LEARNING OBJECTIVES
What is a microorganism?
A microorganism or microbe is an organism of microscopic size, which may exist in its single-celled form or as a colony of cells.
Know the different types of microorganisms- this includes viruses, bacteria, archaea, protozoa, fungi, helminths and algae.
Viruses are obligate intracellular parasites. Bacteria and archaea are prokaryotes on the other hand protozoa, fungi, helminths and algae are eukaryotes.
Bacteria and archaea inhabit the most diverse range of habitats on eath. (deep sea vents, deep earth surface, high temperature, high salt,,,)
Viruses are made up of DNA, protein coat to protect genetic material and lipid envelope for the virus outside.
Protoza are single cellular eukaryotes including amoeba. They move by cilia, flagella and amoeoid movement.
Fungi is unphotosyntheic eukaryotes. Yeast and mould are defined whether they are multicellular or unicellular.
Algae is photosynthetic eukaryotes. They live in sea. Small algae is usually main food source for sea animals and they are usually phytoplankton, and multicellular algae and seaweed and kelphs
Helminths are worm-like eukaryotes. They can range in size from smaller than 1cm to more than 10m. There are nematodes which are round worms and platyhelminths which are flat worms including tapeworms and flukes.
Know what features these microbes have, how to characterise them and the fields of study they belong to.
Growing and idenitifying microbes
Understand where microbes acquire energy and carbon sources for growth.
-Energy source : Light (phototroph), Chemical compounds (chemotroph)
-Carbon source : CO2 (autotroph), Organic compounds (hetero)
Understand the different growth conditions (chemical and physical requirements) which includes the effects of oxygen on the growth of bacteria.
Know the concepts of cell growth that include: Binary fission, exponential growth and growth phases.
Growth Phases
-Lag-> exponential growth phase/ log phase-> stationary phase -> death or logarithmic decline phase
During the lag phase , there is no increse in bacterial number when bacteria are introduced in a new environment.
In the log phase, bacterial number increase exponetially. Most bacteria reproduce by binary fission which means a asexual reproduction by a separation of the body into two new bodies. In the process of binary fission, an organism duplicates its genetic material, or deoxyribonucleic acid (DNA), and then divides into two parts (cytokinesis), There's a time when the rate of cell death is same as rate of cell division which is called stationary phase. In the death phase, numbers of dying bacteria in the culture increase faster than new cells are produced.
Microbes, disease and the human body
Understand definitions relating to human/microbe interactions.
Know the microbial contributions made by Jenner, Pasteur, Lister, Koch, Erhlich and Fleming.
-Jenner : father of immunology/ observed that milkmaids exposed to cowfox did not infected with smallpox.
-Pasteur : pasteurisation/ fater of microbiology/ Defined vaccines with attenuation theory, weakened viruses don't harm the host
-Lister : introduced handwashing to midwives and maternity wards/ antisepsis and sterlisation of surgical instruments
-Koch : postulates 4 criteria of relationship between microbes and diseases
-Erhlich : antibiotic discovery / kill infectious microbes and have no ill effects on the patients
-Fleming : first to observe living organism producing antibiotics
Understand how disease spreads within a host and between hosts. Also how differences in hosts affect disease
Disease can spread in three different ways
First in a contact way, disease can delivered by direct, indirect and in a droplets.
Disease can transmit via a medium from the host.
A vector is a living organism that transmit an infectious agent from an infected animal to a human or another animal.
-contact
-> direct : STDs
-> indirect : hair clothes skin
-> droplets : short distances
-vehicle
-> via a medium (water..)
-vector (A vector is a living organism that transmits an infectious agent from an infected animal to a human or another animal. )
-> mosquito bites
Host can have different prediposing factors such as age, sex, genetics, pre-existing disease, diet and so on
What is a microorganism?
halophiles -salt
thermophiles - heat
methanogens - methane
* However, one particular group of bacteria, the cyanobacteria or "blue-green algae," have left a fossil record that extends far back into the Precambrian - the oldest cyanobacteria-like fossils known are nearly 3.5 billion years old, among the oldest fossils currently known
* Mitochondria and chlroplasts have existed as prokaryote/bacteria and they became a part of eukaryotes.
Engulf/ eukaryotes engulf mitochondria and chlroplasts
nano meters (10^(-9)) / micro meters (10^(-6)) / milli meters (10^(-3))
VIRUSES
Facultative intracellular parasites are capable of living and reproducing in or outside of host cells. Obligate intracellular parasites, on the other hand, need a host cell to live and reproduce. Many of these types of cells require specialized host types, and invasion of host cells occurs in different ways.
They cannot live or reproduce without host cells. Invasion of host cells is needed for them to live.
