Micro Lec test 3

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1

Sterilization

involves destruction of all living microbes, spokes, and viruses.

2

Microbicidal

Killing of all microbes - leads to death = Sterilization

3

Sanitization

reduces the numbers of pathogens or discourages their growth.

4

Heat

one of the most common physical control methods.
-At temperatures above the growth range:
- Proteins (enzymes) denatured
- Nucleic acids are destroyed
- Water is removed

5

(Dry Heat) Incineration

Uses direct flame to kill microbes
(achieves sterilization)
Large scale incineration

- Asian flu
- Mad Cow

6

Bacteria Static

not allowing anymore bacteria to grow
- degerming
- reducing the number of organisms present

7

Thermal death time

The shortest amount of time it takes to kill a microbial species at a given temperature

8

Thermal death point

The minimum temperature at which it dies in a given time period.

9

Dry Heat

Requires long periods of exposure to high temperatures.
- changes microbe proteins
- removes water slowly

10

Moist Heat

Like boiling water is faster and effective at a lower temperature than dry heat

- denatures microbe proteins

11

Moist heat Ex: Boiling Water

May not kill all spores or inactivate all viruses.

12

Moist heat Ex: Pasteurization

Reduces (2 types of ) bacterial populations in food and drink. Leads to
- reduces the chances of spoilage and disease
- Bacterial spores are not affected by (2 types of) Pasteruization

13

Pasteurization type 1: normal Holding Method Pasteurization

- 62.9 C or 141 F
- held for 30 mins
- reduces spoilage and disease

Used on:
- Milk - Doesn't kill taste just pathogenic bacteria
- Kills Mycobacterium bovis
- Endospores not killed
-Juice
-Wine

14

Pasteurization type 2: Flash Pasteurization

- 72 C
- 15 sec
- Sanitizes

15

Pasteurization type 3: Ultrapasteurized

- 140 C
- 3 sec
- Sterility achieved
- Non refrigerated dairy
- changes flavor
- Half & Half & Diary Creamers

16

Autoclave - Leads to sterilization

- 121 C
- 15 min kills vegetative cells
- 30 min kills endorses
- 13-15 psi
- Pressurized steam under high temperature

17

Dry Heat ex: Hot air oven

Vegetative cells killed = 10 mins

Spores Killed = 2 hours

18

Prevacuum autoclave - Leads to sterilization

decreases cycle time and exposure time of sensitive materials

19

Fractional sterilization

- 100 C
- 30 mins a day for 3 days

3 consecutive days of flashing high temp used to kill vegetative cells. Allows time for endospores to germinate and then kills those cells.

20

Important temps

0 C / 32 F - freezing point of water
100 C / 212 F - Boiling point of water

25 C = = ambient / room temperature
37 C = 98.6 F = Human body temp

5 C = Freezer

21

Psycrophiles

- (0 - 20 C)

- Live in freezer / fridge 4-5C = Micrococus Roseus

22

Mesophiles

- (20 - 40 C)
- Human Pathogens
- 25 C = Room Temperature
- 37 C = Human Body Temp
- E. coli

23

Thermophiles

- Like hot temperatures
- B. Sterothermophilis
- > 55 C

24

Non-heat methods

- Filtration traps micro organisms.
- As fluid passes through organisms above a certain size threshold are trapped in the pores.

- Dehumidifier
- ACs
- Vacuum bags
- Nebulizer
- Medical masks w/ small pores
-

25

Filtration

-traps micro organisms.
- As fluid passes through organisms above a certain size threshold are trapped in the pores.

26

Air filtration

Air can be filtered using a High-efficiency particulate air filter.(HEPA)

27

Can autoclave

- endoscopy
- teeth cleaning
- surgical instruments

28

Cannot autoclave

Things that cannot get wet

29

Ultraviolet light -

- Exposure to UV light causes thymine molecules to link together in DNA. Pyrimidine dimers
- Errors in protein synthesis
- impairment of chromosome replication

30

Other sources of light used for bacteria control & sterilization.

Force electrons out of organisms
- X rays
- Gamma rays (ionizing radiation)
- Affects cell metabolism and physiology

31

Non heat ex:Radiation

Radiation
-NASA
- Military

32

Preservation methods:

- Causes bacteria static not bactericidal
- Retard spoilage by microorganims in food
- Drying / Dehydration - removes H20
- Salting causes water to difuse out of organism by osmosis, causing dehydration death
- Low temp - lower microbial metabolic and growth rates

33

Chemical agents:

Chemical agents rarely achieve sterilization

34

CHEMICAL AGENTS (NON-Physical)

...

