Study of the Role of Serum Procalcitonin Level in Differentiation between Bacterial and Viral meningitis

Patients and Methods: The study included 30 adults of septic meningitis and 30 adults with aseptic meningitis admitted in Menouf Fever Hospital and Tropical Medicine Department with fever, headache, vomiting and seizure. The diagnosis of septic meningitis was based on clinical features; physical examination, blood and cerebrospinal fluid (CSF) cytochemical findings, Gram stain and bacterial culture. Thirty cases of aseptic meningitis admitted during same period were also included in the study, and 20 subjects of matched age and sex, free from any CNS diseases undergoing spinal anaesthesia for non CNS surgical causes as control. Serum PCT was measured by Gloryscience ELISA Kit.


INTRODUCTION
Despite the advances in diagnosis and treatment of infectious diseases, meningitis and encephalitis are still considered as important causes of mortality and morbidity [1].To reduce the morbidity and mortality related to bacterial meningitis, it is important to discriminate bacterial meningitis from aseptic meningitis during the acute phase of the disease, when the clinical symptoms are often similar [2].An ideal marker for bacterial infections should allow early diagnosis, inform about the course and prognosis of the disease, and facilitate therapy [3].Clinical criteria, Gram staining, and bacterial antigen testing of CSF as well as the classic biological markers in the blood (C-reactive protein [CRP] level, white blood cell count [WBC], and neutrophil count) or CSF (protein level, glucose level, WBC count, and neutrophil count) used alone do not offer 100% sensitivity with high specificity for distinguishing between bacterial and aseptic meningitis [3].Waiting

PATIENTS AND METHODS
For this purpose, adult patients with clinical presentations of meningitis (41 males and 19 females) were included in the study who presented to Menouf Fever Hospital in the period between April 2014 and March 2015.These patients were classified according to the results of CSF findings into 30 patients of septic meningitis as group I (GI) and 30 patients of aseptic meningitis as group II (GII).In addition to 20 subjects of matched age and sex, free from any CNS diseases undergoing spinal anaesthesia for non CNS surgical causes were included in the study as GIII (control group).
Clinical manifestations; laboratory examination of CSF (glucose, protein, leukocyte count, Gram stain and bacterial cultures); and serum inflammatory markers (peripheral blood leukocyte count and CRP) were evaluated for their ability to differentiate bacterial from aseptic meningitis.
All patients and control were examined using Gloryscience PCT kits for serum PCT level.

Statistical analysis:
Statistical presentation and analysis of the present study was conducted, using the mean, standard deviation, student t-test, Paired t-test, Chi-square and Mann-Whitney by SPSS V17.
The results were tabulated and statistical analysis was done and the results were considered significant at P value < 0.05.

RESULTS
Clinical symptoms and signs were of little assistance in differentiating bacterial from aseptic meningitis except for meningeal irritation signs which were found to be statistically different between septic and aseptic groups.

Examination of CSF revealed:
 A statistically significant difference in aspect of CSF between bacterial meningitis group compared to the aseptic meningitis group (p<0.001)(Table 1). Significantly higher CSF leukocyte count with marked increase in the polymorphnuclear leukocyte count, CSF protein level and low CSF glucose in the bacterial meningitis group compared to the aseptic meningitis group (p<0.001)(Table 2).

DISCUSSION
In the present study, serum PCT level was found significantly higher in the septic meningitis group than the control group.Further in septic meningitis group, higher level was found than aseptic meningitis group.The diagnostic value of serum PCT was calculated with optimum combination of sensitivity and specificity at optimum cut off level obtained through receiver operating characteristic curve (ROC). These

CONCLUSION
Serum PCT may be used as diagnostic marker for septic meningitis and its differentiation from aseptic meningitis.PCT may be used as prognostic marker as all cases that had bad outcome, had higher level of PCT than cured cases.

Conflicts of interest:
The authors declare that there is no conflict of interest.Ethical approval: Was granted by the Institutional Review Board and informed consent was obtained from each patient prior to inclusion in the study . The diagnostic specificity: It is the percentage of non-diseased truly excluded by the test among total non-diseased cases or the ability of the screening test to discover the truly negative cases.c.The predictive value for a positive test: It is the percentage of cases truly diagnosed among total positive cases.d.The predictive value for a negative test: It is the percentage of cases truly negative among total negative cases.e.The efficacy or the diagnostic accuracy of the test: It is the percentage of cases truly diseased plus truly non-diseased among total cases.
validity test: a.The diagnostic sensitivity: It is the percentage of diseased cases truly diagnosed among total diseased cases or the ability of the screening test to discover the truly positive cases.b The mean values of peripheral blood WBCs were 13830 in GI and 8543 in GII respectively, and these results were statistically highly significant (p <0.001 ).
 High statistically significant differences in ESR and CRP between patients with septic meningitis and those with aseptic meningitis.CRPresults were positive in 80% of patients with bacterial meningitis, and 20% of patients with aseptic meningitis (Table4). Table (6): Accuracy of serum PCT level in differentiation between bacterial meningitis and aseptic meningitis PCT ROC curve Figure (1): ROC curve for sensitivity and specificity of serum PCT level in diagnosis of meningitis.
This disagreement may explained by the fact that, the peripheral white blood cells, ESR and CRP can be different very early in the disease and in patients insufficiently treated by antibiotics.In this study, CSF culture was positive in 23 patients of GI (78 %) while it was negative in 7 patients of the same group (22%).Patients with negative culture diagnosed as septic meningitis by CSF parameters (WBCs, glucose level, protein level, aspect of CSF and Gram staining) and other inflammatory markers like CRP, peripheral TLC and ESR.