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Dosage Form Design 2 > Basic Bacteriology > Flashcards

Basic Bacteriology Flashcards

1
Q

What are the characteristics of Bacteria?

A
  • Simple unicellular prokaryotes
    • Prokaryotes lack membrane-enclosed organelles
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2
Q

What is a bacteria’s cell wall made from?

A

Peptidoglycan

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3
Q

How do bacteria reproduce?

A

Binary fission

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4
Q

What is the process of Binary Fission?

A
  • Cell replicates its DNA
  • The cytoplasmic membrane elongates, separating DNA molecules
  • Cross wall forms; membrane invaginates
  • Cross wall forms completely
  • Daughter cells
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5
Q

What are the Characteristics of Fungi and how do they reproduce?

A
  • Diverse group of organisms; molds, mushrooms, yeasts
  • Reproduce asexually or sexually
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6
Q

What are the characteristics of Protozoa?

A
  • Single-celled eukaryotes
  • Diverse group of organisms:
    • Vary in size, shape, features and habit
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7
Q

What are the characteristics of Viruses and how do the reproduce?

A
  • Acellular
    • have DNA or RNA core, surrounded by a protein coat
      • coat may be enclosed in an envelope
  • Only seen with electron microscope
  • Reproduce only in host cell by using its cellular machinery
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8
Q

What are the differences between Prokaryotic Cells and Eukaryotic Cells?

A
  • Prokaryotic Cells
    • ​Smaller, um
    • No true nuclear membrane
    • Haploid
    • Circular DNA
    • Can exist independently in nature or in many environments
    • Ubiquitous in nature
    • Asexual
  • Eukaryotic Cells
    • ​Larger
    • True nucleus
    • Membrane enclosed organelles
    • Linear DNA
    • Diploid
    • Can reproduce sexually
    • Increased genetic diversity
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9
Q

Compare Gram Positive and Gram Negative Bacteria

A
  • Gram Positive
    • ​Thick cell wall
    • Inner membrane
    • Break cell wall, immediate cell death
  • Gram Negative
    • ​Double membrane
      • Thin cell wall, inner and outer membrane
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10
Q

What are the characteristics of Spores?

A
  • Thick-walled, differentiated structure
  • Highly heat, radiation, chemical and dessication resistant
  • Commonly isolated from soil
  • Bacteria can endure nutrient depletion, harsh conditions and facilitate dispersal in the enviornment, wind, water and animal GIT
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11
Q

What is glycolax?

A

A substance that surround bacterial cells

  • Capsule: if organised and firmly attached to cell wall
  • Slime layer: if unorganised and loosely attached to cell wall
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12
Q

Describe the characteristics of the Capsule

A
  • Dense, well-defined polysaccharide or protein layer closely surrounding a cell
  • More resistant to physical and chemical agents and antibiotics
  • Facilitate adherence to host cells and surfaces (biofilms)
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13
Q

What are the characteristics of Flagella?

A
  • Long, thin cellular appendage, capable of rotation in prokaryote cells and responsible for swimming motility
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14
Q

What are the characteristics of Exotoxins?

A
  • Proteins produced more commonly inside gram-positive bacteria, as part of their own growth and metabolism
  • Exotoxins are then secreted or released into the surrounding medium following lysis
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15
Q

What is one of the most potent endotoxin known?

A

Clostridium Botulinum

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16
Q

What are the Characteristics of Clostridium Botulinum and what symptoms do they produce?

A
  • Gram positive rod; anaerobic
  • Form heat resistant spores
  • Produce very potent neurotoxins
  • Symptoms:
    • Initial: Nausea, vomiting, cramps, diarrhoea
    • Neurological symptoms: Flaccid paralysis, death
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17
Q

What are the clinical applications of botulinum toxin?

A
  • Botox treatment
  • Therapeutic agent
    • Blepharospasm
    • Muscle spasms
    • Migraine headaches
    • Excessive underarm sweating
18
Q

What are the Characteristics of Endotoxins?

What symptoms does it cause?

