Biol 2401 Unit 6

antimicrobial agents (AMA)

prevents spread of disease

hierarchy of cleaning

sterilization, disinfection, and sanitization

sterilization

the complete removal or killing of all vegetative cells, endospores, and viruses of environment

aseptic technique

the protocols used to maintain a sterile environment in clinical procedures or microbiology labs

disinfection

the inactivation of microbes on an inanimate surface; its cleaning agents are called disinfectants

antisepsis

the inactivation of microbes on living tissue; its cleaning agents are called antiseptics

sanitization

the cleaning of inanimate objects to remove microbes enough for public use

degerming

the process where microbial numbers are significantly reduced by scrubbing living tissue (mechanical technique)

types of antimicrobial agents

killing agents (suffix is -cide) and inhibiting agents (suffix is -static)

factors affecting effectiveness of antimicrobial agents

amount of time, concentration, presence of organic matter

zone of inhibition

produced in the lab by using a disc-diffusion assay to assess the relative effectiveness of an antimicrobial agent; the larger the circle, the more effective

places of sterilization

equipment and media of microbiology lab, and hospital items (e.g. needles, scapels) that come in contact with susceptible people

methods to achieve sterilization

moist heat, dry heat, slow-freezing, ionizing radiation, non-ionizing radiation, filtration

moist heat

a method of sterilization that uses an autoclave and combines high heat and steam to kill microbes; useful in laboratories; includes media, agar, glassware, and waste disposal

dry heat

a method of sterilization that uses a direct flame or oven; useful for sterilizing anything that can be heated, such as an inoculation loop

slow freezing

a method of sterilization that forms ice crystals, which damage proteins; mainly used for helminths

ionizing radiation

a method of sterilization that uses gamma or X-rays; mainly used to penetrate paper, plastic, or tissue; it is limited use since it damages humans

non-ionizing radiation

a method of sterilization that uses UV rays; it mainly sterilizes the surface; used for purification of water, germicidal lamps

filtration

a method of sterilization that passes gas or liquid through a filter with pores to physically remove microbes from passing through; used for solutions that cannot be heated (e.g. vitamins, antibiotics)

alkylating agents

a chemical method of sterilization; it is carcinogenic, so use cautiously; two types called 2% glutaraldehyde (liquid) and ethylene oxide (gas); used for surgical equipment and hospital surfaces

places of disinfection

outbreaks, deep household cleaning, hospital cleaning, contact with mucus membranes

phenol and phenolics

a chemical method of disinfection that is effective against gram-positive bacteria and fungi; includes Lysol, toothpaste, and anti-bacterial soaps with triclosan

heavy metals

a chemical method of disinfection that is effective against all cells, except endoscopes; it is toxic to humans; examples include clothing embedded with silver, silver nitrate, and mouthwash with zinc

iodophors

a halogen chemical method of disinfection that is effective against all cells, except endospores; examples include water purification, hand scrub before surgery, cleaning of skin wounds

chloride

a halogen chemical method of disinfection that is effective against all cells except endospores; only ONLY chemical of this group can kill endospores called bleach; examples include water purification in pools and drinking

alcohol

a chemical method of disinfection that is effective against bacteria, fungi, and enveloped viruses; it can induce the formation of endospores; water is needed to slow down evaporation of alcohol; examples include 70% ethanol

surfactants (QUATS)

a chemical method of disinfection that is effective against bacteria, fungi, and enveloped viruses; examples include mouthwash and Lysol

peroxygens

a chemical method of disinfection that is effective against everything except endospores; higher concentrations are needed to fight against bacteria that produce catalase and peroxide; examples include hydrogen peroxide and acne medication

places of sanitization

general public use

pasteurization

a method of sanitization that involves mild heating; increases shelf life of food items, such as dairy, alcohol, and juices

refrigeration

a method of sanitization that is bacteriostatic and requires an appliance; short term storage of food items and bacterial cultures

lyophilization

a method of sanitization that is bacteriostatic and requires freeze drying, a process of rapid freezing and rapid drying; it is a long term storage of bacteria and food

osmotic pressure

a method of sanitization that contains high concentrations of sugar and salt; this includes salted foods, honeys, and jams

soaps

a surfactant method of sanitization that involves mechanical removal of microbes through emulsification of oils and microbes into droplets; does not contain any other antimicrobial agent but oil

antimicrobial drugs (AMD)

chemicals used to treat diseases

narrow spectrum antibiotics

only specific subset of pathogens; used when pathogen has been identified and minimizes damage to normal flora; examples include penicillin

broad spectrum antibiotics

antimicrobial drugs that target a wide variety of pathogens; useful if treatment is immediate, prevents invasive surgery, and there was failure from narrow-spectrum antibiotic; risks include normal flora being targeted, risk of opportunistic infections, and antibiotic resistance contributions; examples include tetracycline

Kirby-Bauer technique

a technique used to determine effectiveness of an antibiotic, such as disc diffusion assay, where an effective antibiotic has a larger zone of inhibition; an antibiotic make bacteria be resistance, intermediately susceptible, or susceptible

penicillin

an antibiotic that blocks steps of biosynthesis of peptidoglycan and leads to cell lysis; more effective for gram positive bacteria

polymyxin

a topical antibiotic that inhibits membrane function by its detergent-like properties and can disrupt outer and plasma membranes; should not be ingested

tetracycline

an antibiotic that inhibits the protein biosynthesis (i.e. ribosomes)

sulfonamides

an antibiotic that blocks bacterial enzymes, specifically biosynthesis of folic acid that is necessary for nucleotide synthesis

rifampin

an antibiotic that inhibits nucleic acid synthesis by blocking DNA replication and RNA polymerase to prevent cell functioning; it carries the most side effects

selective toxicity

drugs that target pathogens without harming human cells

Miconazole

Anti-fungal drug that attacks synthesis of ergonsterol

atovaquone

an antiprotozoan drug that affects the electron transport chain maintly used to treat malaria

ivermectin

an antihelminthic drug that binds to chloride channels and disrupt neuronal transmission

anti-viral drugs

type of drugs that is difficult to find because virus uses host cell machinery to replicate; most drugs would also target our cells

neuraminidase inhibitor

type of anti-viral drug that prevents release of virus from infected cells; affects influenza

protease inhibitor

type of anti-viral drug that blocks assembly step of viral life cycle; affected by hepatitis C

RTase inhibitor

a type of anti-viral drug that blocks conversion of viral RNA to viral DNA; affectd HIV

integrase inhibitor

a type of anti-viral drug that prevents formation of pro-virus; affects HIV

fusion inhibitor

a type of anti-viral drug that blocks entry of enveloped virus; blocks HIV

drug resistance

developmental mutation of bacteria due to genetic variation

drug resistance process

when antimicrobial drugs get used, suspectible cells are killed but resistant cells remain; over time, resistant cells become the main species

drug inactivation/drug modification

genes that code for an enzyme that can destroy or modify antibiotic

mechanisms of drug resistance

drug inactivation, inhibit accumulation, target modification, overproduction of target molecule

inhibit accumulation

happens through efflux or preventing entry via outer membrane

efflux

pumps that actively transport the antibiotic out of the cell

overproduction of target molecule

increased production of target molecule or increased bypass of blocked pathways to bind and isolate antibiotic, which allows bacterial cell to continue its functioning

phage therapy

the collection and growth of bacteriophages that target pathogens via intraveous application: advantages include targetting specific bacteria, resident flora is not affected, bacteriophages evolve along side the bacteria so less chance of resistance