Levels of serum immunoglobulin G, CSF IgG and IgG index in acute bacterial meningitis

This study characterised the levels of serum immunoglobulin G (IgG), cerebrospinal fluid IgG (CSF IgG) and IgG index as an aid to the diagnosis and prognosis of acute bacterial meningitis (ABM). A total of 28 patients with proven ABM at admission (age range: one month to 10 years; 17 males, 11 females) (group A) and 17 age- and sex-matched control children (group B) were studied. Levels were also compared between patients with neurological morbidity (n = 4; group C) and without neurological morbidity (n = 24; group D) who were subsets of group A. In addition, patients were divided randomly into two groups based on the treatment received (i.e. ceftriaxone together with dexamethasone [n = 11; group A1] and ceftriaxone only [n = 9; group A2] to assess the effect of dexamethasone. The results (mean +/- SEM) demonstrated intrathecal synthesis of IgG in ABM (group A vs group B: CSF IgG (mg/L): 92.64 +/- 23.54 vs 2.12 +/- 1.08, P < 0.002; IgG index: 0.959 +/- 0.481 vs 0.029 +/- 0.006, P < 0.001) which showed good diagnostic significance. In the patients with permanent neurological morbidity (group C) vs healthy survivors (group D), the CSF IgG and IgG index showed good prognostic significance (group C vs group D: CSF IgG (mg/L): 10.75 +/- 9.75 vs 106.24 +/- 29.37, P < 0.01; IgG index: 0.046 +/- 0.039 vs 1.132 +/- 0.568, P < 0.05). Dexamethasone lowered CSF-IgG and IgG-index levels, but the effect was not statistically significant (group A1 vs group A2: P > 0.1).