bacteria 5,6 Flashcards
when does microbial contamination occur
during manufacturing process and products escape quality assurance checks
what are the impacts of microbial contamination
medicine unfit for use, potential litigation, financial loss, limits supply to patients, health hazards, infections, endoxins
what medicine components/pharmaceutical ingredients are at risk of microbial attacks
active drugs- metabolised to less potent/chemically inactive forms
non/anionic surfactants- alkyl/alkylbenzene sulphonates are readily metabolised
organic polymers (thickening agents)- microbial depolymerisation
humectants- readily metabolised in low amounts
fats/oils- attacked when dispersed in aqueous formulations
sweeteners/flavourings/colouring agents- substrates for bacteria, high conc are resistant to degradation
how to resist microbial contamination
use preservatives
what are visible signs of contamination
unpleasant smell, sour taste, appearance change, texture/viscosity changes, sedimentation, production of bubbles, cracking, change in efficacy
what causes viscosity and textures to change when a medicine component is contaminated
metabolism of thickening agents or sugar polymerisation
what are preservatives used for
resist microbial contamination
factors that affect/cause microbial contamination of a pharmaceutical product
type/size of inoculum, nutritional factors, moisture content (greater solute conc=lower water activity), redox potential, storage temp, pH, packaging design protection of microorganisms in pharmaceutical products
list some non-antibiotic antimicrobials available
antiseptics, disinfectants, preservatives, creams/ointments, disinfectant sprays, biocides, alcohol based gel scrubs
describe how the non-antibiotic antimicrobial, antiseptics, work
destruction/inhibition of microorganisms on living tissue, against sepsis, prevents systemic infection, non toxic to host, ex vivo use (wounds, mouth)
what is ex vivo
outside living body
what is sepsis
body doesnt respond properly to an infection
describe how the non-antibiotic antimicrobial, disinfectants, work
removes microorganisms from inanimate objects/surfaces, kills/reduce numbers to a level that is acceptable for defined purpose, most are too toxic to use on body tissue
describe how the non-antibiotic antimicrobial, preservatives, work
added to pharmaceutical,cosmetics,foods to prevent microbial contamination, non toxic, lower activity level than antiseptics and disinfectants
what trait must a preservative have to be considered efficient
effective against two bacterias, a yeast and a mould
a chemical exhibits antimicrobial activity if…
it interacts and enters a host cell
how do non-antibiotic antimicrobials initially interact with the cell wall/membrane
electrostatic or hydrophobic interactions
how do non-antibiotic antimicrobials enter a cell
porin channels or diffusion
what affects the efficacy of a biocide
affinity for structural/molecular components
what is the rate of non-antibiotic antimicrobials activity affected by
temperature, concentration pH, solubility, type/form of microorganisms present
how do biocides work/exhibit antimicrobial activity
structural damage to cell wall/membrane or interactions with cellular components
why is resistance to biocides not often seen
biocides are short lasting
which type of bacteria is more resistant to biocides
gram-negative
list the 5 methods of sterilisation
moist heat (steam), dry heat, ionising radiation, gas, filtration
describe how moist heat (steam) is used for sterilising, what it is used to sterilise and its lethal effects
used for: culture media, medical implements (tools), aq injections, ophthalmic preparations
lethal effects: denaturation of enzymes or destruction of cell
steams at 121-134c for 20 minutes on phase boundary with water in an autoclave
2 types of steams: wet steam (boiled within autoclave) and dry steam
(boiled externally and supplied under pressure)
what is an autoclave
pressure vessel
why is dry steam preferred over wet steam in moist heat sterilisation
wet steam soaks the load preventing steam penetration
describe how dry heat is used for sterilising, what it is used to sterilise and what is its lethal effects due to
used for: medical implements, glassware, non aqueous thermo stable liquids, powders
lethal effects due to oxidative processes, less effective than moist sterilisation
involves higher temps, 160-180 up to 2 hours, effective destruction of bacterial endotoxins produced by gram negative bacteria
works by conduction, heat absorbed by exterior surface then pass inward to the next layer until entire object reaches proper temp to achieve sterilisation
describe how ionising radiation is used for sterilising, what it is used to sterilise and what its lethal effects are due to
used on: dry products, finish and packaging components, medical implements, medical implants
lethal effects due to microbial DNA damage, leads to cell death as consequence of ionisation and free radical production or excitation from uv
uses accelerated electrons/gamma rays/UV light, exposure to 25 kGy for effective kill
bacterial resistance to irradiation depends of effectiveness of their repair mechanism, UV is less effective as it has lower energy so less DNA damage
what is UV ionising radiation sterilisation useful for
water sterilisation
describe how gas is used for sterilising, what it is used to sterilise and what its lethal effects are due to
used for: reusable medical implements, pharmaceutical components (glassware, plastics, syringes), medical equipment
lethal effects due to alkylation of sulfhydryl, amino, hydroxyl and carboxyl groups on proteins and nucleic acids
uses chemically reactive gases that are toxic to the operator (eg. formaldehyde, hydrogen peroxide, ethylene oxide)
lethality non uniform with increasing conc, temp, humidity
describe how filtration is used for sterilising, what it is used to sterilise
used for: most pharmaceutical solutions and suspensions, biological products (depends on size), air
