what was the organism found in patient 25997's first test of blood culture since 79 months ago?
select microbiologyevents.org_name from microbiologyevents where microbiologyevents.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 25997 ) and microbiologyevents.spec_type_desc = 'blood culture' and microbiologyevents.org_name is not null and datetime(microbiologyevents.charttime) >= datetime(current_time,'-79 month') order by microbiologyevents.charttime asc limit 1