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Fall 2022 > Microbio > Flashcards

Microbio Flashcards

1
Q

Structure of prokaryote

A

No nucleus, DNA stored in cytoplasm. Chromosomes are circular (nucleoid), do not contain introns. Reproduction asexual and results in identical daughter cells

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2
Q

Flagella

A

Elongated protein filament cylinders anchored inside cell wall and plasma membrane of predominantly gram negative bacteria. Propels bacteria , can be useful for identification.chemotaxis regulates movement of flagellum to certain chemicals in the environment

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3
Q

Pili

A

Tiny hairs around bacterium, also present in gram positive bacteria and gram negative. Adhesions at the top play important role in allowing bacterial to attach to surfaces or other organisms

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4
Q

Cell envelope

A

Maintains cells shape of bacteria, prevent lysis from osmosis, determines if bacteria is gram positive or negative.

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5
Q

Capsule

A

Gram positive and gram negative bacteria, called glycocalyx or peri cellular matrix. Composed of glycoprotein and glycolipids. Defends against host immune response.
Medically important bacteria with capsules : e.coli, n. Meningitidis, k. Pneumoniae, salmonella

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6
Q

Outer membrane for prokaryotes

A

Formed by glycolipid bilayer, major component is lipopolysaccharide (LPS- endotoxin that can cause septic shock) (glucosamine disaccharide - selective permeability) found exclusively in gram neg. bacteria.

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7
Q

Cell wall of prokaryotes

A

Made of peptidoglycan (glycan chains of NAG and NAM, peptide inter-bridge connecting tetra peptide chain of amino acids) tetrapeptides connect to NAM on the glycan chains
Gram positive has 5 glycine resides that attach to peptidoglycan (also has teichoic acid that stabilizes cell wall)
Gram negative has one glycine reside that attaches to peptidoglycan (smaller layer, but has lipoproteins in periplasm, lipopolysaccharides, outer membrane layer, and porin protein)
exoskeleton to prevent lysis in hypotonic or isotonic solutions.

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8
Q

Cytoplasmic lipid membrane of prokaryotes

A

No sterols

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9
Q

Envelops of gram positive bacteria

A

No outer membrane. Cell walls much thicker than gram negative. Anionicpolymers-teichoic acid and lipotdichoic acid- weave throughout. Surface proteins that replicate the functions of the proteins situated between outer and inner membranes of gram negative bacteria

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10
Q

Obligate anaerobes

A

Lack superoxide dismutase and catalase to protect them from oxygen free radicals.

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11
Q

Facultative anaerobes

A

Can switch between aerobic respiration and anaerobic fermentation

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12
Q

Fastidious bacteria

A

Picky eaters, only grow when certain nutrients are present

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13
Q

Siderophores

A

Fastidious bacteria will produce this chelating compound to bind to iron with great avidity, stealing it from blood and tissue proteins

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14
Q

Bacterial growth

A

Lag phase- bacteria mature and adapt, reproduction rate is slow
Exponential growth phase (log)- rapid growth. Will continue until resources expire
Stationary phase- physiological limitation, lack of nutrients, accumulation of toxic waste. No growth
Death phase - population declines and dies

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15
Q

Gram staining method

A

Differentiate groups of bacteria based on components of cell wall
Violet dye applied to cells, followed to iodide which binds to dye. Decolonizing agent applied (gram neg become colorless), then pink counter stain (safranin)(gram negative becomes red).

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16
Q

Gram staining results

A

Gram positive exhibit deep purple or blue color due to thick peptidoglycan layer
Gram negative remain pink or red

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17
Q

Acid fast staining

A

Differentiates atypical bacteria . Carbol fuchsin dye stains all cells, washed with acid alcohol, acid fast bacteria exhibit bright red color. (Large amounts of my colic acids in cell walls)
Ziehl- Neelsen stain

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18
Q

Endospore staining- Schaefer Fulton method

A

Stained with malachite green which binds to spores, then counter stained with safranin

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19
Q

Capsule staining

A

Stain the background, not the capsules, with India ink or nigrosine. Bacteria are counterstained, show clear halos around them

