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Unit 1 MCM > Microbiology > Flashcards

Microbiology Flashcards

1
Q

How are infectious diseases influenced by genetic changes in mircroorganisms? (3)

A

Virulence, Host Range, Drug Resistance

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2
Q

What are public health measures that have decreased infectious diseases? (3)

A

Clean Water, Clean Air, Vaccines

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3
Q

What is an example of change in Host Range?

A

AIDs, SARS

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4
Q

What are the 3 processes of the evolution of microorganisms?

A
  1. Development of increasing genome complexity
  2. Minor genetic changes resulting in changing pathogenicity, host range, drug resistance
  3. Natural selection
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5
Q

What are some organisms that spontaneously lost their pathogenicity?

A

Syphilis, Scarlet Fever

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6
Q

Cholera prevention is associated with what public health measure?

A

Clean Water

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7
Q

What are some childhood diseases that are prevented from vaccines?

A

Smallpox, Polio, Diptheria, Measles, Mumps, Rubella

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8
Q

What public health measure prevents respiratory infections like Tuberculosis?

A

Clean Air

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9
Q

What well-known medical conditions have become recognized as infectious etiology?

A

Stomach ulcers- from H. pylori

Cervical cancer- Human papillomaviruses

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10
Q

Why are these medical conditions important in understanding of microorganisms? Alzheimers, MS, Type 2 diabetes, Obesity. Heart attacks and stroke

A

Because they might be caused by infection

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11
Q

Which one of the following infections has declined in severity because of improved hygeine?

A

cholera

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12
Q

Development of a novel human infections can be caused by:

A

Changes in host range

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13
Q

Drug resistant strains of mircoorganims can arise from?

A

Minor genetic changes such as point mutations

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14
Q

What type of genetic material do bacteria have?

A

DNA with NO INTRONS

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15
Q

What makes bacterias’ chromosomes different from eukaryotes?

A

Single, circular chromosome

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16
Q

What is the nucleoid?

A

Non-membrane bound compartment of bacteria composed of the DNA that concentrates in one intracellular postion

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17
Q

What makes bacterial ribosomes a good drug target?

A

They are 70S “Svedburg Units”, not 80S

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18
Q

How do bacteria reproduce?

A

Binary Fission

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19
Q

Four major common appearances of bacteria under light mircroscopy

A

Cocci(round), Bacilli (rods, vibrios-curved rods), Siprochetes (chains)

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20
Q

Procedure for Gram Staining (5 steps)

A
  1. Fixation
  2. Stain (crystal violet)
  3. Iodine Treatment
  4. Decolorization with EtOH
  5. Counterstain with Safranin
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21
Q

What is the basis for gram staining?

A

Cell walls between gram- and + significantly different, can narrow options FASTLY and CHEAPLY, seldom makes diagnosis

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22
Q

Which gram stain has LPS?

A

Gram -

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23
Q

What is different about Gram+ cell wall?

A

3X thicker layer of peptidoglycan, No exterior membrane

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24
Q

What is different about Gram- cell wall?

A

Thinner layer of peptidoglycan, Exterior membrane

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25
Q

What other test is further for Gram- bacteria?

A

Acid Fast- do not stain gram+ but different from gram-

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26
Q

What 3 structural elements of bacteria have pathogenic significance?

A

LPS, Glycocalyx, Pilli/Fimbrae

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27
Q

What structural element found in gram- cell walls can cause septic shocK?

A

LPS

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28
Q

What structural element is a firm enclosure that resists phagocytosis and is a vaccine target?

A

Capsule

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29
Q

What are diverse mircobial communities that may host many organmisms and are more resistant than pure colonies?

A

Biofilms

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30
Q

What are slime layers?

A

Loose coating of polysaccharide the helps bacteria attach to host cells and form biofilms

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31
Q

What are slime layers and capsule made of?

A

Glycocalyx

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32
Q

What structural element is used for attachment and is often a virulence factor?

A

Pili/Fimbrae

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33
Q

What do flagella do?

A

rotate by a molecular motor to propel a bacteriium forward

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34
Q

Why are flagella a good immune target?

A

The polymers of flagellin aren’t found in eukaryotes

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35
Q

What do about 50% of all antibiotics target?

A

70S bacterial ribosomes

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36
Q

3 drugs that target bacterial ribosomes

A

Aminoglycosides, Tetracyclines, Macrolides

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37
Q

How is spore formation triggered?

A

nutrient depletion

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38
Q

Why do we have to autoclave?

A

Because spores survive high temperatures, dehydration, anti-septics, antibiotics

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39
Q

When do spores unpack into normal bacterial form?

