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xS1B5 - Microbiology > S1B5 - Intro to Bacteriology > Flashcards

S1B5 - Intro to Bacteriology Flashcards

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1
Q

Where does oxidative phosphorylation take place within bacterial cells?

A

The cytoplasmic membrane is a phospholipid bilayer. The cytoplasmic membrane functions in

  • Active transport of molecules into the cell.
  • Synthesis of precursors of the cell wall.
  • Energy generation by oxidative phosphorylation. This function differentiates it from eukaryotic cells, which perform oxidative phosphorylation across the inner mitochondrial membrane.
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2
Q

What evidence supports the evolutionary theory that eukaryotic cells phagocytosed bacteria?

A

The resemblance of bacteria to mitochondria, given their use of the cell membrane to generate ATP via electron transport, supports the theory that eukaryotic cells phagocytosed bacteria in a relationship that eventually became dependent and symbiotic.

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3
Q

Are bacteria unicellular or multicellular?

A

Bacteria are unicellular organisms with a cell wall and cell membrane. Bacteria range in size from the size of a large virus (e.g. Mycoplasma), to nearly the size of a human red blood cell (e.g. bacilli).

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4
Q

What subunits make up bacterial ribosomes?

A

Bacterial ribosomes consist of 50S and 30S subunits and function in protein synthesis.

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5
Q

What is the function of the glycocalyx in bacteria?

A

The glycocalyx is a loose network of polysaccharides that mediates adherence to surfaces, especially foreign surfaces such as indwelling catheters.

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6
Q

What is a capsule composed of in context to bacteria? What is the main function of a capsule?

A

Some bacteria possess a capsule, which is an organized, discrete polysaccharide layer (except Bacillus anthracis, which contains D-glutamate) that protects against phagocytosis.

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7
Q

What are the 3 broad morphological categories of bacteria?

A

Bacterial morphology can include

  • Coccus, a term to describe a microorganism whose overall shape is spherical.
    • Diplococcus is a round bacterium that typically occurs in pairs of two joined cells. Examples include Streptococcus pneumoniae and Neisseria spp.
    • Coccobacillus describes an intermediate shape between coccus and bacillus. Examples include Haemophilus influenzae and Chlamydia trachomatis.
    • Streptococci are aggregation of coccoid bacteria that appear as bead-like chains. An example of this is Streptococcus spp.
    • Staphylococci are aggregations of coccoid baceria that appear as grape-like clusters. An example of this is Staphylococcus spp.
  • Bacilli, a term used to describe any rod-shaped bacterium.
  • Spiral, a term used to describe any spiral-shaped bacterium.
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8
Q

What are the two distinct regions visible within a bacterial cell on microscopy?

A

Bacterial cytoplasm has two distinct regions on microscopy, an amorphous matrix and an inner, nucleoid region containing DNA.

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9
Q

What is the function of porin proteins found in bacterial cell walls?

A

The cell wall is spanned by porins which are found in most gram-negative bacteria. Porins are proteins that transmit small, hydrophilic molecules. Many antimicrobials, such as penicillins, enter bacterial cells through porins.

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10
Q

What is the function of peptidoglycan?

A

Peptidoglycan provides rigid support, and protects against osmotic pressure. Peptidoglycan has a sugar backbone with peptide side chains cross-linked by transpeptidase.

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11
Q

What component of lipopolysaccharide is responsible for inducing TNF and IL-1?

A

The outer cell membrane of gram-negative bacteria contain endotoxin, a lipopolysaccharide (LPS), which is a major surface antigen. Lipid A, the innermost region of LPS, induces TNF and IL-1, while O polysaccharide is the antigen. For more information, see Gram Negative Bacteria.

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12
Q

What is the primary polymer component of bacterial cell walls? What is the major surface antigen found in the cell wall of gram-positive bacteria?

A

The cell wall is made up of an inner layer of peptidoglycan, and in the case of gram-negative bacteria an outer membrane of variable thickness. Lipoteichoic acid is the major surface antigen in the cell wall of gram-positive bacteria, inducing TNF and IL-1.

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13
Q

What is facultative bacteria?

A

Facultative: Can grow in the presence or the absence of oxygen

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14
Q

What are fastidious and non-fastidious bacteria?

A
  • Fastidious: special growth requirement
  • Non-fastidious: simple growth requirement
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15
Q

What is capnophilic bacteria?

