Bacteriology - Structure of Bacteria PDF

BACTERIOLOGY – STRUCTURE OF BACTERIA TRANSES BY: FERNANDEZ, KIM │MLS2F OVERVIEW o M. tuberculosis – slow – BACTERIOLOGY growth; they can take 6 Study of bacteria, differentiating it...

BACTERIOLOGY – STRUCTURE OF BACTERIA TRANSES BY: FERNANDEZ, KIM │MLS2F OVERVIEW o M. tuberculosis – slow – BACTERIOLOGY growth; they can take 6 Study of bacteria, differentiating it weeks to incubate from other organisms Study of bacteria, its Diagnosis for Tuberculosis: characteristics, components, o DSSM – Direct Sputum and virulence factors Smear Microscopy – Bacteria o GeneXpert – uses Prokaryotic, no nucleus, no polymerase chain reaction membrane-bound organelles (PCR); it is the ideal Unicellular diagnostic tool for M. – Fungi and Parasites tuberculosis May be unicellular or multicellular GRAM STAINING Eukaryotic, has nucleus and – Initial step of identifying bacteria membrane-bound organelles – Fundamental staining technique – Virus used in bacterial identification Particle, obligate intracellular schemes Not considered a cell – Important factor in identifying No organelles even cytoplasm or bacteria, once the gram staining went has it with very small amount wrong everything will also be wrong Mobile genetic elements – they (domino effect) travel from one cell to another in order to survive – TWO GENERAL TYPES OF BACTERIA: Infect cells in order to replicate in Gram-positive (+) a process of hijacking o Blue or puprle stain o Hijacking – infect DNA/RNA Gram-negative (-) to host to utilize cells and o Red or pink stain their proteins in order to assemble to replicate. – SHAPES OF BACTERIA: Bacilli – HOW DO CELLS DIVIDE? o Rods in shape Eukaryotes – cell division Cocci (mitosis) o Circular in shape Prokaryotes – binary fission – Example: o Example: Gram-positive bacilli o E. coli – 20 mins. Doubling o blue/purple, rods time, they have exponential Gram-negative cocci growth of bacteria o red/pink, circular (1,2,4,8,16); incubate the medium for at least 24 hours  BACTERIOLOGY – STRUCTURE OF BACTERIA TRANSES BY: FERNANDEZ, KIM │MLS2F – Bacterial identification requires to determine the morphology and right medium to be used. Example when culturing Streptococcus, a blood agar plate is used. Mediums have inhibitory agents that could affect the growth of the bacteria if it is not the right – PILI medium used. Small structure protruding outside the bacteria, surrounding – Bacteria nomenclature uses the bacteria Binomial (two name) system Attaches to mucus membrane Genus + Species inside the body Escherichia coli Virulent factor: starts the Escherichia – genus infection coli – species same function as of fimbrae but fimbreae is longer STRUCTURES OF BACTERIA – A bacteria consists of different – SEX PILUS appendages and cellular envelope Important in antimicrobial resistance of bacteria – FLAGELLA Mediate the process of Important part of the bacteria that cojugation aids in their motility – Conjugation Process – Monotrichous If organism is resitant, it should Flagella at one polar end of the have fertility factor to produce cell sex pilus creating bridge to Ex: V. cholerae recipeint, a sensitive organism, – Lophotrichous producing proteins the resist Multiple flagella at one polar end antibiotics. of the cell Ex: H. pylori Resistant Sex Pilus Sensitive – Amphitrichous F-factor F+ Flagella at both polar ends of the Sex pilus is present only in cells that produce a cell protein referred to as the F factor – Peritrichous Sex pilus – create genes that Flagella surrounding the bacteria makes the bacteria resistant to Ex: E. coli antibiotics through the transfer of fertility factor to senstive bacteria creating gene to produce B- lactamase  BACTERIOLOGY – STRUCTURE OF BACTERIA TRANSES BY: FERNANDEZ, KIM │MLS2F Pili – Dipicolinic Acid Calcium chealator Create cell wall/cell membrane to daughter cells, while mother cell will die Daughter cells are enclosed with – Antimicrobial stewardship cell membrane, cell wall, spores helps defeat antimicrobial to protect and survive resistance to the population. In order to live, water should be Most common example is excreted thus calcium will enter requiring drug prescription for the cell, replacing water to be purchase of antibiotics. excreted. – B-lactamases