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All white cells present in a cerebrospinal fluid must be identified. If more than 10 cells/mm3 are present or there is difficulty identifying the few cells that are present, make a cytospin, a filtration, or a sedimentation preparation, stain with Wright-Giemsa, and perform differential count. Cytospins made with a cytocentrifuge are preferred since they are easiest to make and interpret, but filtration and sedimentation methods can also be used to prepare a slide for subsequent staining.

Smith KR, Fisher HC III, Hook, EW III: Prevalence of fluorescent monoclonal antibody-nonreactive Neisseria gonorrhoeae in five North American sexually transmitted disease clinics.J Clin Microbiol 34:1551-1552, 1996We compared a direct fluorescent monoclonal antibody (DFA) test with alternative enzymatic and fermention tests for identifying presumptive gonococcal isolates in a systematic sample from patients attending five sexually transmitted disease clinics in five cities.Fourteen (2.5%) of 556 isolates from three clinics were nonreactive with the DFA confirmatory reagent and reactive by both the Quad-Ferm and Rapid NH tests. The prevalence of DFA-nonreactive Neisseria gonorrhoeae isolates varies geographically and is independent of local methods for the identification of possible gonococci.On the basis of our findings, we recommend that for use in medicolegal and other instances in which a diagnosis of gonorrhea has the potential to have far-reaching effects, it is appropriate to test DFA reagent-nonreactive, oxidase-positive, gram-negative diplococci by alternative methods of gonococcal confirmation.Although the prevalence of such isolates could change, the fluorescent monoclonal antibody confirmation reagents remain useful for many clinical situations. Their ease of use and ready applicability for screening large numbers of isolates make them useful for many laboratories.

The ultimate goal in measuring CYP450 function or identifying polymorphisms is to predict effective therapeutic doses and responses in patients.Polymorphisms are identified using molecular techniques (allele-specific PCR, restriction digests, sequencing, hybridization assays, bead-based systems, microarrays, pyrosequencing, et al).Although most clinical labs do not offer PGx testing, reference labs are beginning to market these tests. For example, one reference laboratory in the Midwest that offers CYP2D6 profiling measures about one dozen of the most common and significant mutation sites on this enzyme. This allows for detection of approximately 98% of the known CYP2D6 polymorphisms. The laboratory then generates a report which will advise the physician on the patient's drug-metabolizing status.Estimates show that 6-10% of the general population have a complete deficiency of CYP2D6, with the prevalence of mutations varying from <1% to as much as 21% within a given population.

Bobby Jones, a phlebotomist at Georgetown Hospital, entered the room of Mrs. Mary Grayson with a physician's order to draw some blood work. After properly greeting Mrs. Grayson, identifying himself and checking her armband, Bobby prepared for the venipuncture. He suddenly notice a sign posted above the bed that read: “Restricted left arm usage. Previous mastectomy - Do no use left arm for venipuncture.” Bobby set up his equipment to use her right arm and noticed an IV line in Mrs. Grayson’s right arm positioned in a vein slightly above her wrist on the dorsum (top) of her forearm.

Red cell morphology can be defined as the appearance of the erythrocytes on a Wright's stained smear.Careful examination of the red cells for the purpose of identifying abnormalities is part of the differential procedure. This examination is important because it may provide valuable diagnostic information to the physician, as well as provide a quality control mechanism to verify red cell indices values as determined by automated or manual methods.Evaluating red cell morphology involves differentiating normal morphology from abnormal and artificial morphology. The abnormal morphology covered in this unit may be seen in a variety of disorders.