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Sem 2 - Infection > Microbes > Flashcards

Flashcards in Microbes Deck (19):

What microorganisms can cause disease?

  • Virus
  • Bacteria
  • Fungi
  • Parasites


What is the structure of a virus?

  • It has spikes on the outside for attaching to specific cell surfaces.
  • Envelope
  • Protein coat
  • Nuclei acid - this can be right or left sided and can be simple or very complex.

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What different types of DNA virus are there?

Single-stranded , non-enveloped eg Parvovirus 19

Double-stranded, Non-enveloped eg Adenovirus,

Double-stranded, enveloped eg Herpes viruses


What different types of RNA virus are there?

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What is a bacteriophage?

These are viruses that infect and replicate inside bacteria.

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What is the structure of bacteria?

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What shape can bacteria be?

Coccus (cocci) - round

Bacillus (bacilli) - rods

Spirillus- spiral they are rare. Only siphylis and some others have this shape.


How can cocci be arranged?

Clusters (staphylococcal infection)

Chains (streptococcal infection)


What is the structure of a gram positive bacteria?

Plasma membrane, Periplasmic space and peptidoglycans.

Go purple with gran stain. They retain the first gram stain colour because of the peptioglycan

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What are gram negative bacteria?

Outer membrane of lipopolysaccharide, periplasmic space between all layers, peptidogycans then the plasma mambrane on the inside.

- It causes gram negative sepsis

Gram negative have a thinner outside wall so dont retain the first stain (purple). They instead absorb the counter stain and go PINK.

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What are aerobes?

They are organisms that can survive in the presence of oxygen.


What are obligate aerobes?

They are organisms that require oxygen for survival


What are Anaerobes?

Organisms that can survive in the absence of oxygen


What are obligate anaerobes?

Organisms that require an oxygen free environments for survival.

(They form spores which allow movement as they protect bacteria from chemicals ect..) e.g. Clostridium Difficile which causes perfuse diarrhoea


How do you name bacteria, fungi and parasites?

Linnaean taxonomy - Genus + Species.

The name can sometimes be supplemented by adjectives describing growth, typing or antimicrobial susceptibility characteristics.


What have some mechanisms of bacterial pathogenesis?

  • Virulence factors
    • Host entry (e.g. polysaccharide capsule)
    • Adherence to host cellls (eg pili and fimbriae)
    • Invasiveness (eg enzymes such as collagenase)
    • Iron sequesterations (siderophores)
  • Toxins
    • Endotoxins  (lipopolysaccharides)
    • Exotoxins (diphtheria toxin)


What are the differences between prokaryotes and eukaryotes?

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What types of fungi are there?

  • Yeasts (single celled)
    • Candida albicans (thrush and sometimes more seriousl blood stream infections) 
    • Cryptococcus neoformans
    • Pneumocystis jiroveci
  • Molds (multicellular)
    • Aspergillus species 
    • Dermatophytes (ringworm, athlete's foot)



What types of parasites are there?

  • Protozoa (single celled)
    • Giardia lamblia
    • Cryptosporidium parvum
    • Plasmodium falciparum
    • Trypanosoma cruzi
  • Helminths (worms, multi-cellular)
    • Roundowrms (e.g. Enterobius vermicularis)
    • Tapeworms (e.g. Taenia saginata)
    • Flukes (e.g. Schistosoma mansoni)