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Microbiology > LEcture 9 > Flashcards

LEcture 9 Flashcards

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1
Q

What would be an example of exponential growth in microbes?

A
  • microbe population that doubles at a constant rate
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2
Q

What are the phases of the growth curve?

A
  • lag phase
  • exponential (log) phase
  • stationary phase
  • death phase
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3
Q

What occurs in the lag phase?

A
  • cell synthesize new components

- this allows them to adapt to new medium

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4
Q

Can the lag phase vary?

A
  • yes, it can be short or absent
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5
Q

What occurs in the exponential phase of growth curve?

A
  • the rate of growth is constant

- population is uniform in terms of chemical and physical properties

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6
Q

What happens in the stationary phase of prokaryote growth?

A
  • growth ceases, maintaining constant # of viable cells

- can occur due to inactivation of reproduction or from same rate of cell death

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7
Q

What are direct methods to measure microbial growth?

A
  • plate counts
  • filtration
  • MPN
  • Direct microscopic count
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8
Q

What are indirect methods of microbial growth?

A
  • turbidity
  • metabolic activity
  • dry weight
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9
Q

What are physical requirements for cell growth?

A
  • temperature
  • pH
  • osmotic pressure
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10
Q

What are chemical requirements for chemical growth?

A
  • carbon
  • nitrogen, sulfur, phosphorous
  • trace elements
  • oxygen
  • organic growth factor
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11
Q

Is the use of a spectrophotometer indirect or direct method of counting?

A
  • indirect method
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12
Q

How have thermophiles made adaptations to survive at extreme temperatures?

A
  • grow at higher temperatures and require
  • more H bonds
  • more prolines
  • chaperones
  • histone like DNA stabilizing proteins
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13
Q

Which type of microbes are able to grow around our body temperature?

A
  • mesophiles
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14
Q

What microbes grow at temperatures below our body temperatures?

A
  • psychrophiles

- psychotrophs

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15
Q

What is an acidophile?

A
  • microbe that grows at pH between 0-5.5
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16
Q

What pH is optimal for neutrophils?

A

-5.5 to 7

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17
Q

What pH is optimal for alkaliphiles?

A
  • 8.5 to 11.5
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18
Q

What is aerotolerance?

A
  • ability of a microorganism to grow in presence or absence of oxygen
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19
Q

Can antibiotics penetrate the biofilm?

A

No, difficult to remove the biofilm as well

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20
Q

How do prokaryotes reproduce?

A
  • binary fission
  • budding
  • conidiospores or actinomycetes
  • filament fragmentation
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21
Q

What do strict anaerobe microbes lack that prevents them from growing in aerobic conditions?

A
  • SOD

- catalase

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22
Q

What are barophilic organisms?

A
  • organisms that grow better in high pressures due to changes in membrane fatty acids
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23
Q

How is a biofilm produced?

A
  • microbes reversibly attach to a surface and release polysaccharrides, proteins and DNA to form extracellular polymeric substance
  • the biofilm matures as more polymers are released
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24
Q

Disinfection?

A
  • destruction or removal of vegetative pathogens but NOT bacterial endospores. Used on inanimate object
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25
Q

Sterilization?

A
  • complete removal of all viable microorganisms, Used on inanimate object
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26
Q

Antisepsis?

A
  • chemical applied to body surface to inhibit vegetative pathogens
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27
Q

Chemotherapy?

A
  • chemicals used internally to kill or inhibit growth of microorganisms within host tissue
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28
Q

Sanitization?

A
  • reduce microbial population to levels deemed safe
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29
Q

What are chemotherapeutic agents kill and what ones inhibit growth?

A

kill: cidal agent

growth inhibition: static agent

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30
Q

What conditions will contribute to the effectiveness of antimicrobial agents?

A
  • population size
  • population composition can change sensitivity to chemical
  • [chemical]
  • length of exposure to chemical
  • temperature (high=death. cold not so dead)
  • local environment: effects are specific to the microbe
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31
Q

What will moist heat destroy?

