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Pathogenic and opportunistic cocci. Classification, biological properties. Staphylococci, streptococci, gonococci and meningococci.
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Staphylococcus Classification Family – Micrococcaceae Genus – Staphylococcus Species: 1.S. aureus 2.S. epidermidis 3.S. saprophyticus
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Staphylococci in the pure culture and in the pus smears
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Culture They grow readily on ordinary culture media The optimal temperature being 37 0 C and pH 7,4-7,6 They are aerobes and facultative anaerobes Culture media: nutrient agar, blood agar, salt media
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Differentiation of the S.aureus from opportunists Hemolysis appearance on the blood agar DNAase activity (on the top)
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Differentiation of the staphylococci Coagulase activity (test is positive for S.aureus) Novobiocin disk test to differentiate S.saprophyticus (left) and S.epidermidis (right)
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Pathogenesis Staphylococcal diseases may be classified as 1.Cutaneous infections 2.Deep infections 3.Food poisoning 4.Nosocomial infections (hospital infections) 5.Skin exfoliative disease (staphylococcal scalded skin syndrome) 6.Toxic shock syndrome
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Laboratory diagnosis Direct microscopy Culture.
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The characteristics help to distinguish the pathogenic strains from non-pathogenic strains Beta type of haemolysis on blood agar Production of a golden yellow pigment Coagulase production Mannitol fermentation Gelatin liquefaction Phosphatase production Production of enzyme deoxyribonuclease Tellurite reduction
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Prophylaxis General prophylaxis.
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Staphylococcus aureus
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Streptococcus Classifications: A. Due to type of hemolysis B. Lancefield´s classification (serological) C. Due to phylogenetic relationship
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Different types of hemolysis Α -Hemolysis Β-Hemolysis Γ-Hemolysis
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S.pyogenes (smears from the agar culture(on the left) and sugar broth (on the right)
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S.pneumoniae (smears from the pure culture and from the sputum)
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Culture aerobes and facultative anaerobes media containing blood, serum or sugars.
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Laboratory diagnosis Suppurative infections : microscopy and pure culture isolation Non-suppurative sequelae: serology
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Streptococcus pyogenes
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Neisseria Classification Family - Neisseriaceae Genus – Neisseria Species: 1.N. meningitidis 2.N. gonorrhoeae
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N. meningitidis in the smears from the pure culture and clinical sample
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Culture They are strict aerobes. The optimum temperature and pH for growth are 35-36 0 C and 7,4-7,6 respectively. Growth occurs in media enriched with blood, serum or ascitic fluid.
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Antigenic classification N. meningitidis has been divided into 13 serogroups
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Laboratory diagnosis Direct microscopy Antigen detection Culture. Serology Polymerase chain reaction.
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Prophylaxis Chemoprophylaxis Immunoprophylaxis.
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Neisseria meningitidis
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N. gonorrhoeae
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Laboratory diagnosis Direct microscopy. Culture. Serology
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