Chapter 1: Microbial World and You

microbe (microorganism)

too small to be seen with unaided eye (need microscope)

bacteria

• bacteriology

• ex. e.coli, salmonella

virus

• virology

• coronavirus, herpes virus ← (viral families), HIV

fungi

• mycology

  • yeast: warm

  • mold: cold

parasites

• parasitology

• protozoan parasites, worm

  • ALWAYS take advantage/harm host

key ecological roles

(microbes’ natural role)

1. decomposers of organic wastes: bacteria/fungi recycle back to nature

2. photosynthesis: bacteria (cyanobacteria)/protozoa (algae) produce oxygen

3. nitrogen fixation: bacteria in soil capture free N2 → nitrates → food for plants

bioremediation

(artificial use of microbes)

1. oil spills: bacteria remove toxins from ocean

2. drain clogs: bacterial enzymes unclog w/o harmful chemicals

commercial uses

• bacteria:

  • dairy products (cheese, yogurt)

  • cosmetics (Botox → bact. toxin)

• fungi (yeast):

  • alcohol (wine, beer)

  • breads (yeast → sugar → CO2 gas → bread ↑)

applications in medicine

produce antibiotics to kill harmful bacteria

• ex. penicillin (fungal molds in gills of mushroom) and neomycin

HARMLESS microbes

• non-pathogenic

• 99% of bacteria

• sometimes beneficial

1. key ecological roles

2. bioremediation

3. commercial uses

4. applications in medicine

HARMFUL microbes

• pathogenic: live agents capable of causing disease (harm) in a host

• <1% of bacteria

  • neisseria gonorrhoeae (bact)

  • tinea pedis (fungal yeast)

normal microbiota

“normal flora” resident microbes in/out body

• produce useful substances (E.coli in colon → vit K → blood clots)

• mass reproduction (no room for invading bact.)

  • ex. streptococci (mouth), staphylococci (skin)

van Leeuwenheok

“father of microbio”

• made lenses to observe microbes/draw

Jenner

“father of vaccines”

• first vaccine for smallpox

  • milkmaids w/ cowpox virus → cowpox pustule → inject healthy human host → NO SMALL POX!

Pasteur

• disproved “spontaneous generation” (non-living thing → thing) w/ beef broth/bent neck of flask (cloudy vs. non-cloudy)

• established “Theory of Biogenesis” (living thing → living thing) later supported by Koch’s “Germ Theory of Disease”

Lister

• surgeon use antiseptics to kill microbes

  • ↓ # surgical infections/death

  • applied “Germ Theory of Dz” (Koch) to medical procedure (pathogenic microbes → Dz)

Koch

• “Germ Theory of Dz” live pathogens (harmful microbiota) → infectious dz

• discovered bact. in cattle/sheep → anthrax

• Koch’s postulates: steps/sets of rules relating specific microbe to specific dz (s/s)

Ehrlich

• tx of dz w/ drugs/drug therapy (chemotherapy against Syphilis)

• “magic bullet” drug selectively target/destroy pathogen (no harm to host)

Fleming

• first abx (Penicillin) from fungal mold

  • inhibited growth of surrounding bact. d/t penicillium

Marshall

proved bacterium H.pylori → peptic ulcers → gastric cancer

Emerging Infectious Diseases (EID)

dz new/changing & ↑ or potential to in future

• COVID-19, Zika, West Nile, Influenza

key factors for EIDs

• global travel

• rapid urbanization: disturb soil → airborne path.

• natural disasters: no electricity → no clean H2O facilities → diarrheal dz

• climate change: wet (mosquito dz) vs. dry (airborne dz) areas

• frequent gene mutations

• developing drug resistance