Lecture 1 Notes - Med Micro

what are the three main problems in microbiology?

1. infectious diseases

2. antibiotic resistance

3. lack of vaccination

what are some examples of infectious diseases?

covid-19, listeria, measles, monkey pox, cyclospora

what is a main re-emerging infectious disease?

tuberculosis (TB)

what are nosocomial infections?

hospital acquired infections (ex: C.diff)

what is antibiotic resistance?

occurs when bacteria change and grow (MRSA, CRE..)

what can occur due to lack of vaccination?

measles, whooping cough, etc

approximately 70% of all antibiotic use in the U.S. is in what?

animals (livestock)

antibiotic concentrations used on livestock are at what level?

sub-inhibitory levels

what are sub-inhibitory levels?

lower than the minimum inhibitory concentration

what does too much antibiotic resistance do to livestock?

triggers stress responses, especially due to the small spaces

what myth started in the late 1990s due to the measles?

that the MMR vaccine causes autism

when did the measles cases begin to rise again in the U.S?

during covid…(another dramatic increase in 2025/26)

what is the infection rate for measles?

90% (one of the most infectious diseases)

what is the hospitalization rate for the measles?

25%

what is the encaphalitis (brain swelling) rate for measles?

0.1%

what is the death rate for measles?

0.1-0.2%

what is the rate of children who contract pneumonia due to measles?

5%

what is the risk of allergic reaction from the measles vaccine?

0.0000035%

what does the whooping cough do (differs between children and adults)?

for children, it is terrible and can break ribs; for adults, it is like a regular cough

what is the death rate in infants for whooping cough?

1-2%

how does the whooping cough spread?

often transmitted to infants due to adult waning immunity or lack of vaccination

how has the polio vaccine changed the amount of cases from the 50s-70s?

went from 15000 to 10 cases

what type of infection is the whooping cough?

bacterial infection

what type of infection is polio?

viral infection

what cell type is bacteria?

prokaryote

what cell type are protists?

eukaryote

what cell type are fungi?

eukaryote

what cell type are viruses?

acellular

what cell type are helminths?

eukaryote

what cell type are prions?

acellular

what was the bloodletting practice?

when physicians would take large amounts of blood hoping to rid the patient of the illness; not proven to do anything helpful

what happened to George Washington?

3 different physicians took 4L of his blood (40%); he fell ill on Friday the 13th and died on the 14th, and a bad situation was made worse

What was the graveyard dance in the mid 1600s?

a ritual performed to “ward off the plague” that didn’t actually work; they just had no idea what it came from

what is science always fighting against?

human old beliefs and mindsets

who were some of the early microscopists?

Robert Hooke and Antonie van Leeuwenhoek

Who discovered the visualization of small living objects?

Robert Hooke

What did Robert Hooke call the small spaces in cork?

“cella”…later become cell

Who had the first visualization of bacterial cells (not viruses)?

Antonie van Leeuwenhoek

what did Antonie van Leeuwenhoek see?

bacteria that he called “wee animalcules”, which were actually microbes

Who were some of the individuals who introduced aseptic technique to medicine?

Ignaz Semmelweis, Florence Nightingale, and Joseph Lister

Who was the Hungarian physician who began washing hands prior to entering maternity wards?

Ignaz Semmelweis

what did washing hands before dealing with births do?

allowed for fewer infections and deaths

Who established formal aseptic practices in nursing?

Florence Nightingale

Who was a british surgeon who is known as the father of modern surgery for cleaning wounds (antiseptic usage)?

Joseph Lister

historically, what caused infectious diseases?

1. spontaneous generation (life generating from non-living things)

2. biogenesis (life generating from life)

what are the current observations made that led to the development of the germ theory of disease?

1. contagious diseases

2. visualization of microscopic organisms

3. aseptic technique saving lives

Who came up with the experiment that determined that maggots in decaying meat were the offspring of flies?

