Laboratory Medicine Updates - September 27, 2002
University of Virginia Health System
Medical Laboratories“Quality You Expect, Service You Deserve”LABORATORY MEDICINE UPDATESeptember 27, 2002 |
Fluids in Blood Culture Bottles
The laboratory strongly discourages the practice on the clinical floors of inoculating normally sterile body fluids (except blood) into blood culture bottles. When fluids are received in blood bottles, the laboratory cannot perform a gram stain or evaluate the quantity of any organisms that grow. Please submit fluids in a sterile leak proof container such as a black top tube with a screw cap or SPS tube.
Blood Culture Collection Guidelines
Where possible, blood specimens for culture should be collected before treatment is initiated. Collect two sets: one from each of two prepared sites, preferably peripheral. The second should be drawn after a brief interval (30 min). Follow up cultures should be limited to one per day.
Skin should be cleansed with 70% alcohol, swabbing in a concentric fashion with an alcohol pad a total of three times using three different alcohol pads. Wait a minute to ensure that site is completely dry before performing venipuncture. Decontaminate diaphragm of blood culture bottle with 70% alcohol before inoculation. Inoculate blood culture bottles with approximately 10 cc. of blood per bottle.
Enterics testing now being performed in Clinical Microbiology
Fecal Lactoferrin, Clostridium difficile EIA and culture for Helicobacter pylori are now being performed in the clinical microbiology laboratory. Results are usually available within 24 hours (except H. pylori culture). H. pylori antibody testing is performed in the Davis Laboratory.
Guidelines for Cryptococcal antigen repeat testing:
When monitoring cryptococcal antigen titers after a positive result, it is recommended to repeat the test no more frequently than every two weeks. This is due to the fact that the cyptococcal antigen is a complex heteropolysaccharide and is not cleared rapidly. Titers in CSF (the specimen of choice) can be helpful in monitoring therapy only when the test is repeated over appropriate intervals (at least two weeks) 1. 1Manual of Clinical Microbiology 7th edition, Murray et.al 1999, pg 1180.
Urine Microscopy Update
The 2002 Laboratory Handbook omitted the corrections made to the Urinalysis testing information. The Hematology Laboratory has updated the procedure for performing urine microscopic exams. A microscopic analysis will be performed on samples from all patients 14 years old and under, regardless of the biochemical findings. A microscopic exam on specimens from patients over 14 years of age will be performed only when indicated: If the urine is anything other than yellow and clear or If the biochemical results for RBC’s, Leukocyte Esterase, or Nitrite are positive or If there is a 1+ or greater protein Please remember that the accuracy of any urinalysis test decreases with time.
Below is a snapshot of the Urinalysis testing information from the Laboratory Handbook. The changes to the Urinalysis testing information are highlighted in red.
TEST NAME: URINALYSIS TEST CODE: UACHG/UASCR CPT CODE: 81001, 81003 SYNONYMS: TEST INCLUDES: Appearance, color, clarity, specific gravity, and chemistries. Microscopic exam on adults (>14 years old) will be performed only when indicated (color other than yellow, clarity other than clear, positive nitrite, blood, leukocyte esterase, > 1+ protein). A Clinitest is performed on children age 2 or under for other reducing substances. LABORATORY: Hematology, Ambulatory Care Services SPECIMEN: Fresh random urine, first morning void recommended MINIMUM VOLUME: 5 mL urine AVAILABILITY: Daily, 24 hours TURNAROUND TIME: Routine 4 hours, STAT 1 hour SPRCIAL INSTRUCTIONS: Cellular elements deteriorate rapidly if specimen not refrigerated or chemically preserved. REFERENCE INTERVAL: See Appendix VI, Table 2. Dipstick Analysis Interferences, See Appendix VI, Table 3.
New Directors of the Molecular Pathology Laboratory
Two new directors of the Molecular Pathology Laboratory have recently joined the faculty of the Department of Pathology.
