Laboratory 2:  Microscopic Examination from Colonies and from Direct Specimens:

Activities:

• Gram Stain of Known and Unknown Organisms From Cultures
• Known Slides -Bacterial Morphology
• Known Slides -Bacterial Morphology (continued)
• Sputa Smear Evaluation
• We will also perform the wet prep lab from Week #1 labs on Wed. 9/6/06

Gram Stain of Known and Unknown Organisms

1. The complete reference for the Gram Stain Procedure is on pp. 267-268 of your text.

2. Perform a Gram Stain on the Quality Control Slide provided.  Both S.aureus & E.coli are present on these slides.

3. Read your quality control slide on the microscope and then show the fields for me to evaluate.

4. Perform a gram stain on the slide having 8 different organisms present in the following quadrants.

Report Form for this laboratory.

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Known Slides -Bacterial Morphology

1. Review the photomicrographs of direct smears on pages 282-299 of your text.

2. Review kodachrome slides 371-408, 427-437, 446-449, 466-469, 501-523 along with the descriptions of each set of slides.

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Sputa Smear Evaluation

Initial Processing of Sputum Specimens for Quality:

Lower respiratory tract infections are difficult to diagnosis because of the difficulty to obtain a satisfactory specimen that is not grossly contaminated with mouth normal flora.  To minimize the problem, methods for evaluating the quality have been developed.  Bartlett et.al. developed a method to quickly perform this evaluation.

1. A Gram stain of the sputum is prepared.

2. Using 10X (low power magnification)) count the number of neutrophils and squamous epithelial cells in 20 to 30 fields.

3. Also note if mucus is present.

4. Consult the following chart to give the specimen a numerical grade.

5. If the sputum has a positive grade, it indicates inflammation is present and should be cultured.  If the sputum is 0 or negative, a new specimen should be obtained.

Report Form for Sputum Evaluation:

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