Francesco Redi

Who came up with the experiment that determined that sealing a flask of meat broth that is boiled fails to spoil because it is sterilized (no microorganisms)?

Lazzaro Spallanzani

Who created the swan neck flask experiments and determined that microbes are everywhere, and are carried by airborne particles (biogenesis)?

Louis Pasteur

Who determined that spontaneous generation was false?

Louis Pasteur

Who directly linked microbes to diseases and helped determine disease origin?

Robert Koch

What did Robert Koch receive a nobel prize for?

his work on TB

Anthrax + Koch’s Postulates step one

organism present in all disease cases (not in healthy individuals)

Anthrax + Koch’s Postulates step 2

organism is isolated from diseased host and is grown as a pure culture

Anthrax + Koch’s Postulates step 3

organism should cause the disease when it is inoculated into a susceptible host (not well applied to viruses)

Anthrax + Koch’s Postulates step 4

organism must be re-isolated from the inoculated, diseased animal

what is a microbiome?

human microflora/normal microbiota

are all microbes harmful?

no!

what can occur when some microorganisms are wiped out?

can lead to a bacterial disease known as C.diff (kills good gut bacteria)

most microbial cells are what?

beneficial to your body; there are 10x more of them than your own cells

how are organisms named?

by genus + species, or named after a person

example of an organism named by genus + species

escherichia coli

example of organism named after a person

helicobacter pylon

what is a strain?

genetic variants of the same species

what often leads to new strains?

mutations and gene transfer

how are strains named?

include numbers/letters after species name (ex: E.Coli K-12)

what is a symbiotic relationship?

a relationship that exists when 2 or more organisms are closely connected

what is microbiota/commensals?

microorganisms found in or on all multicelluar organisms

what are pathogens?

a microorganism that has a parasitic relationship with its host (like a parasite)

the term parasite is mostly associated with what?

helminths (worms) and protozoans

how do you classify bacteria?

1. gram reaction (±)

2. shape and size

3. growth requirements

4. physical components (structure, morphology)

what are prokaryotes?

bacteria and archaea

do prokaryotes have a nucleus?

no

do prokaryotes have membrane-bound organelles?

no

with prokaryotes, all known pathogens are in what domain?

domain bacteria

what does domain archaea include?

extremophiles (harsh environment living; only one human species ID’d so far)

what are eukaryotes?

fungi, protozoa, and helminths

do eukaryotes have a nucleus?

yes

do eukaryotes have membrane bound organelles?

yes

what microbes are acellular?

viruses and prions

what are the three domains of life?

bacteria, archaea, and eukarya

what is the endosymbiant theory?

that mitochondria and chloroplasts are theorized to have been free living bacterial cells at one time in which they contained their own bacteria-like DNA

what could mitochondria and chloroplasts do because of the endosymbiont theory?

transcribe some of their own tRNAs and have their own ribosomes

what happened to mitochondria and chloroplasts?

they were engulfed and maintained by primitive eukaryotes as powerhouses

eukaryote: organisms

unicellular (protists + yeast) and multicellular (animals, plants, fungi)

eukaryote: size

much larger than prokaryotes

eukaryote: cell division

asexual (mitosis) and sexual (meiosis)

eukaryote: plasma membrane

defines the cell; often contain sterols

eukaryote: cell wall

only in plants, fungi, and certain protists

eukaryote: nucleus

yes!

eukaryote: ribosomes

80S (cytoplasm, rough ER); 70S (mitochondria, chloroplasts)

eukaryote: genetic material

DNA

eukaryote: chromosomes

multiple linear chromosomes

eukaroyte: membrane-bound organelles

yes!

prokaryote: organisms

unicellular archaea and bacteria

prokaryote: size

usually much smaller than eukaryotes

prokaryote: cell division

asexual (binary fission; divide into two)

prokaryote: plasma membrane

rarely contains sterols

prokaryote: cell wall

in most of them (except mycoplasma + L forms)

prokaryote: nucleus

no!