<qa>  What is the main reason for a delay in the treatment of pulmonary infiltrateProper diagnosis and prompt treatment favorably impacts survival in the post transplant setting, but is often difficult and frequently results in inappropriate or late therapy. Low yields may be linked with empiric antibody therapy begun prior to the procedure, delayed time to procedure, procedure technique, the presence of graft versus host disease GVHD, neutropenia, and diffuse infiltrates as opposed to localized infiltrates or focal masses and nodules. One recent study found that early FOBs less than or equal to 4 days between detection of pulmonary infiltrates and FOB were 2.5 times more likely to establish a diagnosis of pneumonia compared to late examinations. Delaying this proceduregreater than 5 days between detection of pulmonary infiltrates and FOB was associated with drug resistant organisms, polymicrobial infections, and worsened patient prognosis. 