Lecture 4: Atypical bacteria Flashcards Preview

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Flashcards in Lecture 4: Atypical bacteria Deck (4)
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1
Q

Mycoplasmataceae features

A
  • Mycoplasma pneumoniae, M. genitalium, M. hominis, U. Urealyticum
  • smallest known free-living organisms (0.15 to 0.30 microns, size of poxvirus)
  • minimal set of organelles (growth & replication)
  • lack cell wall (entire life)
  • no synthesis of peptidoglycan (stain pink -ve Gram)
  • resistant: penicillin, cycloserine & lysozyme
  • reproduction: cell elongates (filament), coccoid form from filament (binary fission), released by fragmentation
  • cytoplasmic membrane contains sterols
  • smallest genome capable of self reproduction
  • growth on agar: diphasic colonies (“fried eggs”) all except M. pneumoniae
  • unique attachment organelle: tapered tip + P1 adhesin; destruction: H2O2 & oxygen radical; M. pneumoniae; M. genitalium
2
Q

Rickettsiaeceae features

A
  • Genera: Rickettsia & Orientia
  • obligate intracell pathogens not cultivated on agar; can only be cultured on eukaryotic cells including: cell culture, embryonated eggs, susceptible animals
  • spread to humans by ticks, life, fleas, mites
  • small: 0.3 to 0.5 microns
  • long rod/coccobacillary shaped (pleomorphic)
  • closely related to Gram -ve
  • Diaminopimelic acid
  • some possess capsules ex. R. prowazeki
3
Q

Anaplasmataceae & Coxiella features

A
  • small obligate intracell pathogens
  • zoonotic
4
Q

Chlamydiaceae features

A
  • 2 Genera: Chlamydia (C. trachomatis) & Chlamydophilia (C. psittaci, C. pneumoniae)
  • 2 ecological groups

A. infect humans only C. trahomatis: Trachoma, inclusion conjunctivitis & lymphogranuloma venereum

B. zoonotic infections (birds to humans) C. pneumoniae, C. psittaci

  • small obligate intracell pathogens
  • do not generate ATP (no detectable flavoproteins or cyt)
  • developmental forms (2)
    1. Elementary Body (EB): non-replicating, infectious, possess cell wall, adapted for extracell survival, induce endocytosis, metabolically inactive
    2. Reticulate Body (RB)/ Initial Body (IB): replicating, non-infectious, larger, adapted for intracell growth, does not induce endocytosis, metabolically active, see cell wall in reticulate form

Note: Elementary bodies develop into reticulate bodies after entry into host cell. RB grows & divides by binary fission. W/in 1 to 2 d, RB reorganises back to EB and host cell liberates EB.