A

When water and nutrients are plentiful again

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40
Q

Modified form of binary fission, 2 unequal copies, one daughter cell dies and other receives double cell wall and macromolecules that enable progeny to be thick and rugged

A

Spores

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41
Q

Significance of exponential growth to pathogenesis

A

low number of bacteria can produce very large numbers in very short time, generation time is limited by available nutrients

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42
Q

Describe bacterial growth in a test tube

A

Lag, Log, Stationary, Death

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43
Q

Why does bacterial growth help with diagnostic testing?

A

Short generation time

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44
Q

2 Benefits of Fermentation pathway

A

Don’t have to completely break down glucose

Different waste products–identification in lab testing

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45
Q

What are the usual waste products of Fermentation pathway

A

Organic acids and alcohols

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46
Q

What ability do Oxygen based ATP metabolism bacteria have to have?

A

An ability to detoxify reactive oxygen radicals

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47
Q

What are the waste products of Oxygen-ATP metabolism?

A

CO2, Water

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48
Q

Describe Quorum Sensing

A

Ability of some bacteria to sense their population density and alter their genetic expression accordingly

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49
Q

What is the process of bacteria altering their genetic expression to secrete virulence factors in high population density?

A

Quorum Sensing

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50
Q

What 3 things quorum sensing bacteria require?

A

Secreted Inducer
Receptor for Inducer
Transcription Activator that responds to levels of inducer

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51
Q

Why is quorum sensing beneficial to bacteria?

A

Conserve Energy, Coordinate their attack

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52
Q

3 common ways HAIs are transmitted

A

Direct Contact with individual
Indirect contact with equipment/inaminate objects
Respiratory transmission

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53
Q

Seven Strategies for Prevention of Transmission

A

Hand hygeine
Use of PPE
Isolation of infected individuals
Sterilization of patient care equipment
Clean environment
Room ventilation if expect respiratory infection
Proper disposal of sharps, infectious waste

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54
Q

What is the goal of Infection control?

A

To break the chain of infection

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55
Q

6 parts of the chain of infection

A 
Infectious agent
Reservoir
Portal of exit from reservoir
Vehicle (means of transmission)
Portal of Entry
Susceptible Host
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56
Q

4 CDC Standard Precautions for exposure from blood or bodily fluids

A

Clean hands entering/leaving room
Cover mouth/nose with arm when coughing/sneezing
Gowns/gloves if soiling likely
mask/eye potection if body fluids likely

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57
Q

Airborne (respiratory) Precautions

A

N95 mask/gown, isolation room at negative pressure

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58
Q

Droplet precautions

A

mask and gown when entering the room

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59
Q

Contact precautions

A

gowns entering room, alcohol based products OK

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60
Q

Contact PLUS precautions

A

Room bleached, hand hygeine soap and water ONLY

61
Q

Reverse (protective) Isolation

A

Used for immunocompromised patients

People entering room wear surgical mask, gloves, gown

62
Q

Sterilzation

A

Complete destruction of all forms of microbial life

63
Q

Disinfection

A

Destruction of specific microorganims, does not kill spores

64
Q

Antisepsis

A

Reduction of disease causing germs on body, surfaces

65
Q

Examples of Critical devices

A

Enter the body

Surgical equipment, implants, invasive devices

66
Q

Semicritical items

A

contact mucous membranes and non intact skin
High level disinfectant
Respiratory therapy items, endoscopes, laryngoscope

67
Q

Noncritical items

A

come in contact with intact skin, or non contact

bedpans, BP cuffs, crutches, computers

68
Q

6 techniques used for sterlization

A

Steam sterilization, Dry heat sterilization, Irradiation, Filtration, Gas, Plasma

69
Q

Steam sterilization

A

autoclaving

70
Q

Dry heat sterilzation

A

petroleum based liquids

71
Q

Irradiation

A

damage to Nucleic acid, implants

72
Q

Filtration

A

liquids that contain protein delicate compounds

73
Q

Gas sterilization

A

sterilize surface of porous items

**FLAMMABLE

74
Q

Plasma sterilization

A

H2O2 to form free radicals, for resuable medical equipment

75
Q

Bacterial genotypes (3) for identification

A
  1. Biosynthetic genes
  2. Catabolic genes
  3. Drug resistance genes
76
Q

Differences between eukaryotic and bacterial gene expression

A

Operators/Repressors, no enhancers, no RNA splicing, no post TRXN modification

77
Q

RNA Polymerase

A

Binds to the promoter and intiates gene transcription, leads to production of mRNA

78
Q

Promoter

A

Regulates when, where, and what level a gene is expressed

79
Q

Describe Bacteria Genetic Material

A

Circular Chromosomal DNA
Plasmids that contain 2-3 genes
bacteriophages

80
Q

What are bacteriophages?

