Review Question - QID 218978

A 57-year-old Caucasian male presents to your clinic for evaluation of low back pain. The patient states that it has been present for years and that the anti-inflammatory medication provided by his primary care doctor is no longer effective in managing his pain. Select radiographs of his spine are available for review in Figures A and B, and a clinical photograph of his eyes is available in Figure C. Blood tests ordered by his primary care doctor are notable for HLA-B27 positivity. Compared to those without his genetic predisposition, this patient is at an increased risk of synovitis secondary to which of the following organisms?