Control of Microorganisms

Question 1

sterilization

Answer 1

the killing or removal of all viable organisms including endospores

Question 2

inhibitin

Answer 2

effectively limiting microbial growth

Question 3

decontamination

Answer 3

the treatment of an object to make it safe to handle

Question 4

disinfection

Answer 4

directly targets the removal of all **pathogens not necessarily all microorganisms

Question 5

physical methods (examples)

Answer 5

heat
radiation
filtration

Question 6

chemical methods (antimicrobials) (examples)

Answer 6

external surfaces: sterilants, disinfectants, antiseptics

internal: antibiotics, antivirals, antifungals

Question 7

heat

Answer 7

• high temps *denature macromolecules
• decimal reduction time
• time necessary to kill a defined *fraction is independent of the initial cell concentration

Question 8

decimal reduction time

Answer 8

D
amount of time required to reduce viability tenfold
inversely correlated with temp
-organism specific

Question 9

thermal death time

Answer 9

time needed to kill all cells at a given temp
dependent on the population size of the microorganism
To compare a standardized number of starting cells is needed.

Question 10

Endospores and heat

Answer 10

survive heat that would rapidly kill vegetative cells
-need higher temp
(resistant to boiling for a long time - 5 min for a decimal reduction ie 90% dead)

Question 11

autoclave

Answer 11

sealed device that uses steam under pressure

• the high temp NOT pressure kills microbes
• the sterilization time is when the object being sterilized reaches 120C (NOT the autoclave itself)

Question 12

Pasteurization

Answer 12

process of using precisely controlled heat to reduce the microbial load in heat-sensitive liquids.

• increases shelf life
• reduces pathogens
• flash pasteurization 72C for 15s
• bulk pasteurization 65C for 30 min

Question 13

Radiation

Answer 13

causes modifications and breaks in DNA, inhibits replication, transcription and cuases death

• cannot penetrate solid, obaque surfaces
• used in disinfection of water or air

Question 14

*Ionizing radiation

Answer 14

radiation that produces ions and other reactive molecules

• has a decimal reduction time
• sources of radiation: cathode ray tube, X-rays
• used for sterilization in the medical field and food industry

Question 15

Filter sterilization

Answer 15

• avoids the use of heat on sensitive liquids or gas

- pores of filter are too small for organisms to pass through, so they are caught.

Question 16

Depth filters

Answer 16

fibrous sheet or mate made from an array of fiber

*HEPA filters

Question 17

Membrane filters

Answer 17

• like sieve
• nucleopore filter
• filtration speed can increase by syringe, pump, or vacuum

Question 18

antimicrobial agents

Answer 18

bacteriostatic: inhibit growth of microorganism
bacteriocidal: kill microorganism
bacteriolytic: kill microorganism by inducing lysis
(Think about the associated graphs)

Question 19

minimum inhibitory concentration

Answer 19

smallest amount of an agen needed to inhibit growth of a microorganism

Question 20

minimum lethal concnetration

Answer 20

the lowest concentration of an agent that kills a test *organism

Question 21

minimum bacteriocidal concentration

Answer 21

the lowest concentration of an agent that kills a test *bacterium

Question 22

Viable counts

Answer 22

** MLC and MBC are viable counts

Question 23

disc diffusion assay

Answer 23

antimicrobial agent added to a filter paper disk

Question 24

zone of inhibition

Answer 24

area of no growth around the disk

Question 25

sterilants

Answer 25

destroy all forms of microorganisms, including endospores

Question 26

disinfectants/sanitizers

Answer 26

applied to nonliving objects or surface | do NOT kill endospores

Question 27

antiseptics

Answer 27

applied to the surface of living tissues -nontoxic for humans do NOT kill endospores

Question 28

antimicrobial drugs

Answer 28

applied outside or inside the body of animals/humans -nontoxic for humans do NOT kill endospores

Question 29

antimicrobial drugs - basic facts

Answer 29

- either **bacteriostatic or **bactericidal | - usually have a *specific target

Question 30

synthetic antimicrobial drugs

Answer 30

- Paul Ehrlich studied **selective toxicity: the ability to inhibit or kill a pathogen without affecting the host * *salvarsan: one of the first antimicrobial drugs (syphilis)

Question 31

growth factor analogs

Answer 31

structurally similar to growth factors, but do not function in the cell

Question 32

sulfa drugs

Answer 32

* *sulfanilamide is an analogue of p-aminobenzoic acid. Inhibits folic acid synthesis. - bacteriostatic

Question 33

isoniazid

Answer 33

growth factor analog | interferes with synthesis of mycolic acid

Question 34

nucleic acid base analogs

Answer 34

formed by the addition of Br or F, stop DNA replication

Question 35

quinolones

Answer 35

interfere with DNA gyrase | antibacterial compounds

Question 36

antibiotics

Answer 36

-antimicrobial agents *naturally produced by a variety of bacteria and fungi to inhibit or kill other microbes -semisythetic antibiotics (modified antibiotics to enhance efficacy) -*B-Lactams cell wall is a major factor in the susceptibility of microbes to antibiotics

Question 37

*********Cephalosporins

Answer 37

- used to treat gonorrhea - produced by the fungus Cephalosporium - **can be bacteriolytic or bactericidal - bacteriostatic in isotonic soutions

Question 38

Penicillins

Answer 38

inhibit cell wall synthesis

Question 39

Aminoglycosides

Answer 39

Ex. streptomycin | bactericidal

Question 40

Antibiotic producers

Answer 40

``` tolerant to the antibiotic: -lack target sites -no uptake mechanism resistant: destriction or **modification of the antibiotic -modification of the target site etc ```

Question 41

acquisition of resistance

Answer 41

- the use of antibiotics selects for the spread of R plasmids - most drug-resistant genes are located in the R plasmid

Question 42

protease inhibitors

Answer 42

inhibit the processing of large viral proteins into individual components

Question 43

fusion inhibitors

Answer 43

prevent viruses from successfully fusing with the hose cell

Question 44

Antiviral drugs

Answer 44

- target host structures, resulting in toxicity - **risk to the host may not justify the use of antiviral - most successful: nucleoside analogs - block reverse transcriptase

Question 45

**Fluconazole

Answer 45

anti fungal drug that targets ergosterol synthesis