Flashcards in Unit Four Objectives Deck (86):
the eradication of all organisms, including bacterial endospores and viruses, although not prions, in or on an object
the inhibition or killing of microorganism on skin or tissue by the use of a chemical antiseptic
chemical used to inhibit or kill microorganisms on skin or tissue
Bacteriocides kill bacteria; Fungicides kill fungi; Virucides kill viruses; Sporicides kill all = sterilize
characteristic of an environment or procedure that is free of contamination by pathogens
the removal or microbes from a surface from scrubbing
Will inhibit growth temporarily (refrigeration) bacteriostatic; fungistatic
the use of physical or chemical agents to inhibit or destroy microorganisms on inanimate objects. In water treatment, ozone, UV light, or chlorination kill most microorganisms
the process of disinfecting surfaces and utensils used by the public:
permanent loss of reproductive capacity of a microorganism
a measurement of the efficacy of an antimicrobial agent.
Microbial death rate
List the four general cellular targets of antimicrobial agents. →
Cell wall (enzymes); Cell membrane (surfactant detergents, alcohols, phenols); DNA, RNA (radiation, ethylene oxide, heat, aldehydes); Denature Proteins (heat, aldehydes, alcohols, phenols, heavy metals, halogens, oxidizing agents, ethylene oxide)
List the factors that influence the action of antimicrobial agents. →
site to be treated, does it need to be sanitized or disinfected, and can the site withstand high heat, harsh chemicals, or radiation?
State the three most resistant microbes. Are prions microbes?
Prions, bacterial endospores, mycobacteria, cysts of protozoa. Prions are thought to be infectious pathogens.
Describe the In-Use Test for determining effectiveness of a disinfectant. →
Swab environment before & after use of chemical; Inoculate media, incubate, examine for growth
List the two main types of microbial control methods. →
physical and chemical
Define thermal death point, thermal death time and decimal reduction time and explain the significance of these numbers.
(Heat Denatures proteins, disrupts membranes, cell walls, nucleic acids) Thermal Death Point TDP: Lowest TEMP to sterilize a liquid in 10 min; Thermal Death Time: Shortest TIME to sterilize a liquid at a specific temperature; Decimal Reduction Time (D): Time to kill 90% of microbe population at a particular temperature, Used to measure effectiveness of heat sterilization
100c 10’; does not kill spore; drinking water, baby materials, food, utensils
>1000c; kills spores; Metals, glass, syringes, needles, dressings, animal carcasses
Hypertonic solutions of sugar or salt Cells dehydrate; Honey, jerky, jams, jellies, salted fish, pickles
121ºC 15psi; kills spores 15’; for heat and moisture resistant materials and media
: Bacteriostatic only; 0 - 7 ºC; Slows metabolism; Facultative Psychrophile pathogens (Listeria, Yersinia) can grow in refrigerator; doesn’t kill spores
Not microbicidal; Fluid passed though membrane filter w/pores that exclude microbes & particulates; can sterilize; HEAT SENSITIVE LIQUIDS: Like serum, vaccines, antibiotics, enzymes, eye solutions, liquid vitamins, media (Air: surgical masks, HEPA filters)
: (batch: 63c 30’ then chill) (flash 72c 15” then chill) (ultrahigh temp: 135c 1” then chill) does not kill spores; fresh beverages, milk, juice, wine, beer
Bacteriostatic only; below 0c; does not kill spores; no water available
Cathode-ray, Gamma-ray, X-Ray; ejects orbital electrons from atom; Sporocidal, Protein damage, DNA mutations, Chemical changes in organelles, Produces toxic substances; HEAT/CHEMICAL SENSITIVE MATERIAL, Food, water, MEDICAL SUPPLIES: vaccines, instruments, gloves, Heart valves for grafting, U.S. Mail
~140 ºC ~3” most efficient; kills spores; can store at room temp indefinitely; milk, juice, wine, soup, cosmetics
Ultra high-temperature sterilization:
Dehydration by sun, oven; doesn’t kill spores; Preserve fruit, beans, grains, nuts, peas, yeast
171 ºC / 340 ºF for 1 hr; kills spores; Glassware, metals, powders, oil
UV 260nm excites, not ejects orbital electrons from atom; Sporocidal or Microbistatic, abnormal replication & transcription; Disinfection of air: Food prep, Hospitals, schools, dental offices, Liquid: water, juice, Sewage treatment
Freezing in liquid N or CO2 (dry ice) + Dehydration by sublimation; ; doesn’t kill spores; Preserve food and microbes Prevents ice crystals from damaging cells; freeze drying
Describe the characteristics of a good germicide. →
a chemical agent that destroys pathogens in general; fast and long lasting; Soluble in H2O and alcohol; stable; Kills variety microbes but non-toxic to humans or animals = Selective Toxicity; Resists inactivation by organic matter; Non-corrosive & non-staining; Inexpensive & available.
