Culture and Real-time Polymerase Chain reaction sensitivity in the diagnosis of invasive meningococcal disease: Does culture miss less severe cases?
Sara Guiducci;Maria Moriondo;Francesco Nieddu;Silvia Ricci;Elisa De Vitis;Arianna Casini;Giovanni Maria Poggi;Giuseppe Indolfi;Massimo Resti;Chiara Azzari;
PloS one2019Vol. 14pp. e0212922-
312
guiducci2019plosculture
Abstract
Background Invasive meningococcal disease (IMD) is a highly lethal disease. Diagnosis is commonly performed by culture or Realtime-PCR (qPCR). Aims Our aim was to evaluate, retrospectively, whether culture positivity correlates with higher bacterial load and fatal outcome. Our secondary aim was to compare culture and qPCR sensitivity. Methods The National Register for Molecular Surveillance was used as data source. Cycle threshold (CT), known to be inversely correlated with bacterial load, was used to compare bacterial load in different samples. Results Three-hundred-thirteen patients were found positive for Neisseria meningitidis by qPCR, or culture, or both; 41 died (case fatality rate 13.1%); 128/143 (89.5%) blood samples and 138/144 (95.8%) CSF were positive by qPCR, 37/143 (25.9%) blood samples and 45/144 (31.2%) CSF were also positive in culture. qPCR was 3.5 times (blood) or 3.1 times (CSF) more sensitive than culture in achieving a laboratory diagnosis of IMD (OR 24.4; 95% CI 12.2–49.8; p < .10−4; Cohen’s κ 0.08 for blood and OR 49.0; 95% CI 19.1–133.4; p