Distribution (presence) of GI genes within diverse B. pseudomallei populations. (a) Presence of fhaB gene clusters. (b) Presence of bpaA gene. We note that most B. pseudomallei strains contained either two clusters of the fhaB gene, clusters I and III, or cluster III alone. In addition, the bpaA gene was found only in clinical isolates of B. pseudomallei from Australia.