Laboratory features
Laboratory features that are characteristic of neonatal bacterial meningitis include:
Isolation of a bacterial pathogen from the cerebrospinal fluid by culture and/or visualization by Gram stain
Increased cerebrospinal fluid white blood cell count (typically >1000 white blood cells/μL, but may be lower, especially with Gram-positive bacteria), usually with a predominance of neutrophils
Elevated cerebrospinal fluid protein concentration (>150 mg/dL in preterm (premature birth) and >100 mg/dL in term infants)
Decreased cerebrospinal fluid glucose concentration (<20 mg/dL [1.1 mmol/L] in preterm (premature birth) and <30 mg/dL [1.7 mmol/L] in term (on time) infants)

Causes
Neonatal meningitis is caused by group B streptococci Streptococcus agalactiae (39%-48% of cases), Escherichia coli (30%-35%), other Gram-negative rods (8%-12%), Streptococcus pneumoniae (about 6%), and Listeria monocytogenes (5%-7%). Meningitis is typically caused from either a bacterial or viral infection, however, it can be caused by fungal, parasitic, or amebic infections as well. Even more rare, Meningitis can be caused by some cancers, Lupus, specific drugs, head injuries, and brain surgeries. Most neonatal meningitis results from bacteremia (bacterial infection of the blood) with hematogenous spread to the central nervous system (CNS). Early-onset
In early-onset neonatal meningitis, acquisition of the bacteria is from the mother either before the baby is born or during birth. The most common bacteria found in early-onset are Streptococcus agalactiae, Escherichia coli, and Listeria monocytogenes. In developing countries, Gram-negative enteric (gut) bacteria are responsible for the majority of early onset meningitis. Late-onset
Late-onset meningitis may be caused by other Gram-negative bacteria and staphylococcal species. In developing countries, Streptococcus pneumoniae accounts for most cases of late onset.
Herpes Simplex Virus
In cases of meningitis caused by Herpes simplex virus, antiviral therapy with (acyclovir or vidarabine) must be started immediately for a favorable outcome. Acyclovir is a better antiviral because it shows a similar effect on the infection as vidarabine and is safer to use in neonates. The recommended dosage is 20 mg/kg every six hours for 21 days. Epidemiology
In industrialized countries, the incidence of bacterial meningitis is approximately 3 in 10,000 live births. The incidence of Herpes simplex virus meningitis is estimated to be 0.2-5.0 cases per 10,000 live births. Neonatal meningitis is much more common in developing countries. Neonatal meningitis ranges from 4.8 per 10,000 live births in Hong Kong to 24 per 10,000 live births in Kuwait. In Africa and South Asia, figures ranging from 8.0 to 61 per 10,000 live births are found. It is expected that these numbers are lower than reality due to the difficulty of diagnosing and the healthcare available to underdeveloped countries in Asia and Africa. == References ==