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Medical Microbiology, 2nd class ‫جامعة الكفيل‬ Lecture: 1 ‫كلية التقنيات الصحية والطبية‬ Lec. Dr. Ahmed Abdulridha ‫قسم تقنيات...

Medical Microbiology, 2nd class ‫جامعة الكفيل‬ Lecture: 1 ‫كلية التقنيات الصحية والطبية‬ Lec. Dr. Ahmed Abdulridha ‫قسم تقنيات المختبرات الطبية‬ 2024-2025 ‫المرحلة الثانية‬ Microbiology is a subject which deals with living organisms that are individually too small to be seen with the naked eye. Microbes in Our Lives 1. Microorganisms are important in maintaining Earth’s ecological balance. 2. Some microorganisms live in humans and other animals and are needed to maintain good health. 3. Some microorganisms are used to produce foods and chemicals. 4. Some microorganisms cause disease. Table: Comparison between Prokaryotes and Eukaryotes Characteristic Prokaryotes Eukaryotes Genetic Material Circular DNA (in nucleoid region) Linear DNA (in nucleus) Membrane-bound Absent Present Nucleus Membrane-bound Numerous (e.g., mitochondria, Few or none Organelles ER) Cell Size Usually smaller (1-10 μm) Usually larger (10-100 μm) Ribosomes 70S (smaller) 80S (larger) Cytoplasmic Streaming Absent Present in some cells Mitosis (for somatic cells), Cell Division Binary fission meiosis (for reproductive cells) Examples Bacteria, archaea Animals, plants, fungi, protists Complex with sterols (e.g., Membrane Structure Simple cholesterol) Flagella Structure Simple, without microtubules Complex, with microtubules 1  Medical Microbiology, 2nd class ‫جامعة الكفيل‬ Lecture: 1 ‫كلية التقنيات الصحية والطبية‬ Lec. Dr. Ahmed Abdulridha ‫قسم تقنيات المختبرات الطبية‬ 2024-2025 ‫المرحلة الثانية‬ Branches of Microbiology Bacteriology: Small single-celled prokaryotic organisms (Bacteria). Mycology: The fungi, a group of eukaryotes that includes both microscopic eukaryotes (molds and yeasts) and larger organisms (mushrooms) Virology: Viruses—minute, non cellular particles that parasitize cells. Parasitology: Parasitism and parasitic organisms—traditionally including pathogenic protozoa, helminth worms, and certain insects. Microbial Taxonomy Classification attempts to group organisms according to their similarity. Members of lower level taxa (e.g. Species) are more similar to each other than are members of higher-level taxa (eg. Kingdom or domain). Binomial Nomenclature - Organisms are named using binomial nomenclature (viruses are exceptions) - Binomial nomenclature employs the names of the two level taxa, genus and species, to name a specie. Binomial nomenclature includes: i. Genus comes before species (e.g., Escherichia coli) ii. Genus name is always capitalized (e.g., Escherichia) iii. Species name is never capitalized (e.g., coli) 2  Medical Microbiology, 2nd class ‫جامعة الكفيل‬ Lecture: 1 ‫كلية التقنيات الصحية والطبية‬ Lec. Dr. Ahmed Abdulridha ‫قسم تقنيات المختبرات الطبية‬ 2024-2025 ‫المرحلة الثانية‬ iv. Both names are always either italicized or underlined ( e.g Escherichia coli ) v. The genus name may be used alone, but not the species name (i.e saying or writing “Escherichia “alone is legitimate while saying or writing “coli” is not) Domain: (Bacteria, Archaea, Eukarya): Bacteria Kingdom: Bacteria Phylum/Division: Proteobacteria Class: Zymobacteria Order: Enterobacterales Family: Enterobacteriaceae Genus: Escherichia Species: coli Scientific name: Escherichia coli Bacteria: are single-celled prokaryotic microorganisms, and their DNA is not contained within a separate nucleus as in eukaryotic cells. They are approximately 0.1–10.0 μm in size and exist in various shapes, including spheres (cocci), curves, spirals and rods (bacilli). Bacterial Classification 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. 3  Medical Microbiology, 2nd class ‫جامعة الكفيل‬ Lecture: 1 ‫كلية التقنيات الصحية والطبية‬ Lec. Dr. Ahmed Abdulridha ‫قسم تقنيات المختبرات الطبية‬ 2024-2025 ‫المرحلة الثانية‬ When bacteria are visualized under a light microscope, they exhibit different shapes and arrangements, referred to as bacterial morphology, include: 1. Cocci (Spherical)  Shape: Round or oval  Common Arrangements: o Diplococci: Pairs of cocci (e.g., Neisseria species) o Streptococci: Chains of cocci (e.g., Streptococcus species) o Staphylococci: Grape-like clusters (e.g., Staphylococcus species) o Tetrads: Groups of four cocci arranged in a square 2. Bacilli (Rod-shaped)  Shape: Cylindrical or rod-like  Common Arrangements: o Single Bacilli: Single rod-shaped bacterium (e.g., Escherichia coli) o Diplobacilli: Pairs of bacilli o Streptobacilli: Chains of bacilli (e.g., Bacillus subtilis) o Coccobacilli: Short, oval, and rod-like (e.g., Haemophilus influenzae) 3. Spirilla (Spiral-shaped)  Shape: Rigid, spiral-shaped bacteria  Example: Spirillum species 4. Spirochetes (Corkscrew-shaped)  Shape: Flexible, corkscrew-like bacteria  Example: Treponema pallidum (causes syphilis), Borrelia burgdorferi (causes Lyme disease) 5. Vibrios (Comma-shaped)  Shape: Curved, comma-shaped bacteria  Example: Vibrio cholerae (causes cholera) 4  Medical Microbiology, 2nd class ‫جامعة الكفيل‬ Lecture: 1 ‫كلية التقنيات الصحية والطبية‬ Lec. Dr. Ahmed Abdulridha ‫قسم تقنيات المختبرات الطبية‬ 2024-2025 ‫المرحلة الثانية‬ 2. Staining of bacteria is the process of coloring of colorless bacterial structural components using stains (dyes). Bacterial staining methods include: Simple stain. (Methylene blue stain) Differential stain. (Gram stain, Acid fast stain) Special stain. (Spore stain, Flagella stain) According to Gram-stain technique, the bacterial cells classified: Gram-positive bacteria (purple color), and Gram-negative bacteria (Pink- color) under light microscope. Some bacterial cell cannot be stained with Gram-stain according to the difference of structure in the bacterial cell wall, thus it must be stained with other techniques such as Acid- Fast stain. 5  Medical Microbiology, 2nd class ‫جامعة الكفيل‬ Lecture: 1 ‫كلية التقنيات الصحية والطبية‬ Lec. Dr. Ahmed Abdulridha ‫قسم تقنيات المختبرات الطبية‬ 2024-2025 ‫المرحلة الثانية‬ Cultural Characteristics Colony development on agar surfaces aids microbiologists in identifying microorganisms because individual species often form colonies characteristic size and appearance. Bacterial Colony Morphology 6