week 3 medical microbiology

• What type of bacteria are Firmicutes?


  Low GC gram-positive bacteria
• Are Firmicutes spore-forming or non-spore forming bacteria?


  Non-spore forming bacteria
• What are examples of lactic acid bacteria?


  • Streptococcus
  • Lactobacillus
  • Staphylococcus
  • Listeria
  • Mycoplasma
• What are examples of spore-forming bacteria in the Firmicutes group?


  • Clostridium
  • Bacillus
• What type of bacteria are Actinobacteria?


  High GC gram-positive bacteria
• What are examples of Actinobacteria?


  • Streptomyces
  • Corynebacteria
  • Mycobacteria
• What is unique about the Mollicutes group of bacteria?


  They completely lack a cell wall and only have a plasma membrane
• What is the significance of sterols in the plasma membrane of Mollicutes?


  Sterols strengthen the plasma membrane
• What are lipoglycans and their role in Mollicutes?


  They are involved in avoiding the immune response
• What does pleomorphic mean in the context of Mollicutes?


  They can take on various shapes and sizes
• What is the size range of coccoid cells in Mollicutes?


  0.12µm - 0.25µm in diameter
• Why are most mycoplasmas considered non-motile?


  They lack flagella and other motility structures
• What are the growth characteristics of Mycoplasmas?


  • All are parasites of eukaryotes
  • Many can be grown outside of cells in lab media
  • Require sterols except Acholeplasma, Asteroleplasma, and Mesoplasma
  • Require vitamins, fatty acids, amino acids, purines, and pyrimidines
• What shape do Mycoplasma colonies take on solid agar?


  Fried egg shaped colony
• What is the genome size of Mycoplasma pneumoniae?


  816 kbp
• What is the GC content of Mycoplasma pneumoniae?


  Approximately 25-35%
• What is the smallest known genome of any self-replicating organism?


  Mycoplasma genitalium at 580 kbp
• What are the evolutionary characteristics of Mycoplasmas?


  • Multiple reductions in genome size have occurred
  • Overall rate of evolution is uncharacteristically high
• What type of environment do Mycoplasmas require for growth?


  They require cholesterol and are parasites of animal mucous membranes
• How many species of Mycoplasmas are recognized?


  Over 60 species
• What is Ureaplasma and its growth requirements?


  Microaerophilic, requires cholesterol and urea for growth
• What is the role of urease in Ureaplasma?


  It converts urea into ammonia and CO2
• What is the significance of Acholeplasma in tissue culture?


  Common contaminants of cell lines in tissue culture
• What type of bacteria is Anaeroplasma?


  Strict anaerobes that inhabit bovine or ovine rumen
• What is the characteristic of Spiroplasma?


  Helical and motile, parasites on arthropods and plants
• What are the symptoms of Mycoplasma pneumoniae infection?


  • Mild flu-like disease: headache, sore throat, cough
  • Severe pneumonia: fever, chills, malaise
  • Protracted course with gradual resolution
• How does Mycoplasma pneumoniae bind to respiratory epithelial cells?


  It uses polar tip organelles and specific adhesion proteins
• What is the role of hydrogen peroxide produced by Mycoplasma pneumoniae?


  It is responsible for initial cell disruption in the respiratory tract
• How is Mycoplasma pneumoniae transmitted?


  Through close personal contact via respiratory droplets
• When is the prevalence of Mycoplasma pneumoniae infections typically higher?


  In autumn
• What are the diagnostic methods for Mycoplasma pneumoniae?


  • Clinical symptoms and X-Ray
  • Serological tests (e.g., serum cold agglutination)
  • DNA test (PCR) for definitive diagnosis
  • Microbiological detection (slow culture)
• Why is accurate diagnosis important for Mycoplasma pneumoniae infections?


  Because it is resistant to antibiotics that act on the cell wall
• What are the treatment options for Mycoplasma pneumoniae infections?


  • Erythromycin
  • Doxycycline (not for children)
  • Azithromycin
  • Levofloxacin
• What was the trend in pneumonia cases in 5-14 year olds in the UK?


  Massively increased compared to previous years
• What are the genital mycoplasmas and their associations?

  • Mycoplasma genitalium
  • M. hominis
  • Ureaplasma urealyticum
  • Causes non-gonococcal urethritis (NGU)
  • Associated with infertility in men and women
• How are genital mycoplasmas transmitted?


  By direct venereal contact and vertically from mother to offspring
• What is the recommended treatment for genital mycoplasmas in the UK?


  Doxycycline pretreatment followed by azithromycin or moxifloxacin
• What is the significance of antibiotic resistance in genital mycoplasmas?


  • High levels of antibiotic resistance
  • Azithromycin is a macrolide
  • Moxifloxacin is a fluoroquinolone
• What are the main characteristics of lactic acid bacteria?


  • Produce lactic acid from fermentation
  • Non-spore forming and non-motile
  • Lack cytochromes
  • Obtain energy by substrate level phosphorylation
• How do lactic acid bacteria tolerate acidic environments?


  • They can produce and tolerate high concentrations of lactic acid
  • This ability eliminates competition