Haemophilus parainfluenzae septic arthritis following orthopedic procedures in immunocompetent patients with diverse management: A case report of 2 rare cases

Abstract

Rationale: H. parainfluenzae is an uncommon cause of musculoskeletal infection, particularly after orthopedic procedures.

Patient concerns: Two cases of H. parainfluenzae infection in immunocompetent patients following reverse shoulder arthroplasty and arthroscopic knee procedures.

Diagnoses: H. parainfluenzae was identified as the causative pathogen through synovial fluid culture. Case 1 was identified as periprosthetic joint infection of the shoulder, and Case 2 as septic arthritis of the knee.

Interventions: Case 1 was managed with needle aspiration and oral antibiotics. Case 2 underwent arthroscopic debridement and received antibiotic therapy.

Outcomes: Both patients recovered without recurrence of infection following appropriate treatment. In Case 2, the patient's C-reactive protein levels decreased from 18.3 mg/dL at presentation to 0.217 mg/dL by postoperative day 36, indicating resolution of inflammation and restoration of function.

Lessons: These cases highlight the potential of H. parainfluenzae infection in healthy individuals and underscore the importance of accurate diagnosis and appropriate management to ensure favorable outcomes.

Keywords: arthroscopy; case report; periprosthetic joint infection; septic arthritis; shoulder arthroplasty.

Figure 1.

Protruding mass with turbid yellowish pus in an 87-yr-old man after reverse shoulder arthroplasty. The mass resolved after series needle aspiration and oral antibiotics. Yellow arrow indicates the protruding mass after improvement.

Figure 2.

Septic arthritis with biofilm accumulation in a 42-year-old man’s left knee after arthroscopic fibrolysis. (A) Biofilm accumulation in the medial compartment. (B) After debridement. MC = medial condyle, MT = medial tibial plateau, MM = medial meniscus; asterisk, biofilm.