The cost-effectiveness of the use of selective media for the diagnosis of melioidosis in different settings

BACKGROUND: Melioidosis is a frequently fatal disease requiring specific treatment. The yield of Burkholderia pseudomallei from sites with a normal flora is increased by culture using selective, differential media such as Ashdown’s agar and selective broth. However, since melioidosis mainly affects people in resource-poor countries, the cost effectiveness of selective culture has been questioned. We therefore retrospectively evaluated this in two laboratories in southeast Asia. METHODOLOGY/PRINCIPAL FINDINGS: The results of all cultures in the microbiology laboratories of Mahosot Hospital, Vientiane, Laos and Angkor Hospital for Children, Siem Reap, Cambodia, in 2017 were reviewed. We identified patients with melioidosis who were only diagnosed as a result of culture of non-sterile sites and established the total number of such samples cultured using selective media and the associated costs in each laboratory. We then conducted a rudimentary cost-effectiveness analysis by determining the incremental cost-effectiveness ratio (ICER) per DALY averted and compared this against the 2017 GDP per capita in each country. Overall, 29 patients in Vientiane and 9 in Siem Reap (20% and 16.9% of all culture-positive patients respectively) would not have been diagnosed without the use of selective media, the majority of whom (18 and 8 respectively) were diagnosed by throat swab culture. The cost per additional patient detected by selective culture was approximately $100 in Vientiane and $39 in Siem Reap. Despite the different patient populations (all ages in Vientiane vs. only children in Siem Reap) and testing strategies (all samples in Vientiane vs. based on clinical suspicion in Siem Reap), selective B. pseudomallei culture proved highly cost effective in both settings, with an ICER of ~$170 and ~$28 in Vientiane and Siem Reap, respectively. CONCLUSIONS/SIGNIFICANCE: Selective culture for B. pseudomallei should be considered by all laboratories in melioidosis-endemic areas. However, the appropriate strategy for implementation should be decided locally.