ABSTRACT
Group B Streptococcus (GBS) is the leading cause of neonatal sepsis and meningitis in developed countries. Recommendations for antepartum GBS detection include enriched culture with several options for identifying GBS, some of which are time-consuming. To reduce the time for identification and determination of the maternal GBS colonization status, rapid nucleic acid amplification technologies have been developed and commercialized. For rapid detection of GBS, a three-site clinical study was conducted to evaluate the NeuMoDx GBS assay, a real-time PCR test performed for vaginal/rectal swab specimens in Lim broth enrichment culture on the NeuMoDx 288 molecular system (NeuMoDx system); these data were used to a support 510(k) submission. A total of 1,250 eligible remnant samples were prospectively enrolled and tested during the study. The results of the PCR assay were compared to the results of the Centers for Disease Control and Prevention (CDC)-recommended enriched-culture method, which served as the gold standard reference method for the study. The NeuMoDx GBS assay results yielded a sensitivity of 96.9% (95% confidence interval [CI] = 94.1 to 98.4), specificity of 96.0% (95% CI = 94.6 to 97.1), and a total agreement with the reference method of 96.2% (95% CI = 93.8 to 98.3). NeuMoDx GBS assay results were also compared to results obtained using the BD MAX GBS assay on the BD MAX system. The two systems demonstrated a total percent agreement of 98.0% (95% CI = 95.5 to 100.0). The performance of the NeuMoDx GBS assay implemented on the NeuMoDx system compared favorably to the CDC enriched-culture method and to the BD MAX GBS assay.
Subject(s)
Carrier State/diagnosis , Molecular Diagnostic Techniques/methods , Pregnancy Complications, Infectious/diagnosis , Real-Time Polymerase Chain Reaction/methods , Streptococcal Infections/diagnosis , Streptococcus agalactiae/isolation & purification , Adult , Female , Humans , Infant , Infant, Newborn , Pregnancy , Prospective Studies , Rectum/microbiology , Sensitivity and Specificity , Streptococcus agalactiae/classification , Streptococcus agalactiae/genetics , Vagina/microbiologyABSTRACT
BACKGROUND: BK virus (BKV)-associated nephropathy (BKVAN) is often associated with renal graft dysfunction. When renal transplant recipients present with high clinical suspicion for BKVAN (high serum and urine BKV titer with graft dysfunction) but their graft biopsies stain negatively for BKV, non-correlated situations between the two tests often lead to a dilemma about how to treat them. METHODS: This retrospective investigation was conducted to determine how real-time quantitative PCR (qPCR) for BKV, routinely applied to serum and urine, could be helpful in identifying the existing BKV in biopsy tissue stained negatively for BKV. RESULTS: DNA was extracted from each specimen through the use of five 10-µm curls from the tissue block with use of the QIAamp DNA FFPE Tissue Kit (Qiagen), followed by BKV qPCR to determine copies of BKV/µg of biopsy tissue DNA. Group 1 (11 negative renal controls for BKV) demonstrated 0 to 9 BKV copies/µg DNA. Except for 3 focally staining cases showing low BKV, the remaining 10 positive renal controls in group 2 (13 positive transplant biopsies staining positively) demonstrated elevated BKV up to 160 million copies/µg DNA. Group 3 transplants (13 uncertain transplants with negative BKV staining but positive liquid BKV) were negative for BKV (0-12 copies/µg) in 4 of 13, had low BKV copies (36-346 copies/µg) in 5 of 13, and had high BKV copies (17,240-526,945 copies/µg) in 4 of 13 cases, through the use of qPCR. CONCLUSIONS: The data indicate that qPCR from paraffin-embedded tissue as a backup test is sensitive for ruling in/out BKV infection in renal transplant biopsies, particularly in uncertain cases.
