Medical Microbiology MICR433/533 Overview

Course Information

• Course: Medical Microbiology MICR433/533
• Semester: Spring 2025
• Classroom: SDS 100
• Class Time: 10:00 AM – 10:50 AM
• Instructor: Radhey Kaushik
• Office Hours: Tuesdays, 1:00 PM – 2:00 PM
• Office Location: McFadden Biostress Building-SNP 252B
• Phone: 605-688-5501
• Email: [email protected]
• Course URL: https://d2l.sdbor.edu/
• Textbook: Nester's Microbiology: A Human Perspective by Anderson, Salm, and Beins; 10th edition, 2022

Grading Scheme (Undergraduate)

• Term Tests (3): 40 points each = 120 points total
• Final Exam: 80 points
• Quizzes, Assignments, In-Class Activities: 50 points total
• Total Points Possible: 250 points
• Grade Conversion: Final course grade will be out of 250 points and converted to 100%
• Graduate Students: 50 points additional essay assignment, totaling 300 points

Grading Standards

• A: 89.6% – 100%
• B: 79.6% – 89.5%
• C: 69.6% – 79.5%
• D: 55% – 69.5%
• F: Below 55%

Exam Schedule

• Term Tests: Monday, Feb 3rd; Friday, Feb 28th; Wednesday, April 2nd, 2025 (each test is 40 points)
• Final Exam: Monday, May 5th, 2025, 9:15 AM – 11:15 AM (covers material since the 3rd exam (~55-65 points) plus comprehensive questions from earlier material (~15-25 points))

Tests and Exams

• Format: Written tests may be a combination of essay, case study, short answer, multiple choice, fill-in-the-blank, matching, true/false, etc.
• Administration: Quizzes, term tests, and final exams are administered during scheduled class time/final exam time

Course Format

• Sections: The course material is divided into 3 sections:
  • Review of basic concepts in microbiology
  • Review of host responses to infection
  • System-by-system study of infectious diseases

Microbiology and Microorganisms

• Microbiology: The study of the microbial world
• Microorganisms/Microbes: Existed for several billion years; all higher life forms evolved from microscopic forms; required for all organism survival

Microbiology and Microorganisms (Microbes)

• Characteristics: Can change their properties, are capable of rapid adaptation/evolution due to their rapid and short generation time and relatively simple genome; are very biodiverse; are both beneficial and harmful

The Human Microbiome

• Population: Skin and mucosa are populated with normal microbiota or normal flora
• Ratio: Many sources state there are 10 times as many microbial cells as human cells, but more accurate estimates suggest a closer ratio of 3:1 to 1:1

The Human Microbiome Project

• Started: 2007
• Methods: Used DNA sequencing technologies to characterize microbial communities inhabiting the human body
• Definitions: The term "microbiome" has two overlapping meanings:
  • The total genetic content of a microbial community
  • The microbial community itself

Human Microbiome Roles

• Essential Roles: Preventing disease by competing with pathogens; aiding in food degradation; promoting immune system development; influencing allergies, asthma, and other diseases; affecting brain chemistry, behavior, and weight gain.
• Disturbances: Can create imbalances, causing harm to a person's health

Microorganisms in the Environment

• Recycling Masters: Microorganisms are the masters of recycling
• Oxygen Production: Various photosynthetic microorganisms produce oxygen
• Nitrogen Recycling: They recycle and use atmospheric nitrogen, converting it into a form other organisms can use (nitrogen fixation)

Microorganisms in the Environment (continued)

• Material Degradation: Microorganisms degrade materials that other organisms cannot
• External Degradation: Examples include cellulose degradation in plants (leaves, fallen trees) used for sewage and waste-water treatment
• Internal Degradation: Examples include cellulose degradation in the digestive tracts of animals (cattle, sheep, deer)

Commercial Benefits of Microbes

• Food Production: Bread, beer, fermented drinks, yogurt, buttermilk, cheese, probiotics
• Bioremediation: Using microbes to degrade toxic materials and environmental pollutants (sewage and wastewater treatment, petroleum, PCBs, DDT, trichloroethylene, oil spills, radioisotopes)

Commercial Benefits of Microbes (continued)

• Commercial Products Synthesis: Cellulose, amino acids, hydroxybutyric acid, hydrogen gas, ethanol, oils, insect toxins, and antibiotics
• Biotechnology: Using microbiological and biochemical techniques to solve problems (medically important products like insulin, recombinant proteins, vaccines, resistant plants, and gene therapy)

Microbes as Research Tools

• Model Organisms: Microorganisms are great model organisms for studying metabolic and genetic properties
• Cellular Similarities: All cells are composed of similar chemical elements and synthesize their structures using similar mechanisms
• Ease of Study: Bacterial study is often easier and faster than studying other complex organisms; Bacteria grow rapidly in inexpensive media.

