P025 The knee that gave it away: a case report of melioidosis
Authors: Maksoud Aimen , Sammut Luke 
Published: April 2023

Abstract

Background/Aims
Melioidosis, an infectious disease caused by the Burkholderia pseudomallei is very rare within the UK. This gram-negative bacterium is endemic in Southeast Asia predominately Thailand and Northern Australia which is found within the soil and fresh surface water. We present a challenging case of melioidosis who was diagnosed following a culture of a discharging knee swelling.

Methods
N/A

Results
35-year-old, Caucasian gentleman with no previous past medical history presented with a ten week history of diffuse abdominal pain, weight loss, dry cough, fatigue and night sweats. On examination, he appeared pale and initial bloods showed a CRP of 229 mg/L. His other initial observations and baseline blood tests were normal. Abdominal ultrasound detected free peritoneal fluid and a subsequent CT chest and abdominal showed abnormal thickening of his small bowel, mediastinal and retroperitoneal lymphadenopathy along with bilateral pulmonary nodules. A laparoscopy and laparotomy with peritoneal, intraperitoneal and mesenteric lymph node biopsies were inconclusive. Microscopy and culture (MC&S) as well as acid fast bacilli MC&S were both negative. He continued to have systemic symptoms, as well as elevated inflammatory markers. He underwent a bronchoscopy which showed erythematous and a nodular endobronchial mucosa with white plaques seen within the lower trachea and minor narrowing of the lumen. Endobronchial biopsies showed chronic inflammation with no evidence of any malignant cells. Repeated bloods including retroviral screening, anti-nuclear antibody (ANA) and antinuclear cytoplastic antibodies (ANCA) and serum ACE were normal. At this stage, the clinical picture was suggestive of sarcoidosis, however a subsequent rigid bronchoscopy and biopsy did not evidence of granulomas or vasculitis. The patient started to develop increasing right knee swelling with difficulty in walking. The swelling burst open, and the discharging fluid was sent for MC&S. This was positive for Burkholderia pseudomallei. The gentleman completed a 20-week course of antibiotics with clinical resolution.

Conclusion
Meliodosis can cause a wide range of clinical manifestations varying from asymptomatic to septicemia, osteomyelitis, abscesses, septic arthritis and encephalomyelitis. Our case had travelled to Thailand around 8 months prior to the onset of symptoms. This highlights the possible long latent period between exposure and clinical presentation. Definite diagnosis is through isolation of Burkholderia pseudomallei in cultures. This proved challenging in our case, as multiple biopsies and cultures from different sites did not grow the bacterium. The diagnosis was confirmed following knee fluid culture. Musculoskeletal involvement of melioidosis is a known presentation and its potential to mimic other conditions, may render a diagnostic challenge especially when it occurs outside an endemic area. The case highlights the need for rheumatologists to have a high level of clinical suspicion for early detection, isolation of the organism and proper disease management.
Disclosure
A. Maksoud: None. L. Sammut: Other; LS has received funding for educational events and activities - from Lilly, Roche/Chugai.