35

Antiseptics

used to distroy pathogens on living tissue.

36

Sepsis

Contamination by microorganisms

37

Disinfectants

- Used on surfaces
- Can effect organizations

38

Degerming

means removing organisms from an object's surface

39

Things to consider when using chemical agents

- Microbial susceptibility
- Temperature and PH
- Concentration
- Environment
- Endospore formers
- Has to be effective at room temp (disinfectants)

40

A useful disinfectant or antispectic will be (9)

- Kill / slow growth of microbes
- Be non-toxic to animals or humans
- Soluable in water or alcohol, easy to apply
- Have a long self life
- Used in a dialted form
- nonstaining and noncorrosive
- Orderless
- Easy to obtain
- Relatively inexpensive

41

How are antisepctics and disinfectants (chemical agents) evaluated for effectiviness?

- The phenol coefficient (PC) indicates disinfecting ability compared to that of phenol
- An in-use test to compare samples of substrate before and after disinfecting

- Another way to evaluate effectivness of chemical agents is the (3) Disk Diffusion Method
- exams the effect of different checmical agents of a specific bacterium

42

Other Chemical ways

Halogens - oxidize proteins
- Chlorine- keeps bacterial populations low in municiple water supplies and swimming pools.

- Iodine - used to disinfect wounds, waterm and resturant equipment

43

Chemical agent: Iodophores

release iodine over a long period of time
ex: Betadine

44

Chemical agent: Phenol & Phenolic compounds

- Denature proteins
- Is expensive
- caustic
- has a pungent odor
Deriviatives have:

- Greater germicidial activity
- Lower toxicity than phenol

45

Chemical agent: Bisphenols

combination of two or more phenol molecules

- vespine
- commonly used in disinfection and antiseptics
- ex : lysol, triclosan

46

Chemical agent: Heavy mentals (other chemicals)

interfere with microbial metabolism, killing them
- Mercury
- Coppper - blue salts
- Silver
- PVC
-Silver nitrate ( a compund) - nisseria gonorrhea
Are very reactive with proteins

47

Chemical agent: Alcohols

Work in 3 ways:
- effective against vegetative but not spores
- membrane disruption is caused lipid dissolution
- dehydrates

Most used antispetic and disinfectant (can be used as both)

48

Chemical agent: Soap

removes microbes by emulsifying and solubilizing particles on the skin

-

49

Chemical agent: Detergents

Are Surfactants
- weaken microbial membrane to cause cytoplasm leakage.
- Quanternary ammonium compounds react with cell membranes and destroy some bacteria and viruses
- Dreft

50

Chemical agent: Hydrogen Peroxide

- Toxic to all living things. Damage the cellular components.

- not that stable
- oxidizing agent
- More effective against anaerobic* (or aerobic?) bacteria
- oxygen produced my bacteria is more effective to anaerobic bacteria

51

Hydrogen peroxide / Catalase

- Catalase in wounded tissue turns Hydrogen peroxide into H20 + O2 (oxygen g)

52

Chemical agent: Aldehydes

Cause cross linkage in proteins and nucleic acids that inactivates the protein or N.A.
ex: formaldehyde

53

Chemical agent: Ethylene oxide - Sterility

Causes Sterility
- a gas used in medical packing companies, and pharmaceuticals
- effective but carcinogenic and explosive

54

Chemical agent: Chlorine dioxide - Sterility

Effective non- carcinogenic gas (true?)
- used to decontaminate anthrax- exposed mail in 2001.

