lecture no 1 micro

1. Introduction to Microbiology

2. Medical microbiology is the study of the causative agents of infectious diseases of humans and the reaction to such infections. In other words it deals with etiology, pathogenesis, laboratory diagnosis, specific treatment and control of infection (immunization).

3. Medical microbiology includes: • Bacteriology – The science that study bacteria, the causative agents of a number of infectious diseases. • Virology – The science that study viruses, non-cellular living systems, capable of causing infectious diseases in human being. • Immunology– The science which concerned with mechanisms of body protection against pathogenic microorganisms and foreign cells and substances. • Mycology – The science that deals with the study of fungi . • Protozoology – It deals with pathogenic unicellular animal organisms.

5. Classification of Microorganisms:- • Classification by structure • Subcellular – DNA or RNA surrounded by a protein coat – viruses • Prokaryotic – simple cell structure with no nucleus or organelles – bacteria • Eukaryotic – complex cell structure with nucleus and specialized organelles – protozoa, fungi and parasites.

6. Naming of Microorganisms:- • Standardized naming التسمية الموحدة • Genus • Category of biologic classification • Example – Staphylococcus • Species of organism • Represents a distinct type of microorganisms • Examples – Staphylococcusaureus and Staphylococcusepidermidis • The genus name is written with a capital letter, and the species name – with a small letter.

7. surname

8. How microorganisms cause disease? • Microorganisms cause disease in a variety of ways • 1- By using nutrients needed by cells and tissues • 2-By damaging cells directly • 3-By producing toxins • Transmission • Direct contact • Indirect contact • These microorganisms may remain localized or become systemic

9. Localized symptoms • أعراض موضعية • Swelling • Pain • Warmth • Redness • Generalized symptoms • Fever • Tiredness • Aches • Weakness • Normal flora • Provides a barrier

11. Hepatitis virus 1- Viruses • They are the smallest known infectious agents • They are subcellular microorganisms that : • Have only nucleic acid surrounded by a protein coat • Must live and grow in living cells of other organisms

12. Illnesses caused by viruses • Colds • Influenza • Hepatitis • Warts • AIDS • Vaccines are available for many viruses • Mumps • Rubella • Measles • Herpes النكاف الحصبة الألمانية مرض الحصبة الهربس

13. Bacillus bacterial classification 2-Bacteria • Single-celled prokaryotic organisms that reproduce rapidly . • Classification • Bacteria can be classified according to:- • 1- Shape • 2- Ability to retain dyes • 3- Ability to grow with / without air • 4- Biochemical reactions

14. Main morphological signs of micro-organisms • Shape • Size • Cell arrangement • Structure: • Capsule • Structure of cell wall • Flagella • Endospores

15. Classification and Identification • 1- Shape • Coccus – spherical, rounded, or ovoid • Bacillus – rod-shaped • Spirillum – spiral-shaped • Virbrio – comma-shaped

16. Spherical(cocci)bacteria • Micrococci • Diplococci • Streptococci • Tetracocci • Sarcine • Staphylococci

17. Cocci. Micrococci Diplococci Tetracocci Streptococci Sarcinae Staphylococci

18. 2-Ability to retain certain dyes • Gram’s stain • Acid-fast stain • 3- Ability to grow in presence or absence of air • Aerobes – grow best in the presence of oxygen • Anaerobes – grow best in the absence of oxygen • 4- Biochemical reactions

19. The size of bacteria • The size of bacteria is measured in micrometer(m) or micron () (1 micron or micrometer is one thousandth of a millimeter) and varies from 0.1  to 16-18 . Most pathogenic bacteria measure from 0.1 to 10 . • The other unit of measurement of microorganisms is nanometer (nm) (one millionth of a millimeter) .

20. BACTERIAL CELL

21. Structure of the bacteria Cell envelope: -capsule - Cell wall - Cytoplasmicmembrane Outside appendages: -flagella - Pili or fimbria Inside structure: - cytoplasm - nucleoid - ribosomes - mesosomes - Intracellularinclusion

22. FLAGELLA Electron Micrograph of Bacteria with Flagella

23. SPORE Bacillus anthracis Bacillus megaterium

24. Cell wall • In addition to conferring rigidity upon bacteria, the cell wall protects against osmotic damage • Chemically, the rigid part of the cell wall is peptidoglycan • Cell wall first described by Gram in 1884. It is used to study morphologic appearance of bacteria. Gram's stain differentiates all bacteria into two distinct groups: • a. Gram-positive organisms • b. Gram-negative organisms

25. Feature of the structure Gram-negative cell envelope Gram-negative bacteria are surrounded by a thin peptidoglycan cell wall, which itself is surrounded by an outer membrane containing lipopolysaccharide. Gram-positive bacteria lack an outer membrane but are surrounded by layers of peptidoglycan many times thicker than is found in the Gram-negatives.

26. Features of the structure Gram-positive cell wall Gram-negative bacteria are surrounded by a thin peptidoglycan cell wall, which itself is surrounded by an outer membrane containing lipopolysaccharide. Gram-positive bacteria lack an outer membrane but are surrounded by layers of peptidoglycan many times thicker than is found in the Gram-negatives.

27. Gram Staining Technique

29. Protozoan Trichomonasvaginalis 3- Protozoa • Single-celled eukaryotic organisms, larger than bacteria, they are found in soil and water and they are a leading cause of death in developing countries • Illnesses caused by protozoa are • Malaria • Amebic dysentery

30. Yeast: a single-celled fungi 4- Fungi • Eukaryotic organisms with rigid cell wall • Yeasts • Single-celled • Reproduce by budding • Molds • Large, fuzzy, multicelled organisms • Produce spores • Superficial infections • Athlete’s foot • Ringworm • Thrush • Can cause systemic infections

31. Multicellular Parasites • Organisms that live on or in another organism and use it for nourishment • Parasitic worms • Usually due to poor sanitation • Round worms • Flat worms • Tape worms • Parasitic insects • Bite or burrow under the skin • Mosquitoes • Ticks • Lice • Mites