Controlling microbes notes

microbial control

used to stop the transmission of infection, spoilage, and contamination

ends in -ide or -cidal

kills microbes

ex: biocide/germicide, bactericides/bactericidal

end in -static or -stasis

only inhibit growth of microbes

ex: bacteriostasis, bacteriostatic

daily life routine control

\-wash and scrub with soaps and detergents

\-mechanically remove microbes

\-beneficial skin microbiota not adversely affected by regular use

\-hand washing with soap and water is the most important step in stopping the spread of infectious diseases

hospital control

\-minimizing microbial population is very important

\-danger of healthcare-associated infections

\-patients are more susceptible to infection

\-patient may undergo invasive procedures

\-instruments must be sterilized

\-cleaning is critical in the operating room

\-more pathogens found here and they are the most resistant to antimicrobial agents

methods of microbial control

physical: heat, cold radiation, drying, filtration

chemical: disinfectants, antiseptics, antimicrobial drugs

heat (physical method of control)

\-disrupts cellular structure (protein)

\-can lead to sterilization (destruction or removal of all microbes)

\-two forms: moist and dry

moist heat methods

\-boiling, pasteurization, autoclave (sterilizes at 121\*C/15min/15PSI

dry heat methods

\-incineration, hot air oven, cooking food

low temperatures (physical control)

\-slow microbial growth

\-does not eliminate or kill most microbes

\-refrigeration: slows spoilage of foods, some bacteria and fungi may still be able to grow

\-freezing

radiation

\-UV light: disrupts DNA replication

\-X-rays, cobalt/gamma rays: causes breaks in DNA (used to pasteurize food and to sterilize packaged items, like bandaids)

\-microwaves: uses heat to kill bacteria

Drying

\-removes water

\-prolongs life of perishable foods

\-accomplished by: adding salt and sugar leads to loss of water, lyophilization (freeze-drying)

filtration

\-liquid passes through porous filter

\-microbes trapped on filter

air filtration

\-removes impurities and microbes from the air

\-high efficiency particulate air (HEPA) filters

liquid filtration

\-removes microbes from liquid samples

\-portable water filters

\-often used for heat sensitive liquids

chemical methods of control

\-uses different types of chemicals

\-process is called: disinfection

lowers microbial populations and kills many (but not necessarily all) microbes

disinfectants

\-for use on inanimate objects

\-using disinfectant wipes, roccal on lab benches

antiseptics

\-for use on body surface (living tissue)

\-examples: alcohol swabs before getting a shot,

antiseptics and disinfectants

\-alcohols: ethanol, hand sanitizer

\-halogens: iodine, chlorine (bleach)

\-heavy metals: anti dandruff shampoo, silver, mercury, copper, zinc

\-copper sulfate (algicide) for tanks and ponds

\-ethylene oxide: sterilizing gas thats used for hospital items that are heat or moisture sensitive

\-soaps: surface tension reducers

quaternary ammonium compounds (quats)

used as disinfectant or antiseptic (mouthwash, disinfecting wipes)

phenols

\-carbolic acids, blocks microbial lipid synthesis

\-active ingredient in lysol

\-triclosan (now banned)

selective toxicity

finding and destroying pathogens without damaging the host

antimicrobial drugs

chemicals that interfere with growth of \n microbes within host

chemotherapy

the use of drugs to treat diseases

antibiotics

\-substance produced by an organism to inhibit \n another organism

\-used to treat bacterial infections

\-strep throat

\-most are semisynthetic or synthetic

antiviral drugs

\-used to treat fungal infections

\-yeast infections

\-available drugs affect specific types of virus

\-target different steps in viral replication

\-most only lessen the symptoms or decrease duration of the disease

antifungal drugs

\-few available because most are too toxic and are only for topical use

\-used to treat mycoses

\-some work by making the membrane permeable

antiprotozoan drugs

\-used to treat parasitic diseases

\-quinine and chloroquine

treat malaria killing Plasmodium

\-metronidaze

\-miltefosine

penicillin

\-first antibiotic that was discovered by Alexander Fleming, but he was unable to isolate the chemical so he abandoned research

\-In 1940 Howard Flory and Ernst Chain were able to isolate it and do clinical trials. Mass production during WWII

semisynthetic antibiotic

modify from a natural antibiotic \n to get new features

synthetic antibiotics

made completely in a lab

narrow spectrum of microbial activity

\-affects a small range of microbial types, you have to know what the bacteria is that you are trying to kill

broad spectrum antibiotics

\-affect a large range of gram (+) and gram (-) bacteria

how antibiotics work

\-prevent cell wall formation

\-prevent RNA/DNA replication

\-prevent protein synthesis

\-prevent folic acid production

\-injure the membrane

reasons for antibiotic resistance

\-overuse, abuse, and misuse

\-overprescription by physicians

\-mutations: changes in DNA/genetic material

\-Horizontal gene transfer: sharing of DNA between cells by way of a sex pilus

misuse of antibiotics include

\-using outdated or weakened antibiotics

\-antibiotic abuse in livestock

\-failing to complete prescribed regimen

\-using someone else’s prescription

\-using them for the common cold or other inappropriate conditions

superbugs

\-multi-drug resistant microorganisms

\-resistant to large number of antibiotics

mechanisms of acquired resistance

1. decreased uptake of drug: Changes in bacterial surface to prevent entry of drug
2. drug inactivating enzymes: Destroys antibiotics before it has effect on the bacteria
3. alteration in drugs target site: Does not allow drug to bind and have effect
4. increased elimination of drug: Efflux pumps remove compounds from cell; Resistance is particularly worrisome