carbolic acid; denatures proteins and disrupts cell membranes; intermediate to low activity; cannot sterilize; original surgical antiseptic, now replaces by phenolics
chemically altered phenol
denature proteins and disrupts cell membranes; intermediate activity; cannot sterilize; disinfectants, antiseptics, and as a solvent in tinctures
Alcohols isoopropanol and ethanol:
iodine, chlorine, bromine and fluorine: presumably denature proteins; intermediate activity; cannot sterilize; disinfectants, antiseptics, and water purification
hydrogen peroxide, ozone, and peracetic acid: denature proteins by oxidation; high activity; can sterilize; disinfectants, antiseptics for deep wounds, water purification, and sterilization of food process and med equipment
: quaternary ammonium detergents, soaps: decrease surface tension of water and disrupt cell membrances; low activity; soaps, degermins, detergents, antiseptic; cannot sterilize
mercury, silver and copper: denature proteins; low activity; cannot sterilize; fungistats in paints, silver nitrate cream, surgical dressings, burn creams, and catheters. Coppers: algicide in water reserviors, swimming pools, and aquariums
Glutaraldehyde, formaldehyde: denature proteins; high activity; can sterilize; disinfectant and embalming fluid
chlorine dioxide gas, ethylene oxide gas: denature proteins; high activity; can sterilize; sterilization of heat and water sensitive objects
lysozyme, prionzyme: denature proteins; high activity level against target substrate; can sterilzie; removal of prions on medial instruments
chemical used to treat disease
antimicrobial that has been chemically altered
: any compound used to treat infectious disease; may also function as intermediate level disinfectant
antimicrobial that has been completely synthesized in a lab
antimicrobial agent that is produced naturally by an organism
Which microbial genera are responsible for production of antibiotics? →
What is selective toxicity and explain why it is possible to achieve. →
Drug must be more toxic to pathogen than to host. Easiest for bacteria (least like us) Most antimicrobials are anti-bacterial. Takes advantage of differences between humans and microbial structures or metabolism
List six mechanisms by which antimicrobial drugs affect the growth of pathogens.
Bind to & inhibit enzymes that cross-link NAMs with peptide bridges in new peptidoglycan; Only effective on growing or reproducing bacteria; Cells die due to effects of osmotic pressure when walls weakened; more effective on Gram (+)
beta-lactams (penicillins, cephalosporins):
block docking site of tRNA
: Structural Analogs: they look like the normal substrate & compete for the active site of the enzyme; called Competitive Inhibition: the more drug in the body, the fewer normal substrates are processed by the enzyme; Bacteria is then inhibited because it lacks Folic Acid
Directly interfere w/peptide cross bridges between NAMs in Gram(+);For penicillin allergic patients; For MRSA = methicillin resistant S.aureus; Can be toxic to kidneys
antibacterial; good against G(-); used topically; toxic to kidney
bind to & inhibit DNA Gyrase required for uncoiling of DNA during replication; oral, ophthalmic, bone, joint, soft tissue, GI, UTIs, STD infections; tendon rupture, pregnancy category, dizziness, confusion
Blocks transport of NAG & NAMs from cytoplasm; Major ingredient (with polymyxin & neomycin) in Neosporin
Structural Analogs: they look like the normal substrate & compete for the active site of the enzyme; called Competitive Inhibition: the more drug in the body, the fewer normal substrates are processed by the enzyme; Bacteria is then inhibited because it lacks Folic Acid
sulfonamides (include terms structural analog and competitive inhibition):
streptomycin, gentamicin, neomycin; cause change in 30S shape; mRNA is misread
antifungal; bings to ergosterol(a lipid unique to fungal cell membranes)
polyene amphotericin B:
antifungal; inhibit synthesis of ergosterol
Inhibits heme detoxification & Ca2+ transport
Quinine, Chloroquine, Primaquine; Possible modes of action: Inhibits heme detoxification, raises pH in food vacuoles, interfere w/ETC, increase Oxygen free radicals
stop this enzyme from functioning
non-nucleoside reverse transcriptase inhibitors:
Inhibits protease, an enzyme needed for HIV to mature
Nucleotide / nucleoside analogs are nonfunctional Structural analogs of nucleotides; When incorporated into viral DNA / RNA will block replication, transcription, translation; Viral DNA polymerases are far more likely to incorporate nonfunctional nucleotides than human DNA polymerases
nucleotide/nucleoside analogs: AZT (azidothymine), Valtrex (valacyclovir):
works against Influenza type A virus; Inhibits M2 H+ carrier protein so viral genome cannot uncoat & enter nucleus
Tamiflu (oseltamivir), Relenza (zanamir): Prevent Influenza (like Avian flu) from attaching to or releasing from cells
Describe why selective toxicity in with regard to viral infection is difficult to achieve.
