Transcript Medical Microbiology

现代医学导论
2012级食品安全与营养专业求是科学班
医学微生物学概论
Understanding the medical
microbiology
Dr. Jing Qian
Zhejiang University School of Medicine
April 09, 2014
Definitions
– Microorganisms(Microbes) 微生物
– Microbiology 微生物学
– Medical Microbiology 医学微生物学
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.
Distribution
•The distribution of microorganisms is universal in nature
including air, soil, water, animals, human body.
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.
Microbes in nitrogen cycle
Microbes in carbon cycle
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.
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.
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)
Eubacteria and Archaebacteria
•Eubacteria and Archaebacteria are
the two major types of prokaryotes.
They appear similar morphologically
but
have
major
biochemical
differences.
•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.
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.
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.
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
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.
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.
Medical Microbiology
history and current situation
Infectious Diseases in History
•
•
•
•
•
Tuberculosis
Plague
Smallpox
Syphilis
Influenza
3700 BC
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
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
Influenza Pandemics
• 1918 Spanish flu
• 1957 Asian flu (H2N2)
• 1968 Hong Kong flu
(H3N2)
• 1976 swine flu nonpandemic
• ? Avian flu (H5N1)
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.
30 years of emerging viral diseases
1994 New Variant of
Creutzfeldt-Jakob-Syndroms
1986 Bovine spongiform
encephalopathy
1980 Human T-cellLeukemia-Virus
1999 West Nile fever
2005 HPAI H5N1
1980 Hepatitis D
2013 H7N9??
2003 SARS
1981 HIV/AIDS
1989 Hepatitis C
1976 Ebola fever
1985 HIV/AIDS
1977 Hantaan-Virus
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
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
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
Development of Medical Microbiology
•Medical microbiology has developed from Experience
phase, Experimental phase to Modern phase and is still
keep developing.
•Some landmarks in each phase are:
Time line of Microbiology
Time line of Microbiology
Robert Koch :
Based on his experimental results, he raised a criteria, called as Koch’s
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.
Time line of Microbiology
Time line of Microbiology
Fleming and Florey
(1945 nobel price)
Fei-Fan Tang 汤飞凡
（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.
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.
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 BarréSinoussi and Luc
Montagnier "for their
discovery of human
immunodeficiency
virus".