Topic 11 Microbial Control

Question 1

• practice of limiting growth or completely eliminating microorganisms (bacteria, viruses, and fungi) through various _ and _ methods
• aims to prevent the spread of diseases, food spoilage, and contamination in a given environment or on surfaces

Answer 1

Microbial Control Method
- physical and chemical methods

Question 2

Microbial Control
1. By _ _ - kills or destroys the microorganisms
- -cidal: _ kills bacteria, _ kills fungi
2. By _ _ _ _ _ - inhibit the growth of cells (without killing them)
- -static: _ - inhibits growth of bacterial cells

Answer 2

1. By killing microorganisms - kills or destroys the microorganisms
   - -cidal: bactericide kills bacteria, fungicide kills fungi
2. By inhibiting the growth of microorganisms - inhibit the growth of cells (without killing them)
   - -static: bacteriostatic - inhibits growth of bacterial cells

Question 3

Microbial Control
- microbial growth can be controlled by _ and _ method
- _ _: control as high or low temp, desiccation, osmotic pressure, radiation, filtration
- _ _: disinfectants, antiseptics, antibiotics, chemotherapeutic antimicrobial chemicals

Answer 3

• physical and chemical method
• Physical agents
• Chemical agents

Question 4

Microbial Control Methods:
_ _ - heat (dry and moist), radiation -> sterilization
_ _ - gases, liquids (animate and inanimate) -> s, disinfection, antisepsis
_ _ _ - filtration (air and liquids) -> d, s

Answer 4

Physical agents
Chemical agents
Mechanical removal methods

Question 5

Microbial Control Methods
_ - eliminates most pathogens but not necessarily all types of microbes (kills vegetative cellls and not the spores)
- reduces or minimizes the level of microbial contamination associated with inanimate objects or surfaces to a negligible level
- required for kennels, labs and infected premises

Answer 5

Disinfection

Question 6

Microbial Control Methods
_ - _ procedure kills all microorganisms (bacteria, viruses, fungi, spores) from a surface, object or substance
- required for surgical and lab instruments
- no degrees of _: object is either _ or not

Answer 6

Sterilization
- object is either sterile or not

Question 7

Microbial Control Methods
_ - destruction or inhibition of microorganismss on skin or living tissues using chemical agents
- non-toxic and non-irritating for tissues

Answer 7

Antisepsis

Question 8

Microbial Control Methods
Physical Agents
1. _
- Dry _ - kills organism by oxidative destruction of cells constituents
- spores killed at 160 deg C for 1 hour
- incineration, dry oven
- Moist _ - most effective and efficient - moisture (steam) allows better heat penetration and faster destruction of cells
- kills organisms by denaturing enzymes and proteins
- spores killed by exposure to moist heat at 121 deg C for 10-30 mins

Answer 8

1. Heat
   - Dry Heat - oxidative destruction of cells constituents, 160 deg C 1 hour
   - Moist Heat - denatures enzymes and proteins, 121 deg C 10-30 mins

Question 9

Microbial Control Methods
Physical Agents
1. Heat
_ _
- _ - burns organisms and physically destroys them
- used for needles, inoculating wires
- _ _ - hot air _: 160 deg C/2 hours or 170 deg C/1 hour
- used for glassware, metal, objects that won’t melt

Answer 9

Dry heat
- Incineration
- Dry oven

Question 10

Microbial Control Methods
Physical Agents
1. Heat
_ _
- _ - steam under pressure: 121 deg C for 15 mins
- good for sterilizing almost anything, but heat-labile substances will be denatured or destroyed
- _ - 100 deg C for 30 mins
- kills everything except some endospores
- to kill endospores, very long or intermittent boiling required
- _ - disinfection of beverages, stops fermentation
- exposes beverages to 71.6 deg C for 15s
- prevents transmission of milk-borne diseases - Salmonella, Campylobacter, Listeria, Mycobacteria

Answer 10

Moist heat
- Autoclave
- Boiling
- Pasteurization

Question 11

Microbial Control Methods
Physical Agents
2. _
- _
- Ultraviolet
- _
- Gamma rays (High energy)
- X-rays (Intermediate energy)
- Cathode rays (Least energy)

Answer 11

2. Radiation
   - Nonionizing
   - Ionizing

Question 12

Microbial Control Methods
Physical Agents
2. Radiation
- - _ _
- widely used in BSCs, operating theaters, animal quarters in other areas to reduce airborne infections
- acts by causing errors in replication of DNA
- antimicrobial activity is also affected by the
distance from the _ source

Answer 12

Non-Ionizing - Ultraviolet Light

Question 13

Microbial Control Methods
Physical Agents
2. Radiation
_ Radiation
- energy content much higher than that of UV light
- _ _ (Gamma rays) - used commercially to sterilize syringes, needles, surgical sutures, dressings, bone grafts, catheters, plastic petri dishes etc.

