RELATIONSHIPS AMONG PSEUDOMONAS-PSEUDOMALLEI ISOLATES FROM PATIENTS WITH RECURRENT MELIOIDOSIS

Patients with melioidosis may present with recurrent infections after clinical resolution of their primary illness. Because there has been n o satisfactory typing scheme for Pseudomonas pseudomallei, recrudescen ce could not be distinguished from reinfection. We determined the stra in identity of primary and relapse isolates of P. pseudomallei from 25 patients with culture-proven melioidosis to answer whether secondary infections were due to the initial infecting strain or to the acquisit ion of a new strain. Fifty-four isolates were compared by the patterns of BamHI restriction digests produced after hybridization with a cDNA copy of Escherichia coli rRNA. Twenty-three patients had primary and relapse isolates with identical or highly similar ribotype patterns. T he patterns of isolates from two patients were different; the primary and relapse isolates differed by a single fragment for one, and the ot her had identical primary and first-relapse isolates while the second- relapse isolate was markedly different. The results indicated that rec urrent infection probably resulted from endogenous relapse in most of the melioidosis patients studied, although reinfection from an exogeno us source was also possible in two cases.