final exam Flashcards
sepsis
decay, putrid
bacterial contamination
asepsis
absence of significant contamination
aseptic surgery
prevent microbial contamination of wounds
sterilization
destroying all microbial life
disinfection
destroys harmful microorganisms on surfaces and environments
commerical sterilization
kills clostridium botulism endospores in canned goods
(not completely sterilized to keep the flavor but also reduces endospores)
sanitization
lowering microbial counts on eating utensils
antisepsis
destoys harmful microorganisms from living tissue
degerming
mechanical removal from limited area (injection)
biocide (germicide)
treatments that kill microbes
bacteriostasis
stop, inhibit but not kill microbes
disinfectant must be
-fast acting in presense of organic materials (blood, feces, vomit)
-effective against all microorganisms without destroying tissue or acting as a toxin if ingested
-no discoloration or damage
-stable in environment
-inexpensive
No such thing as a perfect disinfectant
microbial exponential death rate
0 min: 1million survivors (x90%)
6 min 1 survivor
*each minute the treatment is applied, 90% of the pop (remaining) is killed
effectiveness of treatment depends on
of microbes
environment
time of exposure
microbial characteristics (endospore, cell wall)
when the rate of killing is the same it takes
longer to kill all members in a larger population than smaller
damage to plasma membrane
cellular content leakage
interfered cell growth
actions of microbial control agents
damage to protiens and nucleic acids
heat
inhibit protein growth so it denatures enzymes
thermal death point (TDP)
lowest temp at which cells are killed in 10 min
thermal death time (TDT)
minimal time for all bacteria to be killed at particular temp
decimal reduction time (DRT)
minutes to kill 90% of specific pop of bacteria at given temp
moist heat sterilization
moist heat coagulates/ denatures protiens
boiling
free-flowing steam
autoclave
steam under pressure
121 c at 15 psi for 15 min
kills alls organisms (except prions) and endospores
autoclave works by
steam rushes inside, air moves out until old air moves out so steam can build
-steam is passed through inlet
container sizes on autoclave sterilization times for liquid solutions
smaller containers take less time/ quicker
sterilization indicators
indicator lines wrapped in aluminum foil was not sterilized bc steam couldnt penetrate the foil
pasteurization
reduces spoilage organisms and pathogens
-M bovis cattle
High temperature short time (HTST)
72 c for 15 sec
Thermoduric organisms
survive but unlikely to cause disease or to spoil refrigerated milk
heat
ultra high temp treatments
will sterilize and can be stored without refrigeration ex. milk, creamer, juice
shelf life of many months
rapid heated to 140C for 4 sec followed by rapid cooling
dry heat sterilization
kills by oxidation
-flaming loop
-incineration: paper cups, bags, dressings
-hot air sterilization
filitration
used for heat sensitive stuff
-membrane filters remove microbes >22 mM
-small pore sizes filter out viruses and large protiens
low temperature has bacteriostatic effect (psychotropic)
refrigeration
deep freezing
lyophilization: freeze drying
high pressure
-denatures protiens
-alters carb structure
dessication
absense of water prevents metabolism
osmotic pressure uses high conc of salt and sugars to
create hypertonic environment, causes plasmolysis
ionizing radiation (x rays, gamma rays, electron beams)
-ionizes water to create reactive hydroxyl radicals
-damages DNA -> lethal mutations
gamma ray
penetrate deep but takes a long time to sterilize (hours)
high energy electron beams
less penetration, but fast (seconds)
non-ionizing radiation (UV, 260 nm)
damages DNA by creating thyme dimers
UVC “germicidal” lamps
must avoid contact with eyes or skin
effective but doesn’t penetrate
visible blue light (470 nm)
kills wide range of bacteria due to formation of single oxygen
microwaves
kill by heat, not antimicrobial
sonication
high frequency ultrasound waves to disrupt cell structures
*rapid changes in pressure
selective toxicity
selectively destroying pathogens without damaging host
-bacteria -> targets cell wall
chemotherapy
use of chemicals to treat a disease
antibiotic
substance produced by microbe that inhibits the other
antimicrobial drugs
synthetic substance that interferes with growth of microbes
history of chemotherapy