BACTERIA AND ARCHAEA
-Pili : short, hair like structures are involved in reproduction and cell to cell contact.
-Flagella : a whip-like organelles that bacteria use to move about.
-Plasmid : circular double-stranded DNA molecules
-Prokaryotes have CELL WALL !!!
PROTOZA - EUKARYOTIC SINGLE CELLED ORGANISMS
HELMINTHS - EUKARYOTIC, MULTICELLULAR PARASITES
ALGAE - PHOTOSYNTHETIC EUKARYOTES
FUNGI - NONPHOTOSYNTHETIC EUKARYOTES
The left one is bacteria and the right one is algal cell.
Bacteria is prokaryote which doesn't have nucleus. Their genetic material (chromosomes/plasmid) is placed in cytoplasm, not in nucleus. They have pilli on the cell wall.
On the other hand, algae are eukaryotes which photosynthesis for their energy source in chloroplast.
They have nucleus inside the cytoplasm.
Growing and Identifying microbes!
Photo- means they generate energy from light (usually the sun but not always)
Chemo- means they get energy from chemical compounds through redox reaction involving organic and inorganic molecules
Auto- means that they synthesize all their molecule using CO2 as their starting point
Hetero- means that they consume organic compounds such as fats, proteins, sugar and etc to obtain their carbon
Oxygen, Carbon, Nitrogen, Sulfur, Phosphorus
-aero- 호기성의 with air
-anero- 혐기성의 without air
-obligate aerobe
-faculative anaerobe
-obligate anerobe
-aerotolerant anerobe
-microaerophiles
-Nitrogen :
from food / from inorganic ammonium ions NH4+ / soluble nitrates NO3- / gaseous N2 nitrogen fixers
* symbiosis 공생 , rhizobium 뿌리혹박테리아 and legumes 콩과..?
-Phosphorous , sulfur :
from food, from soluble ions such as phosphates and sulphates
sulphate (SO4)2- / phosphate (PO4)3-
-psychrophiles -> psychrotrophs -> Mesophiles -> Thermophiles -> Hyperthermophiles
mesophiles??
A hypertonic solution is any external solution that has a high solute concentration and low water concentration compared to body fluids.
The abbreviation pH stands for
potential hydrogen
It tells us how much hydrogen is in liquids—and how active the hydrogen ion is.
Hypertonic solutions are used for antimicrobial control, on the other hand,
salt and sugar are used to create hypertonic environment for microorganisms and are commonly used as food preservatives.
Packing food in salt or pickling it in a hypertonic solution of sugar or salt creates a hypertonic environment that either kills microbes or at least limits their ability to reproduce
.
Growing bacteria in the lab ->
Historically, this has been the way to obtain bacterial growth in order to determine which organisms are “normal flora” and which bacteria are “bad,” causing disease or infection. Culturing allows “bad” bacteria to be tested for susceptibility to certain antibiotics.
Normal flora are the microorganisms that live on another living organism (human or animal) or inanimate object without causing disease.
Bacteria replicate by binary fission, a process by which one bacterium splits into two. Therefore, bacteria increase their numbers by geometric progression whereby their population doubles every generation time.
lag, exponential, stationary, decline
Gangrene is death of body tissue due to a lack of blood flow or a serious bacterial infection.
The medium is soon depleted of nutrients and enriched with wastes. The stationary phase is often due to a growth-limiting factor such as the depletion of an essential nutrient, and/or the formation of an inhibitory product such as an organic acid.
1. Lag phase : no increase in number of living bacterial cells
2. Log phase/ exponential growth phase : exponential increase in number of living bacterial cells
3. Stationary phase : plateau in number of living bacterial cells; rate of cell division and death roughly equal
4. Death or decline phase : exponential decrease in number of living bacterial cells
PCR polymerase chain reaction
Polymerase chain reaction (abbreviated PCR) is a laboratory technique for rapidly producing (amplifying) millions to billions of copies of a specific segment of DNA, which can then be studied in greater detail. PCR involves using short synthetic DNA fragments called primers to select a segment of the genome to be amplified, and then multiple rounds of DNA synthesis to amplify that segment.
Flow cymetry
Flow cytometry is a lab test used to analyze characteristics of cells or particles. During the process, a sample of cells or particles is suspended in fluid and injected into a flow cytometer machine. Approximately 10,000 cells can be analyzed and processed by a computer in less than one minute.
Your sample of blood, bone marrow or tissue cells is placed in a suspension and injected into the flow cytometer machine. The cells are arranged in a single file line, and then passed in front of a laser beam, scattered light and fluorescent light. Next, the cells are counted and categorized. The data is stored in a computer and reported via a histogram or dot plot.
