Lab 11 Isolation and Identification of Bacteria and

Lab 11 Isolation and Identification of Bacteria and Fungi from Different Parts of the Body and Environment, (Air, Skin, Nares, Throat, Tongue, Gingivae). The microorganisms, that constitutes the normal microflora (indigenous) of human body are usually harmless, some of them are opportunists and has a potential ability to cause diseases under a certain circumstances, such as: the bacteria. Staphylococcus epidermis, Staph. aureus, Streptococcus pyogenes, Strep. viridans Strep. Pneumonia, Neisseria sps. Bacillus sps. , Clostridium sps. Molds such as: Trichophyton, Rhizopus, Aspergillas, Penicillium and yeast such as Candida sps. Isolation of bacteria Materials: Sterile 0. 85% saline tubes Sterile swabs Disinfectant sterile tongue depressors Inoculating loops Gram-stain reagents Bunsen burners

Blood agar plates Nutrient agar plates Tryptic soy agar plates Mac. Conkey agar plates Lactose. Bile broth tubes Eosin methylene blue agar plates (EMB) Vogel-johnson agar plates. I -Isolation from Air Procedures: Open one tryptic soy agar plate in the lab. and one Nutrient agar plate outside the lab. for 1 -hr. Incubate the plates at 25 -30 °c for 48 -72 hrs. In the next lab. Count the colonies. Observe and describe the morphology of the colonies. Do G-stain and exam under microscope. Record you observations and results in a report.

II -Isolation from the skin Procedure Moist a swab in a sterile 0. 85% saline (squeeze out the excess fluid by pressing the swab near the side of the tube. Roll the swab over the arm. Streak Tryptic Soy Agar (TSA)plate with rolling the swab near one edge of the plate. From this area streak with a sterile loop. Repeat the previous steps 2, 3 and 4 with Blood agar plate instead of TSA. Inverte the plates and incubate them at room temp. or at 35°c for 24 -48 hrs. In the next lab. observe and describe the colonies. Select different colonies and do G-stain , exam under microscope. Record your observations in a report III -Isolation from Nares Repeat the exercise II with swabbing from Nares. (Throat, Gingivae, tongue) healthy or infected by swabbing or biopsy specimens