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Laura’s Biochemistry > Microbiology > Flashcards

Microbiology Flashcards

1
Q

Selective vs non selective agar

A

Selective media contain ingredients that inhibit the growth of some organisms but allow others to grow. For example, mannitol salt agar contains a high concentration of sodium chloride that inhibits the growth of most organisms but permits staphylococci to grow.

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2
Q

Test to differentiate staphylococcus aureus

A

Coagulase test. If it’s positive then there is clumps if negative there is no clumps

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3
Q

Antibiotic rings

A

Can see effectiveness if the antibiotics by comparing the radius around the antibiotic rings on the agar

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4
Q

Components of bacteria

A

Pili
Fimbriae
Plasmids
Ribosomes 70s
Cytoplasm
Plasma membrane
Peotidoglycan cell wall
Capsule (lipopolysaccharides)
Nucleotides (circular dna)
Flagellum

No membrane bound organelles
No nucleus

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5
Q

Gram positive vs gram negative bacteria

A

Gram positive has a thick peptidoglycan cell wall and no outer membrane
Gram negative has a thin cell wall and a outer membrane with lipopolysaccharides

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6
Q

Which type of gram bacteria is red when dyed

A

Gram negative

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7
Q

Capnophilic bacteria

A

Needs Carbon dioxide

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8
Q

Facultative bacteria

A

With and without oxygen

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9
Q

Microaerophilic bacteria

A

Requires small amounts of oxygen

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10
Q

Anaerobic bacteria

A

No oxygen needed

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11
Q

Metronidazole

A

Used a lot in dentistry
Used for anaerobic bacteria

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12
Q

Why do we need to know about the bacterial growth cycle

A

Know about the death phase so we can know how to sterilised and kill bacteria on dental instruments

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13
Q

List the steps for gram staining

A
  1. Crystal violet (blue-purple)
  2. Iodine (to fix the crystal violet to cell membrane)
  3. Acetone (to decolorize gram negative)
  4. Red dye (stains gram negative red)
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14
Q

Why does gram positive appear blue-purple?

A

The crystals violet lodges in thick peptidoglycan cell wall

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15
Q

Clinical implications of bacterial cell walls (knowing about penicillin binding proteins in the cell wall)

A

Penicillin binding proteins cross link peptidoglycan side chains.
Penicillin antibiotic acts as an inhibitor. Antibiotic targets these proteins such that the proteins can no longer form cross links and the cell wall lysis

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16
Q

Endotoxin vs exotoxins (with examples)

A

Exotoxins can be produced by both gram positive and gram negative. Exotoxins are polypeptides . (Examples: Toxins produced by Staphylococcus aureus, Bacillus cereus, Streptococcus pyogenes, Bacillus anthrcis(Alpha-toxin, also known as alpha-hemolysin (Hla)))

Endotoxin i produced by gram negative. It is the lipid portion of lipopolysaccharides part of the outer membrane (Examples: Toxins produced by E.coli, Salmonella Typhi, Shigella, Vibrio cholera(Cholera toxin- also known as choleragen))

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17
Q

What’s PVL

A

Panton - Valentine Leukocidin toxin produced by staphylococcal aureus that causes leukocytes to die

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18
Q

Describe the process of action of leukocidin

A
  1. S. Aureus secretes two components of Panton- Valentine leukocidin
  2. The two components interact and assemble into a pore-forming heptaner (7) on polymorphonuclear white cell membranes
  3. High PVL conc causes PMN lysis
  4. LysEd PMNs causes inflammatory response -> tissue necrosis
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19
Q

What is PMN?

A

Polymorphonuclear white cell also known as polymorphonuclear leukocytes

type of immune cell that has granules (small particles) with enzymes that are released during infections, allergic reactions, and asthma.

Eg basophils neutrophils eosinophils

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20
Q

Endotoxin

A

Only released by gram negative

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21
Q

Lipopolysaccharides are what type of toxins

A

Endotoxin. Rmb that lipopolysaccharides are only found in gram negative outer membrane. And endotoxins are found only in gram negative

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22
Q

Prevotella intermedia

A

Bacteria that causes Periodontal disease
LPS has detrimental effect

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23
Q

E. Coli systemic infection

A

Causes sepsis

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24
Q

What is sepsis

A

Body’s extreme response to an infection

Sepsis (also known as blood poisoning) is the immune system’s overreaction to an infection or injury.

