Microbiology: Taxonomy of Microorganisms

• Microbiology, part of the Microbiology course, introduces the taxonomy of microorganisms.
• The course is taught to 2nd-year students in their 2nd semester, with a lecture component of 3 hours and a practical lab of 1 hour, plus 2 hours of immunology

Intended Learning Outcomes

• Ability to define medical microbiology.
• Understanding of the branches and applications of microbiology.
• Remembering at least three pioneers in microbiology.
• Defining taxonomy, identifying its components.
• Describing the role of taxonomy in diagnostic microbiology.

What is Microbiology?

• The study of microorganisms usually less than 1mm in diameter.
• Requires magnification to be seen clearly.

Examples of Microorganisms:

• Bacteria: Unicellular organisms of prokaryotes (e.g., Streptococcus).
• Viruses: Non-living entities able to replicate inside of host cells (e.g., influenza).
• Fungi: Eukaryotic organisms like Candida (yeasts) or molds.
• Parasites: Organisms that live on a host (e.g., Plasmodium).
• Prions: Infectious proteins causing neurological diseases (e.g., Creutzfeldt-Jakob disease).

Branches of Medical Microbiology:

• Bacteriology: Study of bacteria.
• Virology: Study of viruses.
• Mycology: Study of fungi like yeasts.
• Parasitology: Study of parasites.

Pioneers in Microbiology: Louis Pasteur (1822-1895)

• Father of Modern Microbiology.
• Germ theory.
• Developed vaccinations for anthrax and rabies.
• Pasteurization for killing bacteria in liquids.
• The experiment demonstrated that sterile liquid remains sterile unless exposed to external contamination, therefore disproving the spontaneous generation theory.

Pioneers in Microbiology: Alexander Fleming (1881-1955)

• Scottish physician and microbiologist.
• Observed a culture plate of Staphylococcus aureus contaminated by a fungus and the mold (Penicillium) inhibited the growth of the bacteria.
• Discovered penicillin from Penicillium - the first antibiotic in 1928.
• Awarded 1945 Nobel Prize in Physiology/Medicine.

Examples of Antibiotics

• Ampicillin: A penicillin working to prevent building of bacteria cell walls.
• Amikacine: Used for the respiratory system.
• Penicillin G K
• Gentamicin: Inhibits bacterial growth by stopping ribosomes production.
• Hydrocortisone: For respiratory, urinary, and stomach issues

Pioneers in Microbiology: Hans Christian Gram (1853-1938)

• Inventor of the Gram staining technique.
• Working with Carl Friedlander, he created the technique in Berlin in the 1880s.
• The Gram staining technique is used to identify bacteria under a microscope in order to identify infection causes.

Microbial Taxonomy

• Science dealing with the classification, naming, and identification of organisms.
• Diagnostic microbiology: provides accurate diagnosis of disease.
• Consists of 3 components: classification, naming, and identification.

Classification

• Method for organizing microorganisms into groups (taxa).
• Based on similar morphologic, physiologic, and genetic traits.

Hierarchical Classification:

• A system consisting of designations, including:
  • Kingdom: Contains similar divisions or phyla.
  • Phylum: Contains similar classes.
  • Class: Contains similar orders.
  • Order: Contains similar families.
  • Family: Contains similar genera.
  • Genus: Contains similar species.
  • Species: Most exclusive taxa.

Binomial Nomenclature

• The biological system naming where the name has two terms.
• The first term indicates the genus and the second indicates the species of an organism.
• For example Escherichia coli; Escherichia is the genus name and coli is the distinct species.
• It could be coli E., but it doesn't abbreviated the species.

Identification (Typing):

• Microbial identification provides characterization of a certain microorganism through appropriate tests.
• Two main methods: genotypic and phenotypic.

Identification Methods Types

• Phenotypic methods: Based on reaction and physiological function in immunological methods.
• Genotypic methods: Based on RNA using nucleic acid amplification techniques like PCR

Role of Taxonomy in Diagnostic Microbiology

• Facilitates communication between microbiologists with universal names.
• Allows for recognizing emerging pathogenic microorganisms, emerging infections, and diseases caused by microorganisms.
• Helps understand mechanisms of antimicrobial resistance.