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Open Access Research article

Clinical indicators of bacterial meningitis among neonates and young infants in rural Kenya

Michael K Mwaniki1*, Alison W Talbert1, Patricia Njuguna1, Mike English12, Eugene Were1, Brett S Lowe1, Charles R Newton13 and James A Berkley14

Author Affiliations

1 Centre for Geographic Medicine Research (coast), Kenya Medical Research Institute, PO Box 230, Kilifi, Kenya

2 Department of Paediatrics, University of Oxford, The John Radcliffe Hospital, Oxford OX3 9DU, UK

3 Department of Psychiatry, University of Oxford, OX3, UK

4 Centre for Clinical Vaccinology and Tropical Medicine, University of Oxford, Churchill Hospital, Oxford, OX3 7LJ, UK

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BMC Infectious Diseases 2011, 11:301  doi:10.1186/1471-2334-11-301

Published: 1 November 2011

Abstract

Background

Meningitis is notoriously difficult to diagnose in infancy because its clinical features are non-specific. World Health Organization (WHO) guidelines suggest several indicative signs, based on limited data. We aimed to identify indicators of bacterial meningitis in young infants in Kenya, and compared their performance to the WHO guidelines. We also examined the feasibility of developing a scoring system for meningitis.

Methods

We studied all admissions aged < 60 days to Kilifi District Hospital, 2001 through 2005. We evaluated clinical indicators against microbiological findings using likelihood ratios. We prospectively validated our findings 2006 through 2007.

Results

We studied 2,411 and 1,512 young infants during the derivation and validation periods respectively. During derivation, 31/1,031 (3.0%) neonates aged < 7 days and 67/1,380 (4.8%) young infants aged 7-59 days (p < 0.001) had meningitis. 90% of cases could be diagnosed macroscopically (turbidity) or by microscopic leukocyte counting. Independent indicators of meningitis were: fever, convulsions, irritability, bulging fontanel and temperature ≥ 39°C. Areas under the receiver operating characteristic curve in the validation period were 0.62 [95%CI: 0.49-0.75] age < 7 days and 0.76 [95%CI: 0.68-0.85] thereafter (P = 0.07), and using the WHO signs, 0.50 [95%CI 0.35-0.65] age < 7 days and 0.82 [95%CI: 0.75-0.89] thereafter (P = 0.0001). The number needed to LP to identify one case was 21 [95%CI: 15-35] for our signs, and 28 [95%CI: 18-61] for WHO signs. With a scoring system, a cut-off of ≥ 1 sign offered the best compromise on sensitivity and specificity.

Conclusion

Simple clinical signs at admission identify two thirds of meningitis cases in neonates and young infants. Lumbar puncture is essential to diagnosis and avoidance of unnecessary treatment, and is worthwhile without CSF biochemistry or bacterial culture. The signs of Meningitis suggested by the WHO perform poorly in the first week of life. A scoring system for meningitis in this age group is not helpful.

Keywords:
meningitis; "young infants"; neonates; "lumbar puncture"; "clinical signs"; "resource-poor"