Central nervous system infections in a tertiary care hospital: disease patterns and difficulties in diagnosis

Abstract

INTRODUCTION AND OBJECTIVES: Central nervous system (CNS) infections produce high morbidity and mortality, and effective treatment and outcome depend on precise microbiological diagnosis. We aimed to describe the pattern of CNS infections and accuracy of diagnosis in patients presenting to a tertiary care hospital. METHODS: We prospectively studied patients with suspected CNS infection admitted to medical and paediatric units of Colombo North Teaching Hospital over three years. Data related to demographic and clinical features, laboratory findings, treatment and immediate outcome. Diagnosis of CNS infection was categorised as definite, probable, possible, and uncertain. RESULTS: 426 patients (293 adults, 133 children) were studied [57.2% males, mean age (SD) years-adults 44(20), children 4(3.15)]. Of them, 27.5% had received antibiotics before admission. Blood cultures were done in 149 (35%) and only 14 were positive. Lumbar puncture was done in 347 (81.4%). CSF culture was positive only in two patients. CSF Gram stains and TB-PCR were all negative. The likely diagnosis was meningitis in 35.4%, encephalitis in 10.6% and a non-specific 'meningo-encephalitis' in 16.7%. A 'definite' microbiological diagnosis was made only in five patients. Diagnosis was considered 'probable' in, 53.7%, 'possible' in 8.7%, and 'uncertain' in 14.8%. An alternative diagnosis was found in 22% (13.6% adults, 40.6% children). Intravenous antibiotics (86.8%) and acyclovir (42.5%) were widely used on empiric grounds. CONCLUSIONS: Diagnosis of CNS infections is highly unsatisfactory with available facilities, even in a tertiary care setting. Better facilities are needed to improve aetiological diagnosis, and are likely to improve care and minimise treatment costs.