医学微生物学概论 Understanding the medical microbiology

1. 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

2. Definitions • Microorganisms(Microbes) 微生物 • Microbiology 微生物学 • Medical Microbiology 医学微生物学

3. Microorganisms/Microbes • The word “microbe” comes from the Greek words mikros, meaning small, and bios, meaning life. Somicroorganisms/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.

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

5. 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.

6. Microbes in nitrogen cycle

7. Microbes in carbon cycle

9. 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.

10. 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.

11. 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)

12. Eubacteria and Archaebacteria are the two major types of prokaryotes. They appear similar morphologically but have major biochemical differences. 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. 

13. 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 particlesand have no basic cell structure. A simplest virus consists of one core and oneprotein 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.

14. 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.

15. 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

16. Medical Microbiology • The medical microbiology is the study of pathogenic microbes. • It concerns the biological characteristicsof microorganisms and their relationships with human hosts including: • Pathogenicityand immunity • Laboratory diagnosis • Prevention and treatment • etc.

17. 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.

18. Medical Microbiology history and current situation

19. Infectious Diseases in History • Tuberculosis • Plague • Smallpox • Syphilis • Influenza 3700 BC

20. 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

21. 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

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

23. New challenge in medical microbiology • The numerous emergingand re-emerginginfectious diseases such as AIDS,SARS, avian influenza, tuberculosis, viral hepatitis and so on.

24. 1994 New Variant of Creutzfeldt-Jakob-Syndroms • Bovine spongiform • encephalopathy 1980 Human T-cell- Leukemia-Virus 2005 HPAI H5N1 1999 West Nile fever 2013 H7N9?? 1980 Hepatitis D 1977 Hantaan-Virus 2003 SARS 1981 HIV/AIDS 1989 Hepatitis C 1976 Ebola fever 1985 HIV/AIDS 30 years of emerging viral diseases

25. 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

26. 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

27. 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

28. 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:

31. Time line of Microbiology

33. Time line of Microbiology

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

35. Time line of Microbiology

36. Time line of Microbiology

37. Fleming and Florey (1945 nobel price)

39. 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 chlamydiatrachomatis in 1955. So far he is the only Chinese microbiologist who created a research field in microbiology.

40. 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.

44. 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".