麻豆传媒

Three patients diagnosed with melioidosis in a Mississippi Gulf Coast county probably picked up the disease from the local environment, a new report from the CDC confirms.

Researchers recovered Burkholderia pseudomallei, the bacteria that causes melioidosis, from a puddle and soil from the front and backyard of one of the patients' homes -- the first time that the bacteria has been isolated from the environment in the continental U.S., according to Mindy Elrod, BA, from the CDC in Atlanta, and colleagues.

Genomic sequencing revealed that the three patients were infected with the same strain of the bacteria and they all lived within 20 miles of each other and none had traveled to areas outside the U.S. where they may have contracted the disease, the researchers reported in the .

In 2022, the CDC issued a health advisory about melioidosis after the second patient in Mississippi was diagnosed.

"For a long time, we have suspected that it was possible for B. pseudomallei to be present in the environment of the southern United States but have never been able to prove it," Elrod told 麻豆传媒 in an email. "This was an important discovery that took a lot of hard work, essentially the equivalent of finding a needle in a haystack."

Genomic sequencing revealed that the strain of the bacterium indicates a South American origin. However, where exactly it came from, when, and how it arrived in the Mississippi Gulf Coast cannot be determined, the authors wrote. Also, genomic sequencing suggests that this particular strain is unique from the ones that caused a multistate outbreak linked to contaminated aromatherapy spray in 2021 and a in Louisiana.

Melioidosis thrives in the soil of tropical and subtropical regions of the world, but, so far, is a rare occurrence in the U.S. Of the approximately 12 cases reported each year in the U.S., the majority are associated with travel to an endemic region.

the disease has a mortality rate of 10% to 50% and is especially risky in people with comorbidities, such as diabetes, cancer, HIV, and chronic lung disease.

Patients are typically admitted to the hospital with pneumonia and sepsis, Robert Bollinger, MD, MPH, an expert in tropical infectious diseases at Johns Hopkins Medicine in Baltimore, told 麻豆传媒 in an email.

Despite the report's findings, Bollinger advises awareness but not panic. "With only a few confirmed patients over the past few years and the bacteria present in the soil in a few isolated samples from coastal Mississippi, the risk is currently very low in the U.S.," he said.

"In other parts of the world where melioidosis is more common, cases can increase after big storms including hurricanes," Bollinger said. "Clinicians caring for patients along the Gulf Coast may want to be extra vigilant and consider melioidosis as a diagnosis in patients presenting with pneumonia, sepsis, and/or abscesses, particularly in high-risk patients and after storms."

The three patients all reported influenza-like symptoms in the 1 to 3 weeks before presenting at hospitals in 2020, 2022, and 2023, respectively. The first two patients presented with pneumonia and sepsis while the third patient presented with worsening mid-back pain associated with a spinal epidural abscess. All three patients were diagnosed via blood cultures.

The first two patients recovered, and the third was still receiving treatment at the time the report was written. Treatment for melioidosis involves long-term administration of antibiotics.

The CDC and Mississippi Department of Health investigators took 59 samples from the first patient's worksite on a dry-dock tugboat, and 109 samples from household items and the property belonging to the second patient -- but it was additional samples from the soil and a puddle on the first patient's property that finally grew B. pseudomallei. Investigation into the source of infection for the third patient is in progress.

The investigators speculated that inhalation exposure was the most likely mode of transmission in these three cases. The first patient had influenza at the time of diagnosis, which is a common finding with melioidosis, and the second had mediastinal lymphadenopathy.

It is likely that cases of locally acquired melioidosis have gone undiagnosed, the investigators said, and that clinicians should consider it in patients with symptoms suggestive of the disease who live in or have traveled to the Gulf Coast region. Currently, it remains unknown just how widespread B. pseudomallei is in the environment of that area.

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