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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
Symptoms of sepsis
Slurred speech Extreme shivering or muscle pain Passing no urine Feels like death Skin discoloured
26
How does an exotoxins and endotoxin function
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
27
Cocci shape
Round shape Grow in chains
28
Bacilli shape
Rod shaped
29
Gram positive cocci (example of bacteria with this shape and what diseases it causes)
Streptococcus mutants Causes caries, pharyngitis, pneumonia, wound and skin infections, sepsis, and endocarditis
30
Gram positive bacilli (disease)
Bacteria: Clostridium tetani Disease: tetanus, lock jaw
31
Gram negative cocci
Neisseria meningitidis also known as meningococcus Diseases: meningitis
32
Gram negative bacilli
Prevotella intermedia (bacteria) Periodontal disease
33
Mycobacteria cannot be seen with gram stain. Why
Has a thick, waxy cell wall, stain cannot penetrate Use fluorescent stain
34
Mycobacteria example
M. Abscesses (a rapidly growing non tubercle mycobacterium found on water soil)
35
Is streptococcus aerobic or anaerobic. Is it gram positive or negative
Gram positive, facultative anaerobic
36
Four stages of bacterial growth
Lag Log (exponential growth ) Stationary Death
37
Staphylococcus vs streptococcus
Staphylococcus forms clumps while streptococcus forms chains
38
How does Pili work
Pili works by wounding around the host cell glycolipods and proteins on the host cell membrane
39
Pili vs Fimbriae
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
3 Components of lipopolysaccharides
O antigen Core Lipid A
41
What is a prion
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
Where are prions mostly found
In the Brain.
43
What disease does prions cause
vCJD, ie mad cows disease. Transmissible spongiform encephalopathies
44
What is bacteria
Bacteria are single cell organisms and some causes infection and disease in animals and humans
45
Name a type of physiological disease
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
What is the name of the study of fungi
Mycology
47
Mycotoxicology
Study of fungal toxins and their effects
48
3 types of mycoses
Mycoses are diseases caused by fungi Superficial mycoses Subcutaneous mycoses Systemic mycoses (worst)
49
Details of superficial mycoses
Affects skin, nails, mucosal surfaces , keratin containing structures Eg, thrush (which is pseudo membranous candida)
50
Malassezia globosa
Fungi that causes dandruff
51
Most important oral fungal
Candida albicans
52
Subcutaneous mycoses
Traumatic implantation of environmental fungi in the subcutaneous layers. Causing chronic progressive diseases and tissue destruction
53
Systemic mycoses
Opportunistic fungi Usually spread through bloodstream Detrimental cause damages organs
54
How to diagnose fungal infections
Smear (microscopy) Oral rinse (grow in culture ) Swab (grow in culture) Foam pad (grow in culture ) Biopsy (histology)
55
Aflatoxin
A mycotoxin produced by the aspergillus species It is poisoning , carcinogenic, mutagenic
56
Critical group of fungi classified by WHO
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
Esophageal candidiasis is one of the most common infections in people living with HIV/AIDS.2
58
Types of candidiasis
Pseudomemrbanous (white lesions) Angular chelitis (red lesions) Hyperplastic (white lesions) Erythematous (red lesions)
59
Virulent attributes of Candida
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
Shape and structure of dimorphic fungi
Yeast - unicellular and spherical u. Usually found in tissue Mould - multicellular and hyphae, usually found in natural environment
61
Shape and structure of opportunistic fungi
Candida albicans - parent, pseudohyphae, budding yeast/ bastospores Aspergillus - looks like a brush Cryptococcus - capsule
62
Mechanism of action of Candida
Adhere, forms biofilm, hyphae extends down and invades the tissue, enters bloodstream (endothelial colonization and penetration)
63
Why is it hard to treat fungal infections
Fungi have very similar cell structures to mammalian cells, might cause side effects in humans
64
How to target and treat fungal infections
Drugs target mannoprotiens, ergosterol, beta-1,3-glucagon synthase in the fungal cell wall
65
What is a virus
Infectious agent that replicates inside a host cell
66
Structure of virus
Capsid (Capsomeres) Envelope Genetic material either dna or rna
67
6 stages of viral replication
1. Attachment 2. Penetration 3. Uncoating 3. Synthesis 5.assembly 6. Release
68
Effects of virus on the host cell
1. Cell death 2. Latent infection (viral particles left in the host cell) 3. Transformation, could have changed to a cancerous cell
69
Herpes simplex 1
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
How to Diagnose viral infections
Swabs,faeces, aspirates, plasma, serum,Nucleic acid detection , urine heroes simplex virus uses Nucleic acid detection
71
Serology
Looking at antibody titres
72
Common respiratory viruses
Influenza Adenovirus Parainfluenza COVID Meta Pneumovirus Rhinovirus
73
What enzyme is needed for RNA detection for diagnostics
Reverse transcriptase to make cDNA from viral RNA
74
How does antigen detection work for Hep B
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
Is influenza a RNA or DNS virus
RNA
76
3 types of influenza
A B C
77
Components of influenza virus
Hemagglutinin Neuraminidase M2 ion channel (only for A) RNP
78
Key steps in influenza replication
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
M2 channel protein
Allows H+ to enter for Uncoating in influenza A. Some drugs target M2 receptors
80
Characteristic of H and N
H has 18 types N has 11 types Both are glycoproteins
81
Antigenic shift vs drift
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
Can asymptomatic people transmit disease
Yes

Laura’s Biochemistry (7 decks)

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