A

Capnophilic: Requires CO2

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16
Q

What is halophilic bacteria?

A

Halophilic: Salt loving

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17
Q

What are teichoic acid (TA) and lipoteichoic acids (LTA) important for in gram-positive bacteria?

A
  • TA & LTA: Important for viability, virulence and serotyping.
  • Promote attachment to mammalian cells,
  • low endotoxin activity.
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18
Q

Which is better for treating toxigenic diseases? Protein synthesis inhibitors or cell wall inhibitors?

A

Protein synthesis inhibitors serve better in toxigenic diseases than cell wall inhibitors.

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19
Q

What do you need to know about bacterial capsules?

A

Some Bacteria are Encapsulated

  • A loose polysaccharide layer (or a protein layer).
  • Unnecessary for growth but important for virulence
  • Promotes adherence,
  • anti-phagocytic,
  • poor antigen
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20
Q

What do you need to know about gram-positive bacteria and endospores?

A

Some Gram-Positives Produce Endospores

  • Produced under unfavorable conditions.
  • Non-replicating entity with thick coat.
  • Contain DNA and other essential substances.
  • Toughest life form, can germinate back into vegetative cells.
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21
Q

What do you need to know about bacterial flagella?

A

Bacterial -Flagella

  • Flagella are H-antigens
  • Propellers that confer motility towards food & away from poisons.
  • Assist in bacterial attachment to human cells -virulence factor.
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22
Q

What are the different types of flagellated bacteria?

A
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23
Q

What do you need to know about bacterial fimbriae (pili)?

A

Bacteria –Fimbriae (Pili)

  • Fimbriae are F-antigens
  • Hair-like projections, thinner & shorter than flagella
  • Originate in plasma membrane & protrude through the cell wall
  • Can act as adhesins and are major virulence factors
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24
Q

What is the species of bacteria that are obligate anaerobes with a gram-positive beaded filament morphology?

A

Gram-positive beaded filaments – obligate anaerobic

  • Actinomyces israelli
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25
Q

What is the only gram-positive bacteria that has endotoxin?

A

Listeria sp. is the only gram-positive bacteria that might possess endotoxin (lipopolysaccharide-like).

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26
Q

What is the bacterial species that is an obligate aerobe with a gram-positive beaded filament morphology?

A

Gram-positive beaded filament – obligate aerobic

  • Nocardia
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27
Q

How do gram positive bacteria appear on gram stain?

A

Appear blue or violet on gram stain (absorb crystal violet).

28
Q

Do gram positive or gram negative bacteria contain teichoic acids?

A

Gram-positive bacteria contain bacterial polysaccharides called teichoic acids.

29
Q

Name the 3 main bacterial families that are gram-positive cocci.

A

Gram-positive cocci – aerobic/facultative anaerobes

  • Staphylococci spp.
  • Streptococci spp.
  • Enterococcus spp.
30
Q

What are the characteristics of peptidoglycan in gram positive bacteria?

A

Peptidoglycan is multi-layered and thicker compared to gram-negative bacteria.

31
Q

Do gram positive bacteria contain endotoxin?

A

Gram-positive bacteria have no lipopolysaccharide (endotoxin).

Listeria sp. is the only gram-positive bacteria that might possess endotoxin (lipopolysaccharide-like).

32
Q

Name a bacterial family that is an aerobic, spore forming, gram-positive bacilli.

A

Gram-positive bacilli – aerobic, spore forming

  • Bacillus spp.
33
Q

Name a bacterial family that is an obligate anaerobic gram-positive bacilli capable of producing spores.

A

Gram-positive bacilli – obligate anaerobic, spore forming

  • Clostridium spp.
34
Q

What is a family of anaerobic gram-negative bacilli?

A

Gram-negative bacilli – anaerobes include:

  • Bacteroides sp.
35
Q

How do gram negative bacteria appear on gram stain?

A

Appear red on gram stain (do not absorb crystal violet).

36
Q

What are the characteristics of the peptidoglycan layer of gram negative bacteria?

A

Peptidoglycan: thinner, single layer.

37
Q

Name six relevant aerobic gram-negative bacilli.