A
  • virus, fungi, bacteria
    will not destroy endospore
  • is -cidal
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32
Q

What is a sterilization technique effective against all microorganisms?

A

autoclave. Kills spores even!!! OMG My excitement!!!

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33
Q

What is pasteurization?

A
  • process to kill pathogens and reduces spoilage rate by removing number of organisms present
  • NOT sterilization
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34
Q

What is dry heat sterilization?

A
  • less effective than wet heat sterilization

- oxidizes cells constituents and denatures proteins

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35
Q

UV radiation causes thymine dimers and has been used for what cleaning process?

A
  • water treatment
36
Q

What is ionizing radiation effective and not effective against?

A
  • treats bacterial enospores

- not effective against all viruses

37
Q

Phenolics are chemical control agents that act how?

A
  • common disinfectant
  • denature proteins and disrupt cell membrane
  • skin irritant, bad smell
38
Q

Describe aspects of alcohol disinfectants.

A
  • most widely used (ethanol and isopropanol)
  • not sporicidal. bactericidal, fungicidal
  • denature proteins, possibly dissolve lipid membranes
39
Q

What are halogen antimicrobial agents?

A
  • fluorine
  • chlorine
  • bromine
  • iodine
  • astatine
40
Q

Features of iodine.

A
  • skin antiseptic
  • oxidizes cells and iodinates proteins
  • skin damage, staining, allergen
  • spore killer at [high]
41
Q

Features of chlorine.

A
  • oxidize cell constituents
  • water supply disinfectant
  • destroy vegetative bacteria and fungi
  • Cl gas is sporicidal
42
Q

What heavy metals can be used as a chemical control agent?

A
  • Hg
  • Ag
  • Ar
  • Zn
  • Cu
  • work well but are toxic
  • combine to inactivate/precipitate proteins
43
Q

What are quaternary Ammonium compounds?

A
  • detergents with antimicrobial activity and effective disinfectants
44
Q

What type of detergents make good disinfectants?

A
  • cationic as they kill most bacteria and they are safe and easy to use.
  • inactivated by hard water and soap though
45
Q

Why are aldehydes good chemical control agents?

A
  • highly reactive molecules that are sporicidal

- combine to inactivate nucleic acids

46
Q

What are sterilizing gases, ethylene oxide, betapropiolactone, hydrogen peroxide, effective against?

A
  • microbbicidal and sporicidal

- inactivate DNA and proteins

47
Q

What are chemotherapeutic agents?

A
  • antibiotics

- destroy pathogenic microbes or at least inhibit their growth

48
Q

Penicillin?

A
  • block enzyme catalyzing transpeptidation
  • prevents cell wall synthesis, causing cell lysis
  • only acts on growing bacteria
  • binds periplasmic proteins
  • activate bacterial autolysins and murein hydrolases
  • stimulate bacterial holins to form holes or lesions in PM
49
Q

What are narrow spectrum penicillins?

A
  • V and G which are naturally occurring
50
Q

What are broad spectrum penicillins?

A
  • semisynthetic but also have higher rate of resistance
51
Q

What are cephalosporins?

A
  • block enzymes catalyzing transpeptidation
  • prevent cell wall synthesis, causing cell lysis on growing bacteria
  • broken into 4 generations to cover different spectrums
52
Q

What are two glycopeptide antibiotics?

A
  • vancomycin and teicoplanin
53
Q

Vancomycin.

A
  • glycopeptide antibiotic

- treat antibiotic resistant staphylococcal/ enterococcal infection

54
Q

Teicoplanin.

A
  • glycopeptide antibiotic

- treats antibiotic resistant staphylococcal/enterococcal infections

55
Q

What antibiotics inhibit protein synthesis?

A
  • chloramphenicol
  • streptomycin
  • tetracyclines
  • aminoglycosides
56
Q

How does tetracycline work as an antibiotic?

A
  • prevent tRNA from binding at the A site

- bacteriostatic (slow bacterial growth)

57
Q

How does chloramphenicol work as an antibiotic?

