✅2. CLASSIFICATION OF BACTERIA Lecture.pdf
- 1. Classification of bacteria By Dr D. Zimba 1
- 2. EHT students to be able to : Classify bacteria Define bacteriology Label compound microscope Define pathogenic and non pathogenic bacteria Give the morphology of the bacteria 2
- 3. Introduction There are several classes of microorganisms divided in two groups which are eukaryotic and prokaryotic. Protozoa, algae and fungi are Eukaryotic cell types. Bacteria and blue green algae are prokaryotic cell types. These microorganisms can be seen under the Microscope. The inventor of the microscope was Antoine Van Leeuwenhoek. It is cardinal to know parts of commonest a microscope. The study of bacteria is bacteriology. A prokaryotic cell such as a bacterial cell reproduce by binary fission 3
- 4. Parts of a compound microscope 4
- 5. Morphology of micro- organisms in relation to bacteria FOR AZANA EHT KAFUE INSTITUTE OF HEALTH SCIENCES, EDUCATION AND RESEARCH 5
- 6. Definition of bacteriology Bacteriology . it is a science that deals with the study of Micro-organisms called Bacteria. Bacteria are Minute, one-celled vegetable organisms also called germs or microbes. Bacteria are found virtually everywhere, in dirt, dust, refuse and diseased tissues. They can be seen only with the aid of a microscope 6
- 7. TYPES OF BACTERIA: NON-PATHOGENIC AND PATHOGENIC TYPE 1.Non-Pathogenic – it is beneficial or harmless bacteria • Most numerous bacteria. • Useful functions – decompose refuse, improve some conditions • Belong to saprophyte group – require dead matter for growth (a type of nonpathogenic bacteria that causes dead organic matter to decay thus helps enrich the soil 7
- 8. Non pathogenic bacteria cont Some cultures (acidophilus) are used to make yogurt and some cheese, bacteria in yeast cause bread to rise and other bacteria create the alcohol in wine. The other bacteria stimulates immune response Others helps metabolize food Some cultures of bacteria are used to produce penicillin Special types of milk used for gastrointestinal disorders Protects against infection 8
- 9. TYPE II PATHOGENIC BACTERIA – HARMFUL & DISEASE CAUSING Pathogenic Bacteria (germs or microbes) are harmful microorganisms, and although in the minority, that can cause disease or infection in humans when they invade the body, plant or animal tissue. • Fewest Bacteria • Disease producing to live tissue • Enter the body through breaks in the skin, mouth, nose, eyes, ears and unprotected sex. Disease causing bacteria or viruses that are carried through the body in the blood or bodily fluids like HIV and hepatitis are called BLOOD BORNE PATHOGENS. 9
- 10. EXAMPLES OF PATHOGENIC BACTERIA Corynebacterium diphtheriae which causes diphtheria. Neisseria meningitides which causes meningitis. Neisseria gonorrhoeae which causes gonorrhoea. Bacillus Anthracis which causes anthrax. Clostridium perfringens which causes gangrene 10
- 11. EXAMPLES OF PATHOGENIC BACTERIA CONT. Clostridium tetani which causes tetanus. Clostridium botulinum which causes food poisoning. Escherichia coli causes urinary tract infection and diarrhea. Shigella dysenterae which causes bacillary dysentery (shigellosis). Salmonella typhi which causes typhoid fever. Vibrio cholerae which causes cholera. 11
- 12. EXAMPLES OF PATHOGENIC BACTERIA CONT Pseudomonas aeruginosa which causes nosocomial infections and urinary tract infections. Haemophilus influenza causes meningitis and pneumonia. Bordetella pertussis causes whooping cough. Treponema pallidum causes syphilis. Chlamydia trachomatis causes ocular and genital infections. Chlamydia pneumonae causes respiratory diseases. 12
- 13. EXAMPLES OF PATHOGENIC BACTERIA CONT Mycobacterium tuberculosis causes tuberculosis. Mycobacterium leprae causes leprosy. Yersinia pestis causes plague 13
- 14. Bacterial anatomy and functions of bacterium cell parts 14
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- 16. Cell wall Cell wall is smooth in gram positive bacteria whereas gram negative bacteria have convoluted cell surfaces. In gram positive bacteria various proteins and polysaccharides are attached to peptidoglycan present in cell wall. The cell wall is a three layered in gram negative bacteria that is the outer membrane, middle membrane and plasma membrane. 16
- 17. Cell wall functions provides shape to the bacterium Gives rigidity to the organism Protects from environmental factors Site of action of antibody 17
- 18. Cytoplasmic membrane It acts as the osmotic barrier It acts as semipermeable membrane controlling the inflow of metabolites to and from the protoplasm. 18
- 19. cytoplasm Cytoplasm contains ribosomes, mesosomes, vacuoles and inclusions. Ribosomes are centers of protein synthesis Intraplasmic inclusions are sources of stored energy Mesosomes are centers of respiratory enzymes. 19
- 20. Nuclear apparatus or nucleoid It contains DNA DNA is double stranded in form of a circle. The bacterial chromosome replicates by binary fission. 20
- 21. Capsule Protect the bacteria from phagocytosis 21
- 22. flagella Flagella are organs of locomotion and provide motility to the bacteria. 22
- 23. fimbriae Fimbriae are hair like appendages projecting from the cell surface as straight filaments. They are also called pili Its function is to transfer genetic material and organ adhesion. 23
- 24. Morphology of the bacteria • The bacteria are simple, cellular organisms lacking a nucleus as well as other characteristics of prokaryotes which distinguish them from organisms that have nucleated cells. 24
