Recurrent melioidosis: possible role of infection with multiple strains of Burkholderia pseudomallei.

We were interested to read the paper by Maharjan et al. suggesting that reinfection is more common than previously realized in melioidosis (1). There is one other possibility that they did not consider, which might account for isolates from recurrent melioidosis being genotypically distinct from isolates in primary infection, namely, initial infection with more than one genotype. We report here studies that suggest that this is a not infrequent occurrence. Eighteen patients with culture-positive melioidosis seen in Ubon Ratchathani, northeastern Thailand, were studied. Fourteen patients yielded the organism from blood, three presented with localized abscesses with no systemic spread, and one had a urinary tract infection. Sets of 10 to 40 colonies (dependent on the total number of colonies per plate) were selected from primary culture plates of specimens from multiple body sites or from subculture of blood culture broths. Isolates were assigned to a BamHI ribotype pattern, and pulsed-field gel electrophoresis (PFGE) of XbaI DNA digests was used to discriminate further within a ribotype (4). Strains were then allocated a ribotype number or PFGE letter as part of a larger study (3). This showed that 13 of 18 patients were infected with a single