-fleming discovered penicillin produced by penicillium
-prontosil red dye (type of sulfanilamide) used for strep infections
narrow spectrum of microbial activity
drugs that affect a narrow range of microbial types
broad spectrum antibiotics
affect broad range of gram positive and negative bacteria
superinfection
overgrowth of normal microbiota that is resistant to antibiotics
-candida albicans
-c. dificile
development of superinfections
-normal microbiota keeps opportunistic pathogens in check
-broad spectrum antibiotics kill nonresistant cells
-drug resistant pathogens proliferate and can cause a superinfection
dosage
amount of meds given during a certain time interval
-children: based on mass
-adult: standard dosage not based of mass
half life of antibiotic
rate at which 50% of drug is eliminated from the plasma
intravenous administration of a drug
peaks very quickly
orally or intramuscularly administered drugs
take longer for concentration to reach its peak
bactericidal
kills microbes directly
bacteriostatic
prevent microbes from growing
major action modes of antibacterial drugs
inhibition of cell wall synthesis
inhibition of protien synthesis
inhibition of nucleic acid replication and transcription
penecillins
prevent the synthesis of peptidoglycan
-inhibit cell wall synthesis
-against growing cells from mold
inhibiting protien synthesis
target bacterial 70S ribosomes
-chloramphenicol: binds to 50S portion and inhibits formation of peptide bond
-streptomycin: changes shape of 30S, causing code on mRNA to be read incorrectly
polypeptide antibiotics
change membrane permeability
antifungal drugs
combine w membrane sterols
ionophores
antibiotics that allow uncontrolled movt of cations
-cattle feeds (digestive and growth)
polymyxin
changes permeability
inhibiting nucleic acid synthesis
blocks topoisomerase (interferes with dna replication)
block RNA polymerase (interferes with transcription)
inhibiting the synthesis of essential metabolites
antimetabolites compete with normal substrates
-Sulfanilamide: competes with Para-aminobenzoic acid (PABA) stopping the synthesis of folic acid
PABA
substrate formation of folic acid
-similar structure as sulfanilamide
penecillin binding protiens
enzymes that produce peptide cross links in peptidoglycan
penicillin
natural
inhibits PBP (narrow spectrum)
no cross links
weak
burst
lysis
contain B lactam ring
chemical side chains are attached to the ring
G- outermembrane consists of
porins
cycloserine
inhibits part of peptide side chain on NAM
bacitracin
binds to bactoprenol lipid carrier
-transport of dissacharide units of peptidoglycan across cell membrane to the growing chain inhibited
penecillin, vancomycin, cephalosporins inhibit
activity of enzymes that cross-link the peptide side chains
natural penicillins
from penicillium fungi cultures
-pencillin G (injected) and penicillin V (oral)
-narrow spectrum of activity
-susceptible to penicillinases (B- lactamases)
cephalosporins
similar to penecillins
b lactam ring differs from penicillin
4th generation of cephaloporins
pseudonomas
good gram positive
5th generation of cephaloporins
MRSA+
staph aureus
good: gram positive/ negative
bacitracin
b. subtilis and b. lichenform
topical application works against gram positive
vancomycin
streptomyces
resistant to vancomycin
vancomycin resistant enterococcus: nosomial oppurtunistic pathogen
teixobactin
kills some gram positive bacteria (M. tuberclosis, S. aureus, VRE)
isoniazid (INH)
anti-mycobacterial antibiotic
inhibits mycolic acid synthesus in mycrobacteria
ethambutol
secondary drug to avoid resistance
-only acts against mycrobacterium
nitrofurantoin
-attack bacterial ribosomal protiens
-treatment for UTIs
chloramphenicol
inhibits peptide bond formation
-binds to 50S subunit
how does chloramphenicol inhibit protien synthesis
suppresses bone marrow and affects blood cell formation (aplastic anemia)
aminoglycosides
-changes shape of 30S
-auditory and kidney damage
-streptomycin: tuberculosis
tetracylines
produced by streptomyces
interfere with tRNA attachment to ribosome
broad spectrum
against ricketsias and chlymadias
suppress C. albicans
glycyclines (inhibitor of protien synthesis)
broad spectrum
bacteriostatic
30S ribosomal
inhibit rapid efflux
intravenous
useful against MRSA
multi drug resistant glycylcycline
acinetobacter baumannii
macrolide (inhibitors of protein synthesis)
lactone ring