Answer 13

Ionizing Radiation
- Cobalt 60

Question 14

Hierarchy of Pathogen Kill by DIsinfectants
Easier to kill -> Harder to kill
EBFN MBP

Answer 14

Easier to kill -> Harder to kill
Enveloped viruses, bacteria, fungi, non-enveloped viruses, mycobacteria, bacterial spores, prions

Question 15

Characteristics of an ideal antimicrobial agent
1. At low concentration, _ _ of antimicrobial activity
2. _ in water or other solvents
3. _ even upon standing
4. - to humans and other animals
5. _ in composition so active ingredients are present in each application
6. - with extraneous organic material
7. _ to microorganisms at room or body temp
8. Capacity to _
9. - and -
10. _ ability
11. _ capacity
12. Available at _ _

BSSN UNTP NDDR

Answer 15

Characteristics of an ideal antimicrobial agent
1. At low concentration, broad spectrum of antimicrobial activity
2. Soluble in water or other solvents
3. Stable even upon standing
4. Non-toxic to humans and other animals
5. Uniform in composition so active ingredients are present in each application
6. Non-combination with extraneous organic material
7. Toxicity to microorganisms at room or body temp
8. Capacity to penetrate
9. Non-corroding and non-staining
10. Deodorizing ability
11. Detergent capacity
12. Available at reasonable price

Question 16

Microbial Control Methods
Chemical Agents
1. _
- process of exposing equipment or devices to different _ in a closed heated or pressurized chamber
- can pass through a tiny orifice and provide more effective results
- ethylene oxide, formaldehyde, nitrogen dioxide

Answer 16

1. Gases

Question 17

Microbial Control Methods
Chemical Agents
2. _
- Common disinfectants:
10 AHAPI QAABO

Answer 17

2. Liquids
   Aldehydes, Hypochlorites, Alcohols, Phenolics, Iodophors, Quaternary ammonium compounds, Alkalis, Acids, Biguanides, Oxidizing agents

Question 18

Microbial Control Methods
Chemical Agents
2. Liquids
_ - MOA: denatures proteins and disrupt nucleic acids causing irreversible inhibition of microorganism enzyme activity
- bactericidal, virucidal (enveloped and non-enveloped), fungicidal, and sporicidal
- highly irritating, and acutely toxic to humans or animals with contact or inhalation, formaldehyde is a known carcinogen
- a 2% aqueous solution (pH 7.5–8.5) - for disinfecting surgical instruments and equipment, although steam sterilization is preferable

Answer 18

Aldehydes

Question 19

Microbial Control Methods
Chemical Agents
2. Liquids
_ and _ _
- MOA: their electronegative nature denatures proteins
- has broad-spectrum antibacterial activity, hard water resistance, quick action, and cost-effectiveness
- sodium hypochlorite - one of the most widely used
- commercial chlorine bleach contains 5.25% sodium hypochlorite in aqueous solution – household bleach

Answer 19

Chlorine and chlorine compounds

Question 20

Microbial Control Methods
Chemical Agents
2. Liquids
_ - isopropanol and ethanol
- MOA: acts as a dehydrating agent which denatures cellular proteins, causing membrane damage and cell lysis
- considered fast-acting capable of killing most bacteria within 5 minutes of exposure
- limited in virucidal activity and are ineffective against spores
- for efficient sanitization, alcohol concentration must be at least 70% (with 30% water)

Answer 20

Alcohol

Question 21

Microbial Control Methods
Chemical Agents
2. Liquids
_ _ - MOA: denatures proteins and inactivates membrane-bound enzymes to alter the cell wall permeability of microorganisms
- typically formulated with soap (anionic) solutions to enhance their penetrative power
- broad spectrum - considered effective against many bacteria, mycobacteria, fungi, and enveloped viruses
- efficacy against non-enveloped viruses is variable, have minimal sporicidal activity
- maintain activity in hard water and in the presence of organic matter

Answer 21

Phenolic compounds

Question 22

Microbial Control Methods
Chemical Agents
2. Liquids
_ - iodine-based compound (i.e. povidone iodine)
- MOA: penetrate directly inside the cell wall resulting in disruption of proteins and nucleic acids
- broad spectrum, considered effective for a variety of bacteria, mycobacteria, fungi and viruses
- restricted to certain semi-critical medical equipment
- retains the stain and leaves an unpleasant odor

Answer 22

Iodophors

Question 23

Microbial Control Methods
Chemical Agents
2. Liquids
_ _ _ - QUATS or QAC
- MOA: dissociates cellular membrane lipid layers, compromising cellular permeability controls and inducing leakage of cellular contents
- bactericidal (G-, G+), fungicidal, amoebicidal, virucidal against enveloped viruses
- not effective against non-enveloped viruses or mycobacteria, considered sporostatic but not sporocidal
- antibacterial activity is reduced in the presence of organic matter

