RT Journal A1 Murray PR, Jain A, Uzel G, et al T1 Pyoderma gangrenosum–like ulcer in a patient with x-linked agammaglobulinemia: Identification of helicobacter bilis by mass spectrometry analysis JF Archives of Dermatology JO Archives of Dermatology YR 2010 FD May 1 VO 146 IS 5 SP 523 OP 526 DO 10.1001/archdermatol.2010.86 UL http://dx.doi.org/10.1001/archdermatol.2010.86 AB Background  Pyoderma gangrenosum–like ulcers and cellulitis of the lower extremities associated with recurrent fevers in patients with X-linked (Bruton) agammaglobulinemia have been reported to be caused by Helicobacter bilis (formerly classified as Flexispira rappini and then Helicobacter strain flexispira taxon 8). Consistent themes in these reports are the difficulty in recovering this organism in blood and wound cultures and in maintaining isolates in vitro. We confirmed the presence of this organism in a patient's culture by using a novel application of gene amplification polymerase chain reaction and electrospray ionization time-of-flight mass spectrometry.Observation  An adolescent boy with X-linked agammaglobulinemia presented with indurated plaques and a chronic leg ulcer whose origin was strongly suspected to be an H bilis organism. Histologic analysis demonstrated positive Warthin-Starry staining of curvilinear rods, which grew in culture but failed to grow when subcultured. They could not be identified by conventional techniques. A combination of gene amplification by polymerase chain reaction and electrospray ionization time-of-flight mass spectrometry confirmed the identity of this organism.Conclusions  This novel technology was useful in the identification of a difficult-to-grow Helicobacter organism, the cause of pyoderma gangrenosum–like leg ulcers in patients with X-linked agammaglobulinemia. Correct identification of this organism as the cause of pyoderma gangrenosum–like ulcers in patients with X-linked agammaglobulinemia is of great importance for the early initiation of appropriate and curative antibiotic therapy.