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20
Q

Bacteria shapes

A

Rods-mildly elongated coccus like a cocktail weenie
Bacillus- more elongated coccobacilli, like hot dog
Coccus- sphere
Vibrio- comma like
Spirillum- wavy
Spirochete- twisted like the threads on a screw

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21
Q

Diploid

A

Bacteria that form pairs

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22
Q

Chains

A

Bacteria that form short single file lines

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23
Q

Clusters

A

Bacteria that bunch together like grapes

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24
Q

Hyphae

A

Bacteria that form long thread like filaments

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25
Q

Normal flora

A

Microorganisms including archaea, fungi, viruses, that inhabit human body or live on its surface. Not harmful, aid immune system in preventing infection , necessary for survival

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26
Q

Opportunists

A

Potentially pathogens that would not normally inhabit the body but take advantage of the opportunity (weakened immune system)

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27
Q

Pathobionts

A

Typically benign endogenous microorganism, potentially pathogenic that may cause disease when overgrowth occurs

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28
Q

Changes in normal gut flora across lifespan

A

Actinobacteria- half in gut for infants, decrease with age to 5%
Firmicutes- 20% gut bacteria in young children, grows until middle age and begins to decrease again
Proteobacteria- starts at 10% in infants, almost disappears in middle age, increases again to 25% in later life

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29
Q

Skin flora

A

S epidermis, staphylococcus aureus, corynebacterium . Prevents pathogenic colonization through resource competition
Limits growth of pathogenic cutibacterium acnes and pathobionts S aureus

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30
Q

GI tract flora

A

Stomach Hostile to most microorganisms because of low pH. Lower GI lots of normal flora (clostridium, bacteroides, lactobacilli

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31
Q

Oral cavity and upper respiratory system normal flora

A

Many, including streptococcus

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32
Q

Urogenital normal flora

A

Urethra contains enterococci, diptheroids, S epidermis. Vagina peptostreptococcus, corynebacterium, streptococcus, staphylococcus

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33
Q

Sterile sites of body

A

Not normally in contact with environment; blood, brain, bone marrow, liver, kidneys. Pathogens can enter through medical treatment, trauma , etc.

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34
Q

Tissue tropism

A

Pathogens exhibit preference for specific tissue typed

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35
Q

Human intestinal microbiota

A

Responsible for multiple digestive, immune, and metabolic functions. When not properly balanced, dysbiosis occurs caused by overgrowth, too few bacteria, or inappropriate types of bacteria

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36
Q

Streptococcus pneumoniae

A

Bacterial pneumonia

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37
Q

Candida albicans

A

Fungi, infections on interior epithelial surfaces or mucous membranes, causes candidiasis (oral thrush)

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38
Q

Viruses

A

Composed of DNA or RNA surrounded by protein coat, inert outside of other living cells.

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39
Q

Fungi

A

Yeasts single celled, molds multicellular . Have cell wall, considered eukaryotes . Most not pathogenic for humans . Source for many antibiotics, also produce alcohol and carbon dioxide . True nucleus

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40
Q

Staph. Aureus causes

A

Septicemia, toxic shock, food poisoning

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41
Q

Group A strept.

A

Tonsillitis, scarlet fever, sore throat

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42
Q

E.coli causes

A

Diarrhea, septicemia, meningitis

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43
Q

Coccidioides

A

Fungi that causes coccidioidomycosis, histoplasmosis, crytpococcosis, candidiasis

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44
Q

Toxoplasma gondii

A

Protozoan parasite that causes toxoplasmosis and cryptosporidiosis

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45
Q

Salmonella typhi

A

Typhoid fever

46
Q

Bacteria

A

prokaryotes, circular double stranded DNA, haploid DNA
Plasmids replicate independently from bacterial genome

47
Q

Bacterial DNA replication

A

Circular, chromosomal, double stranded DNA first unwound by bacterial helicase (starts at single origin of replication). DNA polymerase 2 replicates the DNA strand, while simultaneously proofreading daughter strand.

