Controlling microorganisms and antimicrobial drugs Flashcards
what is pasteurization?
Moist heat method to reduce pathogens without affecting texture, color, or taste
what is the low temperature long time pasteurization of milk?
(LTLT) (63C for 30 min)
what is the high temperature short time pasteurization of milk?
(72C for 15 sec)
what are the conditions for the ultra high temperature treatment? what does it achieve?
134C (2730F) for 1-2 sec, then rapid cooling
Achieves sterilization and unrefrigerated shelf-life up to 6 months.
what UV light wavelength is bactericidal?
UV light is bactericidal between 200-300nm (254nm)
what does UV light do to the DNA of microbes?
UV light causes Thymidine dimers in DNA
what is boiling a method of?
Moist heat method of boiling water (100C) that kills vegetative cells of bacteria and fungi, protozoan trophozoites, most viruses
what are the four different moist heat methods?
Boiling
Autoclaving
Pasteurization
Ultrahigh-temperature sterilization
what are the three effects of heat on microbes?
- Denaturation of proteins
- Interfere with integrity of cytoplasmic membrane and cell wall
- Disrupt structure and function of nucleic acids
how does dry heat affect microbes?
Denatures proteins and oxidizes metabolic and structural chemicals
how does dry heat methods differ from moist heat methods?
Requires higher temperatures for longer time than moist heat
what is antisepsis?
Killing or removal of disease-producing organisms from living tissues
what is disinfection?
Killing or removal of disease-producing organisms from inanimate surfaces; may not result in sterilization
what is alcohol’s mode of action against microorganisms?
dehydration, protein denaturation, dissolve membrane lipids
what is alcohol’s CDC level of activity?
intermediate
what do soaps have that make them good degerming agents?
they have hydrophilic and hydrophobic ends
what are surfactants?
surface active chemicals that reduce surface tension of solvents
what are cationic detergents?
positively charged organic surfactants
what are Quaternary Ammonium Compounds mode of action?
disrupts membrane
what is the CDC level of quaternary ammonium compounds?
low
what do soaps contain that make them antibacterial?
benzalkonium chloride
what three drugs are metabolic inhibitors?
sulfonamides, trimethoprim, metronidazole
what five drugs are 50s ribosome inhibitors?
chloramphenicol, macrolides, clindamycin, oxazalidinone and streptogramins
what two drugs are 30s ribosome inhibitors?
ahminoglycosides and tetracycline
what drug is DNA replication inhibitor?
quinolone
what drug is RNA polymerase inhibitor?
rifampin
what drug causes cell membrane damage?
polymyxin
what five drugs are cell wall inhibitors?
penicillin, cephalosporin, vancomycin, bacitracin, monobactam
what type of antibiotic is penicillin?
penicillin is a beta-lactam antibiotic
how do beta lactam antibiotics work?
the beta lactam ring is similar to D alanine D alanine part of peptidoglycan.
The beta lactam ring then takes its place while the cell wall is being constructed and makes it weak.
Eventually the cell will lyse.
how does tetracycline work?
Binds 30S subunit and blocks tRNA carrying amino acid from entering the A site
what is amphotericin B? what does it do?
It is under the polyene category of antifungal drugs.
it disrupts membrane integrity.
what are the five mechanisms of antibiotic resistance?
modify the target, destroy the antibiotic, alter the antibiotic, pump the antibiotic out, bypass the metabolic pathway
