tell me the last specimen test given to patient 51177 in 10/2105?
select microbiologyevents.spec_type_desc from microbiologyevents where microbiologyevents.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 51177 ) and strftime('%y-%m',microbiologyevents.charttime) = '2105-10' order by microbiologyevents.charttime desc limit 1