48
Q

Transposons

A

DNA sequences that contain protein coding genes that allow transposition of DNA sequences within a genome. Allow DNA sequences to jump from plasmid to chromosomal dna and vice versa. Must flank both sides of the gene of interest as the enzyme cleaves and ligands the transposon sequence, leaving the gene of interest intact

49
Q

Conjugation

A

F Plasmid contains dna that encodes for production of sex pilus. Sex pilus on F+ connects to another bacterium or similar so same species that does not have F plasmid (F-). When they connect, mating bridge forms. Single strand of double stranded F plasmid is transferred across bridge to other bacterium. After, both restore the double stranded plasmid

50
Q

High frequency recombination strain

A

Hfr contains F plasmid in chromosomal dna, usually integrated through site specific recombination (integration of extrachromosomal DNA sequence into bacterial chromosome at specific locations called insertion sites )

51
Q

Transformation

A

Competent bacteria cell takes up naked dna from environment (usually from lysed cells). Implementation of absorbed bacteria occurs through homologous recombination
Strep. Pneumoniae, haemophilus influenzae type b , e. Coli

52
Q

Transduction

A

Bacteriophage infects susceptible bacterial cell by binding on surface receptors and injecting dna into host bacterial cell.
Host dna hydrolysis into pieces, and phage dna proteins made
Occasionally a bacterial dna fragment is packaged in phage capsule
Transducing phage infect new host cell, where recombination can occur

53
Q

Lytic growth in transduction

A

Some bacteriophages are packaged with host bacterial dna rather than viral dna. (Transducing phages). Does not result in lysis, instead is expression of donor bacterial dna

54
Q

Specialized transduction

A

Temperate bacteriophage infects bacterium and transfers viral dna that incorporated into host dna forming a pro phage . Viral dna becomes dormant and is passed to daughter cells
Bacterial cell has prophage integrated between genes A and B
Occasionally prophage dna exits incorrectly, taking adjoining bacterial dna with it
Phage particles carry bacterial dna along with phage dna
Transducing phage infect new host cell, recombination can occur

55
Q

Lysogenic growth in transduction

A

Prophage dna is imprecisely excised. Bacteriophage formed from this inject a new recipient with the hybrid dna, recipient bacterium genome will include its own dna, bacteriophage dna, and dna from host

56
Q

Virulence factors

A

Protein A
Immunoglobulin (Ig) A protease
M protein

57
Q

Protein A

A

Produced on bacteria cell wall that binds to Fc portion of human IgG, prevents subsequent immune response
Impairs phagocytosis and opsonizatiln

58
Q

IgA protease

A

Protein that binds and degrades IgA antibodies

59
Q

M protein

A

Prevents phagocytosis by preventing opsonization by binding to fibrinogen, forming dense fibrillar barrier bacterial surface interfering with C3b deposition

60
Q

HIV life cycle

A

Virus binds and fuses with host cell
It releases numerous viral proteins, including reverse transcriptase and integrase
Reverse transcriptase converts viral rna to dna
Inside cells nucleus, new viral dna integrated into host dna with integrase
Newly integrated viral dna transcribed by host cell machinery to make new hiv rna, some of which is translated into immature hiv proteins
HIV rna and proteins more to cell surface, assembled into new immature hiv viruses
Immature hiv viruses exit cell and release protease, cleaves immature proteins to yield mature hiv viruses

61
Q

HIV info

A

Primarily infects CD4 lymphocytes, used by the virus to replicate
First infected no symptoms. Acute illness after 2-4 weeks with symptoms like mononucleosis
ELISA screens for hiv. Can detect antibodies. Often confirmation test is required
Patients with this and TB are at increased risk for developing serious life threatening form of TB

62
Q

A. T. Still and microbiology connection

A

3 of his children died if became risk meningitis

63
Q

Pure culture

A

Isolation and cultivation of etiologic agents of disease (first done with bacteria)
Pasteur most famous for his work in developing an effective rabies vaccine

