Test Updates

Molecular Diagnostics Shared Specimens

In order to strictly ensure specimen integrity, the Molecular Diagnostics Laboratory will no longer be accepting commingled or shared specimens.  This is due to the high sensitivity and potential for contamination in molecular testing involving the amplification of DNA.  For tests that are performed within the Molecular Diagnostics laboratory, only one tube is needed for testing ( for example: FVLM, PGM, and MTRB, can all be performed on the same tube.) 

New Molecular Test for Group B Streptococcus (GBS)

1. Geisinger Medical Laboratories will offer the Xpert GBS LB Assay (test code GRBS) to detect GBS DNA from Lim broth-enriched vaginal/rectal swabs
2. GRBS results will appear approximately one day after specimen collection
3. Specimen requirements: swab specimen(s); vaginal/rectal combination (swabbing both the lower vagina and rectum substantially increases the yield compared with sampling the cervix or sampling the vagina alone).
   Approved devices:  Molecular Testing swab (white cap), ESwabs™ (white cap)
4. Transport Temperature:  2-8 degrees C (stability = 6 days).
5. Antibiotic Susceptibility Testing: Susceptibility testing is performed for patients identified as penicillin allergic (PENALL) at the time of test request/order and the GRBS assay is positive. A susceptibility battery (GRBSS-OBL, Group B Susceptibility will be automatically ordered by Laboratory Information System (LIS) and performed by Microbiology.
6. Contraindications: 1) Patients who have used systemic or topical (vaginal) antibiotic treatment in the week prior 2) patients diagnosed with placenta previa 3) males
7. Performance: Demonstrated sensitivity/specificity for detection of GBS is 99.0% and 92.4%, respectively, relative to GBS culture.
8. Standard of Care for prevention of neonatal GBS disease = screening pregnant women with a molecular test method at 35–37 weeks of gestation to determine their colonization status, which can be transient, chronic, or intermittent.