A

Gram-negative bacilli – obligate aerobes include:

  • Coxiella burnetti
  • Bordetella pertussis
  • Brucella sp.
  • Francisella tularensis
  • Legionella pneumophila
  • Pseudomonas aeruginosa

Mnemonic: Gram negative rods Cause Bovine Farmers Lots of Painful whooping cough.

38
Q

What are two gram-negative diplococci?

A

Gram-negative diplococci include:

  • Neisseria spp.
  • Moraxella catarrhalis
39
Q

Endotoxin is found in bacteria with what gram stain?

A

Gram-negative bacteria contain lipopolysaccharide (endotoxin).

The only gram-positive organism with endotoxin is Listeria spp.

40
Q

What effects does endotoxin have when released in high quantities?

A

Endotoxin works to

  • Release endogenous pyrogens such as TNF-α, IL-1, and IL-6
  • Increase vascular permeability
  • Initiate coagulation and complement cascades

These actions of endotoxin can lead to fever, disseminated intravascular coagulation (DIC), hypotension, sepsis and shock.

41
Q

What is endotoxin? What is lipid A? When is endotoxin released?

A

The outer cell membrane of gram-negative bacteria contain endotoxin, a lipopolysaccharide (LPS), which is a major surface antigen that is released after upon cell lysis. Lipid A, the innermost region of LPS, induces TNF and IL-1, while O polysaccharide is the antigen.

42
Q

Can the genetic material for exotoxins be transferred from one bacteria to another?

A

There are many different exotoxins that can be released from Gram+ and Gram- bacteria. They can be encoded for by bacterial chromosomes, plasmids, or phages. In other words, genes encoding for exotoxins can be transferred from one bacteria to another, conferring the same pathogenicity.

43
Q

What are exotoxins?

A

Exotoxins are bacterial products that are excreted from the bacteria and confer an advantage to the organism.

44
Q

What do you need to know generally about acid-fast and partially acid-fast bacteria?

A

Acid-Fast & Partially Acid-Fast Bacteria

  • PG layer is surrounded by a wax-like lipid coat
  • Lipid coat contains mycolicacid, cord factor, wax D, sulfolipids.
  • The lipid coat is responsible for virulence and is antiphagocytic
  • C-chain length of mycolicacids determines acid fastness
45
Q

What are examples of obligate anaerobes?

A

Examples can be remembered by the mnemonic “Anaerobes Frankly Can’t Breathe Air”

  • Fusobacterium
  • Clostridium
  • Bacteroides
  • Actinomyces
46
Q

What is the mechanism of bacterial replication? What type of growth do bacteria exhibit?

A

Bacteria reproduce by binary fission and as a result exhibit exponential growth.

47
Q

What mineral is essential for bacterial growth and how do host and bacterial cells compete for it?

A

Iron is essential to bacterial cell growth.

Human iron binding proteins such as ferritin are up-regulated in disease to prevent iron utilization by bacteria.

Siderophores are bacterial proteins that procure iron for bacterial use.

Clinical Correlate: Anemia of chronic disease is a form of anemia that results when a chronic inflammatory state causes the body to sequester iron so effectively that it denies its own needs for iron. Treatment of the underlying disease results in resolution of the anemia.

48
Q

What are the urease-positive organisms?

A

Urease-positive organisms can be remembered by the mnemonic “CHuck Norris hates PUNKSS”

  • Cryptococcus
  • H. pylori
  • Proteus
  • Ureaplasma
  • Nocardia
  • Klebsiella
  • S. epidermidis
  • S. saprophyticus
49
Q

What organisms are obligate aerobes?

A

Examples include Nagging Pests Must Breathe:

  • Nocardia
  • Pseudomonas aeruginosa
  • Mycobacterium tuberculosis
  • Bordetella pertussis
50
Q

What are the catalase-positive organisms?

A

Catalase degrades H2O2 into H2O and O2 before it can be converted to microbicidal products by the enzyme myeloperoxidase. Examples of catalase-positive organisms (not all) can be remembered by the mnemonic Cats Need PLACESS to hide

  • Nocardia
  • Pseudomonas
  • Listeria
  • Aspergillus
  • Candida
  • E. coli
  • Staphylococci
  • Serratia
  • Burkholderia cepacia
51
Q

Obligate anaerobes are characterized by lack of what key enzymes?

A

Obligate anaerobes lack superoxide dismutase, catalase, and/or peroxidase, and cannot grow in the presence of oxygen. These organism are generally foul smelling due to short-chain fatty acids, difficult to culture, and produce gas in tissue.

