Hmgram positive note

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Human Biology
Jane Mitchell

Gram Positive Enzymes • Staphylokinase: dissolves fibrin threads in blood clots • Lipases: digest lipids allowing staphylococci to grow on the surface of the skin Toxins • Staphylococcus aureus: several toxins that contribute to their pathogenicity o Cytolytic toxins: alpha, beta, gamma and delta toxins are proteins o Exfoliative toxins: two distinct proteins cause the dissolution of epidermal demosomes o Toxic Shock syndrome (TSS) toxin the protein causes toxic shock syndrome o Enterotoxins: have 5 proteins stimu late the intestinal muscle contractions, nausea, and intense vomiting Epidemiology • Staphylococcus epidermidis : on human skin • Bacteria can be transferred from skin • Staphylococcus causes medical problems depending on the site of infections, immune state of its host and toxins and enzyme a particular species Noninvasive Disease • Staphylococcus aureus : more common causes of food poisoning • Commonly affected meats, custard pastries , potato salad and ice cream • Symptoms include nausea, severe vomiting, diarrhea, headache, sweating and abdominal pain that can last for hours Cutaneous Disease • Staphylococcus aureus causes locailized pyogenic • Staphlococcal scalded skin syndrome: is reddening of the skin at the mouth then spreads throughout the body • There are the large blood cells consistence with the disease • The affected layer peals the skin away • Impetigo: small, flattened red patched on the face and limbs particular children who’s immune system are not developed • Folliculitis: is an infection of a hair follicle in which the base becomes red, swollen and pus • Sty: condition at the eyelid • Furuncle: boil is a large painful raised nodules extention of follicu;it is into surrounding tissue • Carbuncle: form deeper in tissues Systemic Diseases • Can cause potentially fatal events Staphylococcal Toxic Shock Syndrome • When strains produce TSS toxin • Fever, vomiting, red rash, low pressure and loss of sheets of skin Bacteremia • S. aureus is the common cause of bacteremia • Blood from a site can cause infections to the body Endocarditis • S. aureus may attack the lining of the heart • Typically patients can have flu -like systems Pneumonia and Empyema • Staphylococcus in the blood can invade the lungs causing pneumonia • Empyema: patients with pneumonia with pus Osteomyelitis • Osteomyelitis: staphylococcus invades the bone • Characterized by bone development • Latter half 20thcentury: genes for B-lactamase which covey resistance to natural penicillin • Methicillin-resistance Staphylococcus aureus (MRSA): major problem in health care settings Streptococcus • Gram-positive bacteria • Known as S. pygenes Pathogenicity • Streptococcus pyogenes have a number of structures, enzymes and toxins • Two main structural features allow S. pyogenes to phagocytose o M protein: a membrane protein that interferes with oponization and lysis o Hyaluronic acid capsule: normally found in cells -> white blood cells may ignore bacteria “camouflage” • Researchers have identified two streptokinases that break through blood clots • Moves to infected areas • Group A: streptococcus secretes 3 pyrogenetic toxins helps stimulate macrophages • These toxins cause the blood to dilate • S. pyogenes can produce 2 different membrane bound proteins called streto lysins which lyse red blood cells, white blood cells and palettes Epidmiology • Group A streptococcus infects pharynx or skin • Usually temporary lasting only adaptive immune responses • Streptococcus pyogene causes normal competing microbiota are depleted Group A Streptococcal Diseases • Group A Streptococcus: causes a number of diseases Pharyngitis • A sore throat can be caused by streptococcus inflammation of the pharynx • Accompanied by fever, malaise and headache • Appears red and swollen lymph nodes and purulent • There are two form of contagious and non-contagious forms Scarlet Fever • Also known as scarlatina usually accompanies streptococcal pharyngitis • After one or two days of pharyngitis: pyrogenic toxins released by streptococci triggered a rash on the tongue then appears on the skin Pyoderma and Erysipelas • Pyoderma: confined, pus producing lesion that usually appears on the face, arms or legs • Direct contact with an infected