oligella (bacterium) oligella (bacterium) oligella is a genus of gram-negative, aerobic bacteria from the family alcaligenaceae. oligella scientific classification domain: bacteria phylum: pseudomonadota class: betaproteobacteria order: burkholderiales family: alcaligenaceae genus: oligellarossau et al. 1987 type species oligella urethralis species o. ureolytica o. urethralis the genus oligella includes at least 2 species. oligella ureolytica is more prominent than oligella urethralis. clinical clinical infections due to these organisms are rare. the common causes are related to the gu tract and urinary tract obstruction.