Citrobacter freundii-associated osteomyelitis and thromboembolic events following Moderna COVID-19 vaccination: a rare case report from Nepal

INTRODUCTION: Vaccination against coronavirus disease 2019 (COVID-19) is essential for controlling the ongoing cases of this disease. Citrobacter infections of the bones and joints are extremely uncommon. Thromboembolism and deep vein thrombosis (DVT) are very rare complications. CASE PRESENTATION: The authors present a rare case of osteomyelitis, septic arthritis, deep venous thrombosis, and pulmonary embolism in a 15-year-old previously healthy boy occurring shortly after receiving the second dose of the Moderna COVID-19 vaccine. He experienced pain, swelling in the right leg, shortness of breath, and fever, followed by chest pain and leg edema. Treatment included anticoagulation, ketorolac for pain management, antipyretics, and intravenous antibiotics (Tazobactam/Piperacillin, Linezolid, Clindamycin) for osteomyelitis. DISCUSSION: The risk of COVID-19 vaccine-related thrombotic events is minimal. Thrombotic events reported among mRNA is very rare. Citrobacter freundii bone and joint infections are very rare, accounting for a small percentage of cases. Some documented cases include cefotaxime-resistant strains causing necrotizing fascitis and osteomyelitis, including postarthroplasty infections. Due to the diverse range of susceptibility patterns and the widespread occurrence of drug resistance, personalized treatment based on culture and sensitivity testing is recommended. However, in rare cases, severe complications like DVT and joint infections associated with Citrobacter infection may occur and should be reported to the vaccine adverse events reporting system. CONCLUSION: Administering the COVID-19 vaccine to enhance natural antibodies is crucial, despite the low risk of infection, thromboembolism, and DVT. Healthcare providers should stay vigilant about adverse effects postvaccination and promptly report those cases.