What\'s the purpose of this lab and the observation and conclusion? LAB 23: ISOL

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What's the purpose of this lab and the observation and conclusion?
LAB 23: ISOLATION AND IDENTIFICATION OF STAPHYLOCOCCI A. Introduction Staphylococci are Gram+ spherical bacteria that form irregular clusters of cells (pus-forming) bacteria: gether with streptococci, the two types of bacteria are referred to as pyogenic in Bergey's) er, the two share very little in common (where they belong to 2 different groups 2. species of staphylococci cause abscesses, boils, carbuncles, osteomyelitis, and most seriously, fatal 4. septicemias to be part of normal Staphylococci were originally isolated from pus in wounds, but later determined flora of the nasal membranes, hair follicles, and skin 5. Up to 90% of hospital workers carry staphylococci which creates a potential epidemiological problem, especially most strains are penicillin-resistant 6. 19 speices of staphylocooci are found in the Bergey'sManual. The most important species are S aureus, s epidermids, and s saprophyticas has the ability coagulate plasma) 7. This lab attempts to isolate staphylococci from the nose and a fomite (nonliving object) and further identify the specific species, universal precautions should be practiced l. This lab will be conducted over 3 lab periods, as a result careful labeling and recording of data are 2. 2-3 students can form a group, each group should obtain 2 test tubes of m-staph broth (nutrient broth added with 10% salt to promote better staphylococci growth) and 2 sterile cotton swabs 3. Dampen the cotton swabs with m-staph broth. 4. Insert one cotton swab into a person's nose and obtain a bacterial sample; while the second swab is swiped over a fomite (e.g. doorknob, tabletop, money, etc.) 5. Place each swab into a tube of m-staph broth and close the cap 6. Write your name and identify the two tubes 7. Place the tubes into the designated rack for incubation 8. In the second lab period, recover your 2 tubes a salt agar plate (MSA plate), draw a median line at the bottom of plate, and label one half as "nose" and the other half as "fomile lo. Follow aseptic procedure with an inoculating loop, transfer a loopful of bacteria from each tube onto the two halves of the plate ll. For each half, perform a quadrant streak in order to isolate the bacterial colonies 12. write your name on the plate and place itin the designated rack inverted for incubation 13. In the third lab period, recover your MSA plate 14. Examine each half of the plate and observe whether the agar has turned yellow 15. A color change of yellow indicates the presence of staphylococci in the nose andor f (if the agar remains pinkish, no staphylococci is present and this lab is done) 16. To confirm the presence of staphylococci, perform a Gram staining procedure to observe under the microscope 17. In addition, inoculate a small amount of culture onto a Staph Latex Test cardboard and add a drop of latex reagent. If the solution shows coagulation, staphylococci are present, if there is no coagulation staphylococci are not present

Explanation / Answer

This practical has been performed for isolation and identification of Staphylococcus aureus (specific species- only species having coagulant property). In this practical the sample has been collected from two sources, one is from nose and second is from fomite. (Since Staphylococcus species could be present everywhere even with nonliving things).

There are 19 staphylococcus species in the Bergey's manual. All shows yellow colour with agar plate. Hence presence of yellow colour confirms the isolation of Staphylococcus strain while if agar remains pinkish, it means staphylococcus is not isolated.

The last step of this practical that is innoculation of small amount of culture onto a Staph Latex test confirms that the isolated staphylococcus is specific species that is staphylococcus aureus. ( Since S. aureus is a only species, out of 19 staphylococcus genera, having coagulant property). Hence, if the solution shows coagulation after adding a drop of latex reagent then it confirms the staphylococcus aureus.

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