has there been a microbiology test held during this month for patient 28447?
select count(*)>0 from microbiologyevents where microbiologyevents.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 28447 ) and datetime(microbiologyevents.charttime,'start of month') = datetime(current_time,'start of month','-0 month')