55

CHAPTER 24:

ANTIMICROBIAL DRUGS

CHAPTER 24:

ANTIMICROBIAL DRUGS

56

Antimicrobial Agents

are chemical substances used to treat infectious Disease - Chemotherapy (drug therapy)

57

Paul Enrlich

history of chemotherapy originated with Paul Ehrlich
- Originated the concept of selective toxicity.
- w/ Sahachiro Hata discovered effectiveness of arsphenamine (Salvarsan) against the syphilis spirochete

58

Salvarsan (arsphenamine)

- First chemotherapy organism
- Used against syphilis spirochete

59

Alexander Fleming

- Used Penicilum Notadum
- Penicillium mold produces a substance that kills gram -positive bacteria.
- all have beta lactam
- started antibiotic era
- now mainly made synthetically. Not directly from mold

60

Important properties of antimicrobial agents

- Synthetic agents 0

61

Selective Toxicity

Drug should harm pathogen not host

Balance of Efficacy w. Toxicity = Selective toxicity

62

Toxic dose

- Concentration of drug causing harm to host

63

Therapeutic dose

- Concentration eliminating pathogens in host

64

Chemotherapeutic index

Together the toxic and therapeutic dose are used to formulate chemotherapeutic index

= Toxic dose / Therapeutic dose

- Must balance Efficacy w. Toxicity = Selective toxicity

65

Antimicrobial Spectrum

Drugs have a range of pathogens on which they have efficacy

66

Broad-spectrum drugs

affect many taxonomic groups
ex:
Tetracyclines = the largest range of bacteria broad spectrum

- Sulfonamides, Cephalosporins, Quinolones Carbapenems

- Penicillins
- Streptomycin

67

Narrow-spectrum drugs

affect only a few pathogens

68

Antiviral drugs

- interfere with viral replication
- Affect picornaviruses (non enveloped viruses)
- Herpes
- Hepatitis B and C
- HIV and influenza

69

Peniclum

Most widley used drug

70

Many Antibiotics target

Many Antibiotics target bacterial ribosomes

71

Antibiotics can target

aspects of bacteria that are different from the host
usually includes:
- Bacterial ribosomes
- Cell wall
- cell membrane?

72

Antiviral: Amantadine

- Penetration / uncoating inhibitors
-

73

Antiviral: Valacylovir and reverse transcriptase inhibitors

Genome replication inhibitors

74

Protease inhibitors

Maturation / release inhibitors
HIV & AIDS
- also can be used for fungal

75

Virsus

- harder to target
- They are genetic meterial wrapped in a protein code:
Proteins, DNA, & RNA
- Viral Chemotheraputic usually have more side effects- wait & see approach usually first course of action.

76

Heavy metals

...

77

Antiobitic drug resistance

- can be caused by improper or excessive use antibiotics
MRSA
VRSA (V stands for?)
Multidrug resistant TB

78

Superinfection

Resistant strains of bacteria spread to other patients

79

Antibiotic dilemma

- Bacteria are promiscuous - conjugation - sharing R-Palsmids
- Are available OTC in some countries
- Used widespread in livestock - transmitted if the animal's meat is consumed

80

Antibiotic resistance effects: Can develop in several ways (4)

1) Antibiotic hydrolysis- Altering of metabolic pathways
2) Antibiotic modification - Inactivating antibiotics
3) Membrane modification - Reducing membrane permeability
4) Target modification - Modifying drug targets

81

Antibiotic resistance caused by (2):

Mutations - spontaneous changes in genetic material

Horizontal gene transfer - From donor cells - Transfer of an antibiotic resistant gene
- transformation - (unpackaged)
- Transduction - (packaged)
- Conjugation - C-Pilus

82

Antibiotic susceptibility tests: agar disk diffusion:

- agar disk diffusion: methods involves different antibiotics diffusing from paper disks on a bacterial confluent growth
- using Mueller-Hinton plates

83

Zone of Inhibition

- Area around antibiotic disk where bacteria does not grow

84

The 3 types of resistance

...

85

Antibiotic susceptibility tests: Tube dilution method

determines the lowest concentration of effective antibiotics (minimal inhibitory concentration)

86

minimal inhibitory concentration

Lowest concentration of effective antibiotics
- Dosage by weight & age. Weight is better.

87

Synthetic Antibacterial Agents target (2)

1) Target cell wall formation

2) DNA synthesis / replication

88

Beta- Lactam Antibiotics

Inhibit Bacteria Cell Wall Synthesis
ex: penicillin

89

Beta Lactamase

- Penicillin resistant bacteria produce beta-lactamases that cleave & inactivate penicillin

90

Penicillin

- some indiviuals expirence anaphylactic shock

91

Aminoglycoside

antibiotic that effects protein synthesis

92

Protozoans cause

Disintary, malaria

93

Heavy metals: can be used to treat Protozoans

Derivative or arsenic used to treat African trypanosmiasis
Dervative of antimony used to treat leishmanasis (pentamidine)
Artemisinin