Predictive value of blood culture in acute bacterial meningitis

Abstract

To evaluate predictive value of blood culture as an effective alternative laboratory tool for isolation of causative organism in acute pyogenic meningitis. It is a hospital based prospective longitudinal hospital based study performed from May 2007 to May 2009. A total number of 310 children of age group 2 months-14 years who presented to the hospital with probability of bacterial meningitis were screened in the study. Eighty cases excluded by preset exclusion criteria and rest 230 formed the analytic sample. Pretreatment blood culture with concomitant lumbar puncture or lumbar puncture within 2 h of antibiotic administration for cerebrospinal fluid analysis was obtained. The main outcome parameter was the predictive value of blood culture for isolation of causative organism in acute bacterial meningitis. Blood culture revealed a sensitivity of 73.28% (95% confidence interval [CI]: 64.85%–80.63%), specificity of 87.88% (95% CI: 79.78%–93.58%), positive predictive value of 88.9% (95% CI: 81.40%–94.13%), negative predictive value of 71.31% (62.42%–79.14%), positive likelihood ratio of 5.97 and negative likelihood ratio of 0.30. Probability of isolation of causative organism by blood culture in bacterial meningitis was found to be highest among infants (82%) and least in children aged above 5 years (54.17%). When compared to gold standard cerebrospinal fluid diagnostic criteria, blood culture has a high sensitivity, specificity, positive predictive value and likelihood ratio to be an effective alternative laboratory tool for isolation of causative organism in acute bacterial meningitis especially in infants and younger children.

Keywords

Bacterial meningitis - lumber puncture - cerebrospinal fluid - blood culture - predictive value