Microbiology Foundations & Modern Context

Course Logistics & Pedagogical Framework

• Duration & Delivery: 4-week block focusing on microbiology, infectious diseases, immunology, and epidemiology.
• Content Tags: Used to signal difficulty or sensitive clinical material; today’s tag = “extremely boring science words.”
• Learning Resources
  • ~11–12 pre-recorded lectures
  • Weekly tutorials with worksheets
  • Online activities + quizzes (quizzes = 10 % of final grade – participation only)
  • Week-7 microbiology test (30 % of final grade)
• Lecturer’s Confidence: Historic cohorts perform well; enthusiasm precedes the rise of AI.

What Is Microbiology?

• Study of organisms too small for naked-eye observation.
• Major groups covered: bacteria, viruses, fungi, protozoa.
  • Mentioned but not examined in this course: archaea & prions (misfolded infectious proteins).
• “Camping-van” analogy: most microbes are single-celled, self-contained units; others multicellular or even sub-cellular (viruses, prions).
• Ecological importance:
  • Oxygen production
  • Waste decomposition
  • Human digestion
  • Industrial bioprocesses
• Asymmetrical dependency: “We’d die without microbes; they’d do fine without us.”

Evolutionary & Historical Timeline

LUCA (Last Universal Common Ancestor)

• Single cell/consortium estimated ≈ 4.2 × 10^9 years ago.
• Thrived in volcanic, anoxic Earth using H₂ and CO₂; possessed large genome + rudimentary immunity.
• Spawned three major lineages:
  \text{Bacteria} \leftarrow LUCA \rightarrow \text{Archaea} \rightarrow \text{Eukaryotes}
• Philosophical aside: “Alien seeding?”—humorous conspiracy, not research.

Pre-Microbiology Human History

• Miasmatic theory: disease blamed on “bad smells.”
• Black Death (14ᵗʰ c.)
  • Agent: Yersinia pestis carried by flea-infested rats.
  • Mortality: Europe “decimated” (≈25–50 % population).
  • Plague doctors’ leather beak masks stuffed with aromatics.
• Early 20ᵗʰ c. killers: pneumonia, tuberculosis, cholera, gastroenteritis, malaria.
• Pandemics:
  • 1918 Spanish Flu
  • 2019 COVID-19 (a 101-y interval)
• Ongoing plague: Arizona pneumonic-plague death 07 Dec 2025 (first US fatality since Feb 2007).

20ᵗʰ-Century Breakthroughs

Epidemiologic Transition

• Data (2019 global): Non-communicable diseases (cardiovascular, cancer) now exceed infectious disease burden—yet infections remain a continual threat.

Contemporary & Emerging Threats

• COVID-19 persistence.
• Avian-origin Influenza (H5-type) now endemic in US dairy cattle; sporadic human spillover but no sustained person-to-person spread yet.
• Mpox (formerly Monkeypox): post-2022 mutation enabled global circulation; less lethal than smallpox yet clinically serious.
• Antibiotic resistance: explains why GPs often offer only symptomatic care for viral/ear infections; lecture to explore mechanisms.
• Climate change: expands habitat for vectors (e.g.
  mosquitoes) → novel outbreaks when naïve populations exposed; overwhelms health systems.

Metric Micro-Measurement

Base Conversions

{1\,\text{m}}=10^2\,\text{cm}=10^3\,\text{mm}=10^6\,\mu\text{m}=10^9\,\text{nm}

Size Spectrum (log-scaled)

Suggestion: Watch linked 2-min POV YouTube animation for intuitive scaling.

Binomial Nomenclature

• Devised by Carl Linnaeus (18ᵗʰ c.) to standardize biological names.
• Each organism has Genus + specific epithet:
  • Italicize or underline both words.
  • Capitalize Genus; lowercase specific epithet.
• Examples
  • Staphylococcus aureus
  • Giardia lamblia (intestinal protozoan)
  • Viruses: practical exception—“SARS-CoV-2” not italicized, caps variable.
• Prevents ambiguity: cougar = mountain lion = puma = one species Puma concolor.

Cell Biology Fundamentals

Eukaryotic Cell (reference)

• Plasma membrane: flexible phospholipid bilayer.
• Nucleus: membrane-bound repository of chromatin → chromosomes during mitosis.
• Organelles (mitochondria, ER, Golgi, etc.) confer compartmentalization.

Prokaryotic (Bacterial) Cell

• Key contrasts to eukaryotes: no membrane-bound nucleus, fewer organelles, smaller size, rigid wall.

Ethical, Philosophical & Practical Implications

• Antibiotic stewardship: urgent to curb resistance—balancing immediate patient relief vs. long-term drug efficacy.
• Pandemic preparedness: surveillance (Koch’s postulates 2.0), vaccine equity, global cooperation.
• Climate adaptation: vector control, infrastructure resilience.
• One-Health perspective: interdependence of human, animal, and environmental health highlighted by zoonoses (bird-flu, Mpox).

Numerical & Conceptual Quick-Reference

• LUCA \approx 4.2\times10^9\,\text{yr BP}
• Pandemic spacing: 1918 \rightarrow 2019 = 101\,\text{yr}
• Plague fatality timeline: 07/12/2025 - 02/2007 first US death in 18 y.
• Microbiology test weight: 30\,\%; quiz participation: 10\,\%.

End-of-Lecture Synthesis

1. Microbiology examines invisible life—bacteria, viruses, fungi, protozoa—integral to planetary systems and human health.
2. Life’s shared origin (LUCA) underscores unity and ancient microbial dominance.
3. Germ theory (Koch) replaced miasma; antiseptics, antibiotics, vaccines revolutionized survival.
4. Metric prefixes allow precise scaling from nanometers to meters; viruses are ~1000× smaller than human cells.
5. Linnaean binomial nomenclature provides universal, two-word scientific names—italicized, genus-capitalized.
6. Prokaryotes: small, wall-encased, nucleus-free; eukaryotes: larger, compartmentalized.
7. Contemporary threats (COVID-19, bird-flu, Mpox, resistance, climate) demand vigilance, research, and policy.

“Nobody gets out of life alive without at least one cold or flu.” – Lecturer’s reminder of microbes’ ubiquity.