because they use our enzymes, So there are the fewest anti-viral drugs
List the characteristics of the ideal antimicrobial drug. →
readily available; inexpensive; chemically stable; easily administered; nontoxic and non-allergenic; selectively toxic against wide range of pathogens
the number of different kinds of pathogens a drug acts against
spectrum of action:
antimicrobial that works against a few pathogens
antimicrobial that works against many pathogens
Swab plate w/microbe; place disks w/drugs that diffuse
Kirby-Bauer diffusion susceptibility test:
Smallest amount of drug that will inhibit growth & reproduction of pathogen; (Broth) Bacteria added to different concentrations of an antimicrobial in broth è grow & measure turbidity; (Etest) Plate swabbed w/microbe; Strip w/gradient of antimicrobial placed on; Elliptical zone of inhibition formed
MIC test: Broth dilution, Etest: (MIC)
in a diffusion susceptibility test, a clear area surrounding the drug-soaked disk where the microbe does not grow
zones of inhibition:
Compare and contrast the different routes of antimicrobial agent administration. →
topical/local (external application); oral (easiest, but drug lower, can abuse); Intramuscular (hypodermic needle into muscle; drug diffuses into blood, lower drug than IV); IV (initial drug high, but live and kidney move rapidly, need continuous supply); Blood brain barrier (blood vessels in brain, spinal cord, eye almost impermeable to many drugs).
List and describe three major antimicrobial drug side effects.
Toxicity to tissues/organs (kidney, liver); Allergic reactions; Suppression & alteration of normal microbiota reduces microbial antagonism of pathogens
: microorganisms that cause disease when the immune system is suppressed, when microbial antagonism is reduced, or when introduced into an abnormal area of the body
condition in which a patient infected with hepatitis B virus is subsequently infected with hepatitis D virus
bacteria that help maintain the natural balance of organisms in the intestines
Describe the development of drug resistance in a microbial population.
A few cells in population naturally resistant to drug (Cells do not mutate in response to drug); Exposure to drug results in survival of resistant microbes; If drug used often, population will eventually adapt & contain mostly resistant microbes
Describe two genomic changes that can cause drug resistance. Define R-plasmids/factors.
new mutations in genome; New DNA called R-plasmids or R-factors obtained via Horizontal Gene Transfer: Transformation, Transduction, Conjugation
Describe six mechanisms by which microorganisms can form drug resistance.
drug inactivation, decreased permeablitly, activation of drug pumps, change in binding site, use of alternate metabolic pathway, biofilms retard diffusion of drugs and microbes can have lower metabloc rates which reduce effectiveness of some drugs.
→ more than 3 drug resistant pathogens. (MRSA methicillin-resistant S. aureus) (VRSA – vancomycin-resistant S. aureus) (VISA – S. aureus w/intermediate level of resistance to vancomycin) (VRE – vancomycin-resistant enterococci) (MDR-TB – multi-drug-resistant tuberculosis) (XDR-TB – extensively-drug-resistant tuberculosis) (CRE – carbapenem-resistant Enterobacteriacae) (NDM-1 – New Delhi metallo-beta-lactamase carbapenem-resistant enterobacteriaceae) (KPC – Klebsiella pneumoniae carbapenemase)
What are superbugs? Give examples.