Variations in Ceftazidime and Amoxicillin-Clavulanate Susceptibilities within a Clonal Infection of Burkholderia pseudomallei

A patient with a clonal infection of Burkholderia pseudomallei had subpopulations with ceftazidime and amoxicillin-clavulanate susceptibilities that differed among the clinical specimens. Resistance was associated with a novel Cys69Tyr substitution in the Ambler class A beta-lactamase. Susceptibility testing of multiple colony variants from different sites should be performed for patients with culture-confirmed melioidosis.