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48 Cards in this Set

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nosocomial infections
hospital-acquired infections
before aseptic techniques caused death in at least 10% of surgical patients and up to 25% of delivering mothers
thermal death point (TDP)
the lowest temperature at which all the microorganisms in a particular liquid suspension will be killed in 10 minutes
thermal death time (TDT)
the minimal length of time for all bacteria in a particular liquid culture to be killed at a given temperature
moist heat
kills primarily by coagulating proteins
protein denaturation
boiling
kills vegetative forms of bacterial pathogens, almost all viruses, fungi and their spores in 10 minutes or less
hepatitis virus can survive up to 30 minutes
endospores can survive more than 20 hours
brief boiling even at high altitudes will kill most pathogens
reliable sterilization with moist heat
steam under pressure;autoclave
the higher the pressure, the higher the temperature;usually set for 15 min. At 15 psi (121oC)
Pasteurization
developed to prevent spoilage in beer and wine
mild heating sufficient to kill organisms that cause spoilage without seriously damaging the taste of the product
used also in milk
intent is to lower microbial numbers which prolongs milk’s good quality under refrigeration
thermoduric (heat resistant) bacteria survive, but unlikely to cause disease or cause refrigerated milk to spoil
classic pasteurization
63oC for 30 minutes
high-temperature short-time pasteurization (HTST)
72oC for 15 seconds
milk flows past a heat exchanger
kills pathogens and lowers total bacterial count
ultra-high-temperature treatments (UHT)
sterilizes
fluid rapidly heated to 140oC for 3 seconds
then rapidly cooled
can be stored at room temperature
Not pasteurization
filter sizes - pore sizes;0.22-0.45 m
traps most bacteria
maybe not spirochetes and mycoplasmas
Listeria monocytogenes
listeriosis;gram-positive rod (but produces endotoxin)
causes stillbirth and neurological disease in humans and other animals
lyophilization
freeze-drying
certain foods are freeze-dried
coffee, some fruit additives for dry cereals
Deinococcus
All members of the genus Deinococcus are very resistant to ionizing radiation (IR). They can survive 10,000 Gy, while a human would be killed by 8 Gy. Gy (gray) is the absorption of one joule of radiation energy by one kilogram of matter.
phenol
carbolic acid
Lister used it
now rarely used
still used in throat lozenges for its local anesthetic effect
antibacterial effect in throat sprays at concentrations above 1%
Phenolics
derivatives of phenol;phenol altered to reduce irritating qualities and increase antibacterial activity
often combines with soap or detergent
injure lipid membranes and walls of mycobacteria
remain active in presence of organic compounds
stable, persist
cresols - derived from coal tar
O-phenylphenol
main ingredient in most formulations of Lysol
Para-tertiary amylphenol
used as a demulsifyer, biocide and in fragrances; an active ingredient of Birex a one-step germicidal detergent used to disinfect countertops
bisphenols
contain two phenolic groups connected by a bridge
hexachlorophene
in pHisoHex
very good against gram positive staphylococci and streptococci
used to wash newborns
excessive use can lead to neurological damage
triclosan
another bisphenol;in antibacterial soaps and one toothpaste
incorporated into plastic kitchen cutting boards and handles of knives and other plastic kitchenware
resistant bacteria have been reported
inhibits enzyme needed for biosynthesis of fatty acids
especially effective against gram-positive bacterial
Pseudomonas aeruginosa
a gram-negative bacterium is very resistant to triclosan
biguanide
can refer to a molecule, or to a class of drugs based upon this molecule. Biguanides can function as oral antihyperglycemic drugs used for diabetes mellitus or prediabetes treatment. They are also used as antimalarial drugs.
chlorhexidine
biguanides;broad spectrum
combined with detergent or alcohol
surgical hand scrubs, preoperative skin preparation
strong affinity for binding to the skin or mucous membranes
injures plasma membrane
mycobacteria relatively resistant
endospores and protozoan cysts not affected
only enveloped viruses affected
iodine
one of the oldest and most effective antiseptic
possible mechanism
combines with certain amino acids
tincture
in solution in aqueous alcohol
chlorine
forms hypochlorous acid (HOCl) with water
strong oxidizing agent that prevents much of the cellular enzyme system from functioning
neutral in electrical charge and diffuses as rapidly as water through the cell membrane?
Used to disinfect municipal drinking water, water in swimming pools and sewage
calcium hypochlorite
[Ca(OCl)2] (chloride of lime)
sodium hypochlorite
NaOCl (bleach)
chlorine dioxide - ClO2
gaseous
used for area disinfection
used to kill endospores of anthrax bacterium in buildings
Used in food processing; does not leave residue or odor
chloramines
chlorine and ammonia
very stable
effective in organic matter
act slowly
used to sanitize glassware and eating utensils and to treat dairy and food-manufacturing equipment
used in municipal water-treatment - helps control taste and odor
toxic to aquarium fish
alcohols
kill bacteria and fungi but not endospores and nonenveloped viruses
protein denaturation and disrupt plasma membranes
evaporates and leaves no residue
degerming before an injection
unsatisfactory for treating wounds
coagulates proteins behind which bacteria grow
pure ethanol less effective than 60-95%
isopropanol better than ethanol
Zephiran (quat in alcohol [tincture]) better than in water
heavy metals
silver, mercury, copper
oligodynamic action
ability of very small amounts to exert antimicrobial activity
combine with sulfhydryl groups on amino acids; denature proteins
silver
1% silver nitrate solution
used to be put in eyes of newborns
gonorrheal ophthalmia neonatorum
silver-impregnated dressings, indwelling catheters
Silver thread in military uniforms
Used as bandages
silver-sulfadizine - topical cream for use on burns
surfacine - silver iodide and biguanide - not yet approved
surface active agents
surfactants;decrease surface tension soaps and detergents
soaps
little antiseptic value
function to help mechanical removal
emulsification - good degermers
detergents - acid-anionic surface active sanitizers
damages plasma membrane
quaternary ammonium compounds
cationic detergents
most widely used surface-active agents
modifications of the four-valence ammonium ion
strongly bacteriocidal against gram-positive bacteria, fungicidal, amoebicidal, virucidal (enveloped)
do not kill endospores or mycobacteria
Zephiran - benzalkonium chloride
Cepacol - cetylpyridinium chloride
Approved as an antimicrobial wash in poultry processing (FDA);certain bacteria (Pseudomonas and Burkholderia) can actively grow in them
sodium nitrate and sodium nitrite
in many meat products
ham, bacon, hot dogs, sausage
bacteria can convert sodium nitrate to sodium nitrite the active ingredient
nitrate reduced to nitrite in anaerobic respiration
functions
red color (reacts with blood components)
prevents germination and growth of botulism endospores (Clostridium botulinum); inhibits iron containing enzymes
aldehydes
most effective antimicrobials
formaldehyde and glutaraldehyde
inactivate proteins by forming covalent cross-links with several organic functional groups
amino group, hydroxyl group, carboxyl group, sulfhydryl group
formaldehyde
formalin - 37% aqueous solution of formaldehyde gas
once extensively used to preserve biological specimens
still used to inactivate bacteria and viruses in vaccines
glutaraldehyde
less irritating, more effective
Cidex -2% solution
used to disinfect hospital instruments
sporicidal in 3-10 hours
could almost be considered a sterilizing agent
used by morticians for embalming
used as a fixative by electron microscopists
ethylene oxide
denatures proteins
hydrogens on sulhydryl groups and carboxyl groups are replaced by alkyl groups (-CH2 CH2OH)
alkylation
4-18 hours
toxic and explosive - mixed with carbon dioxide or nitrogen
used to sterilize spacecraft, mattresses
no heat required
plasmas
A state of matter in which a gas is excited (by an electromagnetic field) to make a mixture of nuclei with assorted electrical charges and free electrons
A partially ionized gas with some free electrons
Electrically conductive
Distinct state of matter separate from gas, liquid, solid
Hydrogen peroxide plasmas
ozone
(O3)
generated by passing oxygen through high-voltage electrical discharges
used in the disinfection of water
expensive
hydrogen peroxide
may slow wound healing
quickly broken down to water and oxygen gas by catalase (present in human cells)
effect on inanimate objects - sporicidal at elevated temps
aseptic packaging, cleaning contact lenses (platinum catalyst removes)
peracetic acid
most effective liquid chemical sporicide
sterilant
many applications
food processing, medical equipment
leaves no toxic residues
Pseudomonas and Burkholderia of special interest
unusually resistant to biocides
grow actively in some disinfectants and antiseptics
most notably in the quaternary ammonium compounds
also resistant to many antibiotics
porins - openings in outer membrane of gram-negative bacteria - highly selective
groups of resistant microbes
mycobacteria
waxy. Lipid-rich component in cell wall
endospores
affected by relatively few biocides
cysts and oocysts of protozoa
prions
special problem
infectious proteins - spongiform encephalopathies
normal autoclaving inadequate
Recommended by CDC and WHO
Combine use of sodium hydroxide and autoclaving at 134oC
Use of proteases
Use of disposable instruments