345. Diagnosis of Acute Bacterial Meningitis by Polymerase Chain Reaction Vis-a-vis Conventional Culture Method

Abstract

BackgroundBacterial Meningitis is one of the leading causes of mortality and morbidity worldwide requiring immediate diagnosis followed by medical intervention to prevent sequeale. Molecular methods can help to detect the pathogens offering a prompt and accurate diagnosis.MethodsOne hundred CSF and blood samples were collected from suspected/clinically diagnosed cases of meningitis over a period of 1year. CSF samples were processed by conventional and molecular methods. The objectives of the study were to identify the common bacterial etiological agent, to assess the utility of PCR in diagnosis of acute bacterial meningitis, and to know the antimicrobial susceptibility pattern.ResultsOut of 100 samples, maximum cases presented with frank meningeal signs (45%) followed by clinically suspected cases (42%). Microscopic examination, CSF culture, PCR detected 7%, 24%, and 40% positive cases, respectively. Thirteen percent were detected positive by blood culture. The positivity on CSF culture was comparable to the study done by Mani et al. (40.5%). The predominant pathogens isolated were K. pneumoniae (37.5%) followed by Streptococcus pneumoniae and Acinetobacter spp. (each 16.67%). PCR positive followed by Gene sequencing revealed Pseudomonas aeruginosa (34.78%) as the predominant pathogen. Culture is considered as the gold standard. However, it fails to identify fastidious organisms and often gives false-negative results. Therefore, the gold standard was modified to consider parameters like-clinical signs of meningitis, CSF biochemistry indicative of meningitis and CSF positive on any one microbiological test (CSF staining/CSF culture/blood culture). The performance of PCR was then improved to sensitivity (67.74%); specificity (72.46%); diagnostic accuracy (71%); PPV 52.50% and NPV 83.34%. The kappa coefficient −0.372 showed a fair agreement, considering the modified gold standard. This criterian was also used in study done by Welinder-Olsson et al.ConclusionGram-negative enteric bacteria were the most common etiology reported by both the methods. PCR could detect more cases than conventional culture method indicating its utility in the diagnosis of acute meningitis. Apart from microbiological parameters, clinical and other laboratory parameters should be considered to achieve a precise diagnosis.Disclosures All authors: No reported disclosures.