Impact of fluoroquinolone administration and gut mucosal colonization on the risk of pre-engraftment bloodstream infections after allogeneic hematopoietic cell transplantation.

Fluoroquinolones (FQ) has been used after allogeneic hematopoietic stem cell transplantation (allo-HCT) for decades. This study on 284 allo-HCT recipients aimed to analyze the impact of FQ on pre-engraftment BSI. A total of 154 patients were colonized with resistant gram-negative bacteria, and 130 patients were not. Colonized patients did not receive FQ ( n  = 147) except 7 who received FQ as sequential therapy; 98 non-colonized patients received FQ, whereas 32 did not. Gram-negative ( p  < 0.0001), and ESBL-E BSI ( p  < 0.0001) were higher in colonized patients receiving FQ. No difference was found in gram-positive BSI ( p  = 0.452). In multivariate analysis colonized patients with ( p  < 0.0001) or without FQ ( p  = 0.007), omission of FQ in non-colonized patients ( p  = 0.038), and active disease ( p  = 0.042) were associated with gram-negative BSI, whereas mismatched unrelated donor transplantations - with gram-positive BSI ( p  = 0.009). Colonized patients with FQ have a higher risk of gram-negative BSI. In non-colonized patients, FQ prophylaxis is effective approach significantly reducing gram-negative BSI risk.