Answer 23

Quaternary Ammonium Compounds

Question 24

Microbial Control Methods
Chemical Agents
2. Liquids
_ _
- MOA: the formation of free radicals can destroy vital biological components such as lipids, DNA, and so on
- at a 5-20% concentration- considered bactericidal, virucidal (non-enveloped viruses may be resistant), fungicidal and at high concentrations sporicidal
- risk-free, eco-friendly and safe for a sustainable environment
- after disposal, it breaks down into natural elements like water and oxygen

Answer 24

Hydrogen Peroxide

Question 25

Conditions Influencing Anti-Microbial Action 1. _ and _ of a chemical agent used 2. _ and _ of a physical agent used 3. _ of _ to the agent 4. _ at which agent is used 5. _ of microorganisms present 6. _ itself 7. _ of material bearing the microorganism CILT NON

Answer 25

1. concentration and kind of a chemical agent used 2. intensity and nature of a physical agent used 3. length of exposure to the agent 4. temperature at which the agent is used 5. number of microorganisms present 6. organism itself 7. nature of the material bearing the microorganism

Question 26

Microbial Control Methods Mechanical removal methods 1. Filtration: _ - _ filters with a porosity of about 0.3 micrometers, commonly referred to as high efficiency particulate air filters (HEPA) filters, used to filter air in lab rooms and biosafety cabinets - commonly used when aerosols of infectious or contaminated materials may be generated

Answer 26

1. Filtration: Air

Question 27

Microbial Control Methods Mechanical removal methods 2. Filtration: _ - sterilizes bacteriologic media, serum, injection solutions (such as vaccines), and other materials containing heat sensitive substances - a pore size of 0.45 μm or less removes most or all bacteria from solutions

Answer 27

2. Filtration: Liquid

Question 28

Classification of Antibiotics Based on: 1. _ _ _ 2. _ _ _ 3. _ _ _ MSM

Answer 28

- Mechanism of action - ICIII - Spectrum of activity - NB - Mode of action - BB

Question 29

Classification of Antibiotics Based on mechanism of action - _ _ Synthesis - Beta Lactams, Vancomycin Bacitracin, Cell Membrane - _ _ Synthesis - Folate synthesis, DNA Gyrase, RNA Polymerase - _ Synthesis - 50S subunit, 30S subunit - ICIII

Answer 29

- Cell Wall Synthesis - Nucleic Acid Synthesis - Protein Synthesis - Inhibition of Cell Wall Synthesis - Cell Membrane Dysfunction - Inhibiting Nucleic Acid Synthesis - Inhibition of Protein Synthesis - Inhibition of Folate Synthesis

Question 30

Classification of Antibiotics Based on mechanism of action - _ _ _ _ _ - _ biosynthesis is essential to the integrity of the cell wall structure, and it is the outermost layer and the main component of the cell wall - targets bacterial peptidoglycan (component of bacterial cell walls, that animal cells lack) - _ _ _ - _ _ provides selective permeability for cellular homeostasis and metabolic energy-transduction - disrupts membrane potential leading to the destruction of membrane structures and functional impairment

Answer 30

- Inhibition of Cell Wall Synthesis - peptidoglycan - Cell Membrane Dysfunction - cell membrane

Question 31

Classification of Antibiotics Based on mechanism of action - _ _ _ _ - can interfere with DNA synthesis - Fluoroquinolones: inhibits the activity of DNA gyrase and blocks DNA replication, killing the cell - can interfere with RNA synthesis - Rifampin: functions by blocking RNA polymerase activity in bacteria and blocks transcription, killing the cell - _ _ _ _ - most _ interfere with the 30S or 50S subunits of the 70S bacterial ribosome to block bacterial protein synthesis - _ _ _ _ - _ _ are the enzymes that are necessary for bacterial protein synthesis and the synthesis of amino acids - Sulfonamides: inhibits the enzyme involved in the production of dihydrofolic acid by block bacterial biosynthesis of folic acid and, subsequently, pyrimidines andpurines required for nucleic acid synthesis

Answer 31

- Inhibiting Nucleic Acid Synthesis - Inhibition of Protein Synthesis - antibiotics - Inhibitio of Folate Synthesis - folic acid

Question 32

Classification of Antibiotics Based on spectrum of activity - _ spectrum - active against either Gram - or Gram + bacteria alone - e.g. penicillin - _ spectrum - active against both Gram - or Gram + bacteria - e.g. chloroamphenicol, tetracycline

Answer 32

- Narrow spectrum - Broad spectrum

Question 33

Classification of Antibiotics Based on mode of action - _ - kills bacteria - _ - inhibits bacterial growth or reproduction - keeps them in stationary phase of growth - relies on body's immune system to eliminate the bacteria

Answer 33

- bactericidal - bacteriostatic