sodC-based real-time PCR for detection of neisseria meningitidis
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2011
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Real-time PCR (rt-PCR) is a widely used molecular method for detection of Neisseria meningitidis (Nm). Several rt-PCR
assays for Nm target the capsule transport gene, ctrA. However, over 16% of meningococcal carriage isolates lack ctrA,
rendering this target gene ineffective at identification of this sub-population of meningococcal isolates. The Cu-Zn
superoxide dismutase gene, sodC, is found in Nm but not in other Neisseria species. To better identify Nm, regardless of
capsule genotype or expression status, a sodC-based TaqMan rt-PCR assay was developed and validated. Standard curves
revealed an average lower limit of detection of 73 genomes per reaction at cycle threshold (Ct) value of 35, with 100%
average reaction efficiency and an average R2 of 0.9925. 99.7% (624/626) of Nm isolates tested were sodC-positive, with a
range of average Ct values from 13.0 to 29.5. The mean sodC Ct value of these Nm isolates was 17.662.2 (6SD). Of the
626 Nm tested, 178 were nongroupable (NG) ctrA-negative Nm isolates, and 98.9% (176/178) of these were detected by
sodC rt-PCR. The assay was 100% specific, with all 244 non-Nm isolates testing negative. Of 157 clinical specimens tested,
sodC detected 25/157 Nm or 4 additional specimens compared to ctrA and 24 more than culture. Among 582 carriage
specimens, sodC detected Nm in 1 more than ctrA and in 4 more than culture. This sodC rt-PCR assay is a highly sensitive
and specific method for detection of Nm, especially in carriage studies where many meningococcal isolates lack capsule
genes.
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THOMAS, Jennifer Dolan et al. sodC-based real-time PCR for detection of neisseria meningitidis. Plos One, San Francisco, v. 6, n. 5, e19361, 2011.