A patient with hypersplenism underwent splenectomy. The most probable oppounistic infection in this patient after the procedure is:

The most serious consequence of splenectomy is increased susceptibility to bacterial infections, paicularly those with capsules such as Streptococcus pneumoniae, Haemophilus influenzae, and some gram-negative enteric organisms. Patients under age 20 years are paicularly susceptible to overwhelming sepsis with S. pneumoniae. The case-fatality rate for pneumococcal sepsis in splenectomized patients is 50-80%. Ref: Henry P.H., Longo D.L. (2012). Chapter 59. Enlargement of Lymph Nodes and Spleen. In D.L. Longo, A.S. Fauci, D.L. Kasper, S.L. Hauser, J.L. Jameson, J. Loscalzo (Eds), Harrison's Principles of Internal Medicine, 18e.