what was the organism name of the last bile microbiology test of patient 7107 since 07/2105?
select microbiologyevents.org_name from microbiologyevents where microbiologyevents.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 7107 ) and microbiologyevents.spec_type_desc = 'bile' and microbiologyevents.org_name is not null and strftime('%y-%m',microbiologyevents.charttime) >= '2105-07' order by microbiologyevents.charttime desc limit 1