Protein (enzyme) produced by – CELLULAR ENVELOPE bacteria Series of structure Helps in defense against anbiotics, leading ineffective – CAPSULE antibiotics to bacteria Important virulent factor, – Penicillin encapsulates the organism Produces B-lactam rings, binding Can cause meningitis as it can to kill the bacteria traverse within the blood brain If antibiotics are combined, it is barrier more effective to kill the bacteria Encapsulated organisms are as second-line of drugs cannot be pathogenic in nature resisted by bacterias. Example of encapsulated organisms that can cause – ENDOSPORES meningitis: Bacillus and Clostridium spp. o S. pneumoniae are spore forming (sporulate) o N. meningitidis Bacillus and Clostridium are o H. influenzae type B spore forming, aerobic, non- o All has vaccines that motile produces anticapsular Protects organism from heat, mechanism chemical, radiation Capsule evades the immune Boiling point can’t kill most of the system by evading phagocytosis bacteria, thus the use of autoclave – Spores – keratin-like coat that is produced if the bacteria has unfavorable environment (no nutrients, physical, chemical)  BACTERIOLOGY – STRUCTURE OF BACTERIA TRANSES BY: FERNANDEZ, KIM │MLS2F – Phagocytosis – CELL WALL Engulfment of bacteria made by Targeted by antibiotics WBC “Peptidoglycan” – polymerization Neutrophils of sugars o Sensitive to chemotactic Cell wall can help to differentiate factor, 60-70% of the WBC gram-positive form gram-negative o First line of defense of bacteria phagocytes o Respond primarily to – Peptidoglycan infection, forming pus Polymerization of polysaccharide Macrophages sugars: o Second line of phagocytosis o N-acetylglucosamine o Consists of different o N-acetylmuramic acid monocytes Consists of alternate GlcNAc and Encapsulated bacteria can slip Mur2Ac or the sugars away from phagocytes – Opsonins Antibodies IgG, complement C3D Creates membrane attack complex Tetrapeptide Opsonization Process Composed of 4 amino o When bacteria slips away acid (L-Alanine, D- Glutamine, L-Lysine, D- from phagocytes, opsonins Alanine) will plug on bacteria’s Peptide interbridge surface rendering the (Pentaglycine cross-link) – holds them further to make the structure bacteria rough edges more stable links the layers of allowing phagocytes to peptidoglycan successfully engulf the Transpeptidase – breaks the bacteria tetrapeptide Transpeptidastion – creates the – GLYCOCALYX peptidoglycan “slime layer” Attachment structure – STRUCTURE OF CELL WALL Used by bacteria to attach to – Gram-positive prosthetics or hospital Blue/purple materials and instruments such Can retain the primary stain as bed railing (methylene blue) Commonly acquires hospital- Has thick peptidoglycan layer acquired infections (10 layers) and inner cell Biofilms – Create a coating to the membrane material where bacteria can Cannot be decolorized multiply  BACTERIOLOGY – STRUCTURE OF BACTERIA TRANSES BY: FERNANDEZ, KIM │MLS2F Pathogenesis of cell Pathogenesis of cell membrane: membrane: o Lipoteichoic acid – extends o Lipopolysaccharide – has up to the cell membrane; three parts that is attached attached to the and situated to the outer phospholipids all throughout membrane the top of peptidoglycan o Very immunogenic and hence immunogenic antigenic o Immunogenic – can ellicit o Outer membrane immune response Somatic O-antigen – antigenic Peptidoglycan nature, where antibodies usually attached o Inner membrane Inner cell membrane (phospholipid bilayer) o Lipid A – Immunogenic, Culprit with septic shock – Gram-negative Red/pink Penicillin Cannot retain the primary stain o have B-lactam, inhibiting the thus counterstain is retain cell wall (Saffranin) o Targeting the tetrapeptide to Easily decolorize the primary be removed, destabilizing stain the structure and eventually Has very thin peptidoglyan (2-3 break the peptidoglycan layers) and two cell membrane leading to the death of the Outer cell membrane organism Peptidoglycan Periplasm Inner cell membrane (phospholipid bilayer) Periplasm o Area where bacteria produces B-lactamase o typically is found only in gram-negative bacteria o contains the murein layer, consists of gel-like substances that assist in the capture of nutrients from the environment