47005827-Bacteriology

MEDICAL MICROBIOLOGY (MMIC 201) Prepared by Nabeel Al-Mawajdeh RN,MSC. King Saud University-Aflaj College : 

1 MEDICAL MICROBIOLOGY (MMIC 201) Prepared by Nabeel Al-Mawajdeh RN,MSC. King Saud University-Aflaj College

Slide 2: 

2 CHAPTER 2 Bacteriology Nabeel Al-Mawajdeh RN.MCS

Bacteriology: 

3 Bacteriology Bacteriology means the study of bacteria . Bacteria are prokaryotic cells (unicellular organisms with no a nucleus) with simple structures that typically range in size from about 0.5 to 20 micrometers. Nabeel Al-Mawajdeh RN.MCS

Bacteria Characteristics: 

4 Bacteria Characteristics The bacterium cell is a prokaryotic cell. Bacterium cell are very small (approximately 0.1to 10.0 μm) Bacteria are widely distributed. It found in soil, air, water, and living bodies. Some bacteria cause diseases for animals and plants. Some bacteria live in our bodies as normal flora which harmless. Nabeel Al-Mawajdeh RN.MCS

Normal Flora : 

5 Normal Flora Normal flora: Species of bacteria that colonize the human body and do not normally cause disease. Normal flora may cause some problems if it displaced or depleted because of using antibiotics. Organisms of the normal flora are normally found on surface tissues (i.e., the skin, mucous membranes, the gastrointestinal system, and vagina). Nabeel Al-Mawajdeh RN.MCS

Functions of Normal Flora: 

6 Functions of Normal Flora They perform important metabolic functions e.g. a. Synthesis of vit. K. b. Conversion of bile pigments and bile acids. c. Absorption of nutrients from the intestine. They inhibit colonization and infection by pathogenic bacteria as they: a. Interfere with bacterial adherence. b. Maintain inhibitory PH in vagina and skin. c. Compete for essential nutrients. d. Produce inhibitory substances e.g. fatty acids and colicins . Nabeel Al-Mawajdeh RN.MCS

Prokaryotic : 

7 Prokaryotic Prokaryotic cells characteristics: They lacks the nuclear envelope so there is no nucleus. There is no nucleolus. Have simple enzyme system and lack most of the cellular organelles like mitochondria. Reproduce by binary fission (simple dividing process) Found in bacteria ad Cyanobacteria. Nabeel Al-Mawajdeh RN.MCS

Eukaryotic: 

8 Eukaryotic Eukaryotic cells characteristics: Have nuclear envelope and cellular organelles. Have nucleolus. Have complex enzyme system. Reproduce by simple and complex processes. All the living cells are eukaryotic cells except that of bacteria. Nabeel Al-Mawajdeh RN.MCS

Bacterial Structure: 

9 Bacterial Structure

Bacteria Structure: 

10 Bacteria Structure Cell envelope Cell membrane (plasma membrane) It is a semi permeable membrane that surrounds the cytoplasm of all bacterial cells, it composed of two layers of phospholipids, proteins, and carbohydrate. Its main function is to maintain a constant environment within the interior of the cell by controlling the transport mechanism between the cell and the surrounding medium. Nabeel Al-Mawajdeh RN.MCS

Bacteria Structure (Cont’d): 

11 Bacteria Structure (Cont’d) Cell wall A structure surrounding the cell, composed of Peptidoglycan (polysaccharides and proteins). Peptidoglycanis responsible for the rigidity of the bacterial cell wall and for the determination of cell shape. There are two main types of bacterial cell walls, Gram positive and Gram negative, which are differentiated by their Gram staining characteristics. Nabeel Al-Mawajdeh RN.MCS

Bacteria Structure (Cont’d): 

12 Bacteria Structure (Cont’d) Capsule It is a gelatinous layer outside the cell wall of some species. It is composed of polysaccharides. It increase the Pathogenicity of bacteria because capsulated bacteria are not easy to be destroyed by host cell. Capsules are not usually stained by gram stain. Flagella Flagellum is an appendage of the cell membrane that helps in bacterial movement, and can play a role in the production of disease. It is composed of a single protein called flagellin. Nabeel Al-Mawajdeh RN.MCS

Bacteria Structure (Cont’d): 

13 Bacteria Structure (Cont’d) Pili (synonym: fimbriae) These are hair like filaments that extend from the cell surface. They are shorter and thinner that flagella and composed of a protein called pilin. They are found mainly on gram negative bacteria. They help bacteria to adhere together and to the surface of host cell. Nabeel Al-Mawajdeh RN.MCS

Bacteria Structure (Cont’d): 

14 Bacteria Structure (Cont’d) Intracellular Structures Cytoplasm Which is a fluid that fills the cell. The ribosome and other internal structures are impeded in cytoplasm. All the internal biochemical activities are occur within it. Nuclear material Electron microscope showed that the bacterial genetic material is composed of a bundle of a double stranded DNA molecule (chromosome) that not surrounds by a nuclear membrane. The chromosome carries the genetic information and it duplicates before cell division. Nabeel Al-Mawajdeh RN.MCS

Bacteria Structure (Cont’d): 

15 Bacteria Structure (Cont’d) Plasmids These are extra chromosomal double stranded circular DNA that are capable of replicating independent of the bacterial chromosome. It helps bacteria to resist antibiotics. Nabeel Al-Mawajdeh RN.MCS

Bacteria Structure (Cont’d): 

16 Bacteria Structure (Cont’d) Ribosomes Ribosome is cellular organelle that found is in cytoplasm. Its function is to synthesize proteins for the bacterial cell. Inclusion granules They are found in cytoplasm. They serve as energy and nutrient reservoirs. They may be rich in lipids and carbohydrates. Nabeel Al-Mawajdeh RN.MCS

