citrobacter braakii citrobacter braakii citrobacter braakii is a gram-negative species of bacteria. it has been reported to cause sepsis in an immunocompromised person. citrobacter braakii scientific classification domain: bacteria phylum: pseudomonadota class: gammaproteobacteria order: enterobacterales family: enterobacteriaceae genus: citrobacter species: c. braakii binomial name citrobacter braakiibrenner et al. 1993