Onchycobacter anthropi is a Gram-negative bacilli rarely implicated as human pathogen. This infection has been described in renal dialysis patients and immunocompromised individuals. We report a case of successfully treated O. anthropi pyomyositis in a 22-year-old immunocompetent patient.

A 22-year-old male presented to medicine OPD with a history of fever and body pain for 20 days duration. Fever was high grade and intermittent with chills. He also complained of the left shoulder pain and restriction of the left shoulder movements. Pain was insidious in onset, gradually progressive, non-radiating, aggravated on the left shoulder movements, and no relieving factor. On examination, his left shoulder warm, tender joint, was noted with severe restriction of shoulder movements. Laboratory finding shows white blood cell count of 5600. Blood culture was sent and the left shoulder MRI was done. He was started empirically on intravenous cefoperazone-sulbactam but he continued to have persistent high-grade fever (103 F).
MRI shows ill-defined diffuse edema with peripheral enhancing collection involving all the rotator cuff muscles, teres major, latissimus dorsi, coracobrachialis and deltoid muscles with provisional diagnosis of pyomyositis with abscess (Fig. 1). MRI also shows marrow edema with patchy enhancement of glenoid, coracoid process, spine of scapula, distal end of clavicle, and acromion suggestive of osteomyelitis (Fig. 2). He was planned for surgical debridement. Surgical debridement was done and frank pus was evacuated. Tissue and pus were taken for biopsy, Genexpert MTB/RIF, Gram staining, and culture-sensitivity. Biopsy confirms pyomyositis (Fig. 3). Genexpert came out to be negative. Direct smear – Gram stain shows Gram-positive cocci in pairs. Organisms isolated in blood and pus culture-sensitivity as Ochrobactrum anthropi showing susceptibility testing of the organism to be sensitive to cotrimoxazole, imipenem, meropenem, tetracycline, tigecycline, piperacillin-tazobactam and resistance to amikacin, cefotaxime, ciprofloxacin, ceftazidime, cefepime, gentamicin, and levofloxacin. He was started on intravenous cotrimoxazole and meropenem. He had an uneventful recovery.

O. anthropi is an emerging pathogen even in immunocompetent patients and there may be an increase in the frequency of orthopedic infection caused by these organisms. This report suggests the ability of O. anthropi to cause pyomyositis in immunocompetent patients. Surgical debridement and treatment with appropriate antibiotics will produce successful results.

This case report underlines the importance of diagnosing pathology causing Onchycobacter anthropi pyomyositis in immunocompetent patients and it’s management. It should be kept in mind that an immunocompetent host does not rule out the Onchycobacter anthropi infection as previously thought.