Locally Acquired Melioidosis Linked to Environment — Mississippi, 2020–2023

Case Reports

Patient 1, a 39-year-old man, presented to a Mississippi hospital in July 2020 (Fig. 1) with fever (temperature, 40. 8°C), in acute respiratory distress, and with multisystem organ failure after 1 week of fatigue, weakness, loss of appetite, worsening dyspnea at rest, and productive cough with hemoptysis. He was admitted to the intensive care unit with bilateral multilobar pneumonia (Fig. 2A) and sepsis. Positive blood cultures growing gram-negative rods were detected on admission and persisted until hospital day 6. On hospital day 7, B. pseudomallei was presumptively identified from the initial blood culture and later confirmed by the Mississippi State Department of Health (MSDH) and the CDC. Patient 1 also tested positive for influenza A virus on admission. The patient’s medical history was notable for type 2 diabetes mellitus, alcohol use disorder (1000 g of alcohol per day), fatty liver disease, and obesity; he smoked tobacco cigarettes (20 pack-years). He reported no travel outside the continental United States in his lifetime VSports.

Patient 2, a 62-year-old man, presented to the hospital in April 2022 (Fig. 1) with left upper lobe pneumonia with associated mediastinal lymphadenopathy (Fig. 2B) and sepsis after 10 days of progressive weakness, productive cough, and subsequent fever, chills, night sweats, and diarrhea. On hospital day 4, B. pseudomallei was presumptively identified from a blood culture obtained on admission. Treatment with oral levofloxacin at a dose of 750 mg per day was started, and the patient was discharged home. He was readmitted 1 week later, still symptomatic, after B. pseudomallei was confirmed by the MSDH, and acute-phase therapy for melioidosis was started. The patient’s medical history included excessive alcohol use, hypertensive heart disease, and prediabetes (glycated hemoglobin level, 6.1); he smoked tobacco cigarettes (>10 pack-years). He reported no travel to a melioidosis-endemic country in his lifetime.

Patient 3, a 64-year-old man, presented to the emergency department in January 2023 (Fig. 1) with progressively worsening midback pain that had begun approximately 3 weeks earlier after he had had an influenza-like illness. A spinal epidural abscess (Fig. 2C) was diagnosed on magnetic resonance imaging, resulting in an emergency thoracic laminectomy with washout. B. pseudomallei infection was confirmed from blood and spinal-abscess cultures. Right-lobe pneumonia was also diagnosed on admission, but cultures of pleural fluid remained negative. His medical history included hypertension and arthritis. He reported no travel outside the continental United States in his lifetime.

Patients 1 and 2 ultimately recovered after completing antimicrobial therapy (a description of the complete clinical course is provided in the Supplementary Appendix, available with the full text of this article at NEJM.org). Patient 3 was still recovering at the time of this report, and his case continues to be investigated.

Methods

VSports最新版本 - Results

Discussion

Our investigation identified an environmental isolation of B. pseudomallei in the continental United States. The clonality of the isolates from the three patients and from the environmental samples, along with the patients’ close geographic proximity and lack of travel history, suggest local acquisition of melioidosis from the environment in Mississippi. All three patients lived within a 20-mile radius in the same Mississippi Gulf Coast county but did not know each other. The genomic sequences of the isolates comprising this new strain, which we are calling GCS2020 (Gulf Coast Strain 2020), are greater than 1000 SNPs distant from any other genome available, which means that it is not a match to any previously encountered isolate and thus is distinct from other strains such as ATS2021, which was implicated in a multistate outbreak caused by an aromatherapy spray,¹⁷ and strain 1026b, which was the source of a melioidosis outbreak among nonhuman primates at the Tulane National Primate Research Center in Louisiana.²⁶ Our analysis groups this new strain with others from South America, but it lacks the resolution to conclude timing, source, or geographic origin for the introduction of this strain to the Mississippi Gulf Coast region. This lack of resolution is due mainly to the limited number of genome sequences that are available from strains in the Americas.

The location of the environmental detection of B. pseudomallei, at 30 degrees north latitude, is outside the typical range for this bacterium but within a predicted geographic area, as determined with environmental suitability modeling.^1,9 Although B. pseudomallei was not detected in the other sampled locations, including the property belonging to Patient 2, this factor does not rule out the presence of the bacterium in those areas. A similar outcome was seen in the 2018 Texas investigation, in which the local environment remains the likely source of exposure in the two patients involved.³

Although the exact mode of transmission and exposure event could not be identified for the patients in this study, inhalation exposure^2,27,28 aligns with the mediastinal lymphadenopathy that was observed on computed tomography in Patient 2 and the patient’s report of fishing during rainstorms.²⁹ Patients 1 and 2 had clinical risk factors (diabetes and excessive alcohol use) that are associated with melioidosis, but Patient 3 did not.^2,30 Patient 1 had a coinfection with influenza A virus, a finding that had been documented in other case reports of melioidosis.^31,32

Because melioidosis was not initially suspected in these patients, appropriate antimicrobial therapy^33,34 was delayed. Additional locally acquired cases may have been missed owing to lack of awareness, misidentification, or misdiagnosis, especially during the coronavirus disease 2019 pandemic. Clinicians should consider melioidosis in patients with a compatible illness who reside in or have traveled to the Gulf Coast region of the southern United States or to areas where B. pseudomallei has historically been endemic. Because culture is the reference standard for diagnosis, clinicians should repeat cultures from all clinically relevant sites, even if initial cultures are negative, in patients in whom there is a high clinical suspicion for melioidosis. Misidentification of the pathogen on automated platforms is possible³⁵ and can delay diagnosis and treatment and potentially worsen outcomes.^36,37

Clinical laboratory scientists should consult with a reference laboratory regarding infection suggestive of B. pseudomallei. Because melioidosis is now a nationally notifiable condition, the Council of State and Territorial Epidemiologists recommends that it be added to the reportable disease list in every U.S. jurisdiction to aid in timely investigation and increase our epidemiologic knowledge of this disease in the United States.³⁸ Environmental sampling and seroprevalence studies are needed to determine how widespread B. pseudomallei is in the environment in Mississippi and other Gulf Coast states where environmental conditions are predicted to be suitable for this bacterium.^7,9

The investigation of non–travel-related melioidosis cases in Mississippi led to the isolation of B. pseudomallei in soil and water and ultimately linked to infection in three patients. These findings indicate that melioidosis may be endemic to the Mississippi Gulf Coast region.

Supplementary Material