How do we count bacteria?
-turbidity of the culture
-absorbance of light
-metabolic activity
-mass (dry weight)
What instrument would you use to measure absorbance?
Absorbance is measured using a spectrophotometer or microplate reader
, which is an instrument that shines light of a specified wavelength through a sample and measures the amount of light that the sample absorbs.
Microbes, diseases and the human body
https://www.who.int/en/news-room/fact-sheets/detail/the-top-10-causes-of-death
The top 10 causes of death
Fact sheet on the 10 leading causes of death. In 2019, the top 10 causes of death accounted for 55% of the 55.4 million deaths worldwide.
www.who.int
Jenner -> milkmaid exposed to cowpox didn't contract smallpox
Vaccines work by activating immune system by presenting it with an agent that resembles a disease-causing microbe
(made usually from a weakened or killed form of the microbe or simply its toxins or surface proteins)
What are the names of the viruses that cause cowpox and smallpox? What must be true about the viruses for cowpox to be able to work as a vaccine against smallpox?
smallpox 천연두 cowpox 우두
Cowpox is a viral skin infection caused by the cowpox or catpox virus. This is a member of the Orthopoxvirus family, which includes the variola virus that causes smallpox. Cowpox is similar to but much milder than the highly contagious and sometimes deadly smallpox disease. Cowpox should also not be confused with cowpock, which is an alternative name for a condition called milker’s nodules, which is caused by a parapox virus.
Jesty -> used a daring needle
Pasteur -> pasteuriseation 저온살균
attenuation 감쇠
* Lister/ Semmelweis - Antisepsis and sterilisation of surgical instruments/ handwashing
In the 1840s, there was no such thing as germ theory (the theory that diseases are caused by organisms only visible with a microscope). People still suspected that diseases transferred from one person to another via toxic odors, not bacteria or viruses. This was called "miasma theory." In washing their hands, they probably wanted to be rid of whatever was causing a terrible odor, not kill germs that might wreak havoc on them or someone else.
Antisepsis 소독 sterilisation 살균
*Paul Erhlich - discover antibiotics
*Alexander Fleming - first to observe living organisms producing antibiotics
syphilis 매독
antibiotic 항생제
*Routes of transmission
-contact : direct, indirect, droplets
-vehicle : water, food, air
-vector : utilizes insects to transport the pathogen. Insects such as fleas, ticks, and mosquitos are unharmed by the pathogens they potentially carry but can transmit the bacteria or virus when they bite a host
*Prediposing factor
: 개인적, 유전적, 행동적, 환경적 요인
*local infection
: 국소감염
*systemic infection
: 전신감염
What is zoonosis ?
동물과 사람 사이에 상호 전파되는 병원체에 의하여 발생되는 전염병을 말한다.
A zoonosis is an infectious disease that has jumped from a non-human animal to humans.
-TB : 결핵
-Gonorrhoea : Gonorrhea is an STD(sexually transmitted disease) that can cause infection in the genitals, rectum, and throat. It is very common, especially among young people ages 15-24 years.
-MRSA : Methicillin-resistant Staphylococcus aureus (MRSA) infection is caused by a type of staph bacteria that's become resistant to many of the antibiotics used to treat ordinary staph infections.
-hospital acquired infections : 원내감염
* Strategies for dealing with or reducing antibiotic resistance 항생제 내성
-rational drug use
-infection control and prevention
-antimicrobial surveillance(감시)
-ban on OTC antibiotic
-educate motivate
-R&D drug/ vaccine
-immunization coverage
-hand hygiene
-std. Treatment guidelines
-New AMR programs
-AMR committee
-essential drug list
-national policy
-increased collaboration
Self-paced quiz
-> Localised infection : Penile infection and diarrhea
->Systemic infection : Rabies, malaria, tetanus
commensal organism / resident normal microbiota/ normal flora : 공생유기체
-> live in a symbiotic공생의 relationship with the host where one benefits( the commensal ) but the other (the host) is neither harmed nor benefits (bacteria on the skin)
-commensals sometimes cause disease if they enter sites they don't normally colonise (opportunistic pathogens)
-pathogen : an organism capable of causing disease 병원균
-communicable disease : a disease that can spread from one host to another directly or indirectly
(eye infections, impetigo 세균감염염증, lice, ringworm, scabies, scarlet fever, strep throat 인두염, measles 홍역, mumps 볼거리, chicken pox 수두 and whooping cough 백일해, tuberculosis)
-contagious disease : a subset category of communicable diseases, which is easily transmitted by physical contact with the person suffering the disease, by their secretions or objects touched by them
(chickenpox, measles, influenza)
SUMMARY
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