Microbial Control

Question 1

Control of microbial growth means to inhibit or prevent growth of microorganisms.

Answer 1

Microbial Control

Question 2

Microbial control is affected in two basic ways:

Answer 2

(1) by killing microorganisms

(2) by inhibiting the growth of microorganisms

Question 3

Why do we need to control microbes?.

Answer 3

(1) prevent diseases

(2) preserve food and increase shelf-life

(3) quality control during production and research

Question 4

Hospital Control

• Antiseptic methods for surgery, boiling of surgical instruments

• Disinfectants for hands and wounds

Answer 4

Joseph Lister & Ignaz Semmelweis

Question 5

Hospital Control

• Sanitary procedures and training

• Procedures for reducing hospital overcrowding

Answer 5

Florence Nightingale

Question 6

6 Basic Principles of Microbial Control

Answer 6

+ Sterilization

+ Aseptic

+ Disinfection

+ Degerming

+ Sanitization

+ Pasteurization

Question 7

The removal or destruction of all microbes, including viruses and bacterial endospores, in or on an object or habitat.

Answer 7

Sterilization

Question 8

An environment or procedure that is free of contamination by pathogens.

Answer 8

Aseptic

Question 9

The killing, inhibition, or removal of microorganisms that may cause disease. The primary goal is to destroy potential pathogens.

Answer 9

Disinfection

Question 10

The removal of microbes from a surface by scrubbing.

Answer 10

Degerming

Question 11

The process of disinfecting places and utensils used by the public to reduce the number of pathogenic microbes to meet accepted public health standards.

Answer 11

Sanitization

Question 12

The use of heat to kill pathogens and reduce the number of spoilage microorganisms in food and beverages.

Answer 12

Pasteurization

Question 13

The permanent loss of reproductive ability under ideal environmental conditions.

Answer 13

Microbial death

Question 14

❑ Used to evaluate the efficacy of an antimicrobial agent.

❑ Usually constant over time for any particular microorganism under a particular set of conditions.

❑ When the microbial death rate is plotted on a semilogarithmic graph, this constant death rate produces a straight line.

Answer 14

Microbial death rate

Question 15

Give damage to a membrane’s proteins or phospholipids and therefore allows the cellular contents to leak out and causes death.

Answer 15

Alteration of cell walls (fungi)

Question 16

Give damage to viral envelope that interrupts the reproduction.

Answer 16

Alteration of cell membranes (virus)

Question 17

Often to select a method to kill the hardiest microorganisms present, assuming that method will kill more fragile microbes as well.

Answer 17

Relative Susceptibility of Microorganisms

Question 18

level kill all pathogens, including endospores.

Answer 18

High

Question 19

level kill fungal spores, protozoan cysts, viruses and pathogenic bacteria.

Answer 19

Intermediate

Question 20

level kill vegetative bacteria, fungi, protozoa and some viruses.

Answer 20

Low

Question 21

Degree of Resistance of Microorganisms

Answer 21

Most Resistant to Most Susceptible

+ Prions
+ Bacterial endospores
+ Mycobacteria
+ Cysts of protozoa
+ Active-stage protozoa (trophozoites)
+ Most Gram-negative bacteria
+ Fungi
+ Nonenveloped viruses
+ Most Gram-positive bacteria
+ Enveloped viruses

Question 22

Environmental Conditions

Answer 22

❑Temperature

❑pH

❑To clean objects before sterilization.

Question 23

• The first method used.

• If >1.0; the agent is more effective than phenol.

• The larger the ratio, the greater the effectiveness.

Answer 23

Phenol Coefficient

Question 24

• The current standard test

• The most effective agent is the one that entirely prevents microbial growth at the highest dilution.

Answer 24

Use-Dilution Test or Disk-diffusion Method

Question 25

• A more realistic method • Swabs are taken from actual objects before and after application of disinfectant. • More accurate determination of a given disinfection agent for each specific situation.

Answer 25

In-use Test

Question 26

2 Antimicrobial Methods

Answer 26

+ Physical Methods + Chemical Methods

Question 27

Physical Methods

Answer 27

1. Heat 2. Cold 3. Desiccation 4. Radiation 5. Ultrasonic Waves 6. Filtration 7. Gaseous Atmosphere

Question 28

Chemical Methods

Answer 28

1. Disinfectants 2. Antiseptics 3. Preservatives

Question 29

High temperatures denature proteins, interfere with the integrity of cytoplasmic membranes and cell walls and disrupt the function and structure of nucleic acids.

Answer 29

HEAT-RELATED METHODS

Question 30

lowest temperature that kills all cells in a broth in 10 minutes.

Answer 30

Thermal death point

Question 31

the time it takes to completely sterilize a particular volume of liquid at a set temperature.

Answer 31

Thermal death time

Question 32

time required to destroy 90% of the microbes in a sample.

Answer 32

Decimal reduction time (D)

Question 33

• To disinfect, sanitize, sterilize and pasteurize by denaturing proteins and destroying cytoplasmic membranes. • More effective than dry heat because water is better conductor than air. • Methods: Boiling, Autoclaving, and Pasteurization

Answer 33

MOIST HEAT

Question 34

• Denatures proteins and fosters the oxidation of metabolic and structural chemicals. • For substances cannot be sterilized by boiling or steam or materials can be damaged by repeated exposure to steam.

