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Basic characteristics Classification Grouping of species Pathogenesis Lab diagnosis Kingdom – Bacteria Phylum - Firmicutes Class – Bacili Order – Lactobacillales Family – Streptococcaceae Genus - Streptococcus Species – 22 sp. Gram-positive Lactic acid bacteria group Spherical Grow in chain (twisted) or pairs Mostly are facultative anaerobes Available in food such as Emmentaler (Swiss) cheese Normal flora of the mouth, skin, intestine and upper respiratory tract of humans Beta hemolysis Alpha hemolysis • Lancerfield serotyping • Based on carbohydrates in the bacterial cell wall • Group A – V (exp, I and J) • Viridans groups • S.pneumoniae separated group β hemolysis Colonies surrounded with a zone complete of haemolysis (decolorize of hemoglobin) More marked when incubate anaerobically Surrounded by an area of partial haemolysis Green-brown colour (reduced haemoglobin) Consist of pneumococci and viridans group( alpha hemolytic and no Lancerfield antigens S.pyogenes (Group A) Acute sore throat Scarlet fever Ear infections Peurperal sepsis Septicemia and occasionally endocarditis Skin infection such as celulitis and impetigo From the implication of pathogenesis, it will leads to a serious stage of diseases: Acute glomerulonephritis Rheumatic fever By S. pyogenes Streptolysin O Streptolysin S Streptokinase (cause fibrinolysis) Hyarulonidase DNAses DPNAse Erythrogenic toxin S.Agalactiae (Group B) Neonatal septicaemia, pneumoniae, meningitis Septic abortion and peurperal sepsis Enterococci (Group D) Urinary tract infection Infections of ulcer and wounds Endocarditis and meningitis Viridans Endocarditis Dental caries Brain abscess Gram positive (purple) Non-motile Long chains Sometimes in pair Aerobically and anaerobically Temperature between (22 – 42o C) And enterococci are between (15 – 45o C) On BA, colony usually less than 1 mm in diameter Grey – white or colourless Dry / shiny, irregular outline Most of the pathogenic streptococcus producing hemolysins Produce beta hemolysis Sensitive to bacitracin (can’t rely 100% to it, coz not only group A sensitive to it) but for viridans it is resistance towards bacitracin A selective BA containing crystal violet was suggested Does not grow in MacConkey agar Optochin resistant but S.pneumoniae is sensitive Beta hemolysis in BA In serum starch agar, it produces orange pigment Species Catalase Bacitracin Optochin Litmus Milk CAMP S.pyogenes - + - - - S. agalactiae - - - - + Enterococci - - - + - Viridans streptococci - - - - - Pneumococci - - + - - Scientific classification Introduction Basic characteristics Pathogenesis Laboratory diagnosis Kingdom: Bacteria Phylum: Proteobacteria Class: Beta Proteobacteria Order: Neisseriales Family: Neisseriaceae Genus: Neisseria Species: N. gonorrhoeae also known as gonococci (plural), or gonococcus (singular), Gram negative Sexually transmitted diseases These cocci are facultatively intracellular and typically appear in pairs (diplococci), in the shape of coffee beans. non-motile and possess a type IV pilus to adhere to surfaces. The type IV pilus operates mechanistically similar to a grappling hook. The pilus extends from the pole of the cell and attaches to a substrate which signals the pilus to retract, dragging the cell forward. Infection of the genitals can result in a purulent (or pus-like) discharge from the genitals which may be foul smelling. Symptoms may include inflammation, redness, swelling, dysuria and a burning sensation during urination. Infection of the genitals in females with N. gonorrhoeae can result in pelvic inflammatory disease if left untreated, which can result in infertility. Pelvic inflammatory disease results if N. gonorrhoeae travels into the pelvic peritoneum (cause conjunctivitis, pharyngitis, proctitis or urethritis, prostatitis and orchitis. Temp 35 -37 degree celcius The selective media is Modified New York City (MNYC) usually isolated on Thayer-Martin agar—an agar plate containing antibiotics (Vancomycin, Colistin, Nystatin, and SXT) nutrients that facilitate the growth of Neisseria species while inhibiting the growth of contaminating bacteria and fungi. Bacteria should be protected from sunlight Further testing to differentiate the species includes testing for oxidase (all clinically relevant Neisseria show a positive reaction) and the carbohydrates maltose, sucrose, and glucose test in which N. gonorrhoeae will only oxidize (that is, utilize) the glucose. Scientific classification Basic characteristics Food production Laboratory diagnosis Phylum: Firmicutes Class: Bacilli Order: Lactobacillales Family: Lactobacillaceae Genus: Lactobacillus Species: 40++ genus of Gram-positive Bacilus in shape facultative anaerobic or microaerophilic bacteria. a major part of the lactic acid bacteria group, named as such because most of its members convert lactose and other sugars to lactic acid. They are common and usually benign. In humans they are present in the vagina[2] and the gastrointestinal tract, where they are symbiotic and make up a small portion of the gut flora. Many species are prominent in decaying plant material. The production of lactic acid makes its environment acidic, which inhibits the growth of some harmful bacteria. Several members of the genus have had their genome sequenced Some Lactobacillus species are used industrially for the production of yogurt, cheese, sauerkraut, pickles, beer, wine, cider, kimchi, chocolate, and other fermented foods, as well as animal feeds, such as silage. Sourdough bread is made using a "starter culture," which is a symbiotic culture of yeast and lactic acid bacteria growing in a water and flour medium. Lactobacilli, especially L. casei and L. brevis, are some of the most common beer spoilage organisms. The species operate by lowering the pH of the fermenting substance by creating the lactic acid, neutralising it to the desired extent. Catalase negative Not often isolated Non motile bacteria Non-sporing Facultative anaerobes Grow best in acid environment Explain what happens in the following biochemical tests: i) Indole test ii) Methyl red test (8 marks) b) Write the scientific name of a bacterium that gave positive results for both tests. (2 marks) State all group of gram positive and gram negative bacteria.
