Diagnosis of Acute Bacterial Meningitis by Conventional Culture Method

Background: Bacterial Meningitis is one of the leading causes of mortality and morbidity worldwide requiring immediate diagnosis followed by medical intervention to prevent sequeale. The clinical presentation is not subtle in all cases, and hence confirmation by laboratory methods is necessary to know the exact etiology. Empiric antimicrobial therapy can be misleading; giving rise to resistant strains or it may further worsen the clinical prognosis, if ineffective. Therefore, in this study, an attempt has been made to diagnose the causative pathogen on conventional culture. Methods: 100 CSF and blood samples were collected from suspected /clinically diagnosed cases of meningitis over a period of 1year. CSF samples were processed by gram stain and conventional Culture. This was followed by Anti-microbial susceptibility testing by Kirby Bauer�s disk diffusion method. The blood samples were collected in BACTEC bottles and subjected to automated system. The objectives of the study were: To identify the common bacterial etiological agent and to know the antimicrobial susceptibility pattern. Results: Out of 100 samples, maximum cases presented with frank meningeal signs (45 %) followed by clinically suspected cases (42 %). Microscopic examination and CSF culture 7 % and 24 % positive cases respectively.13 % were detected positive by blood culture. The positivity on CSF culture was comparable to the study done by R Mani et al (40.5 %). The predominant pathogens isolated were K. pneumoniae (37.5 %) followed by Streptococcus pneumoniae and H. influenzae (each 16.67 %). Discussion: Culture is considered as the gold standard. However, it is not without limitations. It fails to give urgent results. Therefore, preliminary diagnosis was made on gram stain. The kappa coefficient-0.24 showed a fair agreement, and diagnostic accuracy was 79 % considering the modified gold standard. Conclusion: Gram negative enteric bacteria were the most common etiology reported by Conventional Culture. Apart from microbiological parameters, clinical and other laboratory parameters should be considered to achieve a precise diagnosis.