Interlaboratory comparison of PCR-based identification and genogrouping of Neisseria meningitidis

Abstract

Twenty clinical samples (18 cerebrospinal fluid samples and 2 articular fluid samples) were sent to 11 meningococcus reference centers located in 11 different countries. Ten of these laboratories are participating in the EU-MenNet program (a European Union-funded program) and are members of the European Monitoring Group on Meningococci. The remaining laboratory was located in Burkina Faso. Neisseria meningitidis was sought by detecting several meningococcus-specific genes (crgA, ctrA, 16S rRNA, and porA). The PCR-based nonculture method for the detection of N. meningitidis gave similar results between participants with a mean sensitivity and specificity of 89.7 and 92.7%, respectively. Most of the laboratories also performed genogrouping assays (siaD and mynB/sacC). The performance of genogrouping was more variable between laboratories, with a mean sensitivity of 72.7%. Genogroup B gave the best correlation between participants, as all laboratories routinely perform this PCR. The results for genogroups A and W135 were less similar between the eight participating laboratories that performed these PCRs.

FIG. 1.

Sensitivity and specificity of N. meningitidis identification methods. Shaded bars represent individual scores for each laboratory, and black bars are the mean values for sensitivity and specificity for all participating laboratories. Individual values were calculated relative to the consensus results for the identification of N. meningitidis by using two-way tables as the percentage of samples that achieved positive (sensitivity) and negative (specificity) consensus results in each laboratory.

FIG. 2.

Sensitivity and specificity of the four genes used to identify N. meningitidis: ctrA (n = 4), crgA (n = 4), 16S rRNA (two laboratories used only 16S rRNA for identification), and porA (n = 1). Values were calculated as described for Fig. 1.