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25
Q

Symptoms of sepsis

A

Slurred speech
Extreme shivering or muscle pain
Passing no urine
Feels like death
Skin discoloured

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26
Q

How does an exotoxins and endotoxin function

A

An exotoxin releases toxins when the pathogenic bacteria lyses. Endotoxins endotoxins are liberated when the bacteria die and the cell wall break apart. Endotoxins are the lipid portions of LPSs

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27
Q

Cocci shape

A

Round shape
Grow in chains

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28
Q

Bacilli shape

A

Rod shaped

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29
Q

Gram positive cocci (example of bacteria with this shape and what diseases it causes)

A

Streptococcus mutants
Causes caries, pharyngitis, pneumonia, wound and skin infections, sepsis, and endocarditis

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30
Q

Gram positive bacilli (disease)

A

Bacteria: Clostridium tetani
Disease: tetanus, lock jaw

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31
Q

Gram negative cocci

A

Neisseria meningitidis also known as meningococcus
Diseases: meningitis

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32
Q

Gram negative bacilli

A

Prevotella intermedia (bacteria)
Periodontal disease

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33
Q

Mycobacteria cannot be seen with gram stain. Why

A

Has a thick, waxy cell wall, stain cannot penetrate
Use fluorescent stain

34
Q

Mycobacteria example

A

M. Abscesses (a rapidly growing non tubercle mycobacterium found on water soil)

35
Q

Is streptococcus aerobic or anaerobic. Is it gram positive or negative

A

Gram positive, facultative anaerobic

36
Q

Four stages of bacterial growth

A

Lag
Log (exponential growth )
Stationary
Death

37
Q

Staphylococcus vs streptococcus

A

Staphylococcus forms clumps while streptococcus forms chains

38
Q

How does Pili work

A

Pili works by wounding around the host cell glycolipods and proteins on the host cell membrane

39
Q

Pili vs Fimbriae

A

While the fimbriae are bristle-like short fibers occurring on the bacterial surface, Pili are long hair-like tubular microfibers found on the surface of bacteria. The pili are found in some gram-negative bacteria only, whereas the fimbriae are found in both the gram-negative and gram-positive bacteria.

40
Q

3 Components of lipopolysaccharides

A

O antigen
Core
Lipid A

41
Q

What is a prion

A

Prion is a misfolded protein contains no dna or rna. It has the ability to transmit their misfolded shape onto normal variant of the same protein .

42
Q

Where are prions mostly found

A

In the Brain.

43
Q

What disease does prions cause

A

vCJD, ie mad cows disease. Transmissible spongiform encephalopathies

44
Q

What is bacteria

A

Bacteria are single cell organisms and some causes infection and disease in animals and humans

45
Q

Name a type of physiological disease

A

Diabetes type 2
Cancer

Physiological disease is an illness that interferes with the way that the functions of the body are carried out eg diabetes Alzheimer’s Parkinson’s e]rheumatoid arthritis, asthma, leukemia, chd

46
Q

What is the name of the study of fungi

A

Mycology

47
Q

Mycotoxicology

A

Study of fungal toxins and their effects

48
Q

3 types of mycoses

A

Mycoses are diseases caused by fungi

Superficial mycoses
Subcutaneous mycoses
Systemic mycoses (worst)

49
Q

Details of superficial mycoses

A

Affects skin, nails, mucosal surfaces , keratin containing structures

Eg, thrush (which is pseudo membranous candida)

50
Q

Malassezia globosa

A

Fungi that causes dandruff

51
Q

Most important oral fungal

A

Candida albicans

52
Q

Subcutaneous mycoses

A

Traumatic implantation of environmental fungi in the subcutaneous layers. Causing chronic progressive diseases and tissue destruction

53
Q

Systemic mycoses

A

Opportunistic fungi
Usually spread through bloodstream
Detrimental cause damages organs

54
Q

How to diagnose fungal infections

A

Smear (microscopy)

Oral rinse (grow in culture )
Swab (grow in culture)
Foam pad (grow in culture )

Biopsy (histology)

55
Q

Aflatoxin

A

A mycotoxin produced by the aspergillus species

It is poisoning , carcinogenic, mutagenic

56
Q

Critical group of fungi classified by WHO

A

Cryptococcus neoformans (meningitis spreads from lungs to brain/CNS)

