what is the number of patients who received bronchial brush tests in 2105?
select count( distinct admissions.subject_id ) from admissions where admissions.hadm_id in ( select microbiologyevents.hadm_id from microbiologyevents where microbiologyevents.spec_type_desc = 'bronchial brush' and strftime('%y',microbiologyevents.charttime) = '2105' )