Appears As Grape
1. Appears as grape-like clusters when viewed through a microscope, and has large, round, golden-yellow colonies, often with hemolysis, when grown on blood agar plates.
2. Microorganisms that are used to assess the microbial quality of swimming pool and similar environments include heterotrophic plate count – HPC (a general measure of non-specific microbial levels), faecal indicators (such as thermotolerant coliforms, E. coli), Pseudomonas aeruginosa, Staphylococcus aureus and Legionella spp. HPC, thermotolerant coliforms and E. coli are indicators in the strict sense of the definition.
Non-faecally-derived
Can used to determine non-faecal shedding. The absence of these organisms, however, does not guarantee safety, as some pathogens are more resistant to treatment than the indicators, no perfect indicator organisms
3. Staphylococcus aureus is a Gram-positive coccal bacterium that is a member of the Firmicutes, and is frequently found in the human respiratory tract and on the skin.
Red-color dye can bind specifically to the peptidoglycan molecule, Gram positive cell can be stained better.
Gram-positive bacteria have a thick mesh-like cell wall made of peptidoglycan (50–90% of cell envelope), and as a result are stained purple by crystal violet, whereas gram-negative bacteria have a thinner layer (10% of cell envelope), so do not retain the purple stain and are counter-stained pink by the Safranin. There are four basic steps of the Gram stain.
First, the cells are stained purple with crystal violet. The slide is then treated with iodine/iodide solution, and then decolorized with a solvent (acetone, or alcohol) that dissolves the iodine/crystal violet complex. Gram-positive cells remain purple, and Gram-negative cells are decolorized. To see the Gram-negative cells, a red counterstain is used (safranin or acid fuchsin). After counterstaining, the Gram-positive cells are purple and the Gram-negative cells are red.
4. It is positive for catalase and nitrate
2. Microorganisms that are used to assess the microbial quality of swimming pool and similar environments include heterotrophic plate count – HPC (a general measure of non-specific microbial levels), faecal indicators (such as thermotolerant coliforms, E. coli), Pseudomonas aeruginosa, Staphylococcus aureus and Legionella spp. HPC, thermotolerant coliforms and E. coli are indicators in the strict sense of the definition.
Non-faecally-derived
Can used to determine non-faecal shedding. The absence of these organisms, however, does not guarantee safety, as some pathogens are more resistant to treatment than the indicators, no perfect indicator organisms
3. Staphylococcus aureus is a Gram-positive coccal bacterium that is a member of the Firmicutes, and is frequently found in the human respiratory tract and on the skin.
Red-color dye can bind specifically to the peptidoglycan molecule, Gram positive cell can be stained better.
Gram-positive bacteria have a thick mesh-like cell wall made of peptidoglycan (50–90% of cell envelope), and as a result are stained purple by crystal violet, whereas gram-negative bacteria have a thinner layer (10% of cell envelope), so do not retain the purple stain and are counter-stained pink by the Safranin. There are four basic steps of the Gram stain.
First, the cells are stained purple with crystal violet. The slide is then treated with iodine/iodide solution, and then decolorized with a solvent (acetone, or alcohol) that dissolves the iodine/crystal violet complex. Gram-positive cells remain purple, and Gram-negative cells are decolorized. To see the Gram-negative cells, a red counterstain is used (safranin or acid fuchsin). After counterstaining, the Gram-positive cells are purple and the Gram-negative cells are red.
4. It is positive for catalase and nitrate