LG 6.16 - Control Bacterial Growth

Question 1

What is nosocomial infection?

Answer 1

• Healthcare associated infection (HAI)

Question 2

Regarding HAIs, what is infection control?

Answer 2

• Sum of all means used to prevent HAI.

Question 3

What is asepsis?

Answer 3

• Preventing contact between microorganisms and susceptible sites.

Question 4

What is sterilization?

Answer 4

• Destruction or removal of all microbial life. Inanimate objects, destroy endospores.

Question 5

What is disinfection?

Answer 5

• Destruction of most microbial life (destruction or removal of vegetative pathogens but not endospores). Inanimate objects.

Question 6

What is antisepsis?

Answer 6

• Disinfection of living surface.

Question 7

What are some factors affecting death rate?

Answer 7

• # microbes
• What’s in mixture (type of infectious agent)
• Smooth vs. pockets, pores
• Presence of interfering organic matter
• Duration exposure
• Temperature
• Concentration of sterilant/ disinfectant/ antiseptic

Question 8

(3) What are some examples of antiseptic agents?

Answer 8

• Ethyl, isopropyl alcohol
• Iodine
• Chlorhexidine
• Triclosan

Question 9

(3) Why is pasteurization used? What is the difference between batch pasteurization and flash pasteurization?

Answer 9

• Milk is ideal growth medium for microbes
• Pasteurization kills most microbes: not endospores or thermotolerant microbes (lactobacilli, micrococci, yeasts).
• Batch = 63-66 deg, 30 min
• Flash = 72, 15 sec

Question 10

(3) What are the prevention methods take of HAIs in: operating room, hospital ward, outpatient clinic.

Answer 10

• Operating rooms: steril drapes, gowns, instruments, caps, face masks.
• Hospital ward: sterile needles, medications
• Outpatient clinics: segregate ill patients

Question 11

(3) What are the 5 WHO moments for hand hygiene?

Answer 11

• Before touching a patient
• Before clean/aseptic procedure
• After touching a patient
• After touching a patient surroundings
• After body fluid exposure risk

Question 12

(3) When is it recommended to use soap and water vs. alcohol-based hand rub?

Answer 12

• Soap + water: visibly dirty, visibly soiled with blood or other body fluids, after using toilet, exposure to potential endospore forming pathogens suspected.
• Alcohol: routine hand antisepsis in all other clinical situations.

Question 13

Rank a list of microbes in order from most resistant to least resistant

Answer 13

prion>endospore>mycobacteria, naked viruses, protozoan cysts, fungi>most bacterial vegetative cells, enveloped viruses, protozoan trophozoites

Question 14

describe autoclaving as a sterilization method.

Answer 14

-heat/steam killing
-121°C for 15 min
-effective for most materials except temp.- sensitive and water-resistant substances like oils, waxes, powders
-glassware, metallic instruments, non-heat sensitive liquids, waste
•-flash autoclaves used in Ors (134°C, 3 min)

Question 15

how do you sterilize prions?

Answer 15

• moist heat sterilization (autoclave 132°C, 60-90 min)

* chemical sterilization (1 N NaOH, 1 hr)

Question 16

Describe how to use dry heat to sterilize.

Answer 16

• hospital incinerator - good for disposal of infectious material (e.g. syringes dressings, pathology samples)
• oven - used in clinics and labs - good for glassware, metallic instruments, oils, powders (150-180°C, 2-4 hrs)

Question 17

Describe how to use filtration to sterilize.

Answer 17

• pore size determines types microbes removed (effective for viruses)
• applications: liquids that can’t be heated (serum, vaccines, drugs, iv fluids, enzymes, media) and airborne contaminants. doesn’t remove toxins

Question 18

Describe how to use to ionizing radiation (gamma radiation) to sterilize.

Answer 18

• advantages: speed, high penetrating power, absence of heat!
• good for medical products like drugs, vaccines, plastic medical instruments, syringes, surgical gloves, bone, skin, heart valves

Question 19

Describe how to use UV to sterilize.

Answer 19

• disadvantage: poor penetration
• air, surface sterilization (“only really good for air sterilization because doesn’t penetrate”)
• E.g. hospital rooms, OR

Question 20

Describe how to use chemicals to sterilize.

Answer 20

• good for heat sensitives like endoscopes and other microsurgical instruments
• users must remove organic matter first!!
• E.g. per acetic acid, also gas vapor chambers

Question 21

List 3 modes of HAI transmission:

Answer 21

1. self - normal microbiota
2. cross - staff, other patients, visitors
3. environmental - air, food, dust, catheters, bedpans, endoscopes, respiratory equipment