what specimen test was first given until 08/2105 to patient 10686?
select microbiologyevents.spec_type_desc from microbiologyevents where microbiologyevents.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 10686 ) and strftime('%y-%m',microbiologyevents.charttime) <= '2105-08' order by microbiologyevents.charttime asc limit 1