Introduction to Microbiology and Infection Control PDF

10/9/2024 Introduction to Microbiology and Infection Control By Assistant Prof. Omar Abd-Alhakeem Ammar Delta University for Science & Technology...

10/9/2024 Introduction to Microbiology and Infection Control By Assistant Prof. Omar Abd-Alhakeem Ammar Delta University for Science & Technology OBJECTIVES 1. Define microbiology. 2. Distinguish between eukaryotic and prokaryotic cell. 3. List some basic properties of bacteria, virus, and fungi 4. Explain structure and morphology of bacteria 1  10/9/2024 Medical Microbiology  The science which is concerned with the study of microbes and the interaction between microbes and hosts leading to infectious diseases.  Microbes are living organisms that can only be seen by microscopes and they are sometimes called microorganisms. Microorganisms Prokaryotes Eukaryotes Pro = premature Eu = true 2  10/9/2024 Differences between prokaryotes and eukaryotes Prokaryotes Eukaryotes Nuclear Absent Present membrane One copy Chromosomal N. Two copies (Diploid) (Haploid) Ribosome 70 S 80 S Mitosis Absent Present Cell wall Peptidoglycan Absent Examples Bacteria, viruses Fungi Classes of Pathogenic Microorganisms Viruses Bacteria Fungi Size 0.02-0.2 µm 1-5 µm 3-10 (yeast) nucleus No nucleus Nuclear body True nucleus Ribosome No ribosome 70 S 80 S Nucleic acid Either RNA or DNA Both Both replication Intra cellular replication cycle Binary fission Budding or Mitosis Motility None Some None Cell wall Protein or lipoprotein Peptidoglycan Chitin Growth Intracellular Intra and extra cellular The same 3  10/9/2024 Morphology of Bacteria 1- Size of bacterial cell: The size of bacterial cell is measured by micron (micron= 1/ 1000 mm) 2- Gram staining: Bacteria are stained with Gram stain that can differentiate bacteria into: Gram positive bacteria appearing violet or Gram negative bacteria appearing pink. Morphology of Bacteria 3- Shape of the bacterial cell  (a) Cocci or spherical. e.g. Staphylococci  (b) Bacilli or cylindrical e.g. Diphtheria.  (c) Spiral  (d) curved or comma shaped. Most bacteria are either spherical (coccus) or rod-shaped (bacillus) They are usually arranged in a manner characteristic of the genus, growing either singly, in clusters or in chains 4  10/9/2024 Morphology of Bacteria 4- Arrangement of bacteria (*) Single as Gram negative bacilli (E. coli) (*) Pairs. As Neisseria and pneumococci. (*) Tetrads as staphylococci. (*) Grape like as staphylococci. (*) Chains as streptococci, Anthrax bacilli. (*) Angular as Diphtheria bacilli. Bacterial Structure The basic components of bacterial cells include: A)- Cell envelope: » Cell wall. » Cytoplasmic membrane. » Capsule. B)- Cytoplasmic components: » Nuclear body. » Plasmid. » Ribosomes. C)- Cell appendages: » Flagellae. » Fimbriae "Pilli“. 5  10/9/2024 Bacterial Structure A) Cell envelop (1) Cell wall It is the layer that lies outside the cytoplasmic membrane. All bacterial cells, the cell wall composed of , peptidoglycan". The peptidoglycan layer present in both Gram positive & negative bacteria. Differences between Gram positive & Gram negative bacteria cell wall: Gram positive Gram negative Peptidoglycan Thick. Very thin 1.Lipoprotein 2.Outer membrane 1.Teichoic acid Special structure 3.Periplasmic space 2.polysaccharides. 4.Lipopolysaccharides (Endotoins) 6  10/9/2024 Functions of the cell wall Preservation of the shape of the cell Protective function Permeability of the cell Antigenic character Staining reaction Structures outside the cell wall Toxicity Target action of antibiotics:- as penicillin and cephalosporins Bacterial Structure A) Cell envelop (2) Cytoplasmic membrane Def: It is a thin elastic membrane that lies immediately under the cell wall Nature: protein and phospholipids. 7  10/9/2024 Bacterial Structure A) Cell envelop (3) Capsule Def: It is gelatinous material surrounding bacterial cells produced by some pathogenic bacteria inside the host tissue. Chemical structure: All bacteria is complex polysaccharides e.g. Streptococcus pneumoniae. Polypeptides e.g. bacillus anthracis. Functions: 1) Protect bacterial cell against phagocytosis. 2) determining virulence of the organism. 3) antigenic. Bacterial Structure B) Cytoplasmic components (1) Ribosomes:  The factory of protein synthesis in the cell.  Complex structures composed of RNA & proteins.  It is a target for some antibiotic as tetracycline and chloramphenicol. Bacterial ribosomes consist of (70S):  Large subunit: 50S.  Small subunit: 30S.  S value = Svedberg unit. 8  10/9/2024 Bacterial Structure B) Cytoplasmic components (2) Nuclear body (Nucleoid):  No nuclear membrane.  DNA molecules folded on itself.  Single chromosome is double stranded circular DNA carries genetic characters (3) Plasmids:  Extrachromosomal genetic elements.  Circular double stranded DNA.  Carry certain function: antibiotic resistance. Bacterial Structure C) Cell appendages 1- Flagellae:  They are long helical filaments attached to cytoplasm and pass out the cell wall.  Formed of contractile protein "Flagellin". Demonstration:  Motility test: Hanging drop, semisolid agar  E/M. Functions:  1) Motility  2) Antigenicity: H antigen. 9  10/9/2024 Bacterial Structure C) Cell appendages 1- Flagellae: Bacterial Structure C) Cell appendages 2- Fimbriae (Pili):  They are short, hair like filaments.  They are shorter and thinner than flagella straight and not originating from cytoplasm.  They are formed of protein "pilin". Functions: Flagellae and pilli  Organs of adhesion to host cell "common pili".  Sex pili “conjugation”.  Virulence. 10  10/9/2024 Bacterial spores Bacterial endospores are resting body phase formed under unfavorable conditions. They are highly resistant forms produced outside the body by some organisms like Bacillus and Clostridium groups. Structure of bacterial spore Shape: Spores may be spherical or oval. Bacteria Structure and Function 11 10/9/2024 12