11Differential Culture Media and Characteristics MEDIUMIMPORTANT INGREDIENTSPURPOSE AND DIFFERENTIAL INGREDIENTSManitol-Salt Agar (MSA)7.5% NaCl (750g/l) Mannitol Neutral RedPurpose: Selective isolation of Staphylococcus species and preliminary identification of pathogenic species by fermentation of mannitol (pink-to-yellow color change with acid production). Inhibitor: High sodium chloride concentration inhibits many types of bacteria. Carbohydrate Source: Mannitol pH Indicator: Phenol RedSalmonella-Shigella agar (SS Agar)Bile salt (8.5g/l) Sodium citrate (8.5g/l) Brilliant green Sodium thiosulfate Ferric citrate Lactose Neutral RedPurpose: Inhibits the growth of coliform organisms & permits the growth of Salmonella & Shigella species from clinical specimens. Inhibitor: High Bile Salt concentration & Sodium Citrate inhibit all G+ bacteria and many Gram- bacteria. bacteria and many Gram- bacteria Carbohydrate Source: Lactose pH Indicator: Neutral RedPrimary Isolation Media (Inhibitory).MacConkey agar (MAC)Bile salt (1.5g/l) Crystal violet Lactose Neutral RedPurpose: Recover the Enterobacteriaceae & related enteric Gram-negative bacilli. Inhibitor: Bile salt & Crystal Violet. Inhibit the growth of Gram-positive bacteria and some fastidious Gram-negative bacteria. Carbohydrate Source: Lactose pH Indicator: Neutral RedEosin-Methylene-Blue Agar (EMB)Eosin Y Methylene-Blue LactosePurpose: Isolation & detection of the Enterobacteriaceae or related coliform bacilli from specimens with mixed bacteria. Inhibitor: Eosin & methylene blue. Inhibits the growth of Gram-positive bacteria and some fastidious G- organisms Carbohydrate Source: Lactose pH Indicator: Eosin & methylene blue combine to form a precipitate at acidic pH.
12Biohazard discard container Incubate the plate at 37oC for hours.MATERIALS:Sterile cotton swabBacteriological loopNutrient Agar platesBiohazard discard container
13Μακροσκοπική εμφάνιση αποικιών ΜέγεθοςΣχήμαΎψοςΧρώμαΠεριφέρειαΣύσταση (π.χ. βλεννώδης)ΌψηΜεταβολές στο θρεπτικό υλικό
19PRESUMPTIVE TESTS FOR GROUP B STREPTOCOCCI The CAMP TestPRINCIPLE:The hemolytic activity of staphylococcal-hemolysin on RBC is enhanced by an extracellular factor produced by Group B streptococci, called the CAMP factor. Therefore, wherever the two reactants overlap in sheep BAP, an accentuation of the ß-hemolytic reaction will be noted.PROCEDURE:The CAMP test is performed by making a single streak of the streptococcus perpendicular to a strain of Staphylococcus aureus that is known to produce ß-hemolysin. The two streak lines must not touch one another. The inoculated plate must be incubated with an ambient atmosphere (room temperature). The plate should not be incubated in an anaerobic environment because many Group A streptococci are positive in the absence of O2. Positive control: S. agalactiae.