Microbiology Chapter: Disease and Prevention

Microbiology Course Information

• Course Name: Microbiology MCB2004
• Meeting Times: MWF 12pm-12:50pm, HCB0102; M 4:30-5:30pm, HCB0102 or Zoom (details to follow)
• Instructor: Dr. Kathryn Jones
• Instructor Email: [email protected] (use this address!)
• Teaching Assistant (TAs): Gabrielle Fisher and Calvin Mackey
• TA Email: (See Canvas course site)
• Office Hours: Dr. Jones: 1) Monday 12:50pm after class, 2) Monday 5:30pm-?, after recitation. Specific times for TAs available on Canvas.

Microbiology Syllabus

• Refer to the syllabus continuously for semester-long questions.
• First quiz will include questions from the syllabus.
• First-day attendance recorded by completing the Pre-Emergency Contact Form.

Why Study Microbiology?

• Microbiology important due to emerging/emerging infectious diseases like SARS-CoV-2/COVID-19 and H5N1-Bird flu.
• Hospital-acquired infections (nosocomial infections) are serious and easily spread.
• Microbes harmless to one person can be dangerous to immunocompromised individuals.
• Drug-resistant bacteria (e.g., Methicillin-resistant Staphylococcus aureus, Clostridium difficile) pose a constant food-safety concern.
• Many useful food additives, like xanthan gum, are produced by bacteria.

Mortality Rates

• Crude mortality rates for all causes, noninfectious diseases, and infectious diseases were shown in a graph spanning the years 1900-1980.
• Key events, such as plague transmission end, municipal water chlorination initiation in the U.S., the first recorded use of penicillin, the Salk polio vaccine introduction, and the first AIDS case were visualized by the data points on the chart.

SARS-CoV-2/COVID-19 in context

• 2020 was the first year, since 1946, where deaths per 100,000 people exceeded 1,000.
• A graph showing US deaths from 1918 Spanish influenza and deaths from 1946 up to 2020 and 2008.

Important Microorganisms

• Zika virus (in neural cells)
• Ebola virus
• Human papillomavirus (causes genital warts, cervical cancer risk)
• MRSA
• Neisseria meningitidis
• Chikungunya virus
• Plasmodium falciparum (malaria parasite)
• Liberibacter asiaticus (citrus-greening disease)
• Listeria

How to Study Unknown Microorganisms

• Isolate: Can it grow outside a host?
• Fight It: Is it susceptible to antibiotics or antivirals?
• Prevent Transmission: How does it survive in the environment? Is it airborne?

What are Microbes?

• Microbes are living creatures (excluding viruses) with complex biological processes, including metabolism, growth, and reproduction.
• Microbes are much more diverse than animals or plants.
• Microbes vary in size and aren't always too small to see by the unaided eye (some are multicellular)
• Some, such as biofilms, are often visible
• Six major groups of microbes are viruses, bacteria, archaea, eukaryotes, fungi, protozoa, and algae.

Measuring Microbes

• A microbe is generally less than 1mm during its lifespan.
• Microbes are usually too small to be seen by the unaided eye (0.4mm).
• Units of measurement: millimeter (10^-3 m), micrometer (10^-6 m), nanometer (10^-9 m), Angstrom (10^-10m), picometer (10^-12 m). Measurements are relative in size of microbes on scales of cells and their components.

Relative Sizes of Specific Microbes

• Approximate sizes of various microbes (e.g., Varicella-zoster virus, Prochlorococcus, Escherichia coli, Spirogyra, Pelomyxa).

Layers of Masks Needed

• Increased layers of fiber in a mask improve the ability to stop small particles.

How are Microbes Related?

• Archaea have unique adaptations to extreme environments.
• Unusual biochemistry in archaea is a basis for speculation about life on other planets. Microbes from different groups are related via evolutionary trees of cellular organisms, which include eukaryotes, prokaryotes, and, archaea.

The Microbial Family Tree

• Microbial species classification is challenging due to various factors (difficult to distinguish shapes, often reproduce asexually, exchange DNA without reproducing)
• Biochemical procedures (e.g., Gram stain) are used for classification and so are DNA sequences.
• Bacteria are named according to established taxonomic classifications

Bacteria

• Prokaryotic organisms without a nucleus.
• DNA in the cytoplasm.
• Cell walls made of peptidoglycans.
• Divide by binary fission.
• Various energy sources (organic chemicals, inorganic chemicals, photosynthesis).
• Some bacteria can move using flagella.
• Many bacteria exist in human and other environments, with some beneficial and pathogenic varieties.

Archaea

• Prokaryotic; lack peptidoglycans in cell walls
• Many lack cell walls
• Live in extreme environments (e.g., high salt concentration, extremely high temperatures)
• Unique biochemistry.

Fungi

• Eukaryotic organisms; chitin cell walls; derive energy from organic chemicals
• Many fungi are multicellular, with masses of filaments called hyphae, and some are unicellular, like yeasts.

Protozoa

• Eukaryotic; absorb or ingest organic chemicals.
• Mobility via pseudopods, cilia, or flagella.
• Many beneficial protozoa consume waste.
• Some protozoa cause diseases, like malaria (Plasmodium).

Algae

• Eukaryotic organisms; resemble plants in some ways including cellulose cell walls
• Use photosynthesis for energy production
• Produce oxygen in addition to various organic compounds
• Help maintain atmospheric gases by CO2 consumption

Endosymbiont Theory

• Eukaryotes arose from prokaryotic organisms.
• Mitochondria and chloroplasts evolved from engulfed bacteria (endosymbiosis).

Viruses

• Acellular (not complete cells).
• DNA or RNA genome surrounded by a protein coat called a capsid, and possibly an envelope.
• Replicate only in living host cells (intracellular parasites).
• Now being used in vaccines and gene therapy.

Multicellular Parasites

• Eukaryotic; multicellular animals, flatworms, and roundworms (helminths).
• Microscopic stages in life cycles. Examples of some parasites (e.g., parasitic guinea worm)
• Various foundations that work to treat human infections by using various parasites (e.g., Carter Foundation).

Knowledge of Microbiology

• Allows people to control microbial growth through various methods (e.g., preventing food spoilage, controlling disease occurrence)
• Cultivating microbes important for generating food, medications, and cleaning waste/recycling.

Course Assignments

• Details on pre-emergency contact form, career goals survey, and a forthcoming vaccine survey assignment.

Additional Information

• Lecture 2: Introduction to the history and scope of microbiology
• Scientific method: steps for understanding microbes
• Microbiological discoveries (e.g., Hooke and Leeuwenhoek)
• Spontaneous generation debate, including the work of Redi and Pasteur
• Germ Theory of Disease
• Koch's Postulates
• The birth of modern chemotherapy (e.g., discovery of penicillin, synthetic drugs)
• Milestones in Second and Third Golden Ages of Microbiology
• Types of modern microbiology (e.g., immunology, normal microbiota)
• Emerging infectious diseases (viral, bacterial, protozoal) with examples (e.g., Spanish flu, Avian flu, SARS, Zika virus, Ebola, Marburg, HIV/AIDS, COVID-19, MRSA)
• Microbiology for human welfare (benefits and applications in areas like biotechnology and bioremediation)
• Microbes and disease, including biofilms.

Test your knowledge on key concepts in microbiology related to disease transmission and prevention. This quiz covers crucial figures like Joseph Lister and Robert Koch, along with principles of germ theory and public health measures. Explore the challenges in classifying microbial species and more.