General Bacteriology 1 PDF

Level (1) - Semester (1) MICROBIOLOGY D R Z I A D M A LECTURE (2) H A N GENERAL BACTERIOLOGY (1) A  -  Medical Microbiology: science study microbes & interactions between them & hosts leading to infectious diseases.  Cocci: round.  Rod...

Level (1) - Semester (1) MICROBIOLOGY D R Z I A D M A LECTURE (2) H A N GENERAL BACTERIOLOGY (1) A  -  Medical Microbiology: science study microbes & interactions between them & hosts leading to infectious diseases.  Cocci: round.  Rod-shaped bacilli: May with tapered ends like cigars or oval & look like cocci called coccobacilli.  Spiral with one or more twists.  Monomorphic: they have a single shape.  Pleomorphic: they have many shapes.  Bacteria range from 0.2 to 5 μm.  Micron (μ), μm or (one thousandth of a millimeter), -  -  Glycocalyx.  Fimbriae/pili.  Flagella.  Cytoplasm.  Ribosomes.  Nucleoid.  Inclusions.  Cytoplasmic membrane.  External to the cytoplasmic membrane.  In all bacteria (except Mycoplasma species).  Composed of peptidoglycan.  Peptidoglycan:  Formed of N-acetylglucosamine & N-acetylmuramic acid.  Presents in both Gram-positive & Gram-negative bacteria. - Thick & Multilayer. Thinner & Single layer. ① Outer membrane (thick) contains:  Lipoprotein, Phospholipids.  Lipopolysaccharide (lipid A= Endotoxin & O-polysaccharide ① Teichoic acid protrudes outside (antigenic)). the peptidoglycan. ② Periplasmic space: ② Lipoteichoic acids.  Between the outer-membrane & the cytoplasmic membrane contains the peptidoglycan layer & enzymes β-lactamases.  - ① Provides: a. Structural support, b. Maintains the characteristic shape of the cell. ② Toxicity: LPS = endotoxin. ③ Responsible for: Gram staining reaction. ④ Target for: antibiotics as it is unique to the bacteria. ⑤ Antigenic.  Acid-Fast Bacteria. A. shows non-acid-fast bacteria (purple). B. shows acid-fast bacteria (pink). ▪ Induced by Lysozyme: in tears, ▪ Some bacteria, lose ▪ The smallest mucus & saliva. their cell walls & swell bacteria. ▪ Protoplasts from Gram positive into irregularly shaped ▪ NO cells. cells (L forms). peptidoglycan. ▪ Spheroplasts from Gram negative ▪ L forms can live & ▪ Resistant to cell cells. divide repeatedly. wall-inhibiting ▪ Osmotic lysis: water rapidly move ▪ Return to the walled antibiotics. into cells which enlarge & rupture. state.  -  Gelatinous polysaccharide (Streptococcus pneumoniae) or  Formed of pilin. polypeptide (Bacillus anthracis) or both  Long helical tubular structure  Found mainly on Gram-negative cover the cell wall. composed of protein flagellin. bacteria.  The glycocalyx is described as:  Anchored in the cell  More numerous, shorter,  Capsule if it is → firmly attached to membranes by a basal body. thinner, straighter than flagella. the cell wall,  Slime layer if it is → loosely attached.  Protects bacterial cell from phagocytosis.  Promote attachment between:  Antigenic (K antigen): used in:  Organs of motility: Move the  Bacterial cell & the host cell  Serodiagnosis. bacteria toward nutrients & or  Vaccine preparation. other attractants (chemotaxis).  One bacterial cell & another  Plays a role in the adherence of bacteria  Antigenic (H antigen). (f or sex pili). to human tissues.  - Encapsulated Encapsulated Klebsiella pneumoniae in CSF, Klebsiella pneumoniae Gram stain. with Indian ink. Pseudomonas Alkaligens faecalis Campylobacter E. coli.  -  Very thin elastic membrane lies immediately under the  Primary site of protein synthesis cell wall. (translation).  Composed of:  Bacterial ribosomes (70S) consist of 2 ① Phospholipids bilayer subunits: ② Proteins. ① A small subunit 30S.  No sterols, Except Mycoplasma. ② A large subunit 50S.  Each subunit is composed of: ① rRNA molecules ② variety of proteins.  Semipermeability: certain molecules & ions are allowed to pass through the membrane but others are stopped.  Energy production (ATP). ----  Biosynthetic function: carries enzymes & molecules for synthesis of cell wall.  -  They represent stored nutrients.  May be protein, lipid & glycogen.  Metachromatic granules: C.  Thick, semitransparent  No true nucleus. diphtheria (PO4, Granules red with substance inside the  No nuclear membrane. Methylene Blue stain). plasma membrane.  Mostly consists of a single  Contains nucleoid, circular dsDNA. ribosomes & inclusions.  Plasmid.  Has cytoskeleton: a series of fibers has roles in: ---- ---- ① Cell division ② Maintaining cell shape.  -  Some bacteria form endospores under unfavorable in vitro conditions as starvation, desiccation & heat.  Genus Clostridium & Genus Bacillus.  Upon exposure to appropriate nutrients, germination into a reproducing bacterial cell occurs. Clinical Case  A 44 years old man visited the chest clinics suffering from fever, chest tightness and cough with sputum. On Examination his body temperature was 38.5° C. He had dyspnea with chest wheeze. The physician asked him to do microbiological examination for his sputum which recovered Gram positive cocci. ① The difference between Gram positive and Gram-negative bacteria is in the: a. Cell wall. b. Nuclear body. c. Cytoplasmic membrane. d. Ribosomes. ② List 3 functions of the cell wall? ……………………………………………………………………………..………….. ……………………………………………………………………………..………….. ……………………………………………………………………………..…………..