MEDICAL MICROBIOLOGY
FINAL EXAM
Written by: Vishal Kumar
Special mention to Casper Elias Johnsen, Maximilian Marius
Borka & Paal Albert Passot for their contribution in
completing this note
This summary is written based of the material from the lectures + practicals, Sketchy
videos/pdf, Katalin notes
,VISHAL KUMAR 2021/2022
I. General bacteriology, pathogenecity
1. Medical microbiology: significance, sub-fields and brief history
Microbes (living things around us that are too small to be seen by the naked eye) are
everywhere in the biosphere, and their presence invariably affects the environment that
they are growing in. The effects of microorganisms on their environment can be beneficial or
harmful or unapparent with regard to human measure or observation.
Significance of microbiology:
In the material circulation on earth:
- CO2 Fixation: conversion process of inorganic carbon (CO2) to organic compounds.
Planktonic algae and cyanobacteria
- Decomposition or biodegradation: results in the breakdown of complex organic
materials to forms of carbon that can be used by other organisms
- Nitrogen fixation: some bacteria which removes nitrogen from the atmosphere and
converts it to ammonia (NH3), for use by plants and animals. Some bacteria fix
nitrogen in symbiotic associations n plants
- Oxygenic photosynthesis: occurs in plants, algae and cyanobacteria. It is the type of
photosynthesis that results in the production of oxygen in the atmosphere
In industrial and agricultural usage:
- Fermentation:
• Yeast: wine, beer bread
• Lactic acid: yogurt, cheese, sour cream, buttermilk
- Pharmaceutical industry:
• Antibiotics: substances produced by microbes that will kill or inhibit other
microbes. These are used in the treatment of infectious diseases. Antibiotics
are produced in the nature by molds such as Penicillium and bacteria, such as
Streptomyces and Bacillus
- Biotechnology: application of microbial genetics to biological processes for the
production of useful substances
- Model research: the bacterium Escherichia coli and the yeast Saccharomyces have
been used to study cellular life and basic research
In co-habitation with host:
- Useful: normal flora = microbes that normally live in association with humans on
various surfaces of the body, such as Lactobacillus and Bifidobacterium. They protect
their hosts from infections, and otherwise promote nutrition and health
- Harmful: plant, animal and human pathogens
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Sub-fields:
Microbes can be subdivided into the following general groups
Bacteria:
- Prokaryotic organisms – simple unicellular
organisms with no nuclear membrane,
mitochondria, Golgi or ER – that reproduce by
asexual division
- Range in size from 0,5 to 20μm or even larger
- Shape (arrangement):
• Coccus (spheres), diplococci (in pairs),
streptococci (in chains),
staphylococcus (in cluster)
• Bacillus (rods)
• Coccobacilli
• Spirals: spirochetes are very thin and have multiple coils
• Pleomorphic: variable shapes
Viruses:
- Smallest infectious particles (20 – 400nm in diameter)
- Depends upon host cells for necessary functions
- Nucleic acid (RNA or DNA) is enclosed in a protein coat
- Can only replicate within cells, because they lack protein-synthesizing + energy-
generating enzymes
- Viral nucleic acid redirects the host’s enzymatic machinery to functions associated
with replication of the virus
Parasites:
- All parasites are classified as eukaryotic, some are unicellular and some are
multicellular
- Types:
• Protozoa
• Helminth: worms, eggs
• Prion: the only protein + encoded by the host’s chromosomal DNA
Fungi: (3-5μm)
- Eukaryotic organisms that contain a well-defined nucleus, mitochondria, Golgi and ER
- Can exist either in a (1) unicellular form (yeast) that can replicate asexually, (2) in a
filamentous form (mold) that can replicate asexually and sexually or (3) dimorphic
fungi
History of medical microbiology
Antoine van Leeuwenhoek (1676, Dutch)
- Commonly known as the ‘’father of microbiology’’
- Improved the microscope and conducted the first description + illustration of
microbes
, VISHAL KUMAR 2021/2022
Edward Jenner (1796, England): the pioneer of the smallpox vaccine (first vaccine)
Ignaz Philipp Semmelweis (1847, Hungary)
- An early pioneer of antiseptic procedures: introduced hand-washing with chlorine to
prevent the puerperal fever contracted during childbirth (from Streptococcus
pyogenes)
Louis Pasteur (1870, French)
- Discovered the principles of vaccination, microbial fermentation and pasteurization
- Was first one to grow bacteria in a lab culture of yest, sugar and ammonium salts
- Developed vaccines for rabies, anthrax and chicken cholera
- Demonstrated that fermentation is due to the growth
of bacteria
Robert Koch (1880, Germany)
- Founder of modern bacteriology
- Identified specific causative agents for tuberculosis,
cholera and anthrax
- The Koch’s postulates: 4 criteria designed to establish
a causal relationship between a causative microbe
and a disease
Dimitiry Ivanovsky (1892, Russia)
- Discoverer of filterable nature of viruses – founder of virology
- Discovered tobacco mosaic virus
Paul Ehrlich (1909, Germany)
- Founder of modern immunology
- Invented the precursor technique to Gram staining
- Discovered the first medical treatment for syphilis: Salvarsan (606) was the molecule
that was the least toxic, but still toxic enough, to be used as a drug against syphilis
- Established the chemotherapeutic index (theoretical basis for chemotherapy)
- Diphtheria antitoxin theory
Sir Alexander Fleming (1928, Scotland): discovered lysozyme and the antibiotic substance =
penicillin G