Microbes

Aerobes

• require O2 for growth/survival

• Obligate Aerobes: need full Oxygen for cellular respiration (~21%)

• Microaerophiles: need low concentration O2 to thrive (~1%)

Anaerobes

• don’t require O2 for survival

• Obligate Anaerobes: killed by atmospheric oxygen levels

• Facultive Anaerobes: can carry out respiration if O2 is present

Microbes

tiny living organisms too small to be seen with naked eye (humans provide environment to microbes)

Parasitic Relationship

one organism benefits from the expense of other

Symbiotic Relationship

both organisms benefit

Commensalism

one benefits, other doesn’t suffer

Bacteria

• single-celled, no nucleus

• ubiquitous

• most common microbe

• some can be pathogenic

• prokaryotic

Ex: e. coli

Bacteria Replication

replicated via binary fission, which increases genetic diversity and is vital to species success (asexual reproduction)

Vertical Transmission

passing genetic material from parent to offspring

Horizontal Transmission

passing genetic material between individual bacteria and across species lines (drives rapid evolution and adaptation)

Transformation

uptake of naked DNA from environment to combine with chromosomal DNA

Transduction

bacteriophage transfers bacterial DNA to another bacterium

Conjugation

(bacterial sex) direct cell-to-cell contact to transfer material from one bacterium or another

• donor carries F-plasmid (bridge)

Gram Staining (bacteria)

stain to see which category the bacteria falls in or if infection is present

• + purple, blue

• - pink, red

Archaea

• used to be classified as bacteria, but differ

• found in extreme environments

• found in eukaryotic genes

Viruses

obligate intracellular parasites (cannot carry metabolic processes on their own; must invade host species

• composed of nucleic acid (DNA/RNA) and surrounded by protein coat

• viral diseases

Prions

infectious agent that carries transmissible spongiform encephalopathies (TSE)

• individual proteins that can be transmitted by ingestion, transfusion

• can induce shape-change in normal proteins

• can be spread by bloood

EX: Mad Cow disease

Sporadic

occurs at random and irregular intervals

Endemic

present at a steady level, low public health threat

Epidemic:

sudden levels of morbidity/mortality, high public health threat

Pandemic

disease spreading across continents and worldwide

Direct vs Indirect Transmission

Direct: contact, animal bites, transplacental (mother to child)

Indirect: vectors, airborne, vehicles

Microbiome

bacteria, viruses, and eukaryotic organisms that inhabit us

• totality of microbes in a defined environment

• varies globally and established at young age

Gut Microbiome

• metabolizes and regulates growth of immune cells

• affected by diet, which affects BMI

Clostridioides difficile infection (CDI)

• bacterial illness

• all infections nosocomial (acquired in hospital or healthcare facility)

• inflammation of colon and watery diarrhea

• Treatment: Fecal Microbiome Transplantation (FMT) to reconstitute microbiome

  • donation of microbiota via poop of a healthy person