eot microbiology

sterilisation

destruction of all living microbes, spores and viruses

microbicidal (germicidal)

agent kill microbes

bactericidal

agent target and kill bacteria

fungicidal

agent kill fungi

commercial sterulisation

process of killing all pathogens in a product (esp. food supply)

sanitisation

reduce number of pathogens or discourages their growth

microbiostatic

agents inhibit growth of all microbes

bacteriostatic

agent discourage growth of bacterial species

fungistatic

agent discourage growth of fungal

thermal death point

minimum temperature where microbes die in a given time period

incinerations

direct flame

healthcare —> disposable hospital gown, dressing, and certain tool

common practice —> carcasses of diseased cattle

hot air oven

long-term exposure to high temp

160ºC for 2 hours

boiling water

not kill all spores or inactuve viruses

pressurized steam

autoclave

15 psi + 121°C + 15–30 minutes

hospital - sterilize linens and tools

lab - sterilise liquids and glassware

pasteurization

reduce chances of spoilage and disease but not affect bacterial spores

holding/batch method

flash pasteurization

ultra-high-temperature sterilization

methods of pasteurization

higher temperature and longer duration

dry heat vs. moist heat

refrigerators

retard metabolic activity of microbes but does not kill them

reduce food spoilage

keep near 5ºC

psychrophiles

prefer cooler temperature —> can still contaminated in refrigeratored food

freezing

<0ºC —> ice crysrals penetrate cells —> inhibits metabolism and growths of microbes

filtration traps

fluid passes through a membrane filters —> filter by size

high-efficiency particulate air (HEPA) filter

used to filter air

ultraviolet light

thymine link together in DNA —> errors in protein synthesis and impairment of chromosomes

ionising radiation

X-rays and gamma rays force electrons out of microbial molecules —> affect cell metabolism and physiology

lyophilisation

freeze drying

frozen with liquid nitrogen —> vacuum pump —> draw out water —> food lightweight and durable

drying

desiccation

remove water in nonperishable items

salting

water diffuse out of organism by osmosis —> dehydration and death

used for high-sugar foods

chemical methods

rarely achieve sterilization

destroy or reduce pathogen —> disinfect

elevated temperature

destroy protein and nucleic acid

remove water

cold temperature

slow micrbial growth

antiseptics

destroy pathogens on living tissue

aseptic technique

used in surgical setting to prevent contamination

disinfectant

used in inanimate object

reduce or eliminate pathogens

degerming

mechanically remove organism from object’s surface

microbial susceptibility

temperature

pH

concentration

environment

endospore former

factor affecting microbial control

phenol coefficient

indicate disinfecting ability compared to phenol under identical conditions

• >1 → more effective than phenol

• <1 → less effective than phenol

use-dillution test

chemical of various dilutions —> exposured to test microbes for 10 mins —> place in growth medium —> observe which dilutions are clear of growth

in-use test

swabs —> clean with a chemical agent —> incubation —> check growth

disk diffusion method

examine effect of diferent chemical agents against a specific bacterium —> checked for zones of inhibition

halogen oxidized proteins

chlorine

iodine

chlorine

keep bacterial population low in water supply and swimming pool

iodine

used in disinfect wounds, water, and restaurant equipment

iodophores

incl. betadine

release iodine over long period of time

phenol

expensive

caustic

has a pungent odor

derivatives

greater germicifal activity

lower toxicity than phenol

bisphenol

2 phenol

used in disinfection and antisepsis

chlorhexidine, triclosan

bisphenol

heavy metal

inactivate enzyme and denature structural proteins —> disrupt cellular metabolism

