| Match the following: | View Page |
| Match the following: | View Page |
| The presence of Gram negative intracellular diplococci in a female is diagnostic of gonorrhea. | View Page |
| Quality Control Smears Quality control smears are stained at the same time as the patient's slides.They must be examined before you examine the patient's slides.If properly stained, the Staphylococcus aureus on the positive control slide will stain blue, or gram positive.The Escherichia coli on the negative control slide will stain red, or gram negative.If these slides are not stained properly, the problem must be resolved and new slides made before the patient specimen is examined. | View Page |
| The smears used for quality control are: (Choose ALL of the correct answers) | View Page |
| White blood cells White blood cells also stain gram negative and usually have a segmented nucleus. Their average diameter is about 12 microns. | View Page |
| Red blood cells Red blood cells are 6-8 microns in diameter and are Gram negative. | View Page |
| Most background material is Gram negative. | View Page |
| White blood cells are Gram negative. | View Page |
| Match the Gram stain reaction for each of the following nonbacterial elements. | View Page |
| Epithelial cells After finding an appropriate field, identify the nonbacterial cells first. Epithelial cells stain gram negative and are easily recognized by their large size and nonsegmented nucleus. | View Page |
| Identification of bacteria Identification of bacteria in direct smears may be of lifesaving importance. For example, a rapid diagnosis of bacterial meningitis, made after examining a gram stained smear of the patient's cerebrospinal fluid, allows the physician to begin treatment immediately. The appearance of bacteria on gram stained smears is suggestive of a certain species, but identification may not be made on the basis of the stain alone. An exception to this rule is the presence of gram negative intracellular diplococci from a male urogenital specimen, which is presumptive identification of Neisseria gonorrhoeae. In addition, culture results can be correlated with the direct smear report. | View Page |
| Intracellular bacteria. Sometimes bacteria are present within white cells. In this field, there are gram negative bacteria present within a neutrophil.
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| Evaluation of Controls If stains and technique are adequate, S. aureus should be Gram positive (blue) and E. coli should be Gram negative (pink). If control slides do not react appropriately, reliable results cannot be assured for the specimen smears. Check stains and technique and prepare more control smears until proper results are achieved, then remake and stain the new direct smears. If it is impossible to prepare a new smear, the poorly stained smear may still be salvaged. Remove immersion oil from the smear using xylol. Use appropriate procedures and personal protective equipment when using xylol, since it is hazardous chemical. If the smear is underdecolorized, repeat the decolorization and counterstain steps. If the smear is overdecolorized, the slide should be stained again. | View Page |
| Size and Appearance of Cellular Elements Type of Cell Size Shape Stain Epithelial cells 25 microns irregular pink/red White blood cells 12 microns round pink/red Red blood cells 7 microns round pink/red Yeast 7 microns ovoid blue Bacteria 0.5 - 1 micron variable blue or red Epithelial cells are larger than white blood cells and red blood cells, and contain a single nucleus. White blood cells (neutrophils contained in pus) usually show a segmented nucleus. Red blood cells are 1/2 to 2/3 as large as white blood cells, contain no nucleus, and are Gram negative. Hyphae are gram positive tubular filamentous fungal elements which may show branching or intertwining. Yeast cells are round to oval, often budding, Gram positive fungal elements, about the same size as RBCs. They are generally much larger than bacteria. | View Page |
| Reporting Genital Smears Direct smears read specifically for the presence of gonococci should include a direct reference to gram negative intracellular diplococci. | View Page |
| Special Considerations for Genital Smears Gram negative cocci which occur in pairs with their adjacent sides flattened, giving them a coffee bean appearance, are typical of the genus Neisseria. Neisseria gonorrhea is commonly found within white blood cells; these organisms must be carefully sought within genital tract specimens, and their presence or absence should be specifically noted in the report.The presence of intracellular gram negative diplococci in a purulent male urethral smear is presumptive evidence of gonococci, but this assumption cannot be made in a female.Beware of other organisms which resemble gonococci but are found extracellularly, such as Acinetobacter lwoffi, which must be distinguished biochemically.Direct smears read specifically for the presence of gonococci should include a direct reference to gram negative intracellular diplococci. | View Page |
| In a male with a purulent urethral exudate, a presumptive diagnosis of gonorrhea is made by finding Gram negative intracellular diplococci in a direct smear of the exudate. | View Page |
| The staining reaction for yeast is: | View Page |
| A mixture of Gram positive and Gram negative bacteria may be present within the same field of a slide. | View Page |
| Gram Positive and Negative Stain Colors Microorganisms that are Gram positive stain blue while those that are Gram negative stain pink. | View Page |
| Cocci and Rods Bacteria may be either round (cocci) or rod-shaped (bacilli). Either shape may be Gram positive or Gram negative. A mixture of Gram positive and Gram negative bacteria can occur in the same field. Examples of Gram positive bacilli (rods) are shown on the bottom left, and Gram positive cocci are shown on the bottom right. | View Page |
| Select all the choices below than correctly describe this Gram stained smear. | View Page |
| Select all the choices below than correctly describe this Gram stained smear. | View Page |
| Pair Cell Arrangement This field shows examples of Gram positive bacteria in pairs. These are lancet shaped "diplococci" which could represent Streptococcus pneumoniae. However, determination of bacterial species always requires confirmatory testing. This particular image is not from a culture, but from a Gram stained sputum specimen. The large Gram negative pink staining rounded structures in the background are neutrophils. | View Page |
| Select all the choices below than correctly describe this Gram stained smear. | View Page |
| Select all the choices below than correctly describe this Gram stained smear. | View Page |
| Select all the choices below than correctly describe this Gram stained smear. | View Page |
| Gram Negative Bacilli Examples of Gram negative bacilli or rod shaped bacteria are present in this field. | View Page |
| Select all the choices below than correctly describe this Gram stained smear. | View Page |
| Gram Stain The Gram stain provides a fundamental differentiation between types of bacteria. Gram positive bacteria retain the primary stain and are deep violet in color. Gram negative organisms are those that decolorize during the staining process and, after counterstaining, are pink in color. Bacterial organisms occur in two basic shapes: cocci, which are spherical, and bacilli, (also known as rods), which are elongated. Both cocci and rods may be either Gram positive or Gram negative. Examples of Gram positive cocci are shown in the upper image on the right and Gram negative cocci are shown in the lower image. | View Page |
| Single Cell Arrangement These Gram negative bacteria are in a single cell arrangement.
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| Select all the choices below than correctly describe this Gram stained smear. | View Page |