Microbes and Disease

• Beneficial Microbes: Most microbes are beneficial (~87%) and are not harmful
• Disease Causing Microbes: A small minority (~3%) of microbes cause disease (pathogens); 10% are opportunistic microbes.
• Medical Microbiology Focus: The study of disease-causing microbes (pathogens)—viruses, bacteria, prions, fungi, and protozoa

Microbes causing Illness (continued)

• Historical Impacts: Infectious diseases have impacted humans, animals, plants, and microbes for many years; More people died from influenza in 1918–19 than from WWI, WWII, Korean, Vietnam, and Iraq Wars combined
• Past Examples of Disease Impact: Smallpox virus killed millions; Plague (1347-1351) killed 25 million; Foot and mouth disease outbreak in England (2001) implicated deaths of 4 million animals; African swine fever impacting pig populations recently

Microbes and Disease (continued)

• Modern Control Measures: Modern sanitation, vaccination, quarantine methods, and the effective use of antibiotics has significantly reduced infectious disease incidence
• Continued Challenges: The death rate from infectious diseases has decreased over time, but infectious diseases remain common, especially in developing countries

Remaining Major Challenges

• Emerging Infectious Diseases (EIDs): Infectious diseases that have emerged in recent decades (COVID-19; Ebola; congenital Zika syndrome; severe acute respiratory syndrome (SARS); Middle East respiratory syndrome (MERS); Hepatitis C; certain influenza types; Lyme disease; acquired immunodeficiency syndrome (AIDS); Hanta virus pulmonary syndrome; Mad-cow disease )
• More Common Existing Diseases: Long-established diseases such as malaria and tuberculosis have become more common in recent times.

"New" and Newly Recognized Infectious Diseases in Humans & Animals

• Geographic Variations of Disease: Infectious diseases impact human populations globally, with different countries and geographical regions being associated with different infections

Reasons for Emerging or Re-emerging Infectious Diseases

• Pathogen Adaptability: Pathogenicity changes (e.g. HIV, COVID-19); virulence changes (E. coli O104:H4)
• Changing Lifestyle Factors: Changing lifestyles provide opportunities for infectious agents to spread (e.g. hantavirus pulmonary syndrome)
• Antibiotic Resistance: Resistance to antibiotics or antimicrobial medications (e.g. tuberculosis, malaria)
• Vaccination Gaps: Deficiency in childhood vaccinations (measles)
• Elderly Population Susceptibility: Elderly people are more susceptible to variety of infections
• Immunity Deficiencies: Immunocompromised individuals susceptible to various infections (e.g. tuberculosis).

Chronic Diseases Caused by Bacteria/Viruses

• Peptic Ulcers/Indigestion: Bacteria Helicobacter pylori discovered to be a recent cause of chronic indigestion
• Cervical Cancer: Human Papillomavirus (HPV) is a cause of cervical cancer
• Chronic Diseases: Infectious microbes have important roles across various chronic illnesses

Microbial World Classifications

• Domains: All living microorganisms are classified into three main groups/domains: Bacteria, Archaea, and Eucarya
• Prokaryotes: Members of bacteria and Archaea are known as prokaryotes (lack a true nucleus)

The Bacteria

• Characteristics: Single-celled prokaryotes; lack a true nucleus and intracellular lipid-bound organelles; genetic information stored in the nucleoid region; commonly spherical, cylindrical, or spiral; have rigid cell walls containing peptidoglycan; multiply via binary fission; may have appendages (flagella) for motion/pathogenicity

The Archaea

• Similarities to Bacteria: Single-celled prokaryotes, similar shapes and sizes, have cell walls, use flagella for movement, and multiply by binary fission
• Differences: Do not contain peptidoglycan in their cell walls
• Extreme Environments: Tend to thrive in extreme environments (e.g. high salt, high temperatures, extreme cold)

The Eucarya

• Eukaryotes: Members of the Eucarya domain
• Characteristics: May be single-celled or multicellular; always contain a well-defined membrane-bound nucleus; contain internal cell organelles (mitochondria, chloroplasts); internal scaffolding (cytoskeleton) giving the cell shape; are more complex than prokaryotes
• Examples: Algae, fungi, protozoa, and multicellular parasites (helminths)

Scientific Names of Microbes

• Binomial System: Used to name microbes
• Genus and Species: First word is the genus (capitalized), second word is the species (not capitalized)
• Italics: Both words are italicized
• Abbreviations: First word usually abbreviated with first letter capitalized (e.g., E. coli)
• Strain: Members of the same species can have subtle differences, and strains are further designated (e.g., E. coli strain B or E. coli strain K12).
• Informal Naming: Informal names for groups often resemble genus names but are not italicized

Morphology of Bacteria

• Shape Diversity: Bacteria display various shapes (cocci, bacilli, vibrio, spirilla, spirochetes, pleomorphic) which are significant in classification and identification
• Common Shapes: Coccus (spherical); bacillus (rod-shaped); vibrio (short curved rod); spirilla (curved rod long enough to form spirals); spirochetes (long spiral-shaped cells with flexible cell walls); pleomorphic (bacteria with diverse shapes)

Grouping of Bacteria - Colony Structure

• Colony Structure: The colony structure is related to how bacteria divide
• Shape and Types: Bacteria can divide in different planes resulting in diverse forms (chains, packets, clusters)
• Identification Guidance: The shape of the colony structure helps with identifying bacteria

Acellular Infectious Agents

• Composition: Viruses, viroids, and prions are acellular; meaning they are not composed of cells
• Life Status: Viruses, viroids, and prions cannot reproduce independently and thus are considered non-living
• Specific Classifications:
  • Viruses: Consist of a protein coat surrounding a nucleic acid (RNA or DNA); capable of only multiplying within a living host cell.
  • Viroids: Consist only of RNA; Cause plant diseases; much smaller than viruses
  • Prions: Consist only of protein with no nucleic acid; cause neurodegenerative diseases

Acellular Infectious Agents (Table 1.4)

• Summarized characteristics of viruses, viroids, and prions (e.g., composition, replication)

Next Lecture Topics

• Cells and Observation Techniques: Chapter 3, focusing on selected topics relating to cell structure, observation methods, and related systems.

Explore the key details of the Medical Microbiology course MICR433/533 for Spring 2025. This includes important information about grading schemes, exams, and resources for success in the class. Stay informed about the expectations and structure of the course as outlined by the instructor.