Lecture 2 Flashcards
what are the 6 requirements for bacterial growth?
- energy source (sun, organic compounds, inorganic compounds)
- carbon source (organic carbon of CO2)
- major elements (C,H,O,N,S,P,K,Mg, Fe, Ca, Mn)
- trace elements (Mn, Co, Cu, Zn, Mo)
- growth factors (amino acids, vitamins, purines/pyrimidines)
- permissive conditions (temp, pH, osmotic pressure, oxygen)
based on their temp/rate of growth graphs, which bacteria would cause infections in animals?
mesophiles and thermophiles
which is more stable in high temperatures, saturated or unsaturated fatty acids?
saturated fatty acids
the normal pH of mammalian blood is usually between
7.3-7.5
bacteria are more tolerant of osmotic variation than eukaryotic cells because
they have cell walls
why is the presence of oxygen good for some bacteria and bad for others?
all cells have enzymes that react with oxygen which creates ozygen metabolites, and some bacteria can handle these toxic oxygen metabolites and others can’t. main metabolites produced are H2O2 and O2-
describe the difference between the following:
- obligate aerobes
- facultative anaerobes
- aerotolerant anaerobes
- obligate anaerobes
obligate aerobes: requires oxygen for aerobic respiration
facultative anaerobes: preforms aerobic resp when oxygen is available, but can survive by preforming anaerobic respiration
aerotolerant anaerobes: preforms anaerobic resp but can survive in presence of oxygen
obligate anaerobes: oxygen is lethal so they only preform anaerobic resp
describe the difference between sterilization, disinfection, and antisepsis
sterilization: all viable microorganisms are eliminated/destroyed including spores
disinfection: reduction of pathogenic organisms associated with inanimate objects to a level below that which causes an infection
antisepsis: inactivation or destruction by chemical means of microbes associated with the animal
what are the two methods of sterilization and list examples for each method
physical: heat, radiation, filtration
chemical: ethylene oxide, ozone, formaldehyde, gas plasma
what is the difference between boiling and pasturization?
boiling heats to boiling temperature but it is NOT the same as sterilization, it kills most bacteria but spores can be resistant
pasturization is heating of food to a degree that kills all potential human pathogens, ex) milk is heated to 72 degrees C for 15 seconds or 63 degrees for 30 minutes
what makes alcohol a good disinfectant?
what makes alcohol a not so good disinfectant?
it will denature proteins and dissolve lipids, kills many bacteria and viruses, no residual effect
spores are resistant to alcohol and ehtanol specifically can dehydrate tissue
how do you use bleach properly as a disinfectant? what are pros and cons of bleach?
use a 1:10 water to bleach ratio, and make sure there is at least 10 minutes of contact time
clean is a good disinfectant, but it doesn’t clean very well, can damage surfaces, and is inactivated in the presence of organic material
why is virkon a good disinfectant?
it is bactericidal, fungicidal, and virucidal, AND a detergent so it cleans and disinfects, it is non corrosive, needs 10 minutes of contact time
why is it important to know that organic material can inactivate many disinfectants?
you must clean up the JUNK before you disinfect! get rid of all the blood, poop, pee, pus, exudates, etc FIRST
what are the two classic examples of antiseptics used to clean an animals skin? how do they work?
povidone-iodine: interacts with bacterial proteins, nucelotides, and fatty acids to cause cell death
clorohexidine gluconate: interferes with bacterial cell membrane function causing cell death
