Lab 9 and Lab 10

Question 1

Describe Mycobacteria under a microscope

Answer 1

They are slightly curved or straight rods that sometimes branch or form filaments. These filaments readily fragment and into rods and coccoid bodies when distributed

Question 2

What is the difference in growth between pathogenic and non pathogenic mycobacterial species

Answer 2

Pathogenic grow slower than non-pathogenic

Question 3

How long should Mycobacteria be incubated for to form a visible colony? Why?

Answer 3

2-40 days on most solid media ,the grow slow

Question 4

Mycobacterium is a genus of

Answer 4

Actinobacteria

Question 5

Some mycxibacteria are free living _______, but are best known as__________ _________

Answer 5

Saprophytes

Animal pathogens

Question 6

Which bacteria cause tuberculosis ?

Answer 6

M. tuberculosis , M. bovis, M. africannum, M microti

Question 7

Are members of TB complex pathogenic? specially to human?

Answer 7

Yes.

No, M. tuberculosis is for humans jmans, while M.bovis is for animals

Question 8

What is a Mycobacterial cell wall made up of

Answer 8

Mycolic acid–> 60% concentration of a hydrophobic waxy lipid, formed outside a thin layer of peptidoglycan and held together by a polysaccharide

Question 9

Under a microscope, acid fast bacteria appear

Answer 9

Purple to red, slightly red, slightly curved, short or long rods

Question 10

Acid fast stain procedure

Answer 10

1. Make smear of culture
2. Heat fix the slide for a total of 6 times
3. Flood smear with Carbol Fuchsin for 3 min.
4. Rinse slide with tap water
5. Decolorize with acid alcohol for 5 to 10 sec.
6. Rinse with tap water
7. Counterstain with methylene blue for 45 sec.
8. Rinse and blot dry

Question 11

Acid fast appears ««««

Non acid fast appears»»»>

Answer 11

Red

Blue

Question 12

What is Acid fast stain is used to identify

Answer 12

Mycobacterium species and Norcadia species

Question 13

Why is a smear heat fixed for a longer time when preparing slide for Acid Fast staining

Answer 13

It enhances the penetration and retention of the dye

Question 14

Why do Acid fast micro organisms retain the pink or red color

Answer 14

Because the carbolfuchsin is more soluble in the cell wall lipids than in the acid alcohol.

Question 15

Why don’t non acid fast bacteria hold the primary stain

Answer 15

Because their cell walls lack the lipid components and the carbolfuchsin is rapidly removed during Decolorization, leaving the cells colorless.

Question 16

Gram staining of mycobacterium will result in

Answer 16

it may weakly stain gram positive

Question 17

Name to diseases that are caused by pathogenic species of Mycobacterium

Answer 17

1. TB

2. Leprosy

Question 18

What structural feature of the Mycobacterium causes it to be acid fast

Answer 18

The waxy mycolic acid and lipid layer make it impenetrable to basic dyes and resist decolorization from acid alcohol.

Question 19

How do acid fast bacteria resist drying

Answer 19

The cell wall is made up of 60% hydrophobic waxy lipid layer that allows it to maintain its moisture for long periods and prevents him from drying

Question 20

How is acid fast bacteria resistant to acids and disinfectants

Answer 20

The mycolic acid and glycolipuds make it impenetrable to acids, chemicals, and lysosomal components of phagocytes

Question 21

Why do acid fast bacteria have longer generation times

Answer 21

The cell wall makes it hard for nutrients to enter the cell, they enter at a slow rate, and this causes the growth rate to also be slow

Question 22

Sterilizing agent

Answer 22

A sterilant or a substance/mechanism used to remove or destroy all living microorganisms this includes endospores but with the possible exception of prions

Question 23

Disinfectant

Answer 23

A physical or chemical agent used to destroy vegetative pathogens

Question 24

Antiseptic

Answer 24

A chemical used to destroy a vegetative pathogens on living tissue

Question 25

Sanitizer

Answer 25

A chemical disinfectant intended to lower microbial counts to safe public health levels and minimize the chances of disease transmission

Question 26

Bactericide

Answer 26

An agent used to kill bacteria

Question 27

Fungistatic

Answer 27

I need it used to and have it the growth and multiplication of fungi

Question 28

Serratia marcescens: Morphology gram type and other important characteristics that play a role in the effectiveness of chemical agents

Answer 28

Gram negative bacteria Rod shaped cells They have a phospholipid outer cell layer *it is susceptible to disinfectants that are alcohol based. Their lipid outer layers can be dissolved and cause membrane to be weakened.

