IntroductionIntroduction

Medical MicrobiologyMedical Microbiology

Hope Tan

What is Microbes?

Microbes, or microorganisms are minute living things that are usually unable to be viewed with the naked eye.

Bacteria, fungi, viruses are examples!

Many are beneficial Some are pathogenic

Microbes make the Universe

There are > 5 x 1030 types microbes in the world

Humans have intimate relation with microbes > 90% of the cells in our Body are covered with microbes

Microbiology defined as the study of organisms too small to be seen with the naked eye. These organisms include viruses, bacteria, and fungi. Microbiologists are concerned with characteristics and functions such as morphology, cytology, physiology, ecology, taxonomy, genetics, and molecular biology.

Defining Microbiology

IntroductionIntroduction

•　　 ObjectsObjects•　　 ContentsContents•　　 ObjectiveObjective•　　 Techniques Techniques •　　 StatusStatus

Research objectsResearch objects

Definition of microorganism 

an organism that is too small to be seen without the aid of a microscope

Characters of microorganisms

Minute volume, simple structurewide range nutriment 、 active metabolismreproduce quickly 、 large quantity 、 widespreadvariation and adaptability easily

Prokaryotic microorganisms 

Eukaryotic microorganisms 

Non cellular microorganisms 

Classification

Eukaryotic microorganisms 

•  Eukaryotes –  Larger –  Complex structure 

•  Nucleus •  Both DNA and RNA •  Various organelles

Eukaryotic microorganisms 

•  Eukaryotes –  Fungi 

•  Yeasts •  Molds 

–  Reproduction •  Budding •  Production of spores

Prokaryotic microorganisms •  Prokaryotes 

–  Small –  Relatively simple structure 

•  Nucleoid •  Both DNA and RNA •  A single organelle

Prokaryotic microorganisms 

•  Prokaryotes –  Members 

•  Bacteria •  Mycoplasmas •  Rickettsiae •  Chlamydiae •  Spirochetes •  Actinomyces 

–  Reproduction •  binary fission

Non cellular microorganisms •  Smallest •  Simple structure 

–  No cell structure •  Nucleic acid •  Capsid •  Envelope 

–  Either DNA or RNA

•  Obligate intracellular parasites  – Viruses are replicated only when they are in a living host cell•  Members  –  Viruses

•  Reproduction –  Replication

The Importance of MicroorganismsThe Importance of Microorganisms

Circulation of materialsCirculation of materialsMedicineMedicine 、、 FoodFood 、、 IndustryIndustryMicro-ecosystemMicro-ecosystem

Microbes Benefit Humans

Microbes are used to produce Antibiotics

Penicillin

Mold Penicillium notatum

1928 Alexander Fleming

Bacteria synthesize chemicals that our body needs, but cannot synthesize

Example: E. coliB vitamins - for metabolismVitamin K - blood clotting

Microbial Antagonism

Our normal microbial flora prevents potential pathogens from gaining access to our body

Harmful activities:

A portion of microbes can cause diseases and/or are poisonous to animal, plant or human being, and these which cause diseases to human are really that concern us in the study of medical microbiology.

Pathogenic microorganism

Anthrax

Pathogenic microorganism cause many diseases

disease： tetanus、 fungus infection、gas gangrene

tetanustetanus gas gangrenegas gangrene Fungus nailFungus nail

AIDS

SARS

Ebola

DiseasesDiseases

Research contentsResearch contents

Microbiology is the biology of microorganis

ms. It is a bioscience for the study of the evolutio

n, classification , morphology, physiology,

genetics, ecology of microbes under certain defini

te conditions, the law of their life activities, and t

heir interaction with human being, animals or pla

nts as well as with natural environment.

Microbiology

The science that study the biological characters, infectious and immune mechanisms, specific diagnosis, prevention and cure measurement of pathogenic microorganism is called medical microbiology.

Medical Microbiology

Research objectiveResearch objective

Diagnostic assistance: Qualitation and/or quantitation for pathogens

Therapic guidance: Detection of drug resistance

Disease prevention: Development vaccines and/or new generation vaccines

Unique Research TechniquesUnique Research Techniques

The Four Classic Research TechniquesThe Four Classic Research Techniques

Microtechnique Aseptic technique Culture technique Staining technique

Microtechnique

1673-1723, Leeuwenhoek (Dutch) described live microorganisms that he observed in teeth scrapings, rain water, and peppercorn infusions.

Anton van Leeuwenhoek - 1st person to actually see living microorganisms

“wee animalcules”

（ Leeuwenhoek ） 1632-1723

32

He assembled over 247 microscopes, some of which magnified objects 270 times. In the course of his examination of innumerable microorganisms and tissue samples, he gave the first complete descriptions of the bacteria, the protozoans (which he called animalcules), spermatozoa, and striped muscle. He also observed the red blood cells in his detailed study of capillary circulation. He was elected to the Royal Society of England in recognition of his work.

