Module 2: Control of Microbial Growth

Question 1

Define: Infectious

Answer 1

Microorganisms capable of causing disease (also known as pathogens or potential pathogens)

Question 2

Define: Contaminant

Answer 2

Microbes present at a given place and time that are undesirable or unwanted. (i.e. vegetative cells, endospores, protozoan cysts, fungal hyphae, viruses, etc..)

Question 3

Define: Nosocomial Infection

Answer 3

Infections that develop during the course of a hospital stay and not present at the time of admission.

Question 4

What are Standard Precautions as per OSHA intended to limit infection in and transmission by Health-care workers?

Answer 4

Assume that patients are infectious and that blood and body fluids contain pathogens; use appropriate personal protective equipment, engineering controls, and work practice controls (hand washing)

Question 5

What is a BSL?

Answer 5

Biosafety Level

Question 6

Define: Biosafety Levels

Answer 6

Determined by degree of risk; require varying types of PPE

Question 7

Define: BSL-1

Answer 7

Agents having no known potential for infecting healthy people.

Question 8

What pre-cautions are taken in BSL-1?

Answer 8

Standard good laboratory technique.

Question 9

Define: BSL-2

Answer 9

Agents most commonly encountered in clinical samples, including HIV and several more unusual pathogens (not highly transmissible by respiratory route)

Question 10

What pre-cautions are taken in BSL-2?

Answer 10

Standard good laboratory techniques, PPE of lab coat and gloves (certain procedures), limiting access to lab, special training of personnel in handling, and performing aerosol generating procedures in Biosafety Cabinet (BSC)

Question 11

Define: BSL-3

Answer 11

Agents include those that are more unusual or more highly transmissible such as Mycobacterium Tuberculosis, Brucella spp., infrequently encountered viruses, mould stages of fungi (highly transmissible by respiratory route)

Question 12

What pre-cautions are taken in BSL-3?

Answer 12

Level 2 pre-cautions plus routing use of a BSC, wearing of a HEPA-filter mask, special laboratory design and engineering features that contain potentially dangerous material by control of air movement.

Question 13

Define: BSL-4

Answer 13

Agents are certain highly infectious exotic microbes and toxins for which there is no vaccine or effective treatment.

Question 14

What pre-cautions are taken in BSL-4?

Answer 14

Require maximum containment facilities and the highest levels of special protective equipment

Question 15

Define: Sterile

Answer 15

Free of all microorganisms and their spores

Question 16

Define: Sterilization

Answer 16

Use of physical procedures or chemical agents to destroy all microbial forms, including bacterial spores

Question 17

Define: Disinfect/Decontaminate

Answer 17

Use of physical procedures or chemical agents to destroy, inhibit, neutralize, or remove at least most (but not necessarily all) potentially infectious microorganisms on an object or surface

Question 18

Define: Disinfectant

Answer 18

Agent or method (usually chemical agent) used to carry out disinfections; normally used on inanimate objects (may burn or severely irritate skin or tissue). Varrying levels of effects (High, intermediate, low)

Question 19

Define: Antisepsis

Answer 19

Use of chemical agents on the skin or other living tissue to eliminate or inhibit microorganisms; no sporicidal action is implied. achieved y use of antiseptic on skin

Question 20

The suffix Cide or Cidal implies?

Answer 20

Indicates that the chemical or process is destructive to (kill) the microbe. Does not necessarily kill spores

Question 21

Define: Sporicidal

Answer 21

Chemicals destroy spores as well as vegetative cells

Question 22

The suffix Stat or Static implies?

Answer 22

Indicates the chemical or process of inhibiting growth multiplication of bacteria, but not killing

Question 23

Define: Pasteurization

Answer 23

Process of applying mild heat to kill, or significantly reduce the number of, microbes which may spoil food or beverage

Question 24

Define: Aseptic

Answer 24

Free of contaminating or infectious microorganisms; usually refers to technique

Question 25

Define: Thermolabile

Answer 25

Easily altered, decomposed or destroyed by heat

Question 26

Define: Thermostable

Answer 26

Not easily altered, decomposed or destroyed by heat

Question 27

Give microbial resistance to killing in general sequence from most resistant to least resistant.

Answer 27

``` 1- Bacterial Endospores 2- Mycobacterium 3- Protozoan Cysts 4- Non-enveloped Small Viruses 5- Vegetative Bacteria 6- Fungi 7. Enveloped Viruses ```

Question 28

What factors contribute to effectiveness of sterilization or disinfection method/agent?

Answer 28

1. Microbial population composition 2. Microbial Death 3. Population Size 4. Concentration/Intensity of Antimicrobial 5. Duration of Exposure 6. Temperature and pH 7. Presence of protective or neutralizing matter 8. Physical nature of material being treated

Question 29

Which Microbe is the most resistant to antimicrobial control methods?

Answer 29

Bacterial Endospores

Question 30

Which cells are more easily destroyed, Younger cells or Mature cells?

Answer 30

Younger Cells

Question 31

What occurs during microbial death?

Answer 31

Microbes are not killed instantly when exposed to lethal agents, but become dysfunctional and die over a period of time

Question 32

How does population size of microbes affect the effectiveness and choice of sterilization or disinfection method or agent used?

Answer 32

Larger load of contaminating microbes requires a longer exposure time to destroy

Question 33

Concentration/Intensity of antimicrobial affect the effectiveness and choice of sterilization or disinfection method or agent used in what way?

Answer 33

Typically more concentrated chemical or intense a physical agent the more rapidly microorganisms are destroyed.

Question 34

Give an example where a more concentrated antimicrobial is not more effective?

Answer 34

70% ethanol is more effective than 95% ethanol

Question 35

How does duration of exposure to antimicrobial play into the effectiveness of control of microbes?

Answer 35

Longer exposure to a microbicidal agent the more organisms are killed

Question 36

What effect does Temperature and pH play in control of microbes?

Answer 36

Increase in temperature at which a chemical acts often enhances its activity. Heat kills more readily at an acid pH.

Question 37

What effect does the presence of protective or neutralizing matter have on control of microbe?

Answer 37

Organic material protects or inactivates chemical disinfectants and/or protect from heat.

Question 38

The physical nature of materials being treated play what role in control of microbes?

Answer 38

The material i.e. glass, metal, plastic, liquid, pores material. More dense material is easier to kill microbes on.

Question 39

What modes of action are there for microbial control.

Answer 39

- Damage to Cell Wall - Disrupt cytoplasmic Membrane - Inhibit synthesis or proteins and nucleic acids - Alter function of proteins and nucleic acids