A Deadly Soil Bacteria May Be Taking Root in the American South

A rare and potentially lethal infection long considered confined to tropical Asia and northern Australia has now been documented in a Florida resident with no history of international travel, adding to mounting evidence that the bacterium responsible may be establishing itself in the United States. In a case report published in PLOS Neglected Tropical Diseases, physicians describe a patient who developed pulmonary melioidosis after a period of severe weather, presenting with fever, pleuritic chest pain, and dangerously low oxygen levels. The diagnosis, made through imaging and microbiological testing, revealed multiple solid nodules scattered through both lungs, a pattern that initially mimicked more common conditions such as metastatic cancer, fungal infection, or tuberculosis. The case underscores a growing concern among infectious disease specialists: Burkholderia pseudomallei, the soil-dwelling bacterium that causes melioidosis, may now be a permanent resident of the Gulf Coast environment rather than an occasional imported curiosity.

Melioidosis is caused by Burkholderia pseudomallei, a gram-negative bacterium that lives in soil and freshwater. Humans typically acquire it through direct contact with contaminated soil or water, particularly through cuts in the skin, inhalation of aerosolized particles, or, less commonly, ingestion. The disease is notoriously difficult to diagnose because it can present in almost any organ and with an incubation period ranging from days to years. In endemic regions such as northeast Thailand and northern Australia, melioidosis is a leading cause of community-acquired sepsis, with mortality rates that can exceed 40 percent even with treatment. Globally, estimates suggest the bacterium may be responsible for tens of thousands of deaths annually, a burden that many researchers believe is substantially undercounted because of limited diagnostic capacity in the regions where the disease is most common.

For decades, the conventional wisdom held that melioidosis in the United States occurred almost exclusively in travelers returning from endemic areas. That assumption began to erode when environmental surveys detected B. pseudomallei in soil and water samples along the Gulf Coast of Mississippi and Texas, and when cases began appearing in residents of those states who had never left the country. The Centers for Disease Control and Prevention has confirmed sporadic locally acquired cases in recent years, including a cluster in Georgia and cases in Kansas and Minnesota linked to contaminated products or uncertain exposure routes. The Florida case described in the new report fits this emerging pattern: a patient with no recent international travel who nonetheless developed a classic pulmonary presentation of the disease, suggesting that the bacterium had been acquired locally, likely through inhalation of contaminated aerosols stirred up by severe weather.

The patient in the report arrived with a constellation of symptoms that would challenge any emergency department. Fever and sharp chest pain worsened by breathing, combined with measurable hypoxia, pointed initially toward community-acquired pneumonia. But computed tomography of the chest told a more complicated story. Instead of the lobar consolidation typical of bacterial pneumonia, the scan revealed multiple solid pulmonary nodules surrounded by ground-glass opacities, along with enlarged mediastinal lymph nodes. This radiographic pattern is a recognized hallmark of melioidosis, which can seed the lungs hematogenously and produce discrete nodular lesions that resemble metastatic disease. The differential diagnosis for such findings is broad and includes fungal infections like histoplasmosis, mycobacterial disease, vasculitis, and malignancy, and clinicians who do not routinely consider melioidosis may not order the specialized cultures needed to identify the organism.

Laboratory confirmation of B. pseudomallei requires awareness at the microbiology bench as well as at the bedside. The bacterium can be misidentified by automated systems as a less dangerous relative, such as Burkholderia cepacia or even Pseudomonas species, and handling it in the laboratory poses a biosafety risk because it can infect laboratory workers through inhalation. Accurate identification typically depends on matrix-assisted laser desorption ionization mass spectrometry with updated databases, molecular methods, or specific biochemical testing. Serological assays exist but have limited utility in regions where background exposure is low and in patients whose disease is localized rather than disseminated. The delay between presentation and definitive diagnosis is a recurring theme in non-endemic settings, and it matters clinically because early, appropriate antibiotic therapy is one of the strongest predictors of survival in melioidosis.

