To indicate and report the frequency of myelosuppression effect seen with prophylactic dose of Trimethoprim-Sulfamethoxazole (TMP-SMX) in two groups: innate immune defect patients without bone marrow suppression, and immune competent patients for urinary tract infection (UTI)
A retrospective, two groups’ comparative study, of existing data for innate immune defect (i.e. Griscelli syndrome, Chronic granulomatous disease) and UTI patients who received TMP-SMX prophylaxis in Qatar. Data were collected regarding the CBC results (WBC, neutrophils, lymphocytes, and RBC, and platelet counts) at baseline and at maximum myelosuppression seen during the period of TMP-SMX administration.
Total of 44 patients were involved in this study (18 innate immune defect and 26 UTI patients). None of the patients in both groups were received folic acid during the period of TMP-SMX administration. Clinical myelosuppression (i.e. less than normal value for age) was observed at higher rate in innate immune defect patients as compared to UTI patients among different cell lines including: neutrophil count (50% vs. 19.2%), lymphocytes count (33.3% vs. 11.5%), and platelets count (16.7% vs. 7.7%) respectively. Only suppression in neutrophils count was found to be statistically significant between the two groups (p-value 0.031). As most innate immune defect disorder does not associated with myelosuppression, the suppressions observed in this group were most likely due to TMP-SMX effect rather than disease itself.
Innate immune defect patients on TMP-SMX prophylaxis are at higher risk of developing myelosuppression compared to other immune competent patients.