Recurrent bacteremia caused by a "Flexispira"-like organism in a patient with X-linked (Bruton's) agammaglobulinemia

Abstract

Helicobacter spp., except for Helicobacter cinaedi, have only rarely been reported in cases of septicemia. A patient with X-linked (Bruton's) agammaglobulinemia was found to have persistent sepsis with a Helicobacter-like organism despite multiple courses of antibiotics. His periods of sepsis were associated with leg swelling thought to be consistent with cellulitis. The organism was fastidious and required a microaerophilic environment containing H(2) for growth. Optimal growth was observed at 35 to 37 degrees C on sheep blood, CDC anaerobe, and Bordet-Gengou agars. Serial subcultures every 4 to 5 days were required to maintain viability. The organism was strongly urease positive and showed highest relatedness to Helicobacter-like organisms with the vernacular name "Flexispira rappini" by 16S rRNA gene sequence analysis. Genomic DNA hybridization studies, however, found 24 to 37% relatedness to "F. rappini" and even less to other Helicobacter spp. Although the organism phenotypically resembles "Flexispira" and Helicobacter, it is thought to represent a new taxon. The patient's infection was eventually cleared with a prolonged (5-month) course of intravenous imipenem and gentamicin.

FIG. 1

Transmission electron micrograph of the NIH isolate, showing the presence of periplasmic fibers. Bar, 1.0 μm.

FIG. 2

Phylogenetic tree based on 1,381 nucleotides of the 16S rRNA gene, showing the relationship of the NIH isolate to “F. rappini” and Helicobacter sequences. W. succinogenes was used as the outgroup. The bar represents a 1% difference in gene sequence.