MICROBIO 4000 Lab Quiz 5

Ex. 3.4-3.6

Definition of the constructive process

Organisms are added to produce certain food items (intended)

Ex. 3.4-3.6

Definition of the destructive process

Organisms that cause food spoilage (not intended)

Ex. 7.4

Definition of Precipitin Reaction

Antibodies react with soluble antigens to form a complex precipitate

e.g. soluble antigens cause Lyme disease

Ex. 3.4

Purpose of Pasteurization

Control the growth of unwanted microbes

Ex. 3.4

How to view microbes originating from solid food on agar plates?

A suspension of it made in a blender/stomacher

Ex. 3.4

What is the Pour-plate Technique (juice sample)?

1. Add the juice sample on an empty Petri dish

2. Pour Liquefied Potato Dextrose Agar (PDA, 45 °C) and mix it with the sample

3. Incubation after solidified

Ex. 3.4

How buttermilk is made

adding selected material cultures to milk and incubating the mixture until it sours

Ex. 3.5

What is the minimal growth media used in cheese/beef dilution

Peptone Water

Ex. 3.5

What type the Eosin Methylene Blue (EMB used for beef) is?

Selective-differential agar

Ex. 3.4-3.6

Don't forget how to calculate CFU/g

Ex. 3.6

What is the product and reactant in the Yogurt production

Lactose to Lactic Acid via fermentation with S. thermophilus and L. bulgaricus

Ex. 3.6

Role of S. thermophilus and L. bulgaricus in the yogurt production

First phase: S. thermophilus stimulated and becomes predominant organism

Second Phase: A drop of pH makes L. bulgaricus to become dominant

End phase: pH drops to 4.2-4.3 indicating the termination of fermentation

Ex. 6.6

Definition of Transient Microbiota on skin

The bacteria, mold spores, etc. that are the,temporality found on our skin as a result of touching objects in our environment

Ex. 6.6

Definition of Normal microbiota on skin

The bacteria that usually inhabit our body (either on the skin or internally), and they cause us no harm under normal circumstances

Ex. 6.6

Protection factors of skin

1. Low pH

2. Low moisture

3. Urea, salts, etc. secreted by the sweat and oil glands

Ex. 6.8

Definition of Antiseptics

Used on living things

Ex. 6.8

Definition of Disinfectants

Not used on living things and may cause damage to living tissue

Ex. 6.10

Definition of Antibiotics

Chemicals that are naturally produce by some soil bacteria and fungi and either inhibit or kill other microbial organisms

Ex. 6.9

General mode of actions of antibiotics on bacteria (4)

1. Inhibition of Cell Wall Synthesis

2. Inhibition of Protein Synthesis

3. Inhibition of Nucleic-acid Synthesis

4. Negative alteration of the Plasma Membrane

Ex. 6.9

Definition of the minimum inhibitory concentration (MIC)

the lowest concentration (in μg) of an antibiotic needed to inhibit the growth of a particular organism under laboratory conditions

Ex 6.9

Disadvantages (2) of the minimum inhibitory concentration (MIC)

1. MIC is assessed in vitro (outside of the body)

2. The determined MIC may not suitable in body

Ex 6.9

What does the Kirby-Bauer method test for?

Microbial sensitivity to antibiotics

Ex 6.9

What is an Etest strip

A strip with a concentration gradient of a given antibiotic impregnated on one side (can read MIC)

Ex. 6.7-6.8

What method was used for testing the effect of Mouthwashes/Disinfectants/Antiseptics

Filter disk method (Disks that are saturated with a given antimicrobial agent)

Ex. 6.7-6.8

The effect of Mouthwashes/Disinfectants/Antiseptics is measured by?

Zones of inhibition

Ex. 6.9

What is responsible for the Resistance to Ampicillin in Plasmid A

Bla gene that codes for the enzyme beta-lactamase

Ex. 6.9

What is responsible for the green fluorescent in Plasmid A

Production of the green fluorescent protein GFP

Ex. 6.9

What is responsible for the Resistance to Kanamycin in Plasmid B

KanR gene

EX 6.9

Clinical interpretations of the zone of inhibition

Based on the diameter, rated at Susceptible, Intermediate, or Resistant

Ex. 7.3

Definition of Inflammatory Response

Pathogens penetrating the external defense systems of the human body trigger a series of non-specific host defense mechanisms

Ex. 7.3

Major component of the inflammatory response

White blood cells (leukocytes)

Ex. 7.3

Leukocytes recruited to the site of infection (2)

Macrophages and Neutrophils

*Both are phagocytes

Ex. 7.4

Two ways of enhancing phagocytosis

1. Antibodies

2. Complement system

Ex. 7.3-7.4

Definition of Opsonization

Antibodies and complements bind to invading bacteria and attract phagocytes to the site of infection

Ex. 7.3-7.5

What helps the bacteria to evade immune response?

VIrulence factors

Ex. 7.3-7.5

How to determine the virulence of an organism?

The degree of pathogenicity, or the ability of an organism to cause disease

Ex. 7.3

Function of DNase

Hydrolyzes Free DNA present in pus, it does not affect the DNA of living cells

Ex. 7.4

What does coagulase do?

Catalyzes the conversion of fibrinogen (soluble) to fibrin (insoluble)

Ex. 7.3

Bacterial Hemolysins (3)

1. α-hemolysin: Reduce the number of functional RBC

2. β-hemolysin: Damage other cells and tissues in the immediate area

3. γ-hemolysin: Breakdown RBC

Ex. 7.3

How to evaluate if the formation of a plasma clot occurred?

Tipped the tube at a steep angle

Clumps: coagulase produced

Fluidity: No coagulase produced

Ex. 7.3

Hemolysin test results interpretations

1. α-hemolysin: Greenish spot

2. β-hemolysin: Clear spot

3. γ-hemolysin: No change

Ex. 7.4

Definition of Agglutination Reaction

Antibodies react with insoluble antigens to form a clump

Ex. 7.4

Definition of Complement Fixation

Ag-Ab complex triggers the complement system and cause lysis in organism

Ex. 7.4

ABO blood type Agglutination test results

A blood type: A antigens binds with Anti-A antibodies (in B/O blood type)

B blood type: B antigens binds with Anti-B antibodies (in A/O blood type)

O blood type: No antigens

AB blood type: A+B antigens binds with Anti-A/B antibodies (in A/B/O blood type)

Ex. 7.5

Definition of Epidemic

An infectious disease that rapidly spread within a relatively short period of time and present at a high frequency in a community

Ex. 7.5

Advantage of ELISA test

More precise than precipitin and agglutination tests, which detects in the picogram (10^-12) level