What is the probablity of a 5 month old surviving bacterial meningitis?

Treated early. Outcome should be good if treatment is started early.
Depends on variables. Survival & or degree of eventual impairment varies with many variables.The state of the child prior to infection, immunization status, speed of disease recognition & institution of treatment, type of germ involved. Some germs can be deadly quicker than others (meningococcus vs h.Influenza.) most of my cases survived without significant residual damage. The frequency has declined with new vaccines.