52
Q

Where in the cell does electron transport take place in bacteria?

A

Because bacterial cells lack mitochondria, the proton gradient is formed across the cell membrane, rather than the mitochondrial inner membrane as it does in eukaryotes.

53
Q

What are facultative anaerobes?

A

Facultative anaerobes use oxygen when present, but can continue metabolism in the absence of oxygen. Facultative anaerobes utilize fermentation pathways in the absence of oxygen.

54
Q

Define an obligate aerobe.

A

Obligate aerobes (usually referred to as aerobes) require and use oxygen for cellular respiration to metabolize substances. Obligate aerobes utilize oxygen for the terminal electron acceptor for the electron transport chain.

55
Q

How do aerobic bacteria generate ATP?

A

Bacteria generate ATP using electron transport.

56
Q

What are the phases of typical bacterial growth?

A

Typical Bacterial Growth

  • Lag phase - bacteria start to grow
  • Exponential phase - population doubles every 20 minutes
  • Stationary phase - growth stops
  • Death phase - bacteria die faster than they multiply
57
Q

What is the number of bacterial cells in a healthy adult compared to total number of human cells?

A) no bacteria in healthy adult

B) 1/10th the amount of human cells

C) equal number

D) 10 times more than human cells

A

10 times more than human cells

58
Q

What are the low bacteria sites in the body?

A

Low number sites:

  • Bladder
  • Uterus
  • Parts of the digestive and respiratory tracts
59
Q

What are the sterile body sites (no bacteria)?

A

Sterile sites:

  • Blood, lymph
  • CSF
  • Synovial fluid
  • Sub-epidermal tissues
60
Q

What are key general things you need to know about normal flora?

A

Knowing the Normal Flora

  • Few bacteria are always pathogenic, e.g., T. pallidum
  • Some are opportunists e.g., S. aureus, E. coli
  • Some yet to be implicated with a disease, e.g., Bifidobacterium
  • Some cause disease if they enter deep tissues by trauma, surgery.
  • Some bacteria become pathogenic after acquiring extra virulence, e.g. E. coli.
  • If immunocompromised, bacteria that are part of the normal flora can cause disease.
61
Q

What are the obligatory steps for bacterial infections?

A

Epidemiology

  • acquisition/colonization

Virulence

  • immune evasion/infection
  • replication/proliferation
  • dissemination and disease

Identification

  • Treatment
62
Q

What are factors that contribute to transmission of pacterial pathogens?

A

Transmission of Bacterial Pathogens

  • Bacterial shedding.
  • Coughing, sneezing, talking.
  • Talking specially when consonant f, p, t, and s used.
  • Stability in the environment.
  • Living conditions, age group and immuno-competence.
63
Q

What are the key, general mechanisms of bacterial pathogenesis?

A

Mechanisms of Bacterial Pathogenesis

● Enter, stick and defend.
● Utilize host material.
● Virulence factors – role in survival & disease.
● Ability to cause tissue damage (toxins).
● Toxins in blood - system-wide pathogenesis.
● Damage also by hyper-active host defense(ROI,cytokines).

64
Q

What factors affect the outcome of bacterial infections?

A

Factors Affecting Outcome of Bacterial Infections

  • Strain and inoculum
    • <200 Shigella for shigellosis (human to human transmission).
    • >100m for GI infection by Vibrio (No human to human transmission).
  • Length of presence
    • longer in the body - greater chance to cause disease
  • Host factors
    • >106 Salmonella for gastroenteritis in healthy
    • <103 in those with neutral gastric pH
65
Q

What are key general differences between surface and systemic bacterial infections?

A

Surface bacterial infections

  • Infection originates on dry or less moist skin surfaces
  • Less likely to spread within the body but contagious

Systemic bacterial infections

  • If the infection originates in UGT, GI or LRT
  • Easy systemic spread –risk of sepsis
66
Q

What are key general differences between bacterial and viral pathogens?

A

Bacterial Pathogens

● Real pathogens –identifiable and treatable (most of the time).
● Bacterial pathogenesis is better defined.
● Viruses usually predispose us to serious bacterial infections.
● Bacterial pathogens do not respect anatomical boundaries

xS1B5 - Microbiology (14 decks)

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