Understanding the medical microbiology

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?????? 2012???????????????
???????? Understanding the medical microbiology
Dr. Jing Qian Zhejiang University School of
Medicine April 09, 2014
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Definitions

• Microorganisms(Microbes) ???
• Microbiology ????
• Medical Microbiology ??????

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Microorganisms/Microbes

• The word microbe comes from the Greek words
  mikros, meaning small, and bios, meaning life. So
  microorganisms/microbes are small living things
  that are too small to be seen with the unaided
  eye.

• Microorganisms were probably the first organisms
  to appear on the earth.

• However, these organisms were not seen until
  about 3 centuries ago when lenses powerful enough
  to make them visible were made.

• Viruses, bacteria, fungi, protozoa and some algae
  are all in this category.

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Distribution

• The distribution of microorganisms is universal
  in nature including air, soil, water, animals,
  human body.

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Relationship with human beings

• There is a close relationship between
  microorganisms and human beings.

• Beneficial activities Most microbes are of
  benefit to human beings, some are necessary. eg.
  nitrogen, carbon cycles, etc.

• Harmful activities Only a small portion of
  microbes cause diseases and are poisonous to
  human, and these pathogenic microbes are really
  that concern us in the study of medicine.

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Microbes in carbon cycle
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Organizational structure

• Background knowledge
• Cell is the fundamental unit of all living things
  to carry out metabolic processes that transform
  energy and materials for growth and propagation
  (multiplication).

• There are two fundamental types of cells
  Prokaryotes and Eukaryotes with the major
  difference in whether or not the cell have
  membrane bound organelles and nucleus.

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Differences between prokaryotes/eukaryotes

•  The prokaryotic cell, in contrast to the
  eukaryotic cell, has no nuclear membranes,
  mitochondria, endoplasmic reticulum, Golgi body,
  phagosomes and lysosomes.

•  Prokaryotes generally possess only a single
  circular chromosome. Since there is no nuclear
  membrane, the chromosome is bound to a specific
  site on the cell membrane - the mesosome. 

•  Prokaryotic ribosomes are 70S (S means Svedberg
  unit, a measure of size for centrifugation),
  whereas eukaryotic ribosomes are larger (80S).
• Prokaryotic ribosomal subunits are 30S and 50S
  (eukaryotic are larger). The 30S ribosome has 16S
  RNA, while the 50S ribosome contains 23S and 5S
  RNA.

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Classification of microbes

• According to organizational structure, microbes
  can be divided into three types
• Prokaryotes (Eubacteria and Archaebacteria)
• Eukaryotes (fungi, Protozoa, algae)
• Acellular entities (viruses)

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Eubacteria and Archaebacteria

• Eubacteria are "True" bacteria which include
  Bacteria, Chlamydiae, Mycoplasmas, Richettiae,
  Spirochetes, and Actinomycetes. Some of them
  cause human diseases.

• Members of the Archaebacteria are often found in
  extreme environments (methane-containing, high
  salt or hot temperature) environments. They are
  not human pathogens and will not be discussed
  further. 

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Viruses

• Viruses are not living organisms because they do
  not contain all the enzymes required for their
  replication and possess the biologic equipment
  necessary for the production of metabolic energy.

• Morphologically, viruses are very small particles
  and have no basic cell structure. A simplest
  virus consists of one core and one protein coat
  (capsid). The core composed with a nucleic acid
  molecule, either DNA or RNA.

• Viruses are non-cellular microbes. They are
  obligate parasites totally dependent on their
  host for replication.

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Fungi

• Fungi is a kind of eukaryotic cells. So they have
  various organelles, for examples, nuclear
  membranes, mitochondria, endoplasmic reticulum,
  Golgi body, phagosomes and lysosomes.

• There are more than 100, 000 species of fungi,
  but most of them are beneficial to humankind.
  They reside in nature and are essential in
  breaking down and recycling organic matters.

• Only a few of fungi can cause human diseases.

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Microbiology

• Microbiology is the biology of microorganisms.

• It is a bioscience for the study of various
  characteristics or activities of microorganisms
  including microbial morphology, cytology,
  physiology, ecology, genetics, molecular biology
  and taxonomy.

• It has an impact on medicine, agriculture, food
  science, ecology, genetics, biochemistry, and
  other fields.

• Branches of Microbiology are Medical
  Microbiology, Food Microbiology, Public health
  Microbiology, Industrial Microbiology and
  Agricultural Microbiology

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Medical Microbiology

• The medical microbiology is the study of
  pathogenic microbes.
• It concerns the biological characteristics of
  microorganisms and their relationships with human
  hosts including
• Pathogenicity and immunity
• Laboratory diagnosis
• Prevention and treatment
• etc.

