Abstract
Background: Neisseria meningitidis is one of the leading
causes of bacterial meningitis and septicemia worldwide. The
bacteriological culture was a widely used method for the detection of
meningococcus, but it has low sensitivity and long waiting periods.
Molecular detection targeting capsule transport gene was used, but over
16% of meningococcal carriage isolates lack ctrA and generate
false-negative results due to sequence variations. The Cu-Zn superoxide
dismutase gene ( sodC) is specific to N. meningitidis, not
found in other Neisseria species, making it better able to
identify encapsulated meningococci and useful for detecting
non-group-able meningococci without intact ctrA.
Objective: The objective of this study was the validation of
sodC gene-based PCR assay and antimicrobial resistance profiling
of N. meningitidis in asymptomatic carriers Methods: The
sodC gene N. meningitidis detection method was developed
using a pair of primers and optimized. A total of 137 archived samples
that were collected from the asymptomatic carrier suspected of having
meningococcal infection were used for validation of the assay. STATA
version 14.0 was used for analysis of clinical and demographic data
after the data was entered into Epi Info version 7. Graphs and frequency
tables from descriptive statistics were used to summarize the outcome.
Two-by-two tables were used to compare the sensitivity specifically
between the sodC-based PCR assay and culture and
ctrA-based PCR. A Disk diffusion test was used to determine the
antimicrobial sensitivity of the isolates against antimicrobial drugs.
To determine the association between independent and outcome variables,
bivariate and multivariate logistic regression models were used and
P-values less than 0.05 were considered statistically significant.
Result: The PCR assay targeting the sodC gene detected
N. meningitidis DNA in 105 (76.6%) out of 137 clinical samples,
while ctrA-based PCR detected the pathogen in 64 (46.7%) of the
samples, and 49 samples (35.8%) of N. meningitidis were
identified by culture. Then, the concordance of our in-house PCR assay
targeting the sodC gene with ctrA PCR was performed using
137 clinical samples (Nasopharyngeal swabs). Among the 49 DNA samples
from culture-positive N. meningitidis isolates used for
validation, the sodC gene-based PCR accurately identified all 49
culture-confirmed isolates. In contrast, the ctrA gene-based PCR
detected only 33 of these isolates. Out of the 49 N. meningitidis
isolates by culture 43 (87.8%), 42 (83.7%), 32 (65.3%), 22 (44.9%),
and 18 (36.7%), and 7 (15.2%) were resistant to amoxicillin,
ampicillin, trimethoprim-sulfamethoxazole, ceftazidime, ceftriaxone, and
meropenem, respectively. Furthermore, the majority of N.
meningitidis isolates 36 (73.5%) were sensitive to cefepime, 31
(63.3%) of them were sensitive to ceftriaxone and meropenem, and 26
(53.1%) of them were sensitive to ceftazidime. Conclusion: The
sodC gene-based PCR assay demonstrated high sensitivity in
detecting N. meningitidis in carriage specimens compared to
ctrA gene-based PCR. The high prevalence of antibiotic resistance
observed is alarming and highlights the urgent need to continue
monitoring antibiotic resistance to inform treatment strategies
effectively.