narrow spectrum against gram positive: eryhthomycin
azithromycin
streptogramins
attach to 50S subunit
work against gram positives (penecillin, mold, PBP)
synercid: multiple targets/ sites on 50S subunit
NAG-NAM
cell wall - prevents cross link
porins are found
outer membrane
b lactimase
resistant
b lactam ring
cidal
oxazolidinone
bind to 50S/30S interface
synthetic: combat MRSA (linezolid)
pleuromutilin
mushroom
retapamulin: topical and effective against gram positives
lipopeptide (inhibits protien synthesis)
daptomycin: produced by streptomyces, used for skin infections
polymyxin B: against gram negative
polymyxin E (colistin): against gram negative
rifamycin (rifampin)
nucleic acid synthesis inhibitor
-penetrates tissues; antitubercular activity
-mycobacteria, tuberchlosis, leprocy
quinolone and fluoroquinolones
nalidixic acid: synthetic; inhibits DNA gyrase
norflaxin and ciproflaxin: broad spectrum; relatively nontoxic
gemifloxacin, moxifloxcin: newer versions
problem: ruptures tendons
sulfonamides
inhibit synthesis of folic acid needed for nucleic acid and protien synthesis
-structurally similar to PABA (folic acid precursor)
PABA
sulfa drug
structurally similar
antifungal drugs
fungal steroids
-interrupt synthesis of ergosterol, making membrane excessively permeable
polyenes
fungal sterols
interrupts ergosterol synthesis, making membrane excessively permeable
nystatin: most commonly used
-thrush, candida
amphtotericin B: systemic fungal infections; toxic to kidneys
azoles
imidazoles: topical; treat cutaneous mycoses
triazole: treat systemic fungal infections; toxic to the kidneys
allylamines
fungal; azole resistant infections
echinocandins
inhibit synthesis of B-glucan
flucytosine
inteferes with rna synthesis, inhibit nucleic acids
griseofulvin
produced by penicillium
inhibits microtubule formation: mitrosis -> fungal reproduction
active against superficial dermatophytes
what antifungal drug is used to treat tolnafate
tolnaftate
pentamidine
anti- pneumocystis
may bind to dna
immunocompromised
antiviral drugs
entry and fusion inhibitors
-block receptors on host cell that bind to virus
-block fusion of virus and cell
-uncoating, genome integration, nucleic acid synthesis inhibitors
-prevent viral uncoating
-inhibit viral dna integration into host genome
protease inhibitors
block cleavage of protien precursors
example: Paxlovid, used to treat covid19
exit inhibitors
inhibit neuraminidase: enzyme required for viruses to bud from the host cell
interferons
immune signaling molecule, defense
-viral infected cells to inhibit further spread of infection
Imiquimod: promotes interferon production
antiretrovirals
to treat HIV/AIDs
HIV: RNA virus
quinine and chloroquine (antiprotozoan)
treats malaria
bark of cinchona
artemisinin (antiprotozoan)
kills plasmodium that causes malaria
metronidazole, tinidazole, nitrazoxanide
interferes with anaerobic bacteria
-treats trichomonas, giardiasis, amebic dysentry
miltefosine
inhibits cytochrome oxidase in mitochondria
treats amebic encephalitis and leishmaniasis
vectoe: sandfly
niclosamide (antihelmic)
treats tapeworms
prevents ATP production
praziquantel (antihelmic)
alters membrane permeability
treats tapeworms and flukes
mebendazole and albendazole
interfere with nutrient absorption
treat intestinal helminths
ivermectin
treats roundworms and mites
disk diffusion method (kirby bauer test)
paper disks with chemotherapeutic agent placed on agar inoculated with test organism
-zone of inhibition around disk determines sensitivity of organism to the antibiotic
E test
minimal inhibitory concentration (MIC)
lowest antibiotic conc preventing bacterial growth
broth dilution tests
determine MIC and MIB (minimal bactericidal conc) of antimicrobial drug
-99% of cells of inoculation added are killed
-test organism is placed into wells of tray containing dilations of drug; growth is determined
-antibiograms: susceptibility of organisms
if cells grow it means that it is
not cidal
broth dilution tests measure
turbidity
-cells are viable, dead or not growing
MBC is determined by using
tube dilution test and removing antibiotic
-further plating to see if cells survived 3 to 5 times above the MIC
if cells grow in fresh medium without antibiotic
drug is bacteriostatic
if cells dont grow in fresh medium
drug is bacteriocidal
persister cells (resistance to antimicrobial drugs)
microbes with genetic characteristics allowing for their survival when exposed to an antibiotic