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Medical Microbiology

• Branches of medical microbiology include Medical
  Bacteriology (Six eubacterial categories
  Bacteria, Chlamydiae, Mycoplasmas, Richettiae,
  Spirochetes and Actinomycetes), Medical virology,
  Medical Mycology.
• Medical Microbiology contains anti-infectious
  immunity in Immunology.
• In some countries, Parasitology is enclosed
  Microbiology
• Understanding and employing the principles of
  microbiology and the molecular mechanisms of
  pathogenesis enable the physicians and medical
  scientists to control an increasing number of
  infectious diseases.

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Medical Microbiology
history and current situation
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Infectious Diseases in History

• Tuberculosis
• Plague
• Smallpox
• Syphilis
• Influenza

3700 BC
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Smallpox

• Numerous epidemics in Europe, Asia
• Plague of Athens 430 BC
• Antonia Plague of Rome 165-180
• India c. 400
• Introduced to the Americas in 1520 by Cortés,
  killing 25 of Aztec population
• Spread to Incan population via roads
• North America in 1633, Plymouth, MA

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Influenza

• Symptoms described by Hippocrates 412 BCE
• Ascribed to unfavorable astrological influences
  in Italy in the 15th Century
• First pandemic recorded in 1580
• Term influenza used in English in 1743
• Virus discovered by Medical Research Council in
  England in 1933

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Influenza Pandemics

• 1918 Spanish flu
• 1957 Asian flu (H2N2)
• 1968 Hong Kong flu (H3N2)
• 1976 swine flu non-pandemic
• ? Avian flu (H5N1)

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New challenge in medical microbiology

• The numerous emerging and re-emerging infectious
  diseases such as AIDS, SARS, avian influenza,
  tuberculosis, viral hepatitis and so on.

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30 years of emerging viral diseases
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Emerging viral diseases monkey pox virus
A 7 year old girl from Zaire Monkeypox A member
of the orthopox virus (next to Variola) local
outbreaks since 1990 It is a zoonosis in the
Americas prairie dogs
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Emerging viral diseases Kaposi sarcoma
Kaposi-sarcoma origin Human Herpesvirus type 8,
HHV-8 Kaposi-sarcoma-associated
Herpesvirus, KSHV One of the leading diseases in
(untreated) AIDS-patients
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Emerging viral diseases Avian influenza virus

• Influenza
• Hong Kong, 1997 death of 7.000 chicken in 3
  farms
• Crossing of species barrier of a new influenza
  strain (H5N1) from poultry to man
• 20 humans became infected.
• One third die.
• No human to human transmission.
• Killing of 1,6 millions poultry to prevent
  spreading among poultry
• Vietnam, Thailand, China, Laos, Korea, Japan,
  Kambodscha, Indonesien, 2004 reemergence of H5N1
• Suspected human to human transmission

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Medical microbiology has developed from
Experience phase, Experimental phase to Modern
phase and is still keep developing.
Development of Medical Microbiology

• Some landmarks in each phase are

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Time line of Microbiology
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Time line of Microbiology
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Robert Koch Based on his experimental results,
he raised a criteria, called as Kochs Postulate,
to establish the link between a particular
microorganism and a particular disease

1. The microorganisms must be present in every case
   of the disease but absent from healthy
   individuals.
2. The suspected microorganisms must be isolated and
   grown in pure culture.
3. The same disease must result when the isolated
   microorganism is inoculated into a healthy host.
4. The same microorganism must be isolated again
   from the diseased host.

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Time line of Microbiology
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Time line of Microbiology
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Fleming and Florey (1945 nobel price)
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Fei-Fan Tang ???(1897-1958)
The first generation of virologist in China. He
is the first scientist who was successful in
isolating and cultivating chlamydia trachomatis
in 1955. So far he is the only Chinese
microbiologist who created a research field in
microbiology.
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Microbiology in nature science

• Microbiology established a closer relationship
  with other disciplines during the 1940s because
  of its association with genetics and biochemistry.

• More recently, microbiology has been a major
  contributor to molecular biology and has been
  deeply involved in the elucidation of the genetic
  code in studies on the mechanisms of DNA,
  ribonucleic acid (RNA), and protein synthesis
  and in studies on the regulation of gene
  expression and the control of enzyme activity.

• In the 1970s new discoveries in microbiology led
  to the development of recombinant DNA technology
  and genetic engineering.

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The Nobel Prize in Physiology or Medicine 2008
was divided, one half awarded to Harald zur
Hausen "for his discovery of human papilloma
viruses causing cervical cancer", the other half
jointly to Françoise Barré-Sinoussi and Luc
Montagnier "for their discovery of human
immunodeficiency virus".