Mycoplasmas

Question 1

Features of mycoplasmas

• what they are, division, features of cell wall
• shape
• features when grown on agar
• what kind of parasites are they

Answer 1

• Are prokaryotes, but separate to bacteria
  
  • smallest known (also smallest genome)
• multiply by binary fission
• lack cell wall characteristic or bacteria and are bounded by bi-laminar membrane similar to animal cells (therefore resistant to penicillin)
• quite pleomorphic (different shapes)
• characteristic small “fried egg” colony on agar
  
  • central dense core embedded in agar & lighter peripheral zone
• contain intracellular bacterial-like organelles
• are extracellular parasites -> closely associated w/ external membrane of cells

Question 2

Mycoplasma - naming

Answer 2

• Mycoplasma is a common name for an entire group of organisms in class Mollicutes
  
  • one genera is designated Mycoplasma
• difficult to culture
• v. common contamination of cell lines

Question 3

M. pneumoniae

• features
• AKA
• how to get rid of it

Answer 3

• associated disease = primary atypical pneumonia
  
  • won’t put in hospital, called ‘walking pneumoniae’
    
    • is a chronic disease, can take long time to go away
• need right antibiotic
• gives dry cough (no phlegm)

Question 4

Main symptoms of infectious Pneumonia

Answer 4

• Systemic (high fever, chills)
• Central (headaches, loss of appetite)
• Skin (clamminess, chills)
• Lungs (cough w/ phlegm, shortness of breath, chest pain)
• Muscular (fatigue)
• Gastric (nausea, vomiting)
• Joints (pain)

Question 5

Nutritional requirements of Mycoplasmas

Answer 5

• fastidious nutritional requirements
• Media for culture needs to contain extensive range of vitamens and co-factors
• Nucleic acid precursors required (mycoplasmas lack pathway for pyrimidine synthesis and synthesis of purine base)
• long chain fatty acids must be supplied (as also can’t be synthesised)

*in a way, similar to viruses

Question 6

2 basic energy-yielding mechanisms produce toxic metabolites

Answer 6

1. Fermentative;
   - fermentation of sugars via a glycoytic pathway & ATP is formed during glycolysis
   - end products (may be toxic to cell) include lactate, acetate, pyruvate, acetyl methyl carbinol
2. Non-fermentative;
   - Enables mycoplasma to derive most of their energy (ATP) requirements from arginine

Question 7

Ureaplasma species

Answer 7

-require urea for growth (hydrolysed NH3 to CO2)

Question 8

Extracellular toxic products important in pathogenesis of mycoplasmas (5)

Answer 8

• Ammonia
• Mycoplasmas lack catalase (leads to accumulation of H2O2 - most would be degraded by host peroxidases)
• Some have glycoprotein capsule which have toxic properties
• Haemolysisns
• Nucleases and other enzymes

Question 9

Antibiotics - how they work

-feature after cough has gone

Answer 9

• Resistant to antibiotics inhibiting cell wall synthesis
• Tylosin and Tetracyclines most commonly used
  
  • also used for prophylactic treatment for anthrax, bubonic, plague and malaria
• after infection, animals commonly excrete mycoplasmas for long periods (is NOT prevented by antibiotic therapy)
  
  • can be contagious even though no cough

Question 10

Diagnosis of mycoplasmas (3)

Answer 10

• Isolation of mycoplasma (final identification to species lvl accomplished by biochemical and serological tests)
• PCR
• Serological tests for antibody

Question 11

Primary atypical pneumonia

-age group it attacks

Answer 11

• called this because still able to walk around
• common in children and young adults
• cause of up to 30% all pneumonia cases