Bacteria Structure (Cont’d): 

17 Bacteria Structure (Cont’d) Endospores These are small thick walls formed in the cytoplasm that helps to resist the unfavorite environmental conditions like depletion of nutrients, heat, and dryness. The spores formation occurs by the development of an ingrowth of the cytoplasmic membrane cutting off a portion if the cytoplasm. Then a thick cortex and a tough spore coat are formed. Endospores Spores are commonly found in the genera Bacillus and Clostridium. Nabeel Al-Mawajdeh RN.MCS

Bacteria Shapes : 

18 Bacteria Shapes There are three basic shapes: Coccus: An average coccus is about 0.5-1.0 micrometer (µm) in diameter. Rod or bacillus : An average bacillus is 0.5-1.0 µm wide by 1.0-4.0 µm long. Spiral: Spirals range in size from 1 µm to over 100 µm in length. Nabeel Al-Mawajdeh RN.MCS

Bacteria Shapes: 

19 Bacteria Shapes Spiral Coccus Rod

Gram Reactions: 

20 Gram Reactions Gram-positive Gram-positive bacteria have a relatively thick layer of Peptidoglycan and can retain a crystal violet-iodine complex when treated with acetone or alcohol, and appear blue-black or purple when stained using Gram's method. Nabeel Al-Mawajdeh RN.MCS

A Gram-positive cell: 

21 A Gram-positive cell

Gram Reactions (Cont’d): 

22 Gram Reactions (Cont’d) Gram-negative Gram-negative bacteria have a thin layer of Peptidoglycan and cannot retain the crystal violet-iodine complex. Nabeel Al-Mawajdeh RN.MCS

A Gram-negative cell: 

23 A Gram-negative cell

Basic Nutritional Requirements : 

24 Basic Nutritional Requirements Oxygen Requirements Obligate aerobe: Bacteria grow only on the presence of O2. Microaerophilic: These bacteria will grow in low oxygen concentrations. Obligate anaerobe: Grow in the absence of free O2. Facultative anaerobes: Grow in the presence or absence of O2. Nabeel Al-Mawajdeh RN.MCS

Nutritional Requirements (cont’d): 

25 Nutritional Requirements (cont’d) Nutrient Requirements - Autotrophs: Obtain carob and/or sugar from sunlight or chemical reactions . - Heterotrophs : Obtain carob and/or sugar from the environment. Nabeel Al-Mawajdeh RN.MCS

Nutritional Requirements (cont’d): 

26 Nutritional Requirements (cont’d) Temperature According to the optimal temperature, bacteria are classified into 3 groups: Psychrophiles: These live in low temperature (< 20°C) Mesophiles: These live in moderate temperature(20-40°C) Thermophiles: These live in high temperature (> 45°C) Nabeel Al-Mawajdeh RN.MCS

Nutritional Requirements (cont’d): 

27 Nutritional Requirements (cont’d) PH Most bacteria grow at narrow range of PH (7.2- 7.6). Acidophiles are bacteria that grow optimally under acidic conditions (pH < 7.0) Alkaphiles prefer alkaline or basic conditions (pH > 7.0). Nabeel Al-Mawajdeh RN.MCS

Bacteria, Growth & Reproduction: 

28 Bacteria, Growth & Reproduction Bacteria grow and replicate in a process known as binary fission . The typical Bacterial Growth Curve includes 4 phases: 1. Lag phase: It is the first phase during which no cell division occurs. Bacterial cells adapt to the new environment so they don’t divide but they are metabolically active. 2. Logarithmic phase: After the cells adjusted to the new environment, rapid cell division occurs and the number of the cells increase steadily by the time. 3. Stationary phase: The growth rate slows as nutrients become exhausted and waste products accumulate. The rate of the bacterial growth equals the rate of bacterial death. The number of bacterial cells remains constant. 4. Decline phase(Death phase) : Bacteria run out of nutrients and die. Nabeel Al-Mawajdeh RN.MCS

Bacterial Growth Curve : 

29 Bacterial Growth Curve

Binary Fission: 

30 Binary Fission Binary fission is the process by which a bacteria grow and replicate. Bacteria can exchange genetic materials via conjugation. Nabeel Al-Mawajdeh RN.MCS

Binary Fission (Cont’d): 

31 Binary Fission (Cont’d) Stages of binary fission: The bacterial chromosome attaches to the cell membrane. The chromosome duplicates. The 2 copies of the chromosome still attach to the cell membrane. The bacterial cell begins narrowing at the middle. The narrowing continue until the cell divides into two new cells. Nabeel Al-Mawajdeh RN.MCS

Binary Fission: 

32 Binary Fission

Common Bacterial Infections: 

33 Common Bacterial Infections Staphylococcus: a gram-positive bacteria . - S. aureus e.g. food poisoning, impetigo, and furuncles (boils). - S. epidermidis. e.g. endocarditis. Streptococcus. a gram-positive bacteria. e.g. Pharyngitis, scarlet fever, and rheumatic fever. - S. pneumonia is a common cause of bacterial pneumonia and meningitis. Neisseria. - N. gonorrhoea is the causative agent of gonorrhoea. - N. meningitides is a leading cause of adult meningitis . Nabeel Al-Mawajdeh RN.MCS

Common Bacterial Infections (Cont’d): 

34 Common Bacterial Infections (Cont’d) Escherichia. E. coli. e. g. gastroenteritis, UTIs and neonatal meningitis. Salmonella. E.g. enteritis. - S. typhi . e, g. typhoid fever. Vibrio. - V. cholera. E.g. cholera. Clostridium. - C. tetani e.g. tetanus (lockjaw) Nabeel Al-Mawajdeh RN.MCS

Slide 35: 

35 The End Nabeel Al-Mawajdeh RN.MCS