Tracing the environmental source of fatal community-acquired pneumonia and sepsis caused by Burkholderia pseudomallei

Objectives

Melioidosis, which is endemic in Malaysia, is caused by Burkholderia pseudomallei and has an elevated risk of mortality. This study reports a case of fatal melioidosis involving an adolescent, where the B. pseudomallei variant causing the infection was traced to the environment based on whole genome sequencing (WGS) analysis.

Methods

Burkholderia pseudomallei was isolated from an adolescent patient with no known risk factors, who developed fatal community-acquired pneumonia and sepsis. Further investigation and environment sampling were performed to identify the route of infection. Genomic characterization of both clinical and environmental B. pseudomallei isolates was performed to establish genetic relatedness, assess phylogenomic relationships, and identify virulence and antimicrobial resistance genes.

Results

Genomic pairwise SNP distance analysis suggests a shared common ancestor between the patient and environmental isolates. Nevertheless, the identification of the novel sequence type ST1901 in both supports the hypothesis of environmental acquisition from a local source. Further analysis identified strain-specific genes that confirmed the strain's regional specificity and virulence. The patient succumbed to the infection despite the isolate being susceptible to the antimicrobials used for melioidosis, and the lack of correlation with antimicrobial resistance gene mutations suggests that treatment failure was not due to resistance. The fatal outcome may have resulted from a delay in initiating effective treatment, leading to the disease progression.

Conclusion

This study highlights the effectiveness of WGS in tracing B. pseudomallei infections, which could guide improved diagnostics to enhance melioidosis patient management and treatment outcomes.