Delayed diagnosis of bacterial meningitis has a significant impact on prognosis and should not be overlooked. Cases of recurrent bacterial meningitis in infancy may be associated with underlying diseases such as immunodeficiencies and congenital deformities, including those of the inner ear. Streptococcus pneumoniae is a highly invasive causative agent, but the number of patients with meningitis has decreased dramatically in recent years due to the widespread use of the 13-valent pneumococcal conjugate vaccine. However, cases of vaccinated patients having invasive pneumococcal infection have been reported due to serotypes changing. We report a case of recurrent bacterial meningitis in an infant. The second occurrence was associated with Mondini deformity, for which surgical treatment was planned. The third was observed while the patient was awaiting surgery, and the fourth postoperatively. This study presents the clinical course of the Mondini deformity in this patient, which was difficult to manage due to the recurrent bacterial meningitis, and draws on epidemiological data concerning invasive pneumococcal infections occurring between April 2013 and March 2021 in Kawasaki City, Kanagawa Prefecture, Japan.
