We report the first likely known case of reactive arthritis caused by Haemophilus parainfluenzae. An 84-year-old woman developed polyarthritis of the neck, shoulders, and hips. Two months prior to admission, she had received dental treatment for caries; 1 week later, she noted fever and extremity pain. Physical examination revealed that the range of motion of both shoulders was limited to approximately 60°, in abduction and forward flexion, secondary to pain. Laboratory tests showed that the erythrocyte sedimentation rate, C-reactive protein, and serum amyloid A were 99 mm/h, 4.0 mg/dL, and 109.9 μg/mL, respectively. The white blood cell count was elevated (11.9 × 103/μL) with neutrophil predominance (81.8%); the hemoglobin was 9.8 g/dL. Blood glucose and hemoglobin A1c were 216 mg/dL and 9.0%, respectively. Other blood test results, liver enzymes, renal function, serological tests, and urinalysis results were normal. Radiographs of the shoulder, femoral, and knee joints revealed no deformities. Computed tomography showed no remarkable findings. Whole-body gallium scintigraphy revealed marked uptake in the tendon attachments of both shoulders and hips (Figure). Pharyngeal bacterial culture grew H. parainfluenzae, susceptible to ampicillin (ABPC). The patient was treated with 750 mg/d of ABPC for 3 months. Her symptoms improved, and she was followed-up for 1 year, without relapse.
Discussion
H. parainfluenzae is a Gram-negative rod and a common inhabitant of the human oral cavity and respiratory, urogenital, and gastrointestinal tracts. However, it can cause serious infections in immunosuppressed and immunocompetent individuals, including endocarditis, bacteremia, pneumonia, and, very rarely, septic arthritis.1Most patients with septic arthritis present with pain and swelling with hot and tender joints; other symptoms are generally present for <2 weeks at presentation and are limited to the affected joint.1 Patients with septic arthritis caused by H. parainfluenzae may have prior dental procedures, otitis media, or immunosuppression due to steroid use or diseases like diabetes mellitus and leukemia.1 Arthralgia occurs frequently in diabetic patients; differentiation between infectious and rheumatic disease is vital. It is thought that septic arthritis occurring without prior joint surgery or trauma likely develops through hematogenous spread, facilitated by mucosal destruction.2 In our case, unfortunately, we could not perform synovial fluid culture due to no swelling in the involved joints and low synovial fluid volume. Arthritis developing immediately after dental treatment suggested hematogenous spread from the oral mucosa. However, we thought she had reactive, not septic arthritis, because her arthralgias developed in multiple joints and her fever was relatively mild. Poor blood glucose control could also be a cause of the infection.
Reactive arthritis is a nonpurulent joint inflammation triggered by bacterial infections in the urogenital tract or gut. Although reactive arthritis associated with H. parainfluenzae is not reported, reactive arthritis associated with H. influenzae has been reported.3 ABPC is recommended for treatment of H. parainfluenzae septic arthritis and H. influenzae reactive arthritis.1, 3 ABPC effectively reduced our patient’s symptoms, suggesting H. parainfluenzaeinfection.
In conclusion, our patient had H. parainfluenzae reactive arthritis, diagnosed through clinical findings, gallium scintigraphy, and pharyngeal bacterial culture and was cured with steroids and antibiotics. To our knowledge, this is the first report of reactive arthritis caused by H. parainfluenzae in a patient with diabetes mellitus. As differentiating reactive arthritis from other arthritides and identifying the causative bacteria are difficult, clinicians should always perform confirmatory tests prior to considering immunosuppressive treatment.
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-Tomohiro Eguchi, MDa, Taro Horino, MD, PhDa,, Eri Amano, MDa, Osamu Ichii, DVM, PhDb, Yoshio Terada, MD, PhDa
-This article originally appeared in the March issue of The American Journal of Medicine.
