Microbial Control Flashcards by Deleted Deleted

control of microbial growth types and order of less effective to most

cleaning
sanitation
disinfection
sterilisation

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cleaning

Removal of visible soils such as food residues, dust, dirt, corrosion, scale and grease from a surface

Microorganisms are removed but not killed

Often achieved with water and detergent

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sanitation

A process that destroys various microorganisms, reducing viable numbers on clean surfaces to meet
product quality and public health standards

Sanitisers are usually not effective in the presence of organic residues and detergents

Often achieved with moist heat (steam) or chemicals (chlorine)

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disinfection

removal of pathogens only

The process of killing pathogenic organisms or rendering them inert

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sterilisation

removal of all microbes including bacterial spores

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germacide

– An agent that kills pathogenic microorganisms

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2 types of germacide

Disinfectant

Antiseptics

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disinfectant

A substance that removes or causes the destruction of harmful microbes (not usually spores), from inanimate objects

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antiseptic

A disinfectant for animate areas

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what are physical methods for inanimate object - disinfection

Heat (Pasteurisation)
Radiation
Heat

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heat - pasteurisation (what, does, temps)

disinfection - physical method, inanimate

Typically in the range of 60-800C for a few minutes to kill pathogens and to destroy most other bacteria that cause food spoilage (i.e. preservation, to increase shelf life)

Low temp, Long time (LTLT) = 63 ̊C, 30 min
High temp, Short time (HTST) = 72 ̊C, 15 sec

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who developed pasteurisation and what

Louis Pasteur - mid 1800s to prevent spoilage of wine

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radiation

disinfection, physical method, inanimate
Ultra-violet (UV) radiation (usually non-ionising)
– Damages proteins & nucleic acid
– Low penetrating power
– Moderate exposure time (3 hours for a biosafety cabinet)
– Reduction of microbes in air, water & on surfaces

Infra red radiation (non-ionising)
Ionizing radiation (has enough energy to liberate an electron from an atom)

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disinfection - chemicals are for

ome for animate use and some only for inanimate objects

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modes of action for chemical disinfection

Protein coagulation/denaturation
Disruption of cell membrane
Chemical antagonism (inactivation of enzymes)

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organic matter

– Urine
– Vomit
– Diarrhoea
– Sputum – Blood

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modes of inhibition (disinfection) of organic matter

Forms a precipitate with disinfectant - removes disinfectant from contact with bacteria
Reacts with the disinfectant to produce a non-bactericidal agent(s)
Coats bacteria - protects the bacteria from the disinfectant

most common sterilisation method

moist heat under pressure (autoclaving)

why are bacterial spores so hard to kill

bacterial spores are the most heat resistant and difficult to kill microbial structure

The thick spore coat protects from radiation and chemicals

temperature achieved & exposure time important - for moist heat

15min @121 ̊C at 15psi above ambient atmospheric (most common)

sterilisation indicators (moist heat)

Autoclave printouts/monitoring
Biological - Spore strips
Autoclave tape (Bowie-Dick test)

dry heat types sterilisation

Hot Air Oven (time and heat higher than autoclave)
Advantage - Good for glassware, oils, powders - Doesn’t blunt sharps

Incineration (bunsen)

Chemical Sterilisation by Gases & Cold Sterilisation - mode of action

denaturation of proteins

Chemical Sterilisation by Gases & Cold Sterilisation - examples

– Formaldehyde (gas)
– Glutaraldehyde (aqueous)
– Ethylene oxide (gas)
– Plasma sterilisation (hydrogen peroxide gas)

Sterilisation by Moist Heat - mode of action

coagulation & denaturing of proteins

Sterilisation by Filtration – fluids and air (fill out bacteria with pores of....)

pores of 0.45μm or less)

Antibiotic is

Natural compounds produced by microorganisms that kill or inhibit other microorganisms – Synthetic (Artificially made compounds) – Semi-synthetic (Natural antibiotic compounds that have been artificially modified_

Synergism is

Compounds that act together to enhance or improve effect

Antagonism is

Compounds that act against each other to reduce effect

Bacteriostatic is

Compounds that inhibit growth of microorganism (bugs still viable)

Bactericidal is

Compounds that kill microorganisms

Basic sites of action of antibacterial agents

* Inhibitors of cell wall synthesis * Membrane-active antimicrobial agents * Inhibitors of DNA replication * Inhibitors of RNA synthesis * Inhibitors of ribosome function - protein synthesis * Metabolic inhibitors

what does b-lactam group do and why so good

b-lactams inhibit the last stage of the cell wall production process Because eukaryote cells (including humans) do not have a cell wall (only a plasma membrane) and no peptidoglycan, the β-lactams work well in that they kill bacteria without damaging cells of the host (“Magic Bullets”)

what is b-lactam not effective against

resting bacteria

what causes antibiotic resistance

- over-prescribing of antibiotics - patients not finishing their treatment that works - overuse of antibiotics in livestock and fish farming - poor infection control in hospitals + clients - lack of hygiene and poor sanitation - lack of new antibiotics being developed

Antibiotics – Overprescription and Animal Use method of resistant

- drug sensitive cells and drug resistant cells together - drug kills of the sensitive cells - patients stops taking antibiotics - those resistant cells now mutate most cells are now resistant Use in intensive farming of animals as growth promoters • Resistant animal strains of bacteria passed to consumers in foods

Antibiotic creed is

practise for docs to decrease antibiotic resistance

Antibiotic

M - microbiology guides therapy wherever possible I - indications should be evidence based N - narrowest spectrum required D - dosage appropriate to the site and type of infection M - minimise duration of therapy E - ensure monotherapy in most cases

WHO list of bacteria that pose the greatest risk to human health - critical priority

– Pseudomonas aeruginosa, carbapenem-resistant – Enterobacteriaceae, carbapenem-resistant, ESBL-producing – Acinetobacter baumannii, carbapenem-resistant Carbapenems are powerful β-lactams with a broad spectrum of activity

Antibacterial antimicrobials are ineffective against whatttttt

FUNGIIII

fungi are difficult to treat because...

hey are eukaryotic and so have similar structures to human cells – Treatment is usually long-term – Toxicity can be a problem - kidneys, liver, bone marrow

Anti-Viral Chemotherapy - what do types ummm

Drugs that bind free virus preventing entry – Disoxaril for Rhinovirus (treatment for “colds”) Prevention of uncoating of virus – Amantadine for Influenza Inhibit viral replication – Aciclovir for Herpes – Zidovudine (AZT) for HIV – Inhibit protein synthesis Interfere with Viral release – Zanamivir (Relenza) for Influenza