Thursday, July 01, 2021

CDC HAN: Multistate Investigation of Non-travel Associated Melioidosis in Three Patients: Kansas, Texas, and Minnesota—2021


 

#16,043

Late yesterday the CDC issued a HAN (Health Alert Network) Advisory on three unusual non-travel-related cases of Melioidosis (caused by Burkholderia pseudomallei) reported from three states.  While endemic to some regions of South East Asia and the tropics, locally acquired infections in the United States are unexpected. 

The causative agent - Burkholderia pseudomallei - is a gram negative saprophytic (feeds on dead or decaying organic matter) bacterium that is often found in soil and water in endemic regions. It has never, as far I'm aware, been isolated in the wild in the United States. 

Last year the EID Journal published a dispatch (see Melioidosis in a Resident of Texas with No Recent Travel History, United States), on a 63-year-old man from Atascosa County, Texas (again with no travel history) who was hospitalized in November of 2018 with Melioidosis.  His infection shared genetic similarity with another Texas case - reported in the same county -15 years earlier, but the source of his infection remains unknown.

In yesterday's HAN, the CDC reports that 3 more cases have been detected across 3 US states in 2021, and they appear to share a common genetic ancestor. 

While human-to-human transmission of Melioidosis has been documented, it is exceedingly rare. Most infections are due to environmental exposure.  All of which makes the abrupt appearance of these three infections a bit of a mystery. 

Since few doctors would suspect Melioidosis in an American patient without recent travel history to Asia or the tropics, the CDC has issued the following HAN Advisory recommending that doctors `Consider melioidosis in patients with a compatible illness even if they do not have a travel history to a disease-endemic country'.

First the CDC HAN advisory, then I'll return with a postscript.

Summary

The Kansas Department of Health and Environment, the Texas Department of State Health Services, and the Minnesota Department of Health, with assistance from the Centers for Disease Control and Prevention (CDC), are investigating three cases of Burkholderia pseudomallei (melioidosis) infections. Based on genomic analysis, these three cases (one male, two females; two adults and one child) may share a potential common source of exposure. The first case, identified in March 2021, was fatal. Two other patients were identified in May 2021, one of whom is still hospitalized. One has been discharged to a transitional care unit. None of the patients’ families reported a history of traveling outside of the continental United States.
Symptoms of melioidosis are varied and nonspecific and may include pneumonia, abscess formation, and/or blood infections. Due to its nonspecific symptoms, melioidosis can initially be mistaken for other diseases such as tuberculosis, and proper treatment may be delayed.
Background
Initial presentation among the three patients ranged from cough and shortness of breath, to weakness, fatigue, nausea, vomiting, intermittent fever, and rash on the trunk, abdomen, and face, later diagnosed with infectious encephalitis. The fatal case had several risk factors for melioidosis including chronic obstructive pulmonary disease (COPD) and cirrhosis and died ten days after being hospitalized. Genomic analysis of the strains suggests a common source, such as an imported product or animal; however, that source has not been positively identified to date.
Burkholderia pseudomallei, the causative agent of melioidosis, is a Tier 1 select agent which can affect both animals and humans. Cases are most common in areas of the world with tropical and sub-tropical climates. Most cases in the United States occur in persons returning from a country where the disease is endemic. These three cases are unusual because no recent travel outside the United States has been identified.
Melioidosis symptoms are nonspecific and vary depending on the type of infection.
Symptoms may include localized pain or swelling, fever, ulceration, abscess, cough, chest pain, high fever, headache, anorexia, respiratory distress, abdominal discomfort, joint pain, disorientation, weight loss, stomach or chest pain, and muscle pain or joint pain and seizures. Mortality varies depending on disease severity and clinical presentation, with case fatality ranging between 10-50%. People with certain conditions are at higher risk of disease when they come in contact with the bacteria. The most common factors that make a person more likely to develop disease include diabetes, kidney disease, chronic lung disease, and alcoholism. Melioidosis is confirmed by culture and with testing conducted by trained personnel since some automated identification methods in clinical laboratories may misidentify B. pseudomallei as another bacterium.
Melioidosis is not considered to be transmitted person-to-person via air or respiratory droplets in non-laboratory settings. There have only been a few documented cases of person-to-person transmission; percutaneous inoculation is probably the most frequent route for natural infection. In contrast to other healthcare personnel, laboratory personnel are at risk because some procedures may aerosolize particles and release B. pseudomallei into the air. Laboratory personnel can reduce their risk of exposure by following good laboratory practices1. Laboratory staff who may have been exposed to B. pseudomallei should refer to existing CDC guidance2.
Recommendations
  • Consider melioidosis in patients with a compatible illness even if they do not have a travel history to a disease-endemic country.
  • Culture of B. pseudomallei from any clinical specimen is considered diagnostic for melioidosis. If melioidosis is suspected, culture blood, urine, throat swab, and, when relevant, respiratory specimens,abscesses, or wound swabs.
  • When ordering specimen cultures to diagnose melioidosis, advise the laboratory that cultures may grow B.pseudomallei, and the laboratory personnel should observe appropriate laboratory safety precautions.
  • Treatment of melioidosis consists of IV antibiotics (i.e., ceftazidime or meropenem) for at least two weeks. Depending on the response to therapy, IV treatment may be extended for up to eight weeks. Intravenous treatment is followed by oral trimethoprim-sulfamethoxazole (TMP/SMX) for 3-6 months to prevent relapse. Amoxicillin/clavulanic acid can be used in persons with a contraindication to or who cannot tolerate TMP/SMX3.
  • Consider re-evaluating patients with isolates identified on automated systems as Burkholderia spp. (specifically B. cepacia and B. thailandensis), Chromobacterium violaceum, Ochrobactrum anthropi; and, possibly, Pseudomonas spp., Acinetobacter spp., and Aeromonas spp. Laboratory testing involving automated identification algorithms (e.g., MALDI-TOF, 16s, VITEK-2) may misidentify B. pseudomallei as another bacterium. The isolate from the Texas case was initially misidentified as B.thailandensis by MALDI-TOF.
  • If B. pseudomallei is identified or an organism is suspicious for B. pseudomallei, contact your local public health department immediately. The health department can facilitate forwarding the isolate for confirmation to the closest reference laboratory and initiate a public health investigation.
For More Information
Contact your local health department if you have any questions or suspect a patient may be infected with Burkholderia pseudomallei.

 

As mentioned above, Burkholderia pseudomallei is considered a Tier-1 Select agent, because - and I quote the CDC - `. . .  these biological agents and toxins present the greatest risk of deliberate misuse with significant potential for mass casualties or devastating effect to the economy, critical infrastructure, or public confidence, and pose a severe threat to public health and safety"

2014 was a year that will be remembered for a number of laboratory accidents in the United States (see CDC Announces Another Serious Biosecurity Incident and CDC Reports Potential Ebola Exposure At Lab), leading to a national debate over lab safety and gain of function research (see The Laboratory Bio-Safety Backlash Continues).

Among them was the Tulane National Primate Research Center which reported that 3 primates were accidentally infected with Melioidosis, which resulted in a 2-year suspension from their using select agents (see Tulane Primate Center regains permit to work with select agents).

While there is nothing here to suggest that these three recent Melioidosis cases reported in the United States are linked to any lab escape or represent the start of a serious public health threat - this is a particularly nasty pathogen - and so it has (rightfully) caught the attention of public health agencies across the country. 

Now that the word has gone out, and testing for this pathogen will undoubtedly increase, we should learn more in the weeks ahead. 

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