under the microscope
By Rodney E . Rohde , PhD , MS , SM ( ASCP ) CMSV CM , MBCM , FACSc
Raccoons , Aromatherapy , and Burkholderia
Over the past year or so , I ’ ve written about the dangers associated with the bacterial genus Burkholderia . This genus of Proteobacteria include pathogenic members of a diverse group of species responsible for dangerous and often deadly infections . Unfortunately , this group of bacteria can be difficult to isolate and differentiate in the typical clinical microbiology laboratory while becoming more difficult to treat with antibiotic therapy due to resistance .
In a recent CDC Health Alert Network , four cases of melioidosis from Georgia , Kansas , Minnesota and Texas were identified and characterized . The first case ( fatal ) identified in March 2021 occurred in Kansas . The second and third cases , both identified in May 2021 in Minnesota and Texas , were hospitalized for extended periods of time before being discharged to transitional care facilities . The most recent case died in the hospital and was identified post-mortem in late July 2021 in