Lawrence M. Silverman, Ph.D., Scientific Director, joins us from the University of North Carolina, Chapel Hill. While at UNC from 1979-2002, he was director of the Division of Molecular Pathology, Professor of Pathology and Laboratory Medicine, Genetics, and Molecular Biology. His research interests are: (1) modifier genes (2) atypical cystic fibrosis, and (3) novel technologies in molecular diagnostics. Dr. Silverman can be reached at 434-243-2957 and lms7r@virginia.edu.
Mani S. Mahadevan, M.D., Medical Director, joins us from the University of Wisconsin-Madison. While at UW-Madison from 1995-2002, he was associate medical director of the DNA Diagnostics Laboratory and Associate Professor of Medical Genetics. His clinical interests are in the area of human genetics and the application of molecular techniques in the diagnosis of simple and complex genetic disorders. His research interests are focused in the general area of human genetics and triplet repeat mutations. His research lab is funded to study the pathogenesis of Myotonic Muscular Dystrophy. Dr. Mahadevan can be reached at 434-243-4816 and mahadevan@virginia.edu.
Department of Pathology Symposium
On October 14, 2002, the Department of Pathology will sponsor an all day symposium highlighting recent advances in molecular diagnostics and molecular medicine pertaining to inherited diseases. The focus of the symposium will be spinal muscular atrophy, myotonic dystrophy, cystic fibrosis, and inherited breast/ovarian cancer (BRCA1/2). For each of this disorders emphasis will be on recent developments that improve both the molecular testing and the understanding of the underlying molecular pathology. Speakers include: John Day, MD - Univ. of Minnesota Debra Leonard, MD, PhD, Univ. of Pennsylvania Michael Knowles, MD, Univ. of North Carolina Mark Graham, MD, Univ. of North Carolina Mani Mahadevan, MD, University of Virginia Lawrence Silverman, Ph.D., University of Virginia
The complete agenda and registration form are available for download at: www.med.virginia.edu/ed-programs/cme/PATHOLOGY2002/Pathology.htm
Retesting of Individuals for Neisseria gonorrhoeae
The Centers for Disease Control and Prevention have recommended that due to quality control concerns for Abbott reagents used for N. gonorrhoeae testing, clinicians should offer retesting to patients whose test results were negative, who were not presumptively treated, and for whom a clinical suspicion of N. gonorrhoeae carriage remains. For the Medical Laboratories, suspect reagents were in use from January 1, 2002 through July 15, 2002. Letters are being sent to any physician who requested testing during this time and for which negative results were released.
New Tests For Chlamydia trachomatis and Neisseria gonorrhoeae
The Molecular Pathology Lab has changed from the Abbott LCx ligase chain reaction (LCR) based system to the Roche Cobas Amplicor polymerase chain reaction (PCR) based platform for the analysis of swab and urine specimens for Chlamydia trachomatis and Neisseria gonorrhoeae. This change was made primarily due to recurrence of manufacturing problems and recalls of the Abbott reagents, resulting in disruption of clinical service. The sensitivities of the two methodologies are comparable.
Swab specimens can continue to be collected with the Abbott collection devices now in circulation. When that supply has been exhausted, the laboratory will distribute a Roche collection device including M4 Culture Transport Media (MicroTest, Inc.). Endocervical and urethral swab specimens and "first catch" urine specimens are the only specimens acceptable for these tests. These tests are not intended for use with throat, rectal, or other types of specimens. Throat specimens are especially unsuitable, as the test for Neisseria gonorrhoeae may detect non-pathogenic isolates of N. subflava and N. cinerea, common components of normal throat flora.
Test charge, availability and turnaround times will remain the same. Reporting of results will be as follows: None Detected Positive Inconclusive (Equivocal) No Amplification/Suspect Inhibitor Present.
Repeat specimen collection is suggested for samples that are equivocal or fail to amplify if there is strong clinical suspicion of infection. Please direct questions concerning these tests to the Molecular Pathology Lab (434-982-3310).
Transfusion reactions
The following is a list of selected acute transfusion reactions. For the sake of brevity, the list is not complete. Transfusion reactions not discussed include volume overload, citrate toxicity, reactions associated with leukocyte reduction filters, and delayed reactions such as graft verses host disease. Whenever an acute adverse transfusion reaction is suspected, immediately:
|
