Antibio Susceptibility, Phys/Chem Control, Host/Parasite Relationship Flashcards
What is MIC?
[minimum inhibitory], minimum needed antibiotic to prevent visible growth of B on/in lab media
What is MBC?
[minimal bactericidal], minimum antibiotic needed to kill a defined percent of B when a mixture of B and antibiotic are incubated together
What is measured and what are the categories in an agar disc diffusion susceptibility text?
resistant, intermediate, susceptible; measure distance from edge of disc to edge of growth
What is the E test?
gradient diffusion, larger dose of AB further out on the strip
what is the rapid AB susceptibility test?
swab on paper disc, wait for color change (colorimetric), impregnated with labeled Antibody to B lactam (or other) if color change it was hydrolyzed by B
What is antiseptic?
chemical agent used to kill microorganisms on skin, mucus membranes, or other living tissue
what is aseptic?
absence of microorganisms, usually applied to procedures in OR or micro labs which involve preventing microorganisms from reaching protected environment
What is a bactericidal?
capable of killing bacteria
What is bacteriostatic?
capable of inhibiting bacterial growth, multiplication resumes after removal
What is a disinfectant?
substance used on inanimate objects to kill or inhibit growth of microorganisms; endospores and viruses may not be destroyed; reduce or inhibit growth, but don’t sterilize
What is a germicide?
a chemical agent that kills microorganisms, bactericide, kills bacteria, sporicide kills endospores, fungicide kills fungi, virucide kills viruses and amebicide kills amoeba and protazoa
What is septic or sepsis?
presence of unwanted microorgnaisms; usually pathogens on living tissue
What is sterilization?
process of destroying all forms of microbial life (bacteria, endospores, viruses, fungi, etc) has to kill spores!!
What are methods of action of physical and chemical agents for control of microbes?
membrane damage, protein denaturation and modification, and nucleic acid damage
What are some physical controls?
heat (moist- 100C boiling some spores survive, autoclave 120C= sterile), filtration (liquids, air- HEPA 99.7% for <0.3micrometers), radiation (ionizing- xray, gamma, free radicals; nonionizing- UV thymine dimers; microwave- not sterile, heats water, spores survive)
What are some chemical controls?
surfactants, phenol and phenolics, alcohols, heavy metals and their salts, halogens, iodine, chlorine gas, hydrogen peroxide, and alkylating agents
what are some surfactants and how do they work?
soaps- ionize negative so kill, anionic detergents- bactericidal, cationic detergents- for surfaces, like quaternary ammonium, bactericidal, penetrate and puncture membrane
Give examples of phenolics and how they work.
hexylresorcinol- mouth wash, works, 30 min more come back; hexachlorophene; chlorhexidine- keeps B down for a time but stains plaque; triclosan- membrane damage
Give examples of alcohols and how they work.
ethyl- dissolve membranes, kill vegetative, evaporates fast; isopropyl- kills vegetative, evaporates, after 4-5 times should wash hands
Give examples of heavy metals, their salts and how they work.
silver- prevent and treat infections, inhibits normal B function; copper- eye gtts, washes, dressings, catheters, tubing, and air handling
What group does iodine belong to? Forms and uses?
halogen; interferes with protein structure by binding tyrosine, sporicidal, oxidizes sulfhydryls, tincture w/ potassium iodide in alcohol, iodophor (skin, longer its on more it kills)
What group does chloride belong to? Forms and uses?
halogen; gas, sodium hypochlorite (bleach), chlorine dioxide (tent sterilization of building, use marker bacteria to ensure entire building covered), chloramine (drinking water, etc, kills fish)
How is hydrogen peroxide used? effectiveness?
3% solution in home, 35% is sproicidal but can be explosive, time dependent killing; vapor- used in autoclaving room for heat sensitive instruments
What group is aldehyde in? Forms, use, effectiveness?
alkylating; formaldehyde- disinfectant, sporicidal, preservative, but carcinogenic, covalently links amino groups, proteins can’t function; glutaraldehyde- disinfectant, heat sensitive instruments, endoscopes and bronchoscopes
What group is ethylene glycol in? Forms, use, effectiveness?
alkylating; heat sensitive materials, used with nitrogens to make mixture used in sterilizer, sporicidal
What is bacteremia?
presence of bacteria in the blood