64
Q

Koch’s postulate

A
  1. Organism / pathogen must always be found in the diseased animal but not in the healthy ones
  2. Organism must be isolated from diseased animals and grown in pure culture away from the animal
  3. Organism located in pure culture must initiate and reproduce the disease when reinoculated into susceptible animals
  4. Organism should be reisolated from experimentally infected animal

Linked particular pathogen with matching infection or disease

Using anthrax bacteria, he showed pure cultures could cause diseased when re inoculated info healthy animals

65
Q

Sulfonamide

A

Sulfa dedicate of metabolite p-aminobenzoic acid
Prontonsil (1935)

66
Q

Penicillin

A

Florey and chain developed Fleming original discovery of this into a practical means by producing and administering the antibiotic (1940s)

67
Q

Immunity

A

1880s- metchnikoff developed cellular theory of immunity

68
Q

Antimicrobials

A

Early 1900s, Paul erhlich developed concept of magic bullets : forerunners of antitoxins (anti sera) and antibiotics for treating infections. Formulated salvarsan which he used to treat syphilis before penicillin

69
Q

Smallpox

A

Cowpox and milkmaids led to immunity to smallpox, due to similarity between some of antigens present in these 2 viruses

70
Q

Formalinization

A

Permitted production of safe killed vaccines

71
Q

Epidemiology

A

Study of determinants and distribution of health and disease in human populations (infectious and noninfectious )

72
Q

Non communicable infection

A

Not transmitted by person to person or animal to person contact.
Caused by patients normal flora like peritonitis (ruptured appendix) and endocarditis (from stept. Bacteria disseminating from oropharnynx into blood)

73
Q

Other types of infections

A

Caused by organisms common in nature (clostridial gas gangrene, certain fungi)
Ingestion of preformed toxins (botulism- clostidial food poisoning) (staphylococcal food positioning) (can’t be transmitted)

74
Q

Communicable infections

A

Can be spread
Require organisms able to multiply in or on the body and leave body in a form directly infection to others or indirectly infections after development in living insect vector
West Nile disease: requires presence of a biting infected mosquito

75
Q

Endemic

A

Disease present at low but fairly constant level in population (common cold)
Histoplasmosis in US

76
Q

Epidemic

A

Level of infection above usually found in population. Patient develops severe, life threatening water diarrhea with Cholera

77
Q

Pandemic

A

Widespread disease in region or worldwide, with high attack rates

78
Q

Infection

A

Multiplication of organisms in or on the host

79
Q

Disease

A

Clinically apparent response of the host to infection characterized by typical (or atypical) disease manifestations. Less common than infection

80
Q

Subclinical infections and the carrier state

A

In apparent infections- subclinical
Carrier state applies to situations where infectious agent establishes itself as part of a patients indigenous micro-flora or causes low grade chronic disease after occurring as an acute recoverable infection
Ex: staph. Aureus, salmonella typhi (chronic fall bladder colonizations infection following attack of typhoid fever originating in GI tract. Leads to periodic fecal excretion of organisms for years by human carrier)

81
Q

Routes of transmission

A

Reservoirs - refers to only mammalian carriers of infectious agents such as
Humans : principal living reservoir of human disease, clinical and sub clinical
Animals: both wild and domestic,
Zoonoses: diseases that occur primarily in animals and can be transmitted to humans

82
Q

Infectivity

A

Frequency with which infection is transited when there in contact between agent and susceptible individuals

83
Q

Pathogenicity

A

Number of persons who develop disease divided by total number infected

84
Q

Virulence

A

Number of fatal or severe cases divided by total number of cases

85
Q

Incidence

A

Number of new cases of a disease within specified period and also the number of new cases divided by size of population

86
Q

Prevalence

A

Total number of cases existing in given population at risk at a given point in time or during defined period

87
Q

Botulism

A

Number of people consuming food contaminated with performed toxin : no secondary spread

88
Q

Control of epidemics

A

Surveillance, and identify cause and route of spread, notifying and reporting to appropriate authorities

Local, state department of health, CDC
WHO- includes cotuntires with limited reporting capabilities
White House Covid 19 response team

89
Q

Plague

A

Black Death
Pathogen: yersinia pestis- gram negative bacillus
Route: mostly urban rat to flea to human

