has any microbiological test been performed on patient 55281's sputum in 12/2105?
select count(*)>0 from microbiologyevents where microbiologyevents.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 55281 ) and microbiologyevents.spec_type_desc = 'sputum' and strftime('%y-%m',microbiologyevents.charttime) = '2105-12'