4th person in US mysteriously infected with deadly South Asian bacteria

Enlarge / Burkholderia pseudomallei cultured on sheep blood agar for 24 hours. B. pseudomallei is an aerobic gram-negative bacterium, and it is the causative agent of melioidosis.

A fourth person in a fourth U.S. state mysteriously contracted a deadly South Asian bacteria without leaving the continental United States, the Centers for Disease Control and Prevention reported on Monday.

Two of the four cases have been fatal, with the last one identified in Georgia late last month during a post-mortem examination.

CDC investigators have determined that the four cases are linked and they suspect a so far unknown imported product is to blame. The CDC previously issued an opinion on June 30 on the three previous cases.

The first case was identified in an adult in Kansas in March, which was also fatal. In May, investigators identified a case in a 4-year-old Texas girl and another case in an adult in Minnesota. These two patients were hospitalized for long periods before being transferred to transitional care facilities. The Texas girl is said to have suffered brain damage from the infection.

Once again, the CDC is warning health care providers to be on the lookout for the rare and often difficult to diagnose infection called melioidosis, even in people who have not traveled. Meanwhile, the investigation continues into the source of the infecting bacteria, Burkholderia pseudomallei.

According to the CDC, whole genome sequencing performed by the agency has found the B. pseudomallei the strains in each of the four cases closely matched each other. The strains are related to those found in Asia, especially South Asia.

B. pseudomallei is an environmental bacteria that lives in soil and water in tropical and subtropical climates. In the United States, it is most often spotted in people who have recently traveled to places where the bacteria is endemic. However, it has also appeared unexpectedly in the United States in people with no recent travel history. Mysterious past cases have led researchers to speculate that B. pseudomallei can now hide in soils and waters in parts of the United States.

But, in the current cluster of cases, CDC investigators say the strains are most closely related to those from South Asia, not to strains previously identified in North America.

Curious cluster

“Currently, the CDC believes the most likely cause is an imported product (such as a food or drink, personal care or cleaning products, or medicine) or an ingredient in any of these types of products,” the agency said in a statement. “The bacteria normally live in moist soil and water. However, in rare cases, it has also been found to contaminate moist or moist produce in areas where bacteria are common.”

So far, the CDC has collected and tested more than 100 product, soil and water samples from the homes of the four patients, but none have tested positive for B. pseudomallei. The agency noted that the search for a source of B. pseudomallei can sometimes be difficult because the bacteria can take two to three weeks to develop into an infection, widening the window of possible exposure times and testing patients’ memory.

Once melioidosis sets in, its diagnosis can be another difficult process. Melioidosis has been called the “grand mime” because its symptoms can vary widely and be vague. It is sometimes confused with other serious illnesses, such as tuberculosis.

People can become infected by ingesting the bacteria or coming into contact with a skin lesion. Workers in clinical laboratories are also at risk of infection from aerosolized particles. Symptoms may include localized pain or swelling, fever, ulceration, abscess, cough, chest pain, high fever, headache, anorexia, respiratory distress, abdominal discomfort, pain joints, disorientation, weight loss, stomach or chest pain, muscle or joint pain, and seizures, notes the CDC.

In the four linked cases, patients had a range of symptoms ranging from cough and shortness of breath to weakness, fatigue, nausea, vomiting, intermittent fever, and rash on the trunk, abdomen and face.

The death rate from melioidosis ranges from 10 to 50 percent, and people with diabetes, kidney disease, chronic lung disease, and heavy drinking are most at risk. The risks can further increase if there is a delay in diagnoses. B. pseudomallei is inherently resistant to many antibiotic treatments. Delayed diagnosis and treatment with the wrong drugs could allow the infection to spread unchecked. If it becomes systemic, it can be fatal in 90 percent of cases.