Bilateral osteomyelitis and liver abscess caused by hypervirulent Klebsiella pneumoniae- a rare clinical manifestation (case report)

BACKGROUND: Hypervirulent strains of Klebsiella pneumoniae are a recognized cause of a distinct invasive syndrome that results in pyogenic liver abscesses and metastatic complications, particularly in the Asia Pacific region. Reports of hypervirulent K.pneumoniae in Europe, the Americas and Australia indicate worldwide spread. We present a case of multi-focal osteomyelitis, a rarely described complication of hypervirulent K.pneumoniae in the medical literature. The prevalence of this condition in countries outside Asia may be expected to rise with increasing travel. CASE PRESENTATION: A 20-year-old Chinese man residing in Australia for 2 years presented with a 2-week history of gradually worsening leg pain preceded by 2 weeks of constitutional symptoms. Imaging with computerized axial tomography (CT) and other modalities revealed bilateral tibial lesions described as lattice-like linear lucencies involving the cortices with scalloping of the outer involved cortex. Cultures of tissue from a left tibial bone biopsy were positive cultures for K.pneumoniae. Whole-genome sequencing identified the isolate as K1 serotype ST23, a well-recognized hyper virulent strain capable of causing invasive disease. An abdominal CT revealed a 27x22mm liver abscess. The patient had no other metastatic manifestations of the disease, and responded to 6 weeks of intravenous ceftriaxone followed by 3 months of oral Ciprofloxacin. CONCLUSIONS: Increased awareness of the manifestations and subsequent management of hyper virulent strains of K.pneumoniae by clinicians is important to assist early recognition and help minimize serious sequelae. Cases with overseas links, such as previous residence in the Asia Pacific area, are at higher risk for infection with the hyper virulent strain. This case highlights the need for clinicians to be able to recognize this important disease, especially in patients with the right epidemiological links, and to investigate and treat appropriately to prevent severe metastatic complications.