90
Q

Measles

A

Paramyxovirus-single stranded rna with lipid envelope
Route: human to human through respiratory route
One of the most highly communicable viruses infections. Largely controlled with vaccine, only 95% effective

91
Q

Influenza

A

Orthomyxovirus, causes flu, has segmented rna genome with lipid envelope
Neuraminidase (N1-9) and hemagglutinin( H1-6) key identifying components
Route: airborne spread through respiratory route. Led to several epidemics. Vaccines available annually

92
Q

Lyme disease

A

Borrelia burgdorferi, spirochetal bacterium
Route: by hard shelled ticks of lxodes species mostly in nymphal stage of life cycle. Disease prevalent (hyper endemic) in northeast US and Europe

93
Q

AIDS

A

Human immunodeficiency virus, retrovirus
Route: sexual contact, intravenous route, and congenital infection.

94
Q

MERS

A

Middle East respiratory syndrome (2014), one of the corona viruses like SARS-CoV-2

95
Q

Staphylococcus under microscope

A

Gram positive and clusters

96
Q

Streptococcus under microscope

A

Gram pos chains

97
Q

Niceria under microscope

A

Gram negative diploid

98
Q

Bacillus

A

Gram positive rod bacilli chains

99
Q

Lipopolysaccharide

A

In gram neg cell walls
O-antigen, oligosaccharidic core (with outer and inner core), and Lipid A (endotoxin)

100
Q

Lipid A

A

Part of lipopolysaccharide part of gram neg
Can cause fever, hypertension, hypotension, histamine release, neutrophil chemotaxis, DIC
endotoxin

101
Q

Gram nomenclature exceptions

A

Mycobacteria (gram positive, mycolic acid in wall)
Mycoplasma (don’t have peptidoglycan, not gram positive or negative)
Treponema (syphillis)
Legionella, rickettsia, chlamydia, bartonella, ehrlichia, anaplasma

102
Q

Auramine-rhodamine fluorochrome staining

A

New acid fast stain
Less time
Less experience
Lower magnification (x400)
Needs fluorescent microscope

103
Q

Endospores characteristics

A

Viable
Metabolically dormant
Highly resistant

104
Q

Endospore structure

A

From exterior to interior: exosporium(jelly like layer on outside), protein cost, outer membrane, cortex, spore wall (peptidoglycan layer), inner membrane, core (DNA)

105
Q

Types of Endospore shapes

A

Terminal (circle on end of pole)
Central (circle in middle of pole)
Sub terminal (circle almost at end of pole)

106
Q

Endospore growth

A

Stationary phase (growth doesn’t change, where sporulation will take place, lack of nutrients)
Vegetative phase (exponential growth)
Autoclave (only way to kill Endospore)

107
Q

Endospore resistance properties

A

Spore wall/cortex/coat/ exosporium - protects from chemicals
SASPs- small acid soluble proteins. Bind to dna, change P conformation to A, enzyme repair during germination
Ca++/Dipicolinic acid (DPA)- controls damage to Endospore

108
Q

Medically significant Endospore so

A

Bacillus (B. Anthracis, B. Cereus ) gram positive rods , soil growing organism
Clostridia (botulinum(botulism from canned foods), tetani (tetanus, locked musculoskeletal system) perfringens (gangrene), difficile (diarrhea)), soil growing organism , anaerobes

109
Q

Binary fission in prokaryotes

A

Replication of circular chromosome begins at origin of replicated and continues in both directions
Cell begins to elongate. FtsZ protein migrate towards midpoint of cell
Duplicate chromosomes separate and move away toward opposite ends of cell. FtsZ form ring around periphery of midpoint between chromosomes
FtsZ ring direct formation of septum that divides cell. Plasma membrane and cell wall materials accumulate
After septum complete, cell pinches into two, forming two daughter cells. FtsZ dispersed throughout cytoplasm of new cells

110
Q

Aerotolerant anaerobes

A

Fermenters

111
Q

Growth requirements pH

A

Bacteria - slight alkaline
Fungi - slight acid

Fall 2022 (15 decks)

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