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Flashcards in Bugs in the system Deck (15)
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0
Q

Define infection

A

The establishment of an organism on/in a host associated with multiplication and destruction/dysfunction of the host

1
Q

What is the bacterial reproduction mechanism in broth?

A

-Binary fission

2
Q

What can cause infection?

A

Bacteria, archea, protozoa, fungi, prions, viruses

3
Q

What are the possible mechanisms of infection transmission

A
  • Air borne droplets (coughing/sneezing)
  • Direct contact (exchange of bodily fluids)
  • Animal transmission
  • Contaminated products
  • Maternal->foetal
4
Q

Describe the concept of gram staining

A
  • Stain cells with crystal violet
  • Add iodine which forms complexes with crystal violet
  • Add acetone to decolourise cells by removing complexes. Those cells which thick peptidoglycan wall (i.e. gram positive bacteria) will retain crystal violet-iodine complexes as they will be too large to pass through
  • Counterstain with safranin
  • View under microscope to see staining colour
5
Q

Why are acid fast stains useful and what type of bacteria do they stain?

A
  • Stain bacteria which do not have thick peptidoglycan wall content and also have an extra cell membrane
  • Mycobacterium Tb and Leprosy
6
Q

Define pathogen

A

-Any micro/organism which parasitises a host and causes disease

7
Q

Why are bacterial cell walls of interest and significance?

A
  • Used in detection and diagnosis
  • Can be a target for antibiotics
  • Gram -ve have LPS with endotoxin effects
8
Q

Name the most common gram +ve cocci

A
  • Streptococcus

- Staphlococcus

9
Q

Name the most common gram -ve cocci

A

-Neisseria

10
Q

Name the most common gram +ve bacilli

A

-Clostridium

11
Q

Name the mose common gram -ve bacilli

A
  • Escherchia Coli
  • Pseudomonas
  • Helicobacter
  • Salmonella
12
Q

Which microorganisms are prokaryotic and which are eukaryotic?

A
  • Bacteria and Archea are prokaryotic

- Protozoa and Fungi are Eukaryotic

13
Q

List the main differences between prokaryotes and eukaryotes

A

Prokaryotes

  • No membrane bound organelles
  • 1 Chromosome
  • Coupled biochemical reactions
  • V.labile mRNA
  • 30s and 50s ribosomal subunits

Eukaryotes

  • Membrane bound organelles
  • Many chromosomes
  • Compartmentalised reactions
  • mRNA stable
  • 40s and 60s ribosomal subunits
14
Q

Name the main mechanisms by which bacteria aquire antibiotic resistance

A
  • Antibiotic inactivation by hydrolysis, group transfer or redox
  • Target modification
  • Efflux pumps
  • Target Bypass
  • Mutations
  • Horizontal transfer of plasmids