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University of Virginia Health System Medical Laboratories “Quality You Expect, Service You Deserve”

LABORATORY MEDICINE UPDATE

December 3, 2009

Influenza Update

Requests for Influenza testing reached their peak the week of October 19th and have been decreasing since then. Our total requests for the month of October were 525; percent positives for October: 24.6%. Samples from 14 inpatients have been subtyped and all were H1N1.

Peptide Nucleic Acid-Fluorescent In Situ Hybridization (PNA FISH)

For organisms in blood culture:

Effective immediately, PNA FISH results will be available approximately 9 AM and 9 PM Monday through Friday and once in the morning on weekends. PNA FISH is a technology that allows rapid and definitive identification of Staphylococcus aureus, coagulase negative staphylococci, Enterococcus faecalis, Candida albicans and Candida glabrata from blood cultures the same day their growth is detected by our automated blood culture instrument. The results will be called to the appropriate ordering personnel or unit per policy. Results will also be reported in the lab computer system shortly after the test is run. This change will provide definitive results to help provide useful information to guide antibiotic management as much as 12 hours sooner than in the past.

Susceptibilities update:  100% of Enterococcus faecalis isolates are susceptible to ampicillin.  At UVA, only 22% of non-ICU Enterococcus faecium are susceptible to vancomycin. For isolates obtained from ICU patients, the percentage is 14.  Approximately 50% of Staphylococcus aureus isolates are MRSA.  Greater than 95% of Candida albicans isolates at UVA are susceptible to fluconazole. While data are not available for UVA isolates, national data indicate that greater than 99.9% of C. albicans isolates are susceptible to anidulafungin.  At UVA, 87% of C. glabrata isolates are susceptible to fluconazole with MICs of ≤ 64 µg/mL. 71% are highly susceptible to fluconazole (MIC ≤ 8 µg/mL). Greater than 99% of C. glabrata isolates are susceptible to anidulafungin (national study).

of 3 Helicobacter pylori culture and susceptibility testing

Due to extremely small numbers of requests, cultures for H. pylori will no longer be performed by the Microbiology laboratory. This testing can be requested as a send out test and will be sent to a reference lab. Please order routine culture and susceptibility for H. pylori and forward the gastric biopsy to the Core Laboratory as quickly as possible.

Cyclic Citrullinated Peptide (Anti-CCP) in Rheumatoid Arthritis

The Medical Laboratories will begin testing in-house for IgG antibodies against CCP to aid in the early diagnosis of patients with Rheumatoid Arthritis the beginning of December. This assay has an analytical measurement range of 1 – 200 U/mL with a reference interval of <5.0 U/mL. Results >/= 5.0 U/mL are considered positive. Please note that this reference range is different from the current range assigned to the assay at our referral laboratory.

Galactose-Alpha 1,3-Galactose IgE RAST

The Medical Laboratories has begun offering an in-house developed specific RAST assay for the detection of IgE antibodies to Galactose-Alpha 1,3-Galactose (referred to as Alpha-Gal). This clinical assay was developed in conjunction with Dr. Thomas Platts- Mills of the Division of Asthma, Allergy and Immunology in the Department of Medicine. Results <0.35 kU/L are considered negative. Consultation with the Division of Asthma, Allergy and Immunology is recommended before ordering. Results will be reported with the following comment: This test was developed and its performance characteristics determined by UVA Medical Labs. It has not been cleared or approved by the U.S. Food and Drug Administration. The FDA has determined that such clearance or approval is not necessary.

Change in Homocysteine Assay

The Medical Laboratories have evaluated serum homocysteine on a new platform due to notification by the current instrument vendor of plans to discontinue production and support. The new method is a competitive immunoassay with a reference interval of 5.0 – 12.0 umol/L. A gold top (serum) tube is recommended for analysis although plasma is also acceptable. The new assay will begin in December when current reagents have been depleted.

of 3 Change in Routine Serum/Plasma Albumin Assay

The Medical Laboratories’ supplier of albumin assay reagents has changed the standardization of the assay. With the new reagents, albumin results are lower by 8%- 10% (0.4–0.5 g/dL) than in the past. Lower results were seen beginning the week of November 9, 2009.

The suggested regression equation for conversion of the new results to old results: Old Albumin = 1.09 * New Albumin + 0.02 The estimated reference interval with the new reagent is 3.2 – 5.2 g/dL

The reagent change was made to better align results with those of other BCG assays. Unfortunately, advance notice was not given by the assay vendor to the laboratory medical directors.

The change does not affect the urine (“microalbumin”) albumin assays.

Please contact the on-call Director of Clinical Chemistry (PIC 1657) or the Pathology resident on chemistry (PIC 1267) for assistance in the interpretation of these new results.

Change in HSV and VZV Sample Transport (non-CSF specimens) PCR testing only

Mayo Medical Laboratories has notified us that for genital specimens, throat swabs, lesions, and ocular/dermal specimens for Herpes simplex Virus (HSV) and Varicella- Zoster virus (VSV), they no longer recommend placing the swabs in viral transport media. Please send swabs in the original swab cylinder. Please contact Customer Service at 4-LABS (434-924-5227) if you need supplies.