Evaluation of nested PCR method for diagnosis of meningitis due to Neisseria meningitidis and Haemophilus influenzae

Meningitis due to Neisseria meningitidis and Haemophilus influenzae is a common infectious disease among infants and children that can be fatal in the absence of rapid and proper diagnosis and treatment. Therefore, a rapid and sensitive method for diagnosis is a high priority. The aim of this study was to compare the performance of culture, conventional polymerase chain reaction (PCR), and nested PCR methods for diagnosis of meningitis caused by N. meningitidis and H. influenzae. A total of 106 cerebrospinal fluid samples were collected from infants and children suspected of having meningitis. A portion of these samples were used for culture and DNA extraction. The extracted DNA was placed in a PCR reaction that contained specific primers for N. meningitidis and H. influenzae. PCR products from negative samples were reamplified with internal primers by nested PCR reaction. The results indicated that among the 106 samples evaluated for N. meningitides, 1 (0.9%) sample was positive by culture, whereas 3 (2.8%) samples were positive by PCR and 7 (6.6%) were positive by nested PCR. For H. influenzae, 2 (1.9%) samples were positive by culture, whereas 3 (2.8%) were positive by PCR and 9 (8.5%) were positive by nested PCR methods. In conclusion, among the culture, conventional PCR, and nested PCR methods evaluated, nested PCR showed higher sensitivity than culture or PCR methods.