A
  • Lipid portions of lipopolysaccharides (LPSs) that are part of the outer membrane of the cell wall of gram-negative bacteria
  • The endotoxins are liberated when the bacteria die and the cell wall breaks apart
  • Causes fever, low blood pressure, inflammation
    • Responsible for dramatic effect of Neisseria meningitidis
19
Q

What are the phases of the bacterial growth curve?

A
  • A: Bacteria gets used to environment
  • B: Amount of bacteria increases exponentially
  • C: Amount of bacteria generated similar to the amount that die
  • D: Death
20
Q

What are the Factors Influencing Bacterial Growth?

A
  • Temperature
  • pH
  • Water availability and osmotic pressure
  • Oxygen availability
21
Q

Describe the inflence of temperature on bacterial growth

A
  • Minimum: Membrane gelling; transport processes so slow that growth cannot occur
  • Maximum: Protein denaturation; collapse of the cytoplasmic membrane; thermal lysis
22
Q

What is the optimum pH for bacterial growth?

A
  • 7.2-7.6
23
Q

What is an extremophile?

A
  • An organism that grows optimally under one or more enviornmental extremes
24
Q

What is a culture medium?

A
  • Aqueous solution of various nutrients suitable for the growth of microorganisms
25
Q

What are the nutritional requirements for the laboratory culture of microbes?

A
  • Macronutrients: carbon source, nitrogen, potassium, sulphur e.t.c
  • Micronutrients: trace elements e.g. boron, chromium, iron e.t.c
26
Q

What culture media are used in laboratory culture of microbes?

A
  • Liquid
  • Solid: gelling agent usually agar added
27
Q

Describe Chemically Defined Culture

A
  • Exact chemical composition known
  • General Purpose Complex: nutrient/blood agar e.t.c
28
Q

Describe Differential Culture

A
  • Contains indicators such as pH indicators or chromogens to identify target organism
29
Q

Describe Selective Culture

A
  • Combination of chemicals and antibiotics to select target bacteria
  • Suppresses normal flora or contaminating bacteria
30
Q

Describe Selective and Differential Culture

A
  • MacConkey Agar (Mac)
31
Q

What are the Steps when Culturing Bacteria?

A
  • Inoculation
  • Incubation
  • Isolation
  • Inspection
  • Identification
32
Q

Describe the Process of Inoculation

A
  • Producing a culture
  • Introduce a tiny sample (the inoculum) into a container of nutrient medium
33
Q

What is the purpose of Culturing Bacteria?

A
  • Used to manipulate, grow, examine and characterise microorganisms in the lab
34
Q

Describe the Process of Incubation

What are the Types of Culture?

A
  • An inoculated sample is placed in an incubator to encourage growth at optimal temperature
    • 18°C-37°C
    • Can control atmospheric gases e.g. CO2
    • Can recognise growth as turbiditiy in liquid media and colonies on solid media
  • Type of culture:
    • Pure culture: growth of only a single known species (also called axenic)
    • Mixed culture: two or more species
    • Contaminated culture: includes unwanted microorganisms of uncertain identity or contaminants
35
Q

What is the process of Isolation?

A
  • Separating one species from another
36
Q

What are the Steps involved in Inspection and Identification?

A

a. Appearance
b. Metabolism - biochemical tests
c. Genetic analysis - PCR
d. Protein Profile - mass spectrometry

37
Q

Describe Appearance in Inspection and Identification

A
  • Microscopy
    • Observe unstained wet mount of bacteria
      • Determine size and shape of bacteria
      • Motility
    • Stained preparations
      • Bacteria fixed to slide by heat or alcohol
      • Differential stain used:
        1. Gram Stain: +ve or -ve
        2. Add fast stain: to check for acid fast bacteria
        3. Spore stains, flagella stains, capsule stains
38
Q

Describe Metabolism in Inspection and Identification

A
  • Biochemical tests
    • e.g. nitrate broth, catalase
39
Q

Describe Genetic analysis in Inspection and Identification

A
  • PCR
    • PCR to distinguish MRSA from MSSA
    • Separate DNA and Stain
40
Q

Describe Protein Profile in Inspection and Identification

A
  • Mass spectrometry
    • Separates proteins on their size; give proteins at peaks
    • Can’t tell you if resistant or not

Dosage Form Design 2 (11 decks)

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