person can spread the disease • Pus-filled lesion breaks open it forms a yellowish crust • Ersipelas: streptococcal infection involves surrounding lymph nodes and triggers pain and inflammation Toxic-shock-like syndrome • Group A streptococci can spread rarely • Spread leads to bacteremia and severe multisystem infections producing toxic shock-like syndrome (TSLS) • Patients experience inflammation at the sites of infection , fever, chills, malaise, nausea, vomiting and diarrhea Necrotizing Fasciitis • Serious disease caused by S. pyogene • “Flesh eating bacteria” • Streptococci enter the body the skin and secretes enzymes and toxins that destroy tissues and will destroy muscle and fat tissue • It can spread deep into the connective tissue • Involves toxins in the blood Rheumatic Fever • Inflammation leads to damage of heart valves and muscle • The exact cause of the damage in unknown • It is an autoimmune response to S. pyogenes Glomerulonephritis • Antigen of some strains of Stre ptococcus are not removed from circulation, accumulation in the glomeruli of the kidney’s nephrons • Inflammation of the Diagnosis, treatment and prevent ion • Streptococcus: normal in the pharynx • Use penicillin effective against S. pyogene Group B: streptococcus: Streptococcus agalactiae • S. agalactiae forms capsules against antibodies • Produce enzymes called proteases Epidemiology • Colonize the lower GI tract, genital and urinary tract • Infections less than a week in newborns, 3 months Disease • Bacteria is associated with neonatal bacteremia, meningitis and pneumonia Diagnosis, treatment and prevention • Penicillin G is used to treat Other Beta: Hemolytic Streptococci • Streptococcus equisimilis causes pharyngitis • Streptococcus anginoso causes pus containing abscesses • Pencillin can be used to treat both Alpha-Hemolytic Streptococci: The Viridan Group • Lack group specific carbohydrate • Viridans streptococci produce green pigments • Normally inhabits the mouth, pharynx, GI tract and urinary tract of humans • They are opportunists that produce abdominal infections • Large quantities can create biofilm -> dangerous to teeth Streptococcus Pneumoniae • Discovered by Lousis Pasteur in 1881 • Gram positive • He classified the bacteria as diplococcus Pathogenicity • Normal member of pharyngeal microbitia can colonize in lungs, sinuses and middle ear • There are different stains ; more virulent stains have a capsule • Pneumonia can insert itself through cell walls through a chemical called phosporylcholine • Secrete protein adhesion a protein that can bind to blood or brain • Body limits migration of binding microbes Epidemiology • Grows in the mouth and pharynges • 75% of the time they don’t cause harm Pneumococcal Diseases Pnemococcal Pneumonia • Caused by S.pneumoniae • The disease is inhaled and dam ages the lungs • Leukocytes attack the Steptococcus • Causes fevers Sinusitis and otitis Media • Viral infection in the upper respiratory tract • S. pneumoniae can invade the ear and sinuses • Otitis media: inflammation un middle ear Bacteremia and Endocarditis • Can enter through blood or vigourous brushing, chewing on hard foods or dental procedures Pneumococcal Meningitis • Can spread to the meninges via bacterium Diagnosis, treatment and prevention • Antibodies can be used to identify stains • Penicilin can be used to treat • Prevention vaccination however it does not protect against elderly, young children and AIDS patients Enterococcus • Enterococci are spherical and live in the intestines of animals • Used to classified as group D streptococcus Structure and physiology • Short chains and pairs • Grow up to 45 C, pH 9.6 and 6.5% NaCl Pathogenesis, Epidemiology and Diseases • E. faecalis and E.faecium are found in the colon • They secrete bacteriocins which promote the growth of other bacteria • They can cause harm to lungs, urinary tract, bloodstream Diagnosis, treatment and prevention • Entercoccua infections are difficult to treat becaus e it is usually resistant to antibiotics • Good hygiene can be used to prevent the spread of this bacteria Bacillus Structure, Physiology and pathogenicity • Rod shaped anaerobic bacterium • They have protective capsules and a tough external coat and internal chemicals from endospores • Tough coats allow them to
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