what was the name of an organism which was found in the last sputum microbiology test of patient 22648 during their current hospital encounter?
select microbiologyevents.org_name from microbiologyevents where microbiologyevents.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 22648 and admissions.dischtime is null ) and microbiologyevents.spec_type_desc = 'sputum' and microbiologyevents.org_name is not null order by microbiologyevents.charttime desc limit 1