superbugs
resistant genes spread horizontally among bacteria on plasmids or transposons
bacterial pathogens
resistant to nearly all antibiotics; cause HIAs
-acinetobacter baumannii
-p. aeroginosa
mechanisms of resistance
-enzymatic destruction or inactivation of drug
-prevent penetration to the target site within microbe
-alters drugs target site
-rapid efflux (ejection) of antibiotic
-variations of mechanisms of resistance
beta lactamse
break B lactam ring of penicillins and cephalosporins
gram negative bacteria
porins in outer membrane may be modified and prevent access of antibiotic to periplasm
MRSA
modified penicillin binding protien (PBP)
-B lactam antibiotics can no longer bind and halt cross linking of peptidoglycan
therapeutic index
risk vs benefit
clinical considerations
drug concentration > MIC during treatment
-half life depends on how quickly the antibiotic is removed from body via excretion
how long a drug stays in tissue
therapeutic dose
minimum dose per kg of body weight that stops growth
toxic dose
maximum dose tolerated by pt
chemotherapeutic index
ratio of toxic to therapeutic dose
higher the chemotherapeutic index
safer the drug
synergistic drugs
greater effectiveness when used together
ex. aminoglycoside (access to inside the cell) and vancomycin (cell wall)
antagonistic drugs
interfere with each other, decrease effectiveness
ex. penicillin (acts of growing cells) and macrolides (bacteriostatic: inhibits growth)
antimicrobial agents
target virulence factors
sequester iron which feeds pathogens
drugs combat dormant persister cells (antibiotic resistant cells)
target gram negative bacteria (porins outermembrane)
antimicrobial sensitivity
bacteriocins:peptides produced by bacteria (kills other bacteria)
phage therapy: using bacteriophage to treat infection
microbiome
growth of MRSA (resistant S. aureus)
lactobacillus spp grew
phenol and phenolics
plasma membranes, causing leakage
active in presense of organic matter
reduced irritation, increased effectiveness
ex. O-phenylphenol
Bisphenols
two phenol groups connected by a bridge
disrupt plasma membranes
hexachlorophene: control skin infections
triclosan: antibacterial soaps
biguanides
effective against gram positive, gram negative bacteria, enveloped viruses
ex.
Chlorhexidine: surgical hand scrubs
Alexidine: works faster
iodine
impairs protien synthesis and alters membranes
tincture: solution in alcohol
iodophor: combined with organic molecules
povidone-iodine: skin antisepsis
Essential oils
peppermint, pine and orange oil
strong against gram positive bacteria, effectiveness against viruses not studied
tree and pine oil: broad spectrum that includes gram positive and negative bacteria and fungi
chlorine
bleach: hypochlorous acid (HOCL) neutral
chloramine: chlorine and ammonia
municipal water disinfection: compressed chlorine gas
if the water is cloudy/ not clean
2-3 drop bleach
1 L of H2O
30 mins
alcohols
denture protiens and dissolves lipids
require water
alcohol based hand sanitizers: above 62% alcohol
not effective against endospore producers and nonenveloped viruses
-not effective against C. dificile or Norovirus
best alcoholic action
around 65-70%
100% = growth of bacteria
oligodynamic action (heavy metals)
very small amounts
denature protiens
silver nitrate
prevents opthalmia neonatorium
copper sulfate
algicide
swimming pools
Cu2+ and Ag+ ions
used in water disinfection
zinc chloride
mouthwash
antidandruff shampoos
soap
acid anionic sanitizers
-emulsification
break oil film -> soalather and water
phosphoric acid
quaternary ammonium compounds (quats)
cations denature
broad spectrum
except ineffective against endospores and mycobacteria
exception: pseudomonas
organic acids to prevent molds in some foods
sorbic acid
benzoic acid
calcium propionate
nitrites and nitrates
prevent endospore germination (clostridium botulism)
-nitrosamines
bacteriocins
one bacterium that inhibits another
-nisin and natamycin prevent spoilage of cheese
aldehydes
inactivate protiens by cross linking with functional groups
-formalin preserve specimen
-glutaraldehyde: sporicidal in 3-10 hours; used in respiratory therapy equipment, endoscopes, other equipment that can be autoclaved
gaseous chemosterilants
cross links nucleic acids and protiens
heat sensitve material
ethyl oxide
sealed chamber
sterilizes large equipment and furniture depending on chamber size