A

Not essential viruses that infect bacteria
contain small number of genes
can encode virulence factors*

81
Q

Operon

A

Cluster of genes whose expression is controlled by one promoter

82
Q

Ways that transcription is regulated in bacteria

A

By metabolic products or defiencies directly

83
Q

Two types of transcriptional regulation

A

Positive or Negative Regulation

84
Q

Inducible/Positive Expression

A

When lactose is present the genes to metabolize lactose are induced by lactose

85
Q

Repression/Negative Regulation

A

if trp is present, trp repressor binds to trp operator so that trp trxn is repressed

86
Q

Ames Test

A

Tests possible mutagens to see if things are carcinogenic

Quick and Cheap, 85% accurate

87
Q

3 mechanisms for Gene Exchange

A

Transformation, Conjugation, Transduction

88
Q

How was gene exchange in bacteria discovered?

A

In a classical experiment using mice and viral and nonviral bacteria

89
Q

Transformation

A

Cell lysis, neighboring bacteria picks up DNA fragments and incorporates through recombination

90
Q

When is transformation used in medicine?

A

Hep B vaccine, insulin production, virus vectors in gene therapy

91
Q

Conjugation

A

transfer of F-factor plasmid via a sex pillus. Plasmos can seperate from chromosome and be incorporated into some host genes.

92
Q

Transducion

A

Virus mediated transmission of DNA between bacteria

93
Q

Generalized Transduction

A

Phage lyses bacteria and releases all its DNA

94
Q

Specialized Transduction

A

Phage inserts itself into chromosome and acquires regional DNA from bacteria

95
Q

Transposons

A

Can insert themselves and relocate into different sites, pick up different bits of DNA as they move around, move drug resistance genes around together?

96
Q

How can drug resistance come about so quickly?

A

Through a combo of gene exchange mechanisms plus point mutations in the host bacteria, a very drug resistant strain of bacteria like MRSA can come about.

97
Q

Mutualism

A

Symbiosis, Organism 1 benefits, Organism 2 benefits

98
Q

Commenalism

A

organism 1 benefits, organism 2 neither benefits not is harmed

99
Q

Parasitism

A

organism 1 benefits, organism 2 is HARMED

100
Q

Name 3 cases where commensalism can cause disease?

A
  1. Injury or poor hygeine carries bacteria somewhere is doesn’t belong
  2. Immunosuppresion
  3. Commensal in mother infects neonate during birth
101
Q

Normal Flora

A

Commensal and beneficial to healthy individuals from colonization resistance
Some gut bacteria are beneficial

102
Q

Colonization resistance

A

A form of symbiosis that even commensals participate in. Prevents pathogen from successfully colonizing the body. Function of innate immunity.

103
Q

S. epidermis, C. albicans, S. aureus

A

Commensals found on skin

104
Q

Streptococci, Staphylococci, Neissera

A

Commensals found in nose and throat

105
Q

S. mutans

A

Commensal found in mouth, will cause cavities and endocarditis with poor dental hygeine

106
Q

Strep, lactobacilli, yeasts

A

Commensals in the small intestine

107
Q

baceteriods, eubacterium, coliform, clostridium

A

Commensals in the large intestine

108
Q

pH maitenance in the Vagina

A

lactobacilli maintains low pH in Vagina, Candida overgrowth follows rising pH

109
Q

group B strep

A

Commensal in vagina that can cause sepsis and meningitis in newborns if vaginal delivery without antibiotics

110
Q

Asymptomatic infections

A

host defenses clear pathogen before any symptoms of disease are noted

111
Q

communicable

A

Infection passed from host to host

112
Q

Noncommunicable infection

A

comes from the environment, not a previous host (Think botulism)

113
Q

latent infection

A

disease subsides but microorganisms remain in the body and can restart disease later

114
Q

chronic carrier state

A

host survives disease but continues to shed the pathogen indefinitely (TB)

115
Q

epidemic

A

much more frequent infection than usual

116
Q

pandemic

A

worldwide distribution of infection

117
Q

Obligate intracellular parasites

A

all viruses, few bacteria.