involves passing substance through a filter (0.22um) under pressure, removes bacteria instead of destroying, particles entrapped within mesh
what does the efficiency of filtration sterilisation depend on
adsorption, material entrapped, charge effects, mesh structure, depth, initial bioburden
what is bioburden
number of contaminated microorganisms in a material before sterilisation procedure is carried out
what is quality assurance
arrangements put in place to ensure final product is at quality required for its purpose
what does good quality mean
fit for its therapeutic purpose, safe for adminsitration
what is good manufacturing practise (GMP)
part of quality assurance that ensures the product is consistently manufactured
-includes control of ingredients, plant construction, process validation, production, cleaning
what is quality control
part of quality assurance that conducts test at each stage of manufacture, products not released until they pass the test
what is in process control
any test on product during manufacture
-ensures manufacturing equipment/environment is checked before and after use
-test/controls must be documented to confirm pass criteria has been met
what is quality risk management and what happens when a deviation occurs
systemic process for identification, assessment and control of risks to quality of pharmaceutical products across product lifestyle
when deviation occurs, quality management system initiates tests to determine cause and identify corrective actions and risks asses and confirms effectiveness of change
what is HACCP and its steps
hazard analysis of critical control points= risk assessment tool for evaluating steps of a manufacturing process and in response to a deviation
-analyses/identifies potential hazards, determines critical control points (CCP) to control hazard and limit control of CCP, establish in house control methods to contain CCP hazards and corrective measures to correct CCP, confirm HACCP regime is functioning and then documentation of above
name 5 main sources of contamination during pharmaceutical manufacturing process
raw materials- can carry natural bioburden
equipment- used in processing/holding/transferring/packaging, generation of dust and aerosols, improper cleaning
personnel- person to person contact, poor hygiene, natural flora
atmosphere- source of dust and particles including microorganisms and spores
packaging- some dont appropriately exclude microbial contaminants during storage
ways to control microbial contamination
environmental hygiene- disinfect areas, no stagnant water or any water, clean air, educate workers
quality of starting materials- correctly stored, free from bacteria and endotoxins, raw materials stored correctly to prevent contamination, quality checks
process design- user defined requirements, installation and monitoring of equipment, fully defined/evaluated/validated manufacturing process
quality control and documentation- environmental monitoring in process and out of hours, personnel training, documentation of raw materials/packaging materials/intermediate products required for each batch (traceability), room classifications qualified prior to use
packaging/storage- keeps contents in and contaminants out, clean, suitable for purpose, store at appropriate temperature
what does sterile mean
free of viable microorganisms
-product must undergo sterilisation process to ensure minimum level or sterility assurance
what are sterile products
medicines that are administered directly to blood stream or body tissue
-sterile avoids possibilities of microbial degradation or infection
what is sterility assurance limit (SAL)
numerical value that predicts the probability that microorganisms has survived sterilisation process
-acceptable probability for a pharmaceutical product post sterilisation is 10^-6
what is the aim of sterility testing
attempts to reveal presence or absence of viable microorganisms in a sample, only small portion of batch is tested (40-60 out of >100,000), must be conducted in a suitable environment and be validated
if product is manufactured aseptically what is the only available analytical method
sterility testing, show regulatory authorities the sterility status of it
describe sterility test environment
strictly controlled as aseptic processing environment, isolator technology, hydrogen peroxide gassing, environmental monitoring, ISO class 5/GMP grade A
list pharmacopeial requirements for sterility testing
-for products that cant be filtered and medical devices, use membrane filtration or direct inoculation (?)
-media used FTM and TSB
-incubate samples for 14 days at 2 different temperatures to allow microbial growth of bacteria/fungi/yeast
what is FTM and TSB
FTM=fluid thioglycollate medium
TSB=tryptic soy broth
describe the observations/interpretations of results of sterility test
-samples comply or dont (its either a yay or a nay)
-turbidity/growth indicates noncompliance
-test complies if no evidence of microbial growth is found
4 reasons sterility tests can be invalid
- data of microbiological monitoring of sterility testing facility shows a fault
- review of testing procedure reveals fault
- microbial growth found in negative control
- after determination of identity of microorganisms isolated from test, growth of species ascribed unequivocally to faults with respect to materials/techniques used when conducting sterility test (?)
limitations of sterility test
-can only recognise microorganisms able to grow under conditions of the test
-sample size restricted, only provides gross estimate of state of sterility of product
-sample size set arbitrarily so doesnt provide statistically significant population to estimate sterility
-results cant be used independently to determine sterility of a batch
what does the susceptibility of microorganisms to biocides depend on
the microorganism and stage of life cycle
what is bioburden
number of contaminated microorganisms in a material before sterilisation procedure is carried out
