ABSTRACT. Melioidosis is an emerging tropical infectious disease with diverse clinical manifestations and a high fatality rate. We report a rare case of chronic melioidosis manifesting as pulmonary infection, empyema, and splenic abscess. The patient presented with recurrent chest pain, cough, and abdominal discomfort for 11 months, initially misdiagnosed as common bacterial infection. Computed tomography imaging revealed pulmonary infection, left pleural effusion, and multiple abnormal low-density lesions in and around the spleen. Pleural effusion culture identified Burkholderia pseudomallei. Management included thoracic puncture and catheter drainage, an intensive phase of intravenous ceftazidime, followed by an eradication phase with oral trimethoprim/sulfamethoxazole. The patient showed clinical and radiological improvements. Clinicians should consider chronic melioidosis in patients with pneumonia and parapneumonic pleural effusion accompanied by splenic abscesses, particularly in patients with diabetes mellitus from endemic areas. Early recognition, definitive diagnosis, and tailored antimicrobial therapy are essential to prevent the progression of severe pneumonia and sepsis.
Yamei Zheng, Xiaozhou Yao, Min Wang et al.· American Journal of Tropical...· 0 citations
How nutrient stress shapes bacterial evolution and the associated fitness trade-offs remains a central question in microbiology. Using Burkholderia thailandensis as a surrogate for the pathogen B. pseudomallei, we performed adaptive laboratory evolution with casein as the sole carbon source. Over 30 days of serial passaging, the population shifted towards protease deficiency, with mutants constituting 54.94% by the endpoint. These evolved strains exhibited pleiotropic virulence attenuation-including reduced rhamnolipid production, motility, auto-aggregation, and biofilm formation-alongside increased susceptibility to imipenem and chloramphenicol. RNA-seq analysis of evolved strain E3101 revealed 2,836 differentially expressed genes, with significant downregulation of quorum sensing (AHL synthesis), rhamnosyltransferases, flagellar assembly, and biofilm regulatory pathways. Our findings demonstrate that casein-driven evolution selects for social 'cheaters' that conserve energy by downregulating costly virulence determinants, revealing a fundamental virulence-fitness trade-off. The coordinated transcriptional repression of biofilm and antibiotic resistance pathways provides a mechanistic framework for understanding bacterial adaptation strategies and potential therapeutic vulnerabilities in Burkholderia.
