when did patient 69895 receive a microbiology test since 177 months ago first time?
select microbiologyevents.charttime from microbiologyevents where microbiologyevents.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 69895 ) and datetime(microbiologyevents.charttime) >= datetime(current_time,'-177 month') order by microbiologyevents.charttime asc limit 1