Final answer:
The most common cause of neonatal meningitis is Streptococcus agalactiae, or Group B strep (GBS), and it's primarily treated with ß-lactam antibiotics. Diagnosis involves several methods including CSF cultures and PCR. Other bacteria like Neisseria meningitidis, Streptococcus pneumoniae, and Haemophilus influenzae also cause bacterial meningitis but in older children and adults.
Step-by-step explanation:
The most common cause of neonatal meningitis is Streptococcus agalactiae, or Group B streptococcus (GBS). It's an encapsulated, gram-positive bacterium found in the urogenital and gastrointestinal microbiota of about 10-30% of humans. This bacterium can cause meningitis, which is an infection of the protective membranes covering the brain and spinal cord, in individuals of all ages but primarily occurs in newborns up to 3 months old.
Diagnosis of neonatal meningitis includes a range of tests such as cultures of cerebrospinal fluid (CSF), antigen detection by enzyme immunoassay, serotyping, and PCR methods. Treatment typically involves ß-lactam antibiotics like penicillin or ampicillin, combined with an aminoglycoside such as gentamicin. Despite this, there is still a significant mortality rate among affected neonates.
Other common causative bacteria for bacterial meningitis that are not specific to neonates include Neisseria meningitidis, Streptococcus pneumoniae, and Haemophilus influenzae. These pathogens are transmitted via respiratory secretions and can invade the bloodstream, increasing the risk of widespread inflammation and infection throughout the body, including the meninges.