Treatment of melioidosis follows a two-phase strategy refined over decades of clinical trials in Thailand and Australia. The intensive phase uses intravenous ceftazidime or a carbapenem such as meropenem for at least two weeks to bring the acute infection under control. This is followed by an eradication phase, traditionally oral trimethoprim-sulfamethoxazole for three to six months, designed to eliminate the bacterium from intracellular sanctuaries where it can persist and relapse. The Florida patient’s management illustrates how comorbidities complicate this standard approach. Because he had stage 3b chronic kidney disease, his physicians were reluctant to prescribe trimethoprim-sulfamethoxazole, which requires renal dosing and carries a risk of further kidney stress and hyperkalemia. Instead, after completing intravenous ceftazidime, he received oral doxycycline monotherapy as an alternative eradication regimen.

The choice of doxycycline is noteworthy because it departs from the conventional first-line recommendation, and the authors of the report suggest it may serve as a viable option for patients in whom trimethoprim-sulfamethoxazole is contraindicated. Evidence for doxycycline monotherapy in the eradication phase is thinner than for the standard regimen, drawing largely from older trials and in vitro susceptibility data, but the drug offers practical advantages: it does not require renal dose adjustment, is inexpensive, and is well tolerated. The patient’s outcome supports its cautious use in selected cases. At three-month follow-up, repeat imaging demonstrated complete resolution of the pulmonary nodules, and he had achieved a full clinical recovery, an encouraging result in a disease where relapse rates of 10 to 20 percent are reported even after apparently successful therapy.

Underlying conditions play a decisive role in determining who develops symptomatic melioidosis after exposure. Diabetes mellitus is by far the most important risk factor, increasing susceptibility several-fold and accounting for a large proportion of cases in endemic regions. Chronic kidney disease, chronic lung disease, alcohol use disorder, and immunosuppression also elevate risk. The Florida patient’s chronic kidney disease likely placed him in a vulnerable category, and the report’s authors emphasize that clinicians in the southern United States should view diabetes and recent severe weather events as key clinical clues when evaluating unexplained pneumonia or pulmonary nodules. Hurricanes, tropical storms, and prolonged flooding create precisely the conditions under which soil bacteria become aerosolized and inhaled, and climate models suggest that the warm, humid Gulf Coast environment is increasingly hospitable to the environmental persistence of B. pseudomallei.

The broader implications of the case extend beyond a single patient. If B. pseudomallei has established ecological niches along the Gulf Coast and potentially beyond, melioidosis will join the growing list of tropical infections becoming domestically relevant in a warming climate. Physicians who trained with the assumption that melioidosis requires a travel history will need to update that reflex, particularly when evaluating patients with non-resolving community-acquired pneumonia, cavitary or nodular lung disease, or sepsis of unclear origin in the southern states. Public health surveillance will likewise need to adapt, since melioidosis is not uniformly reportable and environmental mapping of the bacterium remains incomplete. Each confirmed locally acquired case is a data point in an unfinished map of where the organism lives and how far it has spread.

For now, the practical lessons of the Florida case are straightforward. Melioidosis belongs on the differential diagnosis for pulmonary nodules and non-resolving pneumonia in the southern United States, even in patients who have never traveled abroad. Severe weather and diabetes should sharpen clinical suspicion. When trimethoprim-sulfamethoxazole cannot be used because of renal impairment or drug interactions, doxycycline may offer an alternative path to eradication, though it should be weighed carefully against the stronger evidence base for standard therapy. And as the environment shifts, so too must the clinical imagination of the physicians who treat the infections it harbors. A bacterium once described as brought with the wind from distant tropics may, in fact, already be home.

Subject of Research: A locally acquired case of pulmonary melioidosis in Florida caused by Burkholderia pseudomallei

Article Title: Brought with the wind: A case of melioidosis acquired in the United States presenting with multiple pulmonary nodules

Article References: Garcia-Santisteban, R., Kaufman, M., Jacqueline Chung, H.-T., Khella, R., Pousa, A., Kujundzic, W., Mbaga, I., & Voin, V. (2026). Brought with the wind: A case of melioidosis acquired in the United States presenting with multiple pulmonary nodules. PLOS Neglected Tropical Diseases, 20(10), e0014790. https://doi.org/10.1371/journal.pntd.0014790

Image Credits: AI Generated

DOI: 10.1371/journal.pntd.0014790

Keywords: melioidosis, Burkholderia pseudomallei, Florida, Gulf Coast, pulmonary nodules, ceftazidime, doxycycline, chronic kidney disease, severe weather, emerging infectious disease, PLOS Neglected Tropical Diseases, diabetes