Question 29

Morphology gram type and other important characteristics that play a role in the effectiveness of chemical agents of bacillus thuringiensis

Answer 29

Gram positive Rod shaped Outer thick layer of peptidoglycan layer that protects the phospholipid cell membrane * Some chemical agents work by disrupting covalent bonds such as those in the peptidoglycan layer and disrupting cell membrane integrity. This weakens the cell structure and makes it susceptible to lysing

Question 30

Control agents are referred to as

Answer 30

Antimicrobial agents

Question 31

How do control agents target cells

Answer 31

1. Damage to cell wall 2. Damage cell membrane 3. Affect protein and nucleic acid synthesis

Question 32

How would you control agents damage the cell wall

Answer 32

By either blocking its synthesis, digesting it, or breaking down it's surface

Question 33

How do control agents damage the cell membrane

Answer 33

By disrupting the cell membrane the cell loses its selective permeability and may suffer osmotic shock and die

Question 34

How do control agents affect protein and nucleic acid synthesis

Answer 34

By interfering with DNA or RNA replication and protein synthesis. They may also alter protein function by denaturation

Question 35

Why are microbial control agents used

Answer 35

To prevent the spread of infections, delay spoilage, and keep commercial and medical products safe

Question 36

Listerine mode of action

Answer 36

Alcohol--> Causes membrane damage; solubilizes lipids, then denatured proteins, cell lysis QAC--> target cytoplasmic membrane (lipid or protein), membrane disorganization, leakage of intracellular material, degradation of proteins and nucleic acids, lysis by autolytic enzymes

Question 37

How does denaturing of proteins affect cell

Answer 37

It interferes with metabolism

Question 38

Mode of action of betadine

Answer 38

Iodine rapidly penetrates into micro organisms and the attacks key groups of proteins, nucleotides, and fatty acids which causes cell death

Question 39

Witch Hazel oil mode of action

Answer 39

Tannins--> tannic acid works like siderophore, inhibiting aerobic respiration and making it unavailable to microorganisms Volatile oils--> degradation of cell wall, damage to cytoplasmic membrane ,cytoplasm coagulation, increased permeability and leaking of cell contents

Question 40

Mode of action of bleach

Answer 40

Hypochlorite ion: Sodium hypochlorite--> Degrades fatty acids transforming them into fatty acid salts and glycerol; reducing surface tension and increasing permeability a membrane Hypochlorous acid--> releases chlorine, when com8with protein amino groups form chloramines-->amino acid degradation-->inhibiting essential bacterial enzymes

Question 41

Mode of action of dishwashing soap

Answer 41

Triclosan--> Inhibits activity of enzymes needed for fatty acid synthesis which affects the integrity of plasma membrane

Question 42

Mode of action of generic mouthwash

Answer 42

fluoride--> Enhances membrane permeability to protons--> compromises function of ATPases in exporting protons--> cytoplasmic acidification--> inhibiting if glycolitic enzymes

Question 43

Which chemical antimicrobial agent from lab works against Endospores

Answer 43

Chlorine is fair and Iodine is poo

Question 44

QAC effective against

Answer 44

Strongly against gram positive bacteria and less active against gram negative bacteria

Question 45

Which alcohol concentration is the most effective

Answer 45

70% but 60% to 95% work well

Question 46

Which disinfectants and lab had a 90% or more reduction of Serratia marcescens

Answer 46

Betadine, bleach and listerine

Question 47

Which disinfectants and lab had a 90% or more reduction of Bacillus thuringiensis

Answer 47

Betadine, bleach, Listerine generic mouthwash,

Question 48

Why was betadine effective

Answer 48

It attack that the fatty acids in the gram negative bacteria and the proteins of the peptidoglycan of the gram positive bacteria

Question 49

Why was Listerine affective

Answer 49

It was more effective against gram negative because of the active ingredient, alcohol, that damage the lipud layer of gram negative bacteria and made it easier to penetrate the peptidoglycan 1layer by the QAC

Question 50

Why was bleach effective

Answer 50

It was more effective against gram negative bacteria because it was able into these cells faster by degrading the lipid layer first and then penetrating through the thin peptidoglycan layer