Week 1

• What are the main aims of the medical microbiology module?

  To introduce bacteriology, virology, protozoan evolution, bacterial phylogeny, and the classification of protozoa and viruses.
• Why is it important to understand the molecular basis of bacterial phylogeny?


  It helps in understanding the evolutionary relationships and classification of bacteria.
• What is taxonomy in microbiology?

  Taxonomy is the classification of organisms based on shared characteristics.
• What does phylogeny measure in microbiology?


  Phylogeny measures the evolutionary relationships between organisms.
• What are the steps in the taxonomic classification of microbes?


  1. Classification: Ordering organisms into groups based on shared properties.
  2. Nomenclature: Naming the classified organisms.
  3. Data acquisition: Determining species based on comparison to known groups.
• What traditional properties are used in the classification of microbes?


  Microscopy/morphology, response to oxygen, mode of energy synthesis, and biochemical tests.
• What is the significance of molecular and genetic methods in microbiology?


  They allow for the amplification and sequencing of genes to create evolutionary models.
• Who defined Archaea as a separate domain of life and when?


  Carl Woese defined Archaea as a separate domain in 1977.
• What are extremophiles in the context of Archaea?


  Extremophiles are organisms that thrive in extreme environmental conditions.
• What are the four types of extremophiles mentioned?

  Methanogens, hyperthermophiles, psychrophiles, and acidophiles.
• What is the significance of GC content in bacteria?


  GC content indicates the percentage of guanine and cytosine in DNA or RNA.
• What are the two types of gram-positive bacteria based on GC content?


  High GC and low GC bacteria.
• What are the methods used for classification of previously unrecorded microbes?

  • Genotypic: Based on genetic similarities.
  • Phenotypic: Based on physical, structural, or metabolic features.
  • Chemotaxonomic: Measures biochemical composition similarity.
• What are the benefits of using genotypic and phenotypic systems for classification?


  Genotypic systems provide genetic insights, while phenotypic systems offer observable traits.
• Why might Carl Woese have faced resistance to his proposal for reclassification of Archaea?


  Due to the established views on bacterial classification and the similarities between Archaea and bacteria.
• What are the similarities and differences between Bacteria and Archaea?


  Similarities:

  • Share shape, size, and microscopic appearance.
  • Both multiply by binary fission.

  
  

  Differences:

  • Archaea lack peptidoglycan.
  • Archaea genes are more similar to eukaryotes.
• What are the characteristics of Pseudomonadaceae and related opportunistic pathogens?


  They are gram-negative bacilli, polar flagella, aerobic, and non-fermentative.
• What is the significance of Pseudomonas aeruginosa in clinical settings?


  It is a common opportunistic pathogen that can cause infections in immunocompromised individuals.
• What infections can Pseudomonas aeruginosa cause in humans?


  Endocarditis, respiratory infections, bacteraemia, CNS infections, ear infections, and urinary tract infections.
• Why is Pseudomonas aeruginosa particularly problematic for cystic fibrosis patients?


  It can develop a mucoid phenotype and form biofilms, making infections difficult to treat.
• What is the role of biofilm formation in Pseudomonas aeruginosa infections?


  Biofilms protect the bacteria from antibiotics and the immune system, complicating treatment.
• What are the common organs affected by Pseudomonas aeruginosa infections?


  The bladder and lungs are commonly affected.
• What environments can Pseudomonas aeruginosa multiply in?


  Nutritionally poor environments such as distilled water and photographic chemicals.
• How does Pseudomonas aeruginosa spread in the environment?


  It spreads via person-to-person contact, fomites, and exposure to environmental sources.
• What is the role of Burkholderia species in human health?


  They can cause serious infections, particularly in immunocompromised individuals.
• What disease does Burkholderia pseudomallei cause?


  Melioidosis.
• How is Burkholderia pseudomallei transmitted?


  Through open wounds and inhalation.
• What are the symptoms of melioidosis?


  Fever, cough, chest pain, abscesses, pneumonia, and septicemia.
• What is the geographic distribution of Burkholderia pseudomallei?


  Primarily found in tropical and subtropical regions, particularly Southeast Asia and Northern Australia.
• What is the significance of Burkholderia cepacia in cystic fibrosis patients?


  It can cause respiratory infections and bloodstream infections in these patients.
• What disease does Burkholderia mallei cause?


  Glanders.
• How is Burkholderia mallei transmitted?


  Primarily through horses but can infect humans.
• What are the symptoms of glanders?


  Skin ulcers, respiratory infections, and septicemia.
• What are the key concepts related to Pseudomonads?


  • Pseudomonads are gram-negative bacteria that can be opportunistic pathogens.
  • Includes Pseudomonas aeruginosa, Burkholderia cepacia, and Burkholderia pseudomallei.
  • Enteric and non-enteric genera classification based on habitat.
  • Opportunistic pathogens cause disease under specific conditions.
  • Multifactorial refers to multiple causes or influences.
• What are the characteristics of Vibrio species?


  • Easily killed by cooking.
  • Includes >50 species such as V. cholerae, V. parahaemolyticus, and V. vulnificus.
  • Similarities with Enterobacteriaceae: gram-negative rods, facultative anaerobes.
  • Differences: 2 chromosomes, single polar flagella, most oxidase positive.
• What are the symptoms of V. cholerae infection?


  Early vomiting, painless watery diarrhea, severe dehydration, and hypovolemic shock.
• What is the pathogenesis of V. cholerae infection?


  Ingestion, colonization of the small intestine, production of cholera toxin, and exit in mucus-associated aggregates.
• How does cholera toxin affect the host?


  It binds to intestinal epithelial cells, causing secretion of fluid and electrolytes, leading to diarrhea.
• What is the appearance of diarrhea caused by V. cholerae?


  Rice-water stool.
• What happens if V. cholerae infection is left untreated?


  Severe cholera can kill about half of infected individuals without treatment.