when did patient 86404 first receive a blood culture microbiological test since 09/2104?
select microbiologyevents.charttime from microbiologyevents where microbiologyevents.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 86404 ) and microbiologyevents.spec_type_desc = 'blood culture' and strftime('%y-%m',microbiologyevents.charttime) >= '2104-09' order by microbiologyevents.charttime asc limit 1