Objective : X-linked agammaglobulinemia (XLA) is a relatively rare form of an immunodeficiency disease that is characterized by a profound deficiency of B lymphocytes. Morganella morganii, tribe Proteeae, is a Gram-negative bacillus that is ubiquitous in the environment and may cause opportunistic infections. Two cases of M. morganii pericarditis after splenectomy following allogeneic bone marrow transplantation for acute lymphoblastic leukemia and mantle cell lymphoma have been described.
Results : A 5-year, 3-month-old boy was evaluated for fever, tachypnea, and chest retraction of 1 day duration and transferred to our hospital because of cardiomegaly on chest radiography. He had been hospitalized frequently for pneumonia since 1 year of age and had recurrent acute otitis media since 2 years of age. On physical examination, a cardiac rub was heard. An echocardiography showed a large circumferential pericardial effusion. he underwent emergency transthoracic pericardiocentesis. The results of the pericardial fluid studies were as follows: white blood cell count, 2,800 cells/mm3 with neutrophilia of 81.3% ,and Gram-negative bacilli present. M. morganii was isolated from the pericardial and blood cultures. Flow cytometry of a blood sample revealed that CD19, a marker of mature B lymphocytes, was decreased to 0.02%. Using direct sequencing of genomic DNA from peripheral blood leukocytes, point mutations were shown to affect splice sites of the BTK gene (c.894+1G>C). He was therefore diagnosed with XLA.
Conclusion : When a child has pericarditis caused by uncommon bacteria, such as M. morganii, the physician should suspect and evaluate if the child is immunocompromised.