Must enter the host cells to reproduce

118
Q

Facultative intracellular parasites

A

Can reproduce outside host cells when they need to (ie bacteria)

119
Q

Opportunistic pathogens

A

very unlikely to cause disease in a healthy person, will take advantage of a host that is injured or immunosuppresed

120
Q

Commensals

A

usually non-pathogens with some opportunistic pathogens

121
Q

Virulence

A

A numerical measure of pathogenicity

122
Q

ID50

A

50% infectious dose- Lower value corresponds to fewer infecting organisms are needed for successful colonization of host

123
Q

LD50

A

50% Lethal dose- lower value corresponds to fewer infecting organisms are needed to kill the host

124
Q

Virulence factors

A

Gene products expressed by pathogens that directly contribute to the disease process. Can be drug targets.

125
Q

Siderophores

A

A molecule that binds and transports Iron in mircroorganisms

126
Q

Name the 5 major activities of Virulence Factors

A
  1. Adhesion
  2. Survive in extreme environments
  3. Immune evasion
  4. Takeover host cell
  5. Poison the host
127
Q

Give an example of adhesion

A

Pili, slime layer, adhesins sticking to host surfaces. Creation of biofilm

128
Q

An example of survival in extreme environments

A

pH tolerance, siderophores, resistance to drying or detergents

129
Q

An example of immune evasion

A

Capsules resist phagocytosis, IgA proteases, inductions of macrophage apoptosis, “serum resistance” factors escaping complement

130
Q

An example of host cell takeover

A

Actin polymerization pathways, endosome escape routes

131
Q

An example of poisoning the host cell

A

Tissue degrading enzyme secretions, endotoxins and exotoxins

132
Q

What are endotoxins?

A

naturally occuring, exposure causes overactivation of immune system

133
Q

Gram negative endotoxin, Gram positive endotoxin

A

negative- LPS, LOS

positive- teichoic acids

134
Q

What are exotoxins?

A

Among the most toxic substances known, secreted by bacteria
exposure induces neutralizing antibodies
you can raise vaccines of inactivated toxoid form of exotoxin

135
Q

Koch’s Postualte- what is it?

A

Proof of Causality of infectious agent- THE GOLD STANDARD

136
Q

Structural appearances and features of Gram negative Cocci

A

(neisseria) diplococci- not quite spherical, grows on chocolate agar, LOS endotoxin in membrane, IgA protesase

137
Q

Structural appearances and features of Staphylococci

A

Coagulate plasma (causes abscess), grows in clumps, catalase positive

138
Q

Structural appearances and features of Streptococci

A

grows in chains (divide and stay attached), use serotypes to identify strains, catalase negative, cell wall include pili

139
Q

Name the 3 important Staphylococci

A

S. aureus, S. epidermis, S. saprophyticus

140
Q

Gram positive, staphylococci, coagulase positive, causes abscesses, R- nose and skin, T- direct, fomites

A

S. aureus

141
Q

Gram positive, staphylococci, catalase positive, coagulase negative, non-hemolytic, novobiocin sensitive, R- skin, mucous membranes T- infected piercings

A

S. epidermis

142
Q

Gram positive, staphylococci, catalase positive, coagulase negative, non-hemolytic, novobiocin resistant, R- women reproductive tract, T- UTIs “honeymoon cystitis”

A

S. saprophyticus

143
Q

Gram positive, streptococci, catalase negative, alpha hemolytic, optochin sensitive, R=T- throat, when fluid clearnace from lungs is altered

A

S. pneumoniae

144
Q

Gram positive, streptococci, catalase negative, alpha hemolytic, optochin resistant, has tissue degrading enzymes, R and T- mouth (can lead to decalcification, plaque, endocarditis

A

Veridans Streptococci- s. veridans, s. sanguis

145
Q

Gram positive, betahemolytic, bacitracin sensitive, reacts to group A antiserum, has pili, numerous toxins, R and T- pharynx and skin, sore throats

A

Group A strep- s. pyogenes

146
Q

Gram positive, streptococci, beta hemolytic, resistant to bacitracin, CAMP test positive, Capsule, R+T- genital tract, transmits meningitis to neonate

A

Group B strep- S. agalctiae

147
Q

Gram positive, streptococci, gamma hemolytic, bile resistant, anaerobic, R+T- normal flora of colon, causes abscesses, UTIs

A

Group D- Enterococcus fecalis

148
Q

Gram negative, grows on chocolate agar, ferments maltose, multiple serotypes, capsule, R+T- 5% of all people in respiratory tract, transmitted by droplets

A

N. meningitides (meningitis)

149
Q

Gram negative, grows on chocolate agar, does not ferment maltose, NO capsule–pili to allow attachment, R+T- sexual and/or neonatal transmission. Chronic infection may be asymptomatic

A

N. gonorrhoeae (gonorhea)

Unit 1 MCM (5 decks)

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