Answer 34

DRY HEAT

Question 35

• Kills vegetative cells of bacteria and fungi, protozoan trophozoites, and most viruses. • Boiling Point and Atmospheric Pressure is important. • higher atm. pressure = higher boiling point

Answer 35

Boiling

Question 36

• Pressure applied to boiling water prevents steam from escaping. • ↑ boiling temp = ↑ pressure • Autoclave – a device that uses steam heat under pressure to sterilize chemicals and objects • 121 deg C, 15 psi, 15 mins

Answer 36

Autoclaving

Question 37

• Heating foods to kill pathogens and control spoilage without altering the quality of foods. • Can be achieved by: + Batch sterilization (62°C for 30 mins.) _LTH + Flash sterilization ( 72°C for 15 sec.) _HTST + Ultra high temp. sterilization (134°C for 1 sec.) _UHT

Answer 37

Pasteurization

Question 38

• Temperature is between 0°C – 7°C for refrigeration and below 0°C for freezing. • It will decrease microbial metabolism, growth and reproduction.

Answer 38

REFRIGERATION and FREEZING

Question 39

• Desiccation or (drying) inhibits microbial growth because the absence of water. • Lyophilization (freeze drying) is a technique combining freezing and drying to preserve microbes and cells.

Answer 39

DESICCATION and LYOPHILIZATION

Question 40

• The passage of a fluid (liquid or gas) through a sieve to trap and separate particles (cells or viruses) from the fluid. • To sterilize heat-sensitive materials (antibiotics, vaccines, enzymes etc.).

Answer 40

FILTRATION

Question 41

• It is the pressure that needs to be applied to a solution to prevent the inward flow of water across a semipermeable membrane.

Answer 41

OSMOTIC PRESSURE

Question 42

consists high- speed subatomic particles that have been freed from their atoms.

Answer 42

Radiation / Particulate radiation

Question 43

energy without mass traveling in waves in the speed of lights.

Answer 43

Radiation / Electromagnetic radiation

Question 44

• Wavelengths shorter than 1 nm. • Electron beams, gamma rays, and x-rays.

Answer 44

IONIZING RADIATION

Question 45

• Wavelength greater than 1 nm. • UV light, visible light, infrared radiation and radio waves.

Answer 45

NON-IONIZING RADIATION.

Question 46

compounds derived from phenol molecules that have been chemically modified by the addition of halogens or organic functional groups.

Answer 46

Phenolics

Question 47

Commonly used in healthcare settings, laboratories and households.

Answer 47

PHENOLS AND PHENOLICS

Question 48

• Commonly used are isopropanol and ethanol. •- ve: not effective against fungal spores or bacteria endospores. •Pure alcohol is not an effective as 70% and 90% because no water.

Answer 48

ALCOHOLS

Question 49

• Peroxides, ozone andnperaceticnacid. • +ve: effective against anaerobic microorganisms contaminating deep wounds. • Used by healthcare workers to kill anaerobes • -ve: ozone is expensive.

Answer 49

OXIDIZING AGENTS

Question 50

Used both alone and combined with other elements in organic and inorganic compounds

Answer 50

HALOGENS

Question 51

• well-known antiseptic for water. • -ve: cannot destroy protozoan cysts.

Answer 51

Iodine

Question 52

• (iodine-containing organic compound) • used in medical institution

Answer 52

Iodophor

Question 53

• treat drinking water, swimming pools and waste water. • -ve: by-products are trihalomethanes (THMs), increased risk of cancer.

Answer 53

Chlorine

Question 54

•To reduce the surface tension of solvents (water)… -ve: not effective;against non-enveloped viruses, mycobacteria and endospores.

Answer 54

SURFACTANTS

Question 55

• Such as arsenic, zinc, mercury, silver and copper. • Low-level bacteriostatic and fungistatic agents. • -ve: mercury is a metabolic poison, silver nitrate is irritating.

Answer 55

HEAVY METALS

Question 56

• Suitable for large or bulky items. •Gases such as ethylene oxide,… •-ve: can be extremely hazardous (explosive and poisonous) to the people using them.

Answer 56

GASEOUS AGENTS

Question 57

• Antibiotics, semi-synthetics and synthetics. • Typically used for treatment of disease.

Answer 57

ANTIMICROBIAL DRUGS

Question 58

chemicals produced naturally by microorganisms like bacteria and fungi.

Answer 58

Antibiotics

Question 59

antibiotic undergo modification.

Answer 59

Semisynthetic

Question 60

In body fluids to be transported in the body and reach the infectious organisms.

Answer 60

SOLUBILITY

Question 61

They must be more toxic to microorganisms than to host cells.

Answer 61

SELECTIVE TOXICITY

Question 62

It is not easily altered: should have a standard toxicity and not be made more or less toxic by interactions with foods or other drugs.

Answer 62

TOXICITY

Question 63

Should not cause an allergic reaction.

Answer 63

NONALLERGIC

Question 64

Maintenance of a constant, therapeutic concentration in blood and tissue fluids - should have the same therapeutic activity over many hours.

Answer 64

STABILITY

Question 65

Resistance by microorganisms not easily acquired.

Answer 65

RESISTANT

Question 66

To destroy a prion, it must be denatured to the point that it can no longer cause normal proteins to misfold. Sustained heat for several hours at extremely high temperatures will reliably destroy a prion.

Answer 66

(900°F and above)

Question 67

was an antiseptic used during surgery in the late 1800s.

Answer 67

Phenol

Question 68

A resistant asexual spore that develops inside some bacteria cells

Answer 68

Endospores

Question 69

water inside. the relative concentrations of solute and water are equal on both sides of the membrane..

Answer 69

Isotonic

Question 70

Water outside. If a cell is placed in a hypertonic solution, water will leave the cell, and the cell will shrink.

Answer 70

Hypertonic

Question 71

The most reliable and universally applicable method is sterilization. The most practical, efficient, and inexpensive method of sterilization.

Answer 71

Heat