[CLINICAL BACTERIOLOGY LAB] MODULE 2. MICROBIAL CONTROL

Microbial control is the control of spread of microbes in the laboratory that is facilitated by?

Killing of microorganisms and inhibiting the growth of microorganisms

The complete destruction and removal of all forms of bacterial life including spores

Sterilization

They are highly resistant structures that can be killed with the use of sterilization

Spores

Destruction and removal of pathogens

Disinfection

TRUE OR FALSE. Disinfection can destroy and remove pathogenic and non-pathogenic microbes

FALSE

Disinfectant that is applied to the skin is called?

Antiseptic

Disinfecting agent applied to the surfaces is known as?

Disinfectant

Substances that can destroy or kill bacteria

Bactericidal

These are chemicals that can kill a bacteria

Biocides and germicides

This inhibits bacterial growth

Bacteriostatic

Growth in bacteriology means?

Increase in number

REVERSIBLE OR IRREVERSIBLE. Bactericidal

IRREVERSIBLE

REVERSIBLE OR IRREVERSIBLE. Bacteriostatic

REVERSIBLE

What are the factors that affect the effectiveness of microbial control methods?

Number of microbes present, Type of microbes present, Environmental influences, Time of exposure

2 Types of microbes that are difficult to eliminate

Sporolytic, hyperthermophilic microbes

These materials can inhibit the actions of some antimicrobial properties of some methods

Organic materials (feces, blood, saliva)

A treatment wherein the longer the bacteria are exposed, the better the action

Chemical/Radiation treatment

A treatment where it requires a low temperature but exposure is longer

Heat/boiling/autoclaving treatment

This is when there is an increased temperature but exposure is shorter

Incineration

This kills microorganisms by denaturing their enzymes and other proteins

Heat

________ is the lowest temperature at which of all the microbes in a liquid suspension will be killed in ______

Thermal Death Point; 10 minutes

______ is the minimal length of time in which all bacteria will be killed at a _______

Thermal Death Time; given temperature

_______ is the time in minutes at which ____ of bacteria at a given temperature will be killed?

Decimal Reduction Time; 90%

This is used in canning industry to ensure that there is little to no bacteria is in canned foods.

Decimal Reduction Time

What are the two types of heat

Moist heat and dry heat

This includes coagulation where they coagulate the protein components of the bacteria including its enzymes

Moist heat

What are the three types of moist heat?

Autoclave, Tyndallization, Inspissation

Mechanism of Autoclave

Protein denaturation and Steam under pressure

In what degree, minutes, and pounds per square inch is used when sterilizing used and unused culture media?

121C for 15-30 minutes at 15 psi

In what degree, minutes, and pounds per square inch is used when sterilizing contaminated microbiological materials?

121C for 30 minutes at 15 psi

In what degree, minutes, and pounds per square inch is used when sterilizing infectious medical wastes?

132C for 30-60 minutes

What is the biologic indicator of autoclave?

Geobacillus stearothermophilus

What is the one bacteria that the autoclave cannot kill?

Prions

What is used to kill prions?

Extended Steam Sterilization in conjunction with Sodium Hypochlorite

Mechanism of Tyndallization

Allows spore germination

Instrument/s used for Tyndallization

Arnold’s sterilizer and flowing steam

In what degree, and minutes is used for Tyndallization

100C for 30 minutes each day for 3 days

Mechanism of Inspissation

Thickening of bacteria

In what degree, and minutes is used for Inspissation

75-80C for 2 hours each day for 3 days

Instrument/s used for Inspissation

Inspissator

Inspissator is effective to sterilize culture media with?

Increased protein component

Examples of media that have an increased protein component that are used for mycobacteria

Lowenstein Jensen, Petragnani, ATS media

Media’s that are used for mycobacteria are high in protein content because are?

Egg based media

Tyndallization and Inspissation is a type of?

