By Stan Deresinski, MD, FACP, FIDSA
Clinical Professor of Medicine, Stanford University
SYNOPSIS: Exposure to contaminated soils in the U.S. Gulf Coast is a risk factor for acquiring melioidosis.
SOURCE: CDC Health Advisory. CDC Health Alert Network. Melioidosis locally endemic in areas of the Mississippi Gulf Coast after Burkholderia pseudomallei isolated in soil and water and linked to two cases — Mississippi, 2020 and 2022. https://www.emergency.cdc.gov/han/2022/pdf/CDC_HAN_470.pdf
Two patients living in the Gulf Coast region of southern Mississippi, neither of whom had recently traveled outside the United States, were found to have melioidosis — one in 2020 and one in 2022. Each had pneumonia and bacteremia and recovered after antibiotic therapy.
Burkholderia pseudomallei was recovered by both culture and polymerase chain reaction (PCR) from soil and water from the property of the 2020 case and was genetically identical to isolates from each of the patients. It was concluded that the organism had been present in the environment for at least two years and was the source of infection of the patients. The isolates were the same as a strain of the organism that had been identified previously in the Western Hemisphere.
COMMENTARY
B. pseudomallei is an aerobic gram-negative bacillus found in soil and water in tropical and subtropical climates around the world, but it had never previously been recovered from the environment in the United States. Of the approximately one dozen cases of melioidosis identified there each year, almost all have a history of travel to an endemic region or, in some cases, exposure to contaminated materials imported from such areas. A recent example of this was a cluster of four cases that occurred after exposure to an aromatherapy product that had been manufactured in India and sold by Walmart and online.1,2 Another recent case was that of a 56-year-old woman in whom the infection was traced to her freshwater aquarium.3 In addition, cases have occurred in the United States with no known risk factors in terms of prior travel or exposure, such as a 63-year-old man from south Texas who became ill in November 2018.4
B. pseudomallei is a Tier 1 Select Agent together with such organisms as the anthrax bacillius, but it only became a Nationally Notifiable Disease in the United States in 2022. Although the extent of contaminated soil remains unknown, the Centers for Disease Control and Prevention recommends that residents of the Mississippi Gulf Coast, especially those with comorbid conditions such as diabetes mellitus or excessive alcohol use, should take precautions when experiencing environmental exposure.
The identification of B. pseudomallei in soil is an indication that exposure to the organism naturally occurs in the United States and that it is likely that many more cases have been acquired, at least along the Gulf Coast, than has been recognized previously. Alert clinicians who suspect possible melioidosis should alert their laboratory to that possibility to assure the safety of laboratory workers. In addition, they should become alert to the possibility that the organism may be misidentified with the use of some automated laboratory systems.
REFERENCES
- CDC Health Network. Source identified and case definition established: Multistate investigation of non-travel associated Burkholderia pseudomallei infections (melioidosis) in four patients: Georgia, Kansas, Minnesota, and Texas – 2021. https://emergency.cdc.gov/han/2021/han00456.asp?ACSTrackingID=USCDC_511-DM69519&ACSTrackingLabel=HAN%20454%20-%20General%20Public&deliveryName=USCDC_511-DM69519
- Deresinski S. Melioidosis in the United States. Infect Dis Alert 2021;41:29.
- Dawson P, Duwell MM, Elrod MG, et al. Human melioidosis caused by novel transmission of Burkholderia pseudomallei from freshwater home aquarium, United States. Emerg Infect Dis 2021;27:3030-3035.
- Cossaboom CM, Marinova-Petkova A, Strysko J, et al. Melioidosis in a resident of Texas with no recent travel history, United States. Emerg Infect Dis 2020;26:1295-1299.
