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MBBS - Year 1 > Intro to Microbiology > Flashcards

Intro to Microbiology Flashcards

1
Q

Eukaryotic species

A

A group of closely related organisms that breed among themselves

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2
Q

Prokaryotic species

A

A population of cells w/ similar characteristics

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3
Q

Clone

A

Population of cells derived from a single cell

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4
Q

Strain

A

Genetically different cells within a clone

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5
Q

Viral species

A

Population of viruses w/ similar characteristics that occupies a particular ecological niche

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6
Q

Gram stain +ve and -ve

A

Bacteria to be characterised as Gram +ve if they retain the violet dye (peptidoglycan layer) or Gram -ve if they don’t (lipopolysaccharide layer)

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7
Q

Process of the Gram stain

A

Crystal violet –> iodine treatment –> decolorisation

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8
Q

Microorganism shapes

A

Round cells are called cocci (sing. coccus)

Rod-shaped cells are bacilli (bacillus)

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9
Q

Acid Fast Bacilli stain

A

Mycobacteria aren’t stained during gram test due to mycolic acid layer in membrane. Waxy layer that is v. thick and very dense so doesn’t even pick up pink colour

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10
Q

Process of acid fast bacilli stain

A

Apply primary stain of carbolfuschin for 30 seconds
Heat fix cells to the slide using the flame
Decolorize with acid alcohol for 15-20 seconds
Apply counterstain of methylene blue for 30 seconds then rinse excess stain

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11
Q

Other ways to classify bacteria

A

Classification by phenotype
Classification by genotype
Classification by analytical methods

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12
Q

Classification of bacteria by phenotype

A

How they behave w/ diff substrates/ Abx

Latex agglutination

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13
Q

Classification of bacteria by genotype

A

G + C ratio
DNA hybridisation
DNA fragment analysis
Whole genome sequencing

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14
Q

Classification of bacteria by analytical methods

A

Whole cell lipids
Cell wall
Whole cell protein (proteomics)

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15
Q

Mycoses

A

Infections caused by fungi

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16
Q

Arguments for viruses being living

A

Can mutate
Reproduce, only in living host cells
Respond to environmental stress

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17
Q

Arguments for viruses being non-living

A

Acellular; no cytoplasm or cellular organelles
Carry out no metabolism on their own – use host mechanisms. New viral components are synthesized and assembled within infected host cell
Vast majority of viruses possess either DNA or RNA not both

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18
Q

Prions

A

Protein containing particles w/ no detectable nucleic acid
‘Slow’ infectious diseases
Highly resistant infectious agent
No inflammation or immune response in affected

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19
Q

Antibiotic susceptibility

A

Create ‘lawn’ of bacteria
Add filter disc w/ known quantity of antibiotic
Inhibition of growth around disc
‘Cut - off’ size of zone correlates to conc. of antibiotic in blood following normal dose

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20
Q

Non-culture methods

A

Look for antigen
Look for antibody
Look for genome

21
Q

Looking for antigen

A

Known antibody will bind to antigen in sample
ELISA
Immunofluorescence

22
Q

Looking for antibody

A

Know antigen will bind to antibody in sample
ELISA
CFT

23
Q

Looking for genome

A

PCR: detect known sequence of DNA/RNA within sample

‘Fingerprinting’: compare DNA fragments w/ reference stains

24
Q

Examples of Abx resistant microorganisms

A

MRSA
C. difficile
ESBL bacteria
VRE

25
Q

MRSA

A

A Staphylococcus aureus that is methicillin and therefore penicillin, flucloxacillin resistant

26
Q

C. difficile

A

Anaerobic bacterium that lives in gut

Can become deregulated via the use of broad-spectrum antibiotics and overgrow causing pseudomembranes and colitis

27
Q

ESBL bacteria

A

Extended Spectrum Beta-lactamases
Gram -ve Enterobacteriaceae that are resistant to all penicillin-based Abx
Usually complicate urinary catheter and in situ drains

28
Q

VRE

A

Vancomycin-resistant enterococcus
Commensal bacteria but can cause infections of the urinary tract, the bloodstream, or of wounds associated w/ catheters or surgical procedures
Usually causes infections on hosp

29
Q

Causes of antibiotic resistance

A

Over-prescription of antibiotics
Patients not finishing entire antibiotics course
Antibiotics in livestock and fish farming
Poor infection control in healthcare settings
Poor hygiene and sanitation
Absence of new antibiotics being discovered

30
Q

How do organisms cause disease

A

Invasion and damage to host cells; cell death and infl response –> toxin production (systemic or local) —> response to infection; “immune mediated”

31
Q

Types of innate defences

A

Mechanical
Chemical
Cellular

32
Q

Mechanical innate defences

A

Respiratory tract
GI tract
Skin

33
Q

Respiratory tract as a mechanical innate defence

A 
Nasal hair 
URT anatomy 
Secretions
Epithelial sloughing 
Muscociliary apparatus
Expulsion
34
Q

Muscocilliary expulsions

A

Uses motion of ciliated epithelium to bring out bacteria

35
Q

GI tract as mechanical innate defence

A

Secretions
Epithelial sloughing
Peristalsis
Elimination

36
Q

Skin as mechanical innate defence

A

Waterproofing

Tight junctions

37
Q

Chemical innate defences

A

Lysozyme
Iron binding proteins e.g. lactoferrin
Defensins e.g. cathelicidins
Surfactant

38
Q

Chain of infection

A

Microbe —-> Reservoir —> Escape route —-> Transmission —> Point of entry —> Host —->

39
Q

Reservoir

A

Place where infection is prevalent

Can be animal

40
Q

Esacpe route

A

How microbe spreads from reservoir

41
Q

What does the environment classify

A

Transmissibility of viruses by the environment they spread from

42
Q

Airborne spread

A 
Tiny particles 1-5 micrometres
Cough aerosol 
Remain suspended in air indefinitely
Can reach alveoli easily 
Low numbers but high virulence organisms e.g. TB, measles
43
Q

Droplet spread

A

Remain suspended for 17 mins
Deposit in upper airway
1m spread
Impact on mucous membrane

44
Q

Person to person transmission

A 
Direct contacts - skin to skin 
Faecal-oral 
Inhalation 
Sexual transmission 
Blood to blood 
Vertical
45
Q

Examples of vertical transmission

A

Mother to foetus

Mother to baby

46
Q

Fomite

A

An inanimate object that is capable of transmitting infectious organisms from one individual to another e.g. keyboard

47
Q

Vertical transmission routes

A

Mother’s bloodstream
Mother’s genital tract
Breast-feeding

48
Q

What your does Gram-ve bacteria stain

A

Pink

MBBS - Year 1 (93 decks)

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