Which bacterium is commonly associated with bacterial meningitis in newborns?

Group B streptococcus (GBS) is commonly associated with bacterial meningitis in newborns, making it the correct choice. GBS is a major cause of neonatal infections, including meningitis, sepsis, and pneumonia. In fact, pregnant women can carry GBS in their vaginal flora, which poses a risk to newborns during delivery if bacteria are transmitted. As a result, routine screening for GBS in pregnant women is conducted between the 35th and 37th weeks of gestation, and prophylactic antibiotics are often administered during labor if GBS is detected.

Other bacteria listed, such as Streptococcus pneumoniae and Neisseria meningitidis, are more commonly associated with meningitis in older children and adults rather than in neonates. Listeria monocytogenes, while also a cause of meningitis, is less prevalent than GBS in newborns, typically affecting adults, particularly those who are immunocompromised or elderly. Therefore, GBS's specific association with newborns as a leading cause of early-onset meningitis makes it the most pertinent answer in this context.