Anton van Leeuwenhoek

Magnifier

Light microscope

electron microscope

atomic force microscope

Aseptic technique

1859, Louis Pasteur discoved that the deterioration was caused by microbes and invented pastereurization.

Louis Pasteur was born on December 27, 1822 Louis Pasteur was born on December 27, 1822 in Dole, in the Region of Jura, France. His in Dole, in the Region of Jura, France. His discovery that most infectious diseases are caused discovery that most infectious diseases are caused by germs, known as the"germ theory of disease", is by germs, known as the"germ theory of disease", is one of the most important in medical history. His one of the most important in medical history. His work became the foundation for the science of work became the foundation for the science of microbiology, and a cornerstone of modern microbiology, and a cornerstone of modern medicine.medicine.

In 1865, Joseph Lister, a British surgeon, established antiseptic surgery by introducing aseptic technique to this field.　For many years he had explored the inflammation of wounds at the Glasgow infirmary. These observations had led him to considered that infection was not due to bad air alone, and that 'wound sepsis' was a form of decomposition

Cuture technique

In 1881, Robert KochIn 1881, Robert Koch, a German bacteriologist, isolated bacteria using solid medium and then he associated many diseases with specific microbes. In 1884, he devised a hypothesis known as Koch’s Postulates designed to establish a causal relationship between a causative microbe and a disease .

Koch’s postulatesKoch’s postulates1. The same organisms must be found in all cases of a given

disease.2. The organism must be isolated and grown in pure culture.3. The isolated organism must reproduce the same disease

when inoculated into a healthy susceptible animal.4. The original organism must be isolated again from the

experimentally infected animal.

Staining technique

Amidobenzene was applied to stain bacteria in suspension by German pathologist named Weigert, then Koch improved it and stained the bacteria on a slide. In 1884, Christian Gram, a famous Denmark pathologist invented a stain technique which is known as Gram Stain now to stain bacteria on a slide, by this technique, all bacteria can be classified as G+ and C-

The protocol of Gram stain

Gram stain morphology Shape

coccibacilli spiral or curved

Single or multiple cellsclusters (e.g. streptococci)chains (e.g. streptococci)

Gram positive or negative

Significance of Gram Stain 

•  Differentiate bacteria: G + / G   

•  Helpful to select sensitive antibiotics. 

•  identify different virulent factors of bacteria. 

–  G + : exotoxin 

–  G   : endotoxin.

Research StatusResearch Status

A

Diagnosis——pathogen and its antigen, nucleic acid, metabolites, antibody

Prevention——vaccines

Therapy——antibiotics

The first medical revolution

Achievements

The second medical revolution

Discovery origin for hereditary material

Tools for gene engineering research

Model for human genome research

B

Developmental direction and perspectives

•Emerging and re-emerging pathogens•Pathogenic mechanisms•Development and exploitation for anti-infection drugs• Development and improvement of vaccines

Nowadays New pathogens emerged continuously

Hepatitis viruseHIVTTVPrionsCoronavirus and SARS

Re-emerging of traditional pathogensDrug resistance became more severeMycobacterium toberculosis

Progress of Hepatitis Viruses 1947, concepts of hepatitis A and serum-tra

nsmitted hepatitis

1970, Dane particle was observed (hepatitis B virus)

1973, hepatitis A virus

1978, non-A, non-B hepatitis viruses (NANBV)

1989, hepatitis C virus (HCV), hepatitis E virus (HEV)

1990-1994, non A-E hepatitis viruses

1995, hepatitis G virus (HGV)

1997, TT virus (TTV)

Human Immunodeficiency Virus & AIDS

1981, the first cases report about AIDS

1983, HIV was isolated 1990s, HAART (cocktail

therapy) was employed So far, no effective vaccine

available

Prions Infectious pro

teinsKuruCJDMad cow dise

aseScrapie

Kuru

vCJD

BSE

Developmental direction and perspective

•Emerging and re-emerging pathogens•Pathogenic mechanisms•Development and exploitation for anti-infection drugs• Development and improvement of vaccine

How to Study Medical Microbiology?

Fundamentals of Microbiology

Bacteriology

Virology

Mycology

•Biological Properties•Morphology, identification, •Antigenic structure

•Pathogenesis and Pathology•Clinical findings

•Diagnostic Laboratory Tests•Immunity•Treatment & Prevention

•Epidemiology & Control

•  The definition of microorganisms •  The classification of microorganisms •  The differences among viruses, bacteria, 

and fungi 

Summary

•  The four main research techniques