Performance Comparison of Two In-House PCR Methods for Detecting Neisseria meningitidis in Asymptomatic Carriers and Antimicrobial Resistance Profiling

<b>Background/Objective:</b> Bacteriological culture has been a widely used method for the detection of meningococcus, but it has low sensitivity and a long turnaround time. Molecular detection targeting capsule transport A (<i>ctrA)</i> gene has been used, but over 16% of meningococcal carriage isolates lack <i>ctrA</i>, resulting in false-negative reports. The Cu-Zn superoxide dismutase gene (<i>sodC</i>) is specific to <i>N. meningitidis</i>, and is not found in other <i>Neisseria species</i>, making it a useful target for improved detection of non-groupable meningococci without intact <i>ctrA</i>. The primary objective of this study was to evaluate the performance compassion of two in-house PCR methods, <i>sodC</i> gene- and <i>ctrA</i> gene-based PCR assays, for detecting <i>N. meningitidis</i> in asymptomatic carriers. The secondary objective was to assess antimicrobial resistance profiling of <i>N. meningitidis</i> isolates. <b>Methods:</b> The performance of <i>sodC</i> gene-based PCR assay compared to <i>ctrA</i> gene-based PCR for detection of <i>N. meningitidis</i> was evaluated using clinical samples (pharyngeal swabs; <i>n</i> = 137) collected from suspected asymptomatic carriers and culture-confirmed meningococci isolates (<i>n</i> = 49). Additionally, the antimicrobial sensitivity of the 49 isolates against antimicrobial drugs was determined using a disk diffusion test. <b>Result:</b> Of 49 DNA samples from culture-positive <i>N. meningitidis</i> isolates, the <i>sodC</i> gene-based PCR accurately identified all 49, whereas the <i>ctrA</i> gene-based PCR identified only 33 out of 49. Of 137 pharyngeal swabs, the <i>sodC</i> gene-based assay detected <i>N. meningitidis</i> DNA in 105 (76.6%), while the <i>ctrA</i>-based assay detected <i>N. meningitidis</i> DNA in 64 (46.7%). Out of the 49 N. meningitidis isolates, 43 (87.8%) were resistant to amoxicillin, 42 (83.7%) to ampicillin, 32 (65.3%) to trimethoprim-sulfamethoxazole, 22 (44.9%) to ceftazidime, 18 (36.7%) to ceftriaxone, and 7 (15.2%) to meropenem. Additionally, the majority of the isolates, 36 (73.5%), were sensitive to cefepime, 31 (63.3%) to ceftriaxone and meropenem, and 26 (53.1%) to ceftazidime. <b>Conclusions</b>: The findings of this study highlight the necessity of adopting non-capsular <i>sodC</i>-based PCR to replace <i>ctrA</i> in resource-constrained laboratories to improve <i>N. meningitidis</i> detection, and underscore the importance of periodic antimicrobial resistance surveillance to inform and adapt treatment strategies.