A
  • binds 50S region and inhibits peptidyl transferase reaction
  • inhibits polypeptide elongation
  • dangerously toxic
58
Q

How does streptomycin work as an antibiotic?

A
  • alters 30S shape, causing mRNA strand to read incorrectly

- altering the polypeptide sequence

59
Q

How do aminoglycosides work as an antibiotic?

A
  • bind to 30S and inhibit translation process and causing misreading.
  • has levels of resistance and can be toxic
60
Q

What is a macrolide drug?

A
  • erythromycin broad spectrum bacteriostatic
  • inhibits peptide chain elongation
  • used in place of penicillin allergy
61
Q

What do metabolic antagonists, that act as antimetabolites, do?

A
  • antagonize or block functioning of metabolic pathways by competitively inhibiting metabolites by enzymes
62
Q

What are sulfonamides?

A
  • broad spectrum antibiotic that inhibit folic acid synthesis
  • PABA (paminobenzoic acid) analog that has different funciton
63
Q

How does sulfamethoxazole work?

A
  • analog of PABA, but blocks transition from PABA to dihydrofolic acid by competitive inhibition
64
Q

How does trimethoprim work?

A
  • blocks the transition from dihydrofolic acid to tetrahydrofolic acid
  • causes photosensitivity and ABD pain
65
Q

What is the overall function and effect of sulfonamides?

A
  • blocking synthesis prevents the activation of DNA/RNA precursors and prevents DNA/RNA formation
66
Q

What are quinolones?

A
  • broad spectrum synthetic that inhibits bacterial DNA gyrase and topoisomerase II
  • bactericidal for wide range of infections
67
Q

What are two examples of quinolones?

A
  • nalidixic acid

- norfloxacin

68
Q

Describe features of antifungal drugs.

A
  • low therapeutic index with high toxicity.

- treats superficial mycoses better than systemic

69
Q

Why is it important to treat systemic mycoses?

A
  • difficult to control and can be fatal
70
Q

What are three common drugs used to treat systemic mycoses?

A
  • amphotericin B
  • 5-flucytosine
  • fluconazole
71
Q

How does amphotericin B work on systemic mycoses?

A
  • binds to sterols in the membrane
72
Q

How does 5-flucytosine work on systemic mycoses?

A
  • disrupts RNA function
73
Q

When is fluconazole used and why?

A
  • low side effects

- used prophylactically

74
Q

What is amantidine?

A
  • anti viral Rx

- blocks penetration and uncoating of influenza virus

75
Q

Adenine arabinoside (vidarabine)

A
  • anti viral

- inhibit herpes virus; DNA and RNA synthesis proteins

76
Q

Tamiflu?

A
  • anti viral influenza

- nueraminidase inhibitor

77
Q

Acyclovir?

A
  • anti viral

- inhibits herpes virus DNA pol

78
Q

Valacyclovir?

A
  • anti viral

- prodrug form of acyclovir

79
Q

Ganciclovir?

A
  • anti herpes virus drugs
80
Q

Foscarnet?

A
  • inhibits herpes virus DNA pol
81
Q

HPMPC (cidofovir)

A
  • broad spectrum anti DNA virus drug
  • inhibits viral DNA pol of:
  • papovavirus, adenovirus, herpes virus, iridovirus, poxvirus
82
Q

Azidothymidine

A
  • nucleoside reverse transcriptase inhibitor
83
Q

Ritonavir

A
  • viral protease inhibitor
84
Q

Fusion inhibitors?

A
  • prevent HIV entry into cells
85
Q

In what ways can a drug be resisted by a microbe?

A
  • prevent entrance, promote loss of drug
  • inactivate drug
  • modify target enzyme/organelle
  • increase production of targeted meatabolite
86
Q

What is an immunity gene?

A
  • genes that protect antibiotic producing microbes from their own product
87
Q

What is carried on R plasmid and how can it be transferred?

A
  • multiple resistance genes

- transferred by conjugation, transformation, transduction

Microbiology (14 decks)

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