Candida’s auris (serious infections , bloodstream, affects blood heart brain)

Asperigillus fumigatus (mould, infection in the lungs or sinuses that can spread t other parts of the body, produces aflatoxin)

Cardia albicans (vaginal, oral, invasive like GI tract etc)

57
Q

Esophageal candidiasis is one of the most common infections in people living with HIV/AIDS.2

A
58
Q

Types of candidiasis

A

Pseudomemrbanous (white lesions)

Angular chelitis (red lesions)

Hyperplastic (white lesions)

Erythematous (red lesions)

59
Q

Virulent attributes of Candida

A
  1. Ability to adhere and form biofilms on host tissues
  2. Modify surface antigens to evade immune cells
  3. Form hyphae that help in tissue invasion and adherence
  4. Extracellular phospholipids and proteinase which break down host cell wall
60
Q

Shape and structure of dimorphic fungi

A

Yeast - unicellular and spherical u. Usually found in tissue

Mould - multicellular and hyphae, usually found in natural environment

61
Q

Shape and structure of opportunistic fungi

A

Candida albicans - parent, pseudohyphae, budding yeast/ bastospores

Aspergillus - looks like a brush

Cryptococcus - capsule

62
Q

Mechanism of action of Candida

A

Adhere, forms biofilm, hyphae extends down and invades the tissue, enters bloodstream (endothelial colonization and penetration)

63
Q

Why is it hard to treat fungal infections

A

Fungi have very similar cell structures to mammalian cells, might cause side effects in humans

64
Q

How to target and treat fungal infections

A

Drugs target mannoprotiens, ergosterol, beta-1,3-glucagon synthase in the fungal cell wall

65
Q

What is a virus

A

Infectious agent that replicates inside a host cell

66
Q

Structure of virus

A

Capsid (Capsomeres)
Envelope
Genetic material either dna or rna

67
Q

6 stages of viral replication

A
  1. Attachment
  2. Penetration
  3. Uncoating
  4. Synthesis
    5.assembly
  5. Release
68
Q

Effects of virus on the host cell

A
  1. Cell death
  2. Latent infection (viral particles left in the host cell)
  3. Transformation, could have changed to a cancerous cell
69
Q

Herpes simplex 1

A

Infections are transmitted through contact with HSV in herpes lesions, mucosal surfaces, genital secretions, or oral secretions. HSV-1 and HSV-2 can be shed from normal-appearing oral or genital mucosa or skin.

70
Q

How to Diagnose viral infections

A

Swabs,faeces, aspirates, plasma, serum,Nucleic acid detection , urine

heroes simplex virus uses Nucleic acid detection

71
Q

Serology

A

Looking at antibody titres

72
Q

Common respiratory viruses

A

Influenza
Adenovirus
Parainfluenza
COVID
Meta Pneumovirus
Rhinovirus

73
Q

What enzyme is needed for RNA detection for diagnostics

A

Reverse transcriptase to make cDNA from viral RNA

74
Q

How does antigen detection work for Hep B

A

2 antibodies are produced during infection. IgM is produced first then IgG is produced about 2 weeks later. You can use the antibodies u find to distinguish the time course of an infection

75
Q

Is influenza a RNA or DNS virus

A

RNA

76
Q

3 types of influenza

A

A B C

77
Q

Components of influenza virus

A

Hemagglutinin
Neuraminidase
M2 ion channel (only for A)
RNP

78
Q

Key steps in influenza replication

A

Hemagluttinin binds to sialic acid receptors.
Receptor mediated endocytosis
Uncoating due to H+ ions
Release of viral components
RNA polymerase makes positive RNA from negative RNA
Neuraminidase allows replicated virus to break free from rebinding to sialic acid

79
Q

M2 channel protein

A

Allows H+ to enter for Uncoating in influenza A. Some drugs target M2 receptors

80
Q

Characteristic of H and N

A

H has 18 types
N has 11 types
Both are glycoproteins

81
Q

Antigenic shift vs drift

A

Drift - minor, point mutations, influenza a b c

Shift - major, pandemic, influence A ONLY, reassortment/ combination of the 8 genomes from two different strains.

82
Q

Can asymptomatic people transmit disease

A

Yes

Laura’s Biochemistry (7 decks)

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