Fractionated/serial/discontinued sterilization

This type of sterilization is not an efficient sterilization method

Fractionated sterilization

Oxidation of bacterial components

Dry heat

Types of Dry Heat

Direct flame, dry/hot air oven, incineration

This is direct application of flame in aseptic technique

Direct flame

This is used in the sterilization of heat resistant materials

Dry/hot air oven

Effective temperature of dry/hot air oven

160-180C for 1.5-2 hours

Biologic indicator of dry/hot air oven

Bacillus subtilis variety niger

Burns materials into ashes; used in the disposal of biological waste

Incineration

Effective temperature of incineration

870-980C for 2 seconds

Works by alkylation of nucleic acid of bacteria using high energy short wavelength

Ionization Radiation

Ionization radiation is used to sterilize what?

Heat sensitive material

Biologic indicator of Ionization radiation

Bacillus pumillus

FILTRATION. Most bacteria, yeasts, and molds are retained by may allow passage of ______ organisms

0.45-0.80 um; pseudomonas-like

FILTRATION. Used to filter _________ organisms

0.22 um; pseudomonas-like

This size of filtration is used for critical sterilization of parenteral solution

0.22 um

FILTRATION. Able to retain small viruses

0.01 um

In AIR FILTRATION we use what type of filter?

High Efficiency Particulate Air filters

Pore size of HEPA filter used in AIR FILTRATION

0.03 um

When is AIR FILTRATION used?

Biological safety cabinet and rooms of immunocompromised patients

What are the chemical methods for sterilization?

Peracetic acid, Formaldehyde vapors, glutaraldehyde, and ethylene oxide gas

Peracetic acid is used to sterilize?

Surgical instruments

This is used for the sterilization of HEPA filters, large spaces, as well as vapor phase water

Formaldehyde vapors

Glutaraldehyde is used for the sterilization of?

Medical instruments

This is used for the sterilization of large spaces and other heat sensitive materials

Ethylene Oxide Gas

Use of Ethylene Oxide Gas in sterilization is also termed as?

Cold Sterilization

Biological indicator of Ethylene Oxide Gas

Bacillus subtilis variety globijii

Killing/destroying pathogenic microbes

Disinfection

What are the physical methods in disinfection?

Boiling and Pasteurization

This destroys vegetative cells of bacteria but not their spores

Boiling

Effective temperature for boiling

100C for 15-30 minutes

Used for preservation of alcoholic beverages and dairy products

Pasteurization

Different of methods of pasteurization

Batch method, flash method, ultra high temperature method

Effectiveness temperature for pasteurization, batch method

62.5C for 30 minutes

Effectiveness temperature for pasteurization, flash method

72C for 15 seconds

Effectiveness temperature for pasteurization, ultra high temperature method

Repeating temperature from 72-100-72C; within 5 seconds

This is used as a disinfection method for milk/dairy products

Ultra high Temperature method

Uses low energy long wavelength UV rays to disinfect heat sensitive materials and large spaces

Non-ionizing radiation

Type of sterilization that uses a high energy, short wavelength

Ionizing

Preferred concentration of alcohol

70%

What type of agent is alcohol?

Dehydrating agent

Mechanism of agent of Alcohol

Dehydration, lipid dissolution and protein denaturation

Minimum contact time of alcohol

1-2 minutes/until alcohol evaporates

Mechanism of action of halogens

Inhibits protein function and acts as strong oxidizing agents

Two types of halogens used as disinfectants

Chloride and Iodine

This is used as disinfecting agents in many laboratory and hospital spaces, surfaces and also in treat water

Chloride

What is known as 10% household bleach

Sodium hypochlorite

The most common used disinfectant and is also the best disinfectant to remove _______

Sodium hypochlorite; blood spills

CDC recommends 2 dilution for Sodium hypochlorite which are

Porous surfaces, hard/smooth surfaces

Recommended dilution for Porous surfaces

1:10

Recommended dilution for hard/smooth surfaces

1:100

Recommended contact time for HBV

30 minutes

Recommended contact time for HIV

2 minutes

What virus is susceptible to Sodium hypochlorite?

HIV

This can be used as a substitute if Sodium Hypochlorite is not available

Vinegar

Used as household antiseptics and surgical antiseptics

Iodine

3 forms of iodine in clinical setting

Povidone, Iodophor, Iodine tincture