A wolf in sheep's clothing: An unusual zoonotic pathogen in peritoneal dialysis effluent and an important diagnostic...

Brucellosis is an infectious disease characterized by a natural foci, caused by Brucella, a genus of Gram-negative bacilli known for its obligate aerobic growth and capability for intracellular parasitism. This pathogen can be transmitted zoonotically between animals and humans. Due to its mechanism of intracellular survival, monotherapy with a single antibiotic often proves ineffective in eradicating Brucella. Therefore, clinical management necessitates the implementation of multidrug combination therapy alongside extended therapeutic regimens to achieve optimal bacteriological clearance. Conventional diagnostic methods, such as bacterial culture and serological testing, are frequently hindered by the fastidious growth requirements of the pathogen and the risk of false-positive serological cross-reactivity. These limitations may result in delayed diagnosis or unnecessary interventions. Recent advancements in molecular biology-particularly genomic analysis technologies-have revolutionized pathogen detection by facilitating rapid and precise identification of elusive pathogens. This study reports the first documented case of refractory peritoneal dialysis-associated peritonitis caused by Brucella diagnosed via metagenomic next-generation sequencing (mNGS). By employing mNGS to identify the pathogen, we summarize the clinical characteristics of this case and highlight the diagnostic advantages of this technology. Our findings aim to guide clinicians in selecting appropriate diagnostic approaches for similar cases, avoiding unnecessary delays and optimizing resource utilization in clinical practice.