UMMC experts explain rare bacterium discovered on Mississippi Gulf Coast

Published on Monday, August 1, 2022

By: Ruth Cummins

A rare bacterium discovered on the Mississippi Gulf Coast is here to stay. It can’t be killed.

But to become infected from Burkholderia pseudomallei, the uncommon organism that causes the disease melioidosis, the conditions must be right, University of Mississippi Medical Center experts say.

“Infections in very general terms are dependent on the route of exposure, the length of time of exposure, and the amount of exposure,” said Dr. Larry McDaniel, a professor in the Department of Cell and Molecular Biology and the Center for Immunology and Microbial Research. “It needs to have the right situation.”

That includes location. The Mississippi State Department of Health, in a joint investigation with the Centers for Disease Control and Prevention, identified the bacterium in soil samples after two Gulf Coast residents were sickened with melioidosis two years apart. The soil samples that tested positive for the bacterium were taken from the grounds at both people’s homes, and it’s believed the bacterium had been there since at least 2020.

The bacterium is found in dirt and water, “and sometimes on plants,” McDaniel said. You can become infected by inhaling contaminated soil, dust or water droplets, and it can attach to the coats of animals, who also can be infected.

It’s largely associated with tropical and sub-tropical locales such as India, Southeast Asia, northern Australia or Central or South America. “Transmission from human to human is highly unlikely unless there is prolonged close contact with someone infected,” McDaniel said.

Most people won’t get infected – the bacterium enters the body through cuts and broken skin - and “even if you do, it will probably be a relatively mild infection,” McDaniel said. The incubation period is one to 21 days.

People with chronic diseases such as diabetes, kidney or lung disease, or excessive alcohol use are at risk for severe illness. Symptoms include fever, cough, shortness of breath, joint pain and headache. The infection can sometimes lead to pneumonia and sepsis, a life-threatening blood infection.

That group should take specific precautions that include avoiding contact with soil or muddy water, or water that gathers following rain or a storm, especially if you have cuts or broken skin. Wear waterproof gloves when gardening or working with soil in addition to waterproof boots. Forget the boots, and your feet and lower legs can become badly infected.

“People should be cautious about whatever they are doing when they dig in the dirt, or do anything that could disturb the organism,” McDaniel said.

“The most important step is to have a high level of suspicion. The quicker someone is diagnosed with melioidosis, the lower the chance of a worse outcome,” said Dr. Tulip Jhaveri, an assistant professor in the Division of Infectious Diseases. And, “patients can have a rapid course, including fever, chills, productive cough and respiratory distress. Diagnosis can be tricky because the infection can mimic common respiratory viral or other bacterial infections,” he said.

One example is tuberculosis, a potentially serious infection that affects the lungs.

“Melioidosis can also be chronic,” he said. “In 9 percent of cases, it can easily masquerade as tuberculosis. In both conditions, patients present with slowly progressive cough, shortness of breath, fatigue and weight loss. The infection can involve other sites including kidneys, brain, skin, bone and joints.

“This bacterium usually grows well in standard sputum, blood, urine or pus cultures,” Jhaveri said. “However, it may be misidentified as a different bacterium. If you suspect a patient to have this disease, the lab should be notified immediately so that they can take necessary precautions to improve the chances of accurate identification, as well as for the safety of lab personnel. This bacterium can be released into the air during processing.”

In serious cases, “it generally causes a pneumonia,” said Dr. Ben Brock, associate professor of medicine in the Division of Infectious Diseases. “We wouldn’t normally suspect melioidosis in a patient in Mississippi who presents with pneumonia, but if we grow it in a culture, the antibiotic would be changed to target that specific germ.”

But don’t forget, he said, that “there are lots of other causes of pneumonia that are really what we need to focus our concerns on, and COVID is at the top of the list.”

Someone with a severe infection needs IV antibiotics for at least two weeks, and depending on the response to therapy, can go up to eight weeks followed by months of oral antibiotics to prevent relapse, Jhaveri said. Occasionally, a patient with a mild infection can be treated with oral antibiotics, he said.

The discovery of the same rare bacterium in this country is uncommon, but there are recent cases. The CDC in October 2021 identified Burkholderia pseudomallei in an aromatherapy spray in the home of a Georgia resident who became ill with melioidosis a few months earlier. The spray was manufactured in India. All told, four people became infected over a four-state area, and two of them died.

It’s unknown how the bacterium made its way to the Gulf Coast, but Jhaveri believes “climate change had something to do with it.” Increasing numbers of severe storms leads to warmer temperatures, wet soil and contaminated water, Jhaveri and Brock said.

“That in turn becomes a perfect environment for this bacterium to stir up and evolve,” Jhaveri said.

“Bacteria reproduce and spread,” McDaniel said. “When microbes get into a favorable environment, they can grow to high numbers. Given the warming conditions now, it leads to its propagation.

“I’d presume that the highest numbers of organisms would be in the warmer months. There’s likely to be fewer in the colder months, but that’s not to say you shouldn’t take precautions.”

To say that the organism can travel from one location on the Gulf Coast to another would be speculation, McDaniel said. “It has to have the right conditions to propagate: humidity, water, moisture. Animals that go into an area with the bacterium could pick up the organism on their coat and carry it to another location.

“The organism is here, and you’re not going to get rid of it,” McDaniel said. “You can’t spray the soil and make it go away. You should use common sense to protect yourself and others.”