Neonatal bacterial meningitis.
To address the following aspects of diagnosis and management of neonatal bacterial meningitis:
When should neonatal bacterial meningitis be suspected and a lumbar puncture performed in neonates?
How to interpret cerebrospinal fluid (CSF) findings.
Role of rapid diagnostic tests (including C-reactive protein [CRP]) in diagnosis.
Optimal duration and choice of antibiotics.
Role of adjunctive therapies in management.
The highest incidence of meningitis across all age groups is in the neonatal period. Neonatal bacterial meningitis is a potentially devastating disease. Not only does it increase the risk of mortality, it can also have disastrous long-term neurodevelopmental consequences. The risk of mortality in neonates with meningitis has been reported to be 16−58% in various studies throughout the world. The risk of moderate to severe neurodevelopmental disability following meningitis depends upon the etiologic organism, and is markedly increased compared to controls without meningitis, with 11−56% of neonates surviving meningitis suffering from such impairment. Two specific neurologic sequelae of meningitis are sensorineural hearing loss, which occurs in around 4% of cases, and hydrocephalus, reported in 3% of cases. The above data suggest that neonatal meningitis is a serious disease, and one cannot afford to miss the diagnosis. Neonates with bacterial meningitis may demonstrate encephalopathy, seizures, a bulging anterior fontanel, signs of raised intracranial pressure, or other neurologic findings. However, the manifestations of neonatal meningitis are usually nonspecific or absent. Therefore, unlike in older children and adults, one cannot rely on clinical signs to decide whether to perform a lumbar puncture (LP). The currently acceptable reference standard for the diagnosis of neonatal meningitis is a positive CSF culture or Gram stain. Because CSF culture positivity rates are low in routine clinical practice and it takes about 48−72 hours to get a culture report, clinicians tend to rely on rapid diagnostic tests performed on CSF to arrive at a diagnosis. These include the total CSF white blood cell count, glucose level, and protein level. However, the diagnosis of neonatal meningitis based on rapid diagnostic tests is beset with controversy; because the levels of these parameters change with postnatal age, abnormal levels are not clearly defined, the sensitivity and specificity of these tests is uncertain, and CSF samples are often contaminated with blood from a traumatic lumbar puncture.
LP should be performed in neonates based on the probability of their having meningitis, and not based purely on the presence or absence of clinical manifestations.
In attempting to identify meningitis, CSF examination, culture, and Gram stain results represent the reference standard. Several parameters (CSF white blood cell count, glucose level, and protein level) are commonly used for rapid diagnosis. However, no single parameter or combination of these commonly used parameters is diagnostic.