- 25. Classification of bacteria Bacterial classification depends on the following characteristics. 1. Morphology and arrangement 2. Staining 3. Cultural characteristics 4. Biochemical reactions 5. Antigenic structure 6. Base composition of bacterial DNA 25
- 26. Classification of bacteria cont Morphology and staining of bacteria are the commonly used characteristics to classify bacteria 26
- 27. 1. Morphology of bacteria 27
- 28. Bacterial Morphology are as follows: Cocci – spherical / oval shaped major groups Bacilli – rod shaped Vibrios – comma shaped Spirilla – rigid spiral forms Spirochetes – flexible spiral forms Actinomycetes – branching filamentous bacteria Mycoplasmas – lack cell wall 28
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- 30. 1. Morphology of bacteria When bacteria are visualized under light microscope, the following morphology are seen. 1. Cocci (singular coccus): Round or oval bacteria measuring about 0.5-1.0μmb in diameter. They are found in single, pairs, chains or clusters. 30
- 31. COCCI Division in one plane Diplococci Neisseria 31
- 32. Cocci: Chains Division in 2 Planes Streptococcus 32
- 33. Cocci: Clusters Division in 3 planes Staphylococcus 33
- 34. Gram Positive Cocci Staphylococcus aureus These bacteria can break down all tissues of body. 34
- 35. Morphology of bacteria cont. 2. Bacilli (singular bacillus): Stick- like bacteria with rounded, tepered, square or swollen ends; with a size measuring 1-10μmin length by 0.3- 1.0μm in width. 35
- 36. Rods: Straight E.G E. coli 36
- 40. Morphology of bacteria cont 3. Coccobacilli (singular coccobacillus): Short rods. 4. Spiral: Spiral shaped bacteria with regular or irregular distance between twisting. E.g. Spirilla and spirochete's 40
- 41. Spiral Forms 41
- 42. Gram Negative Spirochetes pathogenic very flexible tightly coiled, helically coiled Example ◦ syphilis Treponema pallidum 42
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- 44. 2. Staining of bacteria 44
- 45. 2. Staining of bacteria Bacterial staining is the process of coloring of colorless bacterial structural components using stains (dyes).The principle of staining is to identify microorganisms selectively by using dyes, fluorescence and radioisotope emission. The bacteria or its parts are stained by the dye. Eg.Eosin stain, Carbol fuchsin stain, Methylene blue stain, Crystal violet stain 45
- 46. Staining of bacteria Multiple stains are used in differential staining method to distinguish different cell structures and/or cell types. Eg. Gram stain and Ziehl-Neelson stain 46
- 47. A. Gram staining method 47
- 48. Gram staining method cont Developed by Christian Gram. Most bacteria are differentiated by their gram reaction due to differences in their cell wall structure. Gram-positive bacteria are bacteria that stain purple with crystal violet after decolorizing with acetone- alcohol. Gram-negative bacteria are bacteria that stain pink with the counter stain (safranin) after losing the primary stain (crystal violet) when treated with acetone-alcohol 48
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- 52. Gram-positive bacterium ……………Purple Gram-negative bacterium …………..Pink 52
- 53. DIFFERENCE BETWEEN GRAM NEGATIVE AND GRAM POSITIVE BACTERIA. GRAM NEGATIVE BACTERIA GRAM POSITIVE BACTERIA They have complex cell wall They have simple cell wall They have thin peptidoglycan cell wall layer They have thick peptidoglycan cell layer They have outer lipopolysaccharide wall layer They have no outer lipopolysaccharide wall layer They retain safranin. They appear pink or red They retain crystal violet or iodine. They appear blue or purple. 53
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- 58. Examples of gram positive and gram negative organisms Gram positive organisms Gram negative organisms Staphylococcus e.g. staph aureus Neisseria gonococcus Streptococcus Neisseria Meningococcus Pneumococcus Salmonella Clostridium Shigella Mycobacterium Haemophilus Bacillus Vibrio cholerae Corynebacterium diptheriae Pseudomonas 58
- 60. Gram positive Endospore Forming Rods Difficult to get rid of because of endospores Example ◦ Clostridium tetani 60
- 61. Gram positive Endospore Forming Rods Difficult to get rid of because of endospores Example C. perfringens – gangrene 61
- 62. Gram positive Endospore Forming Rods Bacillus B. Anthracis – anthrax zoonosis 62
- 63. Gram Negative Neisseria Spirillum 63
- 64. Gram Negative Aerobic Rods ◦ Pseudomonas aeruginosa (pigmented) Needs moisture Common in hospitals Opportunistic pathogen – causes UTI, skin, and lung infection 64
- 65. Gram Negative Cocci or Coccobaccilli (plump rods) Neisseria gonorrhoeae – Usually a diplococcus in PMN Sexually Transmitted Disease very antibiotic resistant 65
- 66. B. Ziehl-Neelson staining method 66
- 67. Ziehl-Neelson staining method Developed by Paul Ehrlichin1882, and modified by Ziehl and Neelson Ziehl-Neelson stain (Acid-fast stain) is used for staining Mycobacteria which are hardly stained by gram staining method. Once the Mycobacteria is stained with primary stain it can not be decolorized with acid, so named as acid-fast bacteria. 67
- 68. Ziehl-Neelson staining method cont. Reagents required: . Carbol-fuchsin . Acid-Alcohol . Methylene blue/Malachite green 68
- 69. Mycobacteria Gram positive and Acid Fast Mycobacterium tuberculosis Respiratory Pathogen MDR-TB In the 1950s we sent people with TB to the sanitariums 69
- 70. Mycobacteria Gram positive and Acid Fast ◦ M. leprae Causative agent of leprosy Not very common Only affects areas of body that are below body temperature Natural reservoir is the armadillo 70
- 71. Interpretation: Acid fast bacilli…………..Red Back ground………………Blue 71
- 72. THANKS 72