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243: Medical Microbiology > Things I Struggle With > Flashcards

Things I Struggle With Flashcards

1
Q

How can we detect growth in lactose medium

Note: not macconkey that’s somet else

A

pH changes and oxygen is produced

Solution turns from red -> yellow

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2
Q

What infection is known to produce insoluble hydrogen sulphide

A

Salmonella

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3
Q

What do bile salts in macconkey agar prevent the growth of

A

Gram positives

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4
Q

What type of bacteria contain endospores

A

Gram positives

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5
Q

What are the 3 components of a gram-negative cell wall

A

Lipopolysaccharide
Porin
Periplasm

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6
Q

What is a heterotroph

A

A bacteria that fix their carbon using sugars

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7
Q

What are autotrophs

A

Bacteria that fix inorganic carbon

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8
Q

Give an example of a autotroph

A

Guild F = green & purple sulphur bacteria

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9
Q

Give an example of a heterotroph

A

Guild B = gliding bacteria

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10
Q

Where do organotrophs source electrons

A

Organic matter

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11
Q

Where do lithotrophs source electrons

A

Inorganic compounds

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12
Q

What are guild D bacteria used for

A

Used to leach materials & oxidise iron

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13
Q

What are pathobionts

A

Normal flora that become pathogenic

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14
Q

Draw the difference between laminar flow and turbulent flow

A

Straight lines = laminar Flor

Turbulent flow = lots of mixing, no discrete lines

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15
Q

What provides structure and integrity to the biofilm matrix

A

Exopolymeric substances

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16
Q

What are 3 components of exopolymeric substances

A

Lipids
Polysaccharides
Proteins
Extracellular DNA

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17
Q

Name 3 examples of biofilms

A

Skin
Teeth (plaque)
Mucosa (respiratory tract)

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18
Q

What sloughs cells from a biofilm

A

Phagocytes (amoeba) grazing on the surface

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19
Q

What does lux R and lux I do

A

Lux R = recruits rna polymerase to transcribe the operon when conc of autoinducer is high

Lux I = produces autoinducer

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20
Q

What do the police of Neisseria gonorrhoea bind to

A

Galactose

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21
Q

What bacteria uses collagenase

A

Clostridium

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22
Q

Give an example of a cytolytic toxin

A

Staph aureus alpha toxin

- inserts into host membrane forming a pore which cell contents flow out of

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23
Q

Give an example of a A-B toxin

A

Clostridium botulinum

- binds to pre synaptic membrane preventing ach release

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24
Q

What do B subunits bind to in A-B toxin

A

Glycans in cell wall

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25
Give an example of a superantigen
Staph aureus toxic shock syndrome toxin 1 | - secretion of fluids and electrolytes
26
How do superantigens work
Stimulate immune cells to produce cytokines = severe inflammation, shock and organ failure
27
How does the gastroenteritis toxin work
Toxin is endocytosed into the cell where it is transported to the ER via phagosome Causes CAMP increase and electrolyte imbalance = water leaves causing dehydration & diarrhoea
28
Give 3 examples of PAMPs
Adhesions O antigens of LPS Peptidoglycan
29
What type of receptors do amoeba have | - how do they work?
Pattern recognition receptors | - binding directly induces phagocytosis 
30
How do bacteria avoid ingestion;
Altering PAMPS | Offensive & defensive virulence factors
31
How do bacteria avoid digestion
- Leave food vacuole and divide in cytoplasm - Produce chaperonins that re-fold incorrectly folded polypeptides - Produce protease that disrupts host superoxide anion generation
32
What do aminoglycosides target
Mainly gram negative bacteria
33
Name two ribosomal protection proteins
Tet M | Tet O
34
How do ribosomal protection proteins work
Find to the ribosome changing its confirmation, prevents tetracycline from binding without stopping synthesis
35
What does Tet X gene do
Produces a protein that chemically modifies tetra cycling in the presence of oxygen and NADPH
36
Name three mechanisms of tetracycline resistance
Tetracycline efflux Ribosomal protection proteins Tetracycline inactivation
37
What are the two types of resistance to antibiotics
Intrinsic resistance which is naturally occurring Acquired resistance e.g. genetic transfer
38
How do bacteria biofilm resist antibiotics
Covered in polymeric substance that prevents antibiotic penetration
39
How can a phage induce antibiotic resistance in a population
Bacteriophage infect bacterial cells and break down the host chromosome Sometimes host DNA is repackaged into the phage genome Phage is released and reinfects another cell where recombination occurs (lysogenic life cycle)
40
What do beta lactams bind to which weakens the cell wall
Bind to penicillin binding proteins = weakening cell wall
41
What gene confers resistance in MRSA
Mec A
42
What is the mortality rate for postsplenectomy sepsis
50-70%
43
How can we prevent aspergillus
Filter hospital air | Give respiratory protection to vulnerable patients
44
How can we prevent legionella
Prohibit showers = sponge baths Monitor the water supply Surveillance on cases
45
Why does diabetes affect necrotising fasciitis
Reduce blood flow to extremities means it’s harder to mobilise the immune system
46
How many organisms are Manuka honey effective against
80
47
Describe the new properties of teixobactin 
New antibiotic that treats gram-positive infections (via disturbing cell wall synthesis) Effective at low-dose, not yet approved
48
Describe the life cycle of leishmaniasis
Sandfly ejects infected stage Promastigotes phagocytosed by macrophage Transform into amastigotes = multiply Infected macrophages are consumed in blood meal
49
What test can be used to diagnose L. Donovani & L. Infantum
Immunochromatographic strip = nitrocellulose with antigens that detects any antibodies X - lots of false positives
50
What happens to ingested giardia cysts
Excyststion in small intestine = trophozoites which multiply Encystation towards the colon = cysts pass in faeces
51
Life cycle of cryptosporidium
Ingest oocyst & excystation Sporozoites parasitise epithelial cells of gut 2 types of oocysts produced = thick walled excreted from host
52
Gold standard for detecting cryptosporidium
Direct fluorescence assay | Antigen & conjugated antibody
53
What are subunits that make a capsid called
Capsomers
54
Describe the replication cycle of a virus
Adhesion, entry and uncoating Viruses with ssRNA form ds intermediate using RNA polymerase = allows mRNA to be formed Translation occurs using host machinery Assembly of new virus in the nucleus Pinches off by budding
55
What did Fraenkel find
RNA is the genetic material of TMV
56
Average latent period for covid-19
5.6 days
57
Describe measles
R0 = 15 | Respiratory disease that can spread to the rest of the body
58
Describe the stages of HIV infection
Flu like symptoms CD4 T cells decline and immune system declines anti-HIV antibodies rise anti-HIV can no longer be produced virus becomes prevalent and can survive outside of T cells Virus reproduces uncontrollably = fatal
59
How does Dicer work
Double stranded RNA genomes are recognised by DICER proteins These are cleaved into pieces and catalysed further by RISC or Argonaut
60
How do PAMPs work
Detect infection and recruit adaptor molecules Phosphorylation of Irf3 forms a dimer that binds to the promoter region and causes gene expression Process encodes interferons
61
What do interferons do
Bind to receptors in adjacent cells activating STAT pathway Priming the cells to fight viruses that have not yet arrived
62
What produces interleukin 4, what does it do
T-helper type 1 cells Converts naive t helper cells into t helper type 2 cells Negative inhibition= prevents cytokine storm
63
Since 2000 how many cases of polio in 21 cases
760 Most being vaccine derived polio
64
What does acyclovir do
Inhibits viral DNA synthesis

243: Medical Microbiology (27 decks)

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