what was the number of patients that were tested in 2105 for direct antigen test for herpes simplex virus types 1 & 2 microbiology?
select count( distinct admissions.subject_id ) from admissions where admissions.hadm_id in ( select microbiologyevents.hadm_id from microbiologyevents where microbiologyevents.spec_type_desc = 'direct antigen test for herpes simplex virus types 1 & 2' and strftime('%y',microbiologyevents.charttime) = '2105' )