number of patients who had a viral culture:r/o herpes simplex virus microbiology test in 2104.
select count( distinct admissions.subject_id ) from admissions where admissions.hadm_id in ( select microbiologyevents.hadm_id from microbiologyevents where microbiologyevents.spec_type_desc = 'viral culture:r/o herpes simplex virus' and strftime('%y',microbiologyevents.charttime) = '2104' )