<xhtml:span xmlns:xhtml="http://www.w3.org/1999/xhtml" xml:lang="en">Title: <em>B. trematum</em> Bacteraemia Secondary to an Empyema in an Immunocompromised Host: A Case Report and Review of the Literature. </xhtml:span>

Introduction: Bordetella trematum infection remains uncommon. More cases of bacteraemia are reported in recent years with the primary infection largely originating from skin and soft tissue sites. Yet, our understanding of its virulence, antibiotic susceptibility profile and treatment is still limited. Case presentation: We report the first case of B. trematum bacteraemia from a left-sided empyema. An 87-year old lady with a past medical history of ischemic heart disease, diabetes mellitus complicated by nephropathy and locally advanced left breast adenocarcinoma presented with fever, productive cough and shortness of breath. The B. trematum isolates from blood and pleural fluid were identified by MALDI-TOF and 16S rRNA sequencing. Ceftriaxone and azithromycin commenced empirically on admission were switched to piperacillin-tazobactam after 2 days due to lack of clinical improvement. Despite a pleurocentesis and one week of piperacillin-tazobactam with microbiological clearance in blood, she continued to deteriorate. Decision to withdraw treatment was made in view of her prognosis, and she succumbed on the 14th day of admission. The isolate was susceptible to piperacillin-tazobactam, imipenem and meropenem but had reduced susceptibility or was non-susceptible to cefuroxime, cefotaxime, ceftazidime, cefepime, the aminoglycosides and fluoroquinolones. Conclusion: Invasive B. trematum infection is associated with significant mortality. Consensus for antibiotic treatment remains unclear, with limited susceptibility data to support specific antibiotic use. We expect more clinical cases will surface with improved microbial identification systems, as well as enhanced clinical awareness. Standardised and more robust susceptibility work are needed to provide clear recommendations and establish consensus in treating invasive infections.