LOGOFK UNISBA 2009/2010

INTRODUCTION TO MICROBIOLOGY

INTRODUCTION TO MICROBIOLOGY

Julia Hartati, dr.

LOGOHistory of MicrobiologyHistory of Microbiology

1674 the Dutch biologist Anton van Leeuwenhoek: ground microscopic lenses at a drop of water and discovered a world of millions of tiny "animalcules."

Almost 100 years later the Danish biologist Otto Müller: beginning of the taxonomic classification of microbes

1840 the German pathologist Friedrich Henle: the "germ theory" of disease

1870s and 1880s Robert Koch and Louis Pasteur: a series of elegant experiments proving that microorganisms were responsible for causing anthrax, rabies, plague, cholera, and tuberculosis

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The Henle-Koch postulates can be freely formulated as follows:The Henle-Koch postulates can be freely formulated as follows:

The microorganism must be found under conditions corresponding to the pathological changes and clinical course of the disease in question

It must be possible to cause an identical (human) or similar (animal) disease with pure cultures of the pathogen.

The pathogen must not occur within the framework of other diseases as an “accidental parasite”.

LOGOHistory of MicrobiologyHistory of Microbiology

1910 the German chemist Paul Ehrlich: discovered the first antibacterial agent

1928 Alexander Fleming: discovered of penicillin1935 Gerhard Domagk: discovery of

sulfanilamide 1943 Selman Waksman: discovery of

streptomycin 1946 the American microbiologist John Enders:

leading the way to the large-scale production of virus cultures for vaccine development

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LOGOIntroduction to MicrobiologyIntroduction to Microbiology

To understand this information and organize it in a useful manner, it is important to understand some of the basic aspects of medical microbiology

The microbes can be subdivided into the following four groups: viruses, bacteria, fungi, and parasites

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LOGOVIRUSESVIRUSES

The smallest infectious particlesdiameter from 18 to nearly 300 nanometers (most

viruses are less than 200 nm and cannot be seen with a light microscope)

Twenty-five families with more than 1550 species of viruses have been described, and many are associated with human disease

Viruses consist of either deoxyribonucleic acid (DNA) or ribonucleic acid (RNA) (but not both) enclosed in a protein coat, or capsid. The capsid protects the nucleic acid and facilitates attachment and penetration of the host cell by the virus.

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LOGOVIRUSESVIRUSES

Viruses are true parasites, requiring host cells for replication. They make copies of their nucleic acid, after which the new genomes are packaged individually, all within the confines of an infected cell.

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LOGOBACTERIABACTERIA

Prokaryotic organisms-simple unicellular organisms with no nuclear membrane, mitochondria, Golgi bodies, or endoplasmic reticulum

Reproduce by binary fissionThe cell walls of these organisms are rigid (with some

exceptions, e.g., the mycoplasma). Consisting of one of two basic forms: a gram-positive cell wall with a thick peptidoglycan layer, and a gram-negative cell wall with a thin peptidoglycan layer and an overlying outer membrane

External to the cell wall may be flagella, pili, and/or a capsule

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LOGOBACTERIABACTERIA

Size: 1 to 20 μm or largerShape: spheres, rods, spiralsSpatial arrangement: single cells, chains,

clusters

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LOGOBACTERIABACTERIA

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LOGOFUNGIFUNGI

Fungi (Mycophyta) are nonmotile eukaryotes with rigid cell walls and a classic cell nucleus.

Eukaryotic organisms that contain a well-defined nucleus, mitochondria, Golgi bodies, and endoplasmic reticulum

The fungi are nonphotosynthetic protists growing as a mass of branching, interlacing filaments ("hyphae") known as a mycelium.

The mycelial forms are called molds; a few types, yeasts, do not form a mycelium but are easily recognized as fungi by the nature of their sexual reproductive processes and by the presence of transitional forms.

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LOGOFUNGIFUNGI

Fungi are subdivided as follows: Zygomycotina (the phycomycetes), Ascomycotina (the ascomycetes), Basidiomycotina (the basidiomycetes), and Deuteromycotina (the imperfect fungi).

Of more than 50 000 fungal species, only about 300 are known to be human pathogens.

Most fungal infections occur as a result of weakened host immune defenses.

Pathogenic fungi can cause diseases, ranging from skin infections (superficial mycoses) to serious, systemic infections

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LOGOFUNGIFUNGI

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LOGOPARASITESPARASITES

All parasites are classified as eukaryotic Range in size from tiny protozoa as small as 1 to 2μm in

diameter (the size of many bacteria) to arthropods and tapeworms that can measure up to 10 meters in length

Protozoa are single-celled, nonphotosynthetic, eukaryotic organisms that come in various shapes and sizes. Many protozoa are free-living, but others are among the most clinically important parasites of humans.

They can be intracellular parasites, or extracellular parasites in the blood, urogenital region, or intestine.

Transmission is generally by ingestion of an infective stage of the parasite or by insect bite.

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LOGOPARASITESPARASITES

Helminths are groups of worms that live as parasites. They are multicellular, eukaryotic organisms with complex body organization.

They are divided into three main groups: tapeworms (cestodes), flukes (trematodes), and roundworms (nematodes).

Helminths are parasitic, receiving nutrients by ingesting or absorbing digestive contents, or ingesting or absorbing body fluids or tissues.

Their life cycles are equally complex, with some parasites establishing a permanent relationship with humans and others going through a series of developmental stages in a progression of animal hosts

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LOGOPARASITESPARASITES

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