Chapter 13: Sterilization/Disinfection, Antibiotics Flashcards
variables that dictate the most appropriate antimicrobial strategy used
type of microbe, number of microbes, risk of infection, object being sterilized/disinfected
most resistant microbes
prions, endospores
moderately resistant microbes
mycobacteria, non-enveloped viruses
moderately susceptible microbes
gram-negative bacteria, eukaryotes
most susceptible microbes
gram-positive bacteria, enveloped viruses, mycoplasmas
process (chemical or physical) by which ALL living cells, spores, and viruses on an object are destroyed
sterilization
chemical agent used to sterilize
sterilant
killing or removal disease-producing organisms from inanimate surfaces (chemical or physical)
disinfection
chemical used on inanimate objects to disinfect
disinfectant
killing or removal of most pathogens from living tissues (most often chemical), does not always result in sterilization
antisepsis
chemical used to remove/eliminate pathogens from living tissue
antiseptic
reduces the microbial population to safe levels, usually involves cleaning, not complete removal of pathogens
sanitation
agents with antimicrobial chemicals that kill microbes
cidal agents
agents with antimicrobial chemicals that inhibit/control growth
static agents
antimicrobial measures can typically affect _______________ as well
nonpathogenic microbes
microbes die at an _____________ rate in the presence of killing agents
exponential
measures efficacy of disinfecting and sterilizing agents, time it takes to kill 90% of the population, important to measure effectiveness of a disinfectant or antimicrobial
decimal reduction time (D-value)
uses high pressure and high temp to sterilize objects, sufficient for destroying endospores after 20 mins, ex: autoclaves, pressure cookers, bench top sterilizers
pressurized steam sterilization
biohazardous waste is destroyed by burning, for single-use items only
incineration
for moisture-sensitive items, not as effective as steam sterilization but can sterilize if done correctly
dry oven
kills most organisms and viruses, but NOT for spores or hyperthermophiles
boiling (100C)
heating of food at a temp and time combination that kills pathogens, cannot eliminate all microorganisms and spores, goal is to kill pathogens without affecting texture, color, or taste of food
pasteurization
all pharmaceutical drugs must be safe, but some are sensitive to heat or chemical sterilization
filtration
sterilization can be performed through filtration where solutions are passed through filters with _________ (0.2um removes all cells, 0.02um removes viruses)
tiny pore size
food is bombarded with high-energy electromagnetic radiation; viruses, endospores, and prions are very resistant to this method because they are very small
irradiation
factors that influence the efficacy of a chemical disinfectant
presence of organic matter, kind of organisms present, corrosiveness, stability, odor, and surface tension
presence of organic matter: chemicals bind to any organic material present, lowering _________ of agent against microbes
effectiveness
kinds of organisms present: should be effective against a broad range of _________
pathogens
corrosiveness: disinfectant should not damage the _________
surface it is on
stability, odor, and surface tension: chemical should be ______ when stored, ________ odor, ______ surface tension to access cracks
stable; neutral/pleasant; low
drug that slows/inhibits bacterial growth, effective therapy that reduces bacterial burden until it can be cleared by the host
bacteriostatic drug
drug that kills bacteria cells
bactericidal drug
antibiotic that targets one or limited groups of bacteria, pathogen must be identified before use (may take time), less disruption to normal microbiota
narrow spectrum antibiotic
antibiotic that targets large groups of bacteria, used when treatment is urgent before the pathogen can be identified, can lead to disruption of the host microbiota
broad spectrum antibiotic
we don’t use broad spectrum antibiotics for every bacterial infection because it can lead to _________ of the hosts’s normal microbiota and contribute to the development of ____________
disruption; antimicrobial resistance
factors that health care providers need to consider when administering an antimicrobial drug
tissue distribution, excretion, and metabolism of drugs, allergies/other health concerns, half life of drugs
effect where one drug inhibits the function of another
antagonistic effect
effect where two drugs work better together than their additive effects
synergistic effect
ability to kill/inhibit the infecting organism without damaging the host, difficult to achieve to minimize host side effects, goal of antimicrobial therapy
selective toxicity of a drug
concentration of drug needed to completely inhibit bacterial growth in culture, lower = more effective antibiotic
minimum inhibitory concentration (MIC)
tests a bacterial culture for susceptibility to antibiotics on a plate; the zone of inhibition of bacterial growth is assessed to determine the susceptibility of pathogens to various antibiotics
disk diffusion assay (Kirby-Bauer disk susceptibility test)
mechanisms of antibacterial activity
metabolic inhibitors
DNA replication inhibitors
RNA polymerase inhibitors
protein synthesis inhibitors
cell membrane damage
cell wall inhibitors
drug that targets the unique ergosterol membrane or DNA synthesis
antifungal drug
fungi have efficient _______________ that further complicate antifungal development
drug detoxification systems
drug that targets metabolic functions
antiprotozoal drug
_____________ can be used by protozoa (single-cell eukaryotes) for metabolism releasing free radicals that damage the parasite
nitroimidazoles
general strategies for bacteria to resist antibiotics
- prevent intracellular accumulation: destroy antibiotic, pump the antibiotic out, reduce membrane permeability (prevent entry of antibiotic)
- prevent antibiotic binding to target: alter the target, modify the antibiotic (B-lac)
- dislodge the ribosome: protect the ribosome (target for antibiotics)
acquired resistance due to inherent characteristics of the organism
innate (intrinsic) resistance
examples of innate resistance of antibiotics
gram-negative bacteria have an outer membrane that prevents entry;
mycobacterium have a waxy mycolic acid cell wall, grow slowly, and can grow inside of host cells
drug resistance that arises through genetic changes through mutations or acquisition of new genes
acquired resistance
transfer of genes between neighboring cells, responsible for generation of multi-drug resistant bacteria
horizontal gene transfer
How does horizontal gene transfer affect antibiotic resistance of otherwise-susceptible bacteria when antibiotics are misused?
An antibiotic susceptible pathogen can infect the lungs to cause pneumonia, pathogen replicates and a spontaneous antibiotic resistant mutant arises
Patient is given antibiotic (selective pressure), susceptible bacteria dies but not the resistant ones
Patient starts to get better then relapses, antibiotic-resistant bacteria start to replicate through HGT, patient risks transmitting the antibiotic-resistant strain to new person
Why does antibiotic misuse lead to resistance?
If you take an antibiotic when you have a viral infection, the antibiotic attacks bacteria in your body. These are bacteria that are helpful or are not causing disease. This incorrect treatment can then promote antibiotic-resistant properties in harmless bacteria that can be shared with other bacteria
