what was patient 57023's last blood culture ( myco/f lytic bottle)'s microbiology test time in the last month?
select microbiologyevents.charttime from microbiologyevents where microbiologyevents.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 57023 ) and microbiologyevents.spec_type_desc = 'blood culture ( myco/f lytic bottle)' and datetime(microbiologyevents.charttime,'start of month') = datetime(current_time,'start of month','-1 month') order by microbiologyevents.charttime desc limit 1