Abstract Adenosine deaminase (ADA) is a well-known biomarker for tuberculous pleural effusion1, but elevated levels may also occur in other inflammatory conditions, occasionally leading to a diagnostic dilemma2. Achromobacter xylosoxidans is a rare, multidrug-resistant Gram-negative bacillus most frequently identified in patients with cystic fibrosis or immunocompromised states3. Its association with high-ADA empyema is exceedingly rare. Case Presentation A 35-year-old man with severe traumatic brain injury and chronic ventilator dependence via tracheostomy was admitted with anemia, fever, and leukocytosis. Imaging revealed a large, loculated left pleural effusion with air-fluid levels. Thoracentesis drained 3.5 liters of foul-smelling purulent fluid. Pleural fluid analysis showed a markedly elevated ADA of 192 U/L, initially raising concern for tuberculous empyema.Cultures grew A. xylosoxidans, resistant to most antibiotics. AFB studies were negative, and the interferon gamma release assay was indeterminate, having previously tested negative. Additional culture isolates included Stenotrophomonas maltophilia and Pseudomonas aeruginosa. Empiric cefepime/vancomycin was tailored to piperacillin-tazobactam, vancomycin, and levofloxacin based on sensitivity studies. Owing to persistent loculations and pneumothorax ex vacuo, he underwent thoracotomy with decortication, pleurodesis, and two chest tube placements. Multiple doses of intrapleural dornase and alteplase were given to disrupt persistent septations and enhance drainage. He completed four weeks of targeted therapy with progressive clinical and radiographic improvement. Repeat CT imaging at discharge showed near-complete resolution of atelectasis, consolidations, and effusion. Discussion and Conclusion To our knowledge, this represents one of the few reported cases of A. xylosoxidans empyema causing markedly elevated ADA levels. Elevated ADA has always been considered pathognomonic for tuberculosis. A. xylosoxidans should be recognized as a potential cause of non-tuberculous, high-ADA empyema and a clinically significant cause of empyema in non-cystic fibrosis, ventilator-dependent patients. Early culture-directed antibiotic therapy and aggressive pleural drainage remain critical for favorable outcomes. References: Shaw et al Pleural tuberculosis: A concise clinical review. Clin Respir J. 2018 May;12(5):1779-1786. doi: 10.1111/crj.12900. PMID: 29660258. Valdés et al Adenosine deaminase (ADA) isoenzyme analysis in pleural effusions: diagnostic role, and relevance to the origin of increased ADA in tuberculous pleurisy. Eur Respir J. 1996 Apr;9(4):747-51. doi: 10.1183/09031936.96.09040747. PMID: 8726940.Menetrey et al Achromobacter xylosoxidans and Stenotrophomonas maltophilia: Emerging Pathogens Well-Armed for Life in the Cystic Fibrosis Patients’ Lung. Genes (Basel). 2021 Apr 21;12(5):610. doi: 10.3390/genes12050610. PMID: 33919046; PMCID: PMC8142972. This abstract is funded by: None
Musa et al. (Fri,) studied this question.