism
- prior to defining the sterilising cycle
- allows sterilisation cycles to be run with acceptable SALs and minimal product detoriation
What is the bioburden?
number of viable organisms a batch contains
What is terminally sterilised vs non terminally sterilised products?
- terminally sterilised
- products sterilised in their final container
- method of choice whenever possible
- manufactured in cleanroom
- pyrogen free product
- low microbial and particulate counts prior sterilisation
- non-terminally sterilised
- prepared under aseptic conditions from previously sterilised materials
- processed in cleanrooms
- until sterilised
- filled into final container in aspetic areas
What are examples of terminally sterilised vs non terminally sterilised products?
terminally sterilised:
- steam sterilisation (heating in autoclave)
- dry heat sterilisation
- ionising radistion sterilisation
non-terminally sterilised:
- filtration
Describe heat sterilisation.
- most reliable, versatile and readily available and economic method of sterilisation
- materials must be stable
- heat decomposition of drug, interaction between drug and additives, modification of pharmacological activity of drug
- stability of containers and closures
- safer compared to chemical sterilisation
net result depends on balance between
- heat increasing rate of chemical reactions within bacteria cells = increased growth rate
- destructive effect on more heat sensitive components of cell
What is bacteriostasis?
point at which organisms die at the same rate they reproduce
What is a further increase in temp past bacteriostasis point called?
destructive bactericidal effect
death rate increased and time to sterilise decreased