Hg, Cu, Ag

alcohol

denature proteins

lipid dissolution —> disrupt membrane

against vegetative cells, not spore

used in hand sanitizers

soap

emulsify and solubilize particles on skin —> remove microbes

detergent and surfactant

cause cytoplasm leakage from microbial membrane

quaternary ammonium

react with cell membrane —> destroy some bacteria and viruses

one of detergent and surfactant

hydrogen peroxide

catalase in wounded tissue —> transforms to oxygen and water

oxygen —> effective against anaerobic bacteria

sterilizing gases

used on heat-sensitive plastics

ethylene oxide

one of sterilizing gases

used as chemical counterpart to heat- and pressure-based autoclave

aldehyde

cross-linking —> inactivate protein and nucleic acid

i.e. formaldehyde

ethylene oxide

effective but carcinogenic and explosive gas

chlorine dioxide

nontoxic and noncarcinogenic gas

used to decontaminate anthrax-exposed mail

ehrlich and sahachiro hata

discover effectiveness of arphenamine (salvarssan) against syphilis spirochete treponema pallidum

gerhard domagk

protosil (red dye) —> inhibit gram-positive bacteria species

alexander fleming

penicillin - penicillium mold —> kill gram-positive bacteria

waksman

state antibiotic are derived from metabolism of living organisms

synthetic drug

antimicrobial synthesized in lab

semisynthetic drug

antimicrobial produced by chemically modifying a naturally produced drug

dosing

drug spectrum

using drugs in combination

key therapeutic success

selective toxicity

drug harm pathogen but not the host

toxic dose

concentration causing harm to host

therapeutic dose

concentration eliminating pathogen in host

therapeutic window

toxic doses + therapeutic doses

broad-spectrum drug

affect many taxonomic groups

narrow-spectrum drug

affect only a few pathogens

secondary metabolites

not used by organism for growth and reproductio

sulfonamide

target specific metabolic reaction (folic acid synthesis) —> prevent nucleic acid synthesis and DNA replication

competitive inhibition

bacteriostatic

synthetic antimicrobial

inhibit DNA replication

quinolones

inhibit enzyme needed for DNA synthesis

used for gram-positive and gram-negative

can develop resistance

fluoroquinolones

i.e. ciprofloxacin

treat UTIs, gonorrhea, chlamydia, GI infections

isoniazid

disrupt cell wall synthesis in species of Mycobacterium

beta-lactam antibiotic

target bacterial cell wall synthesis

penicillin

include a beta-lactam ring

against gram-positive and gram-negative

interfere with cell wall synthesis (in rapidly growing cells) —> cell burst

natural penicillin

i.e. penicillin G, penicillin V

produced by fungus - penillium notatum

semisynthetic penicillin

avoid beta-lactamases (penicillin-resistant)

i.e. ampicillin, amoxicillin

MRSA

resistant to semisynthetic penicillin and natural penicillin

beta-lactamase inhibitors

co-drugs work synergistically with penicillin

cephalosporin

used with penicillin resistance and penicillin allergy

against gram-negative

carbapenem

resistant to beta-lactamase enzyme

prevent premature degradation of kidneys

last resort

beta-lactam antibiotic

what drug class do penicillin, cephalosporin, and carbapenem?

glycopeptide antibiotic

what drug class does vancomycin ?

vancomycin

against gram-positive

damage to ears and kidneys

polypeptide antibiotic

what drug class do bacitracin and polymyxin?

bacitracin

interfere with transport of cell wall precursors through membrane

treat skin infection by gram-positive and gram-negative

neosporin

bacitracin + neomycin + polymyxin B

polymyxin

increase membrane permeability of gram-negative rods —> cell death

polymyxin E

against many superbugs

polysporin

polymyxin B + bacitracin

aminoglycoside

attach to bacterial ribosomes (30S subunit) —> block transcription

streptomycin

aminoglycosides

co-drug used to treat antibiotic-susceptible cases of tubereculosis

tetracycline

target attachment of tRNA to 30S subunit

have a benzene ring formation

destroy intestial microbiota

side effects - staining of teeth, stunted bones

doxycycline

treat infection of gram-negative bacteria (incl. syphilis, gonorrhea, and pneumococcal pneumonia)

glycylcycline

administered intravenously

treat MRSA

broad-spectrum

chloramphenicol

broad-spectrum

treat - typhoid, epidemic typhus, Rocky Mountain spotted fever

side effect - aplastic anemia