Test 3-8 (Steri,Disinf and Antisep)

Question 1

parts of the body that are colonized

Answer 1

skin, mucous membranes, gastrointestinal tract

Question 2

sterile parts of the body

Answer 2

musculoskeletal sys, bloodstream, most organs

Question 3

Sterilization process

Answer 3

is harsh to kill off even the most resistant of microorganisms

Question 4

disinfection process

Answer 4

medical devices and surgical instruments go through this when they cannot handle the stresses of sterilization

Question 5

antisepsis process

Answer 5

used to eliminate microbes from skin

Question 6

COMMON HOSPITAL INFECTIONS

Answer 6

• Surgical wound infections.
• Respiratory tract infections.
• Urinary tract infections (UTI; most common hospital-acquired infections).
• Bacteremia – could arise from different sources.
– Primary bacteremia – due to direct bacterial entry into the bloodstream, for example from contaminated intravenous fluids.
– Secondary bacteremia by spread from an infection elsewhere in the body for example a UTI.
• Gastroenteritis and hepatitis outbreaks may occur in the hospital setting.

Question 7

Most common cause of hospital infections

Answer 7

staphylococci and E. coli are the most common cause of hospital infections.

Question 8

before antimicrobial therapy most common infections due to:

Answer 8

gram positive– ex) streptococcus pyogenes and staphylococcus aureus

Question 9

after penicilin and antibiotics most common infections:

Answer 9

Gram negative bacteria like E. coli and Pseudomonas aeruginosa

Question 10

With the development of more powerful and broad spectrum antimicrobial agents and an increase in invasive procedures, there have been higher incidences of

Answer 10

• antibiotic-resistant Gram positive bacteria such as coagulase negative staphylococci, enterococci (especially ones resistant to vancomycin; VRE) and MRSA (which is increasingly becoming a source of community acquired infections as well)
• multi-drug resistant Gram negative organisms including the ones that produce expanded spectrum beta-lactamases (ESBLs)
• Candida.

Question 11

most of the common hosptial infections are…

Answer 11

opportunisitc! people already be sick so easier to get sick

Question 12

most common hospital viral infections:

Answer 12

including influenza, respiratory syncytia virus, parainfluenza, varicella-zoster virus, HSV, noroviruses, Norwalk-like virus, hepatitis, B and C viruses, HIV, and HTLV etc

Question 13

sources and routes of hosptial infections

Answer 13

• Human – self, other patients, hospital staff, and sometimes visitors (infected individuals, healthy carriers, people who are incubating an infection).
• Environment – fomites, food, water or air.
• The source could become contaminated from an environmental reservoir or organisms, for example contaminated antiseptic solution distributed for use into sterile containers. Thus, the source as well as the reservoir has to be eradicated.
• The same routes of infection are important for spread in a hospital setting as anywhere else, such as air-borne, contact, and common vehicle. Vector-borne spread as well as sexually transmitted infections is quite uncommon in hospitals.
• The same organism can be transmitted by more than one route, for example Streptococcus pyogenes may be transmitted by droplets or dust or by contact with an infected lesion.

Question 14

uncommonly spread viral infections in hospitals

Answer 14

Vector-borne spread as well as sexually transmitted infections

Question 15

consequences of hospital infections:

Answer 15

-Hospital infections affect both the patient as well as the community and can cause
• serious illness or death.
• extended stay in the hospital, which is expensive and results in loss of earnings and hardship for the patients as well as their family.
• a need to use more antimicrobial therapy, which again is costly, can be toxic to the patient and can potentially result in emergence of antibiotic resistance to the hospital pathogens.
• the infected patient to become a source of contamination of others.

Question 16

PREVENTION OF HOSPITAL INFECTIONS

Answer 16

An important aspect of the control of infections is an understanding of the principles of sterilization, disinfection, and antisepsis.

Question 17

STERILIZATION definition

Answer 17

TOTAL destruction of all microorganisms including the more resistant forms like the bacterial spores, Mycobacteria, nonenveloped viruses, and fungi.

Question 18

common sterilization

Answer 18

• Moist heat
• dry heat
• ethylene oxide gas
• formaldehyde gas
• glutaraldehyde
• irradiation

Question 19

irradiation

Answer 19

• sterilization
• UV radiation=used in laboratory safety cabinets, hospital operating rooms, ionizing, prevention of growth in water in apparatus like the auto-analyzers; inefficient as a sterilant; use limited due to potential for damage to the cornea and skin.
• Ionizing radiations =(X- and Gamma rays – used to sterilize heat-sensitive, pre-packed, single use plastic items, including syringes and catheters; produces DNA damage by the production of free radicals, blocks microbial replication. Limitation is that direct exposure is required.

Question 20

Glutaraldehyde

Answer 20

• sterilization

- 2%, oxidizes with toxicity issues, but less toxic than formaldehyde.

Question 21

formaldehyde gas

Answer 21

• sterilization
• used as a disinfectant as well as a sterilizing agent in both liquid and gaseous state.
• inactivates microorganisms by alkylating the amino and sulfhydryl groups of proteins and ring nitrogen atoms of purine bases.
• Formaldehyde gas is used to sterilize HEPA filters. Not used in other devices because the residue could be carcinogenic.
• Liquid formaldehyde is a 37% solution in water, called formalin. Different concentrations of formalin have different microbicidal effects. For example, a 37% solution is bacteriostatic while a 20% solution is bactericidal. A 20% solution combined with 70% ethanol has even more microbicidal activity.

Question 22

ethylene oxide gas

Answer 22

• sterilization
• toxic alkylating agent used for sterilizing heat- and moisture-sensitive medical devices without deleterious effects on the material used.
• the absorbed toxic or mutagenic by-products must be allowed to dissipate by aeration of the materials. It is a colorless gas that is also highly flammable and explosive.
• -It alkylates protein, DNA and RNA within cells which prevents normal cellular metabolism and replication.*
• The effectiveness of ethylene oxide sterilization depends on 4 parameters: gas concentration (450-1200 mg/l); temperature (37-63°C); relative humidity (40-80%); and exposure time (1-6 hours).

Question 23

dry heat

Answer 23

• sterilization
• oven (commonly 1 hour at 170°C, 2 hours at 160°C, or 3 hours at 150°C).
• Kills spores (oxidation of cellular components) but may not eliminate pyrogens (fever-inducing agents).
• It should be used only for materials that can be damaged by moist heat or where moist heat cannot penetrate (e.g. powders, petroleum products, and sharp instruments). Dry heat is nontoxic and does not harm the environment; it penetrates materials and is non-corrosive for metals and sharp instruments.
• -Denatures and coagulates proteins and causes single strand breaks in DNA.*
• -Also destroys membrane integrity.*

Question 24

moist heat

Answer 24

• sterilization
• saturated steam under pressure, as in an autoclave (121-132°C for 15 minutes or more),
• ***-is the most widely used and most dependable method of sterilization.
• nontoxic, inexpensive, and rapidly kills bacteria as well as spores.
• Prions can be destroyed by boiling in 1N NaOH for 10 minutes followed by extended autoclaving.
• -Moist heat irreversibly denatures and coagulates enzymes and structural proteins and causes single strand DNA breaks.*
• It also destroys membrane integrity.
• Steam sterilization should be utilized whenever possible on all heat- and moisture-resistant critical and semi-critical items.

Question 25

DISINFECTION

Answer 25

It is the process of removing or killing most, but not all, viable organisms.

• More resilient organisms like Mycobacteria, viruses, fungi and the bacterial spores may survive the procedures.
• It employs either a chemical agent to kill pathogens or a physical process which reduces the load of viable organisms.

Question 26

High level disinfection

Answer 26

can approach sterilization in effectiveness in that it can destroy all microorganisms except large numbers of bacterial spores. For this reason high level disinfection is oftentimes confused and used interchangeably with sterilization.

Question 27

Low level disinfectants

Answer 27

can kill most vegetative bacteria, some fungi and some viruses in a reasonable period of time

Question 28

intermediate level disinfection

Answer 28

• able to kill mycobacteria, vegetative bacteria, most viruses, and most fungi
• cannot kill bacterial spores

Question 29

important disinfectant qualities

Answer 29

o	Antimicrobial activity
o	Solubility
o	Stability
o	Penetration
o	Non toxicity to humans
o	Non-corrosive and does not stain
o	Deodorizing ability
o	Detergent capability
o	Availability

Question 30

high level disinfectants methods

Answer 30

moist heat, glutaraldehyde, oxidizing agents (peracetic acid, hydrogen peroxide, ozone and plasma gas etc.) and chlorine compounds. These procedures approach sterilization and may kill spores (a few discussed in the sterilization section above).
-FOR CRITICAL GEAR THAT COMES IN DIRECT CONTACT AND CANNOT BE STERILIZED

Question 31

hydrogen peroxide gas

Answer 31

• disinfectant
• oxidant, sterilizer as gas; liquid, a 3-6% solution kills most bacteria; 10-25% kills all organisms including spores. It produces hydroxyl free radicals that can attack membrane lipids, DNA, and other essential cellular components. H2O2 can be used to disinfect plastic implants, contact lenses, and surgical prostheses.

Question 32

aqueous solutions of chlorine

Answer 32

• rapidly bactericidal.
• However, bacterial spores are 10-1000 fold more resistant than vegetative bacteria. The greatest activity of chlorine compounds is at acidic pH. Their mechanism of action is irreversible oxidation of sulfhydryl groups of essential enzymes.
• Hypochlorites are the most widely used chlorine disinfectants (liquid - sodium hypochlorite [household bleach] or solid - calcium hypochlorite).

Question 33

most widely used disinfectants

Answer 33

hypochlorites

Question 34

Intermediate Level Disinfectants

Answer 34

• such as alcohols, iodophor compounds and phenolic compounds.
• These agents are used on semi-critical instruments which are unlikely to be contaminated with bacterial spores or resistant organisms e.g. laryngoscopes, endoscopes, vaginal specula, anesthesia breathing circuits etc. These instruments come into contact with mucus membrane or non-intact skin.

Question 35

intermediate level disinfectants on spores

Answer 35

CANNOT KILL

Question 36

Low Level Disinfectants

Answer 36

-ex) quaternary ammonium compounds and triclosan are used to clean non-critical instruments such as stethoscopes, blood pressure cuffs, and electrocardiogram electrodes.
• Even though these instruments come into contact with patients, they contact only intact skin and do not penetrate through mucosal layer or into sterile tissue.
• Many organisms survive these processes.

Question 37

ANTISEPSIS definiton

Answer 37

disinfectants used to lower the number of microorganisms on skin surfaces.

Question 38

antisepsis cannot

Answer 38

kill bacterial spores

Question 39

antisepsis very effective against

Answer 39

vegitative bacteria

Question 40

Alcohols

Answer 40

-antiseptic
-Ethanol and isopropanol are often used to clean the skin before immunization or venipuncture.
• They kill most organisms including Mycobacteria, fungi, and most viruses. They do not kill spores.
• They are relatively non-toxic but do have a dehydrating effect on the skin because they hydrolyze lipids.
• They act mainly by denaturation of bacterial proteins, but can also inhibit the synthesis of metabolites essential for rapid cell division.
• On the other hand, they have no residual killing effect on the skin and are inactivated by organic matter.
• They are most effective in the presence of water, thus 70% alcohol is more effective than 95% and is often used to clean the skin prior to venipuncture.
• However, since it is not as effective as iodine containing compounds, the latter should be used prior to obtaining a blood culture and installing intravenous catheters.

Question 41

Phenolic compounds

Answer 41

-antisepsis
-penetrate and disrupt the cell wall in high concentrations and denature proteins and lipids within the cytoplasmic membrane and lyse the cells. Low concentrations of phenol inactivate essential bacterial enzyme systems and cause leakage of essential metabolites from the cell wall.
• Bactericidal for both Gram positive and Gram negative bacteria.
• They can kill Mycobacteria, fungi, and viruses but are not effective against bacterial spores.
• They are rarely used today.
• Their antimicrobial action is improved by halogens (e.g. hexachlorophene).
**• The phenol coefficient is a rating scheme for antibacterial agents. It measures the ratio of germicidal activity by a test compound to that by a specific concentration of phenol. A compound that is more effective than phenol is given a phenol coefficient of >1. For example a coefficient of 5 means 5X as effective as phenol **

Question 42

Iodine

Answer 42

is the most effective skin antiseptic used in medical practice and should be applied before obtaining a blood culture and installing intravenous catheters to remove problematic contaminants like Staphylococcus epidermidis, a member of the skin flora.
• For example, tincture of iodine (2% solution of iodine and potassium iodide in ethanol) is effective at preparing the skin prior to blood culture.
• However, it can irritate the skin so should be removed with alcohol.
• Iodophors are a combination of iodine and a stabilizing agent or carrier.
• Povidone iodine is the best known and most commonly used iodophor. It is a stable, non-toxic agent for skin and tissue.
• These compounds kill many microorganisms but not spores.
• They can be used with alcohols for skin disinfection.
• They are slightly more toxic to skin than alcohols, have some residual antiseptic ability, but are inactivated by organic matter.
• Iodine can quickly penetrate the cell wall of microorganisms and cause disruption of protein and nucleic acid structure and synthesis.

Question 43

most effective antiseptic?

Answer 43

iodine

Question 44

Chlorhexidine

Answer 44

-antiseptic
-are antiseptics that have broad antimicrobial activity but a slow rate of killing than alcohols.
• They kill microorganisms by membrane disruption.
**• They have some residual activity but it is diminished by organic matter and high pH.
• They kill many bacteria but not the spores.
• Chlorine is a powerful oxidant (replaced hexachlorophene).
• Chlorhexidine is often used for general skin cleansing, a surgical scrub, and a pre-operative skin preparation.
• Some studies have shown chlorhexidine to be a better skin disinfectant in preventing bloodstream infections in patients with central lines as compared to povidone iodine.

Question 45

Quaternary ammonium compounds

Answer 45

-antiseptic
-like benzalkonium chloride have four organic groups linked to nitrogen.
**• They attack energy-producing enzymes, denature cell proteins and disrupt the cell membranes.
• They are not very effective against a number of organisms e.g. Pseudomonas, viruses, spores, Mycobacteria etc.

Question 46

Triclosan

Answer 46

-antiseptic
-is active against bacteria including some Mycobacteria but does not kill bacterial spores.
• It inhibits bacterial lipid synthesis and may also disrupt the cell membrane at high concentrations.
• It is often found as an antiseptic agent in deodorant soaps and some tooth paste products.

Question 47

PASTEURIZATION

Answer 47

• It is the process of heating liquids (like milk, beer or fruit juices) to a specific temperature (55-75°C) for a specific period of time in order to destroy harmful organisms like viruses, bacteria, protozoa, molds, and yeast. It does not destroy spores.
  • Unlike sterilization, pasteurization is not intended to kill all pathogenic microorganisms in the food.
  • Instead, pasteurization aims to achieve a “logarithmic reduction” in the number of viable organisms, reducing their number so they are unlikely to cause disease (assuming the pasteurized product is refrigerated and consumed before its expiration date).
  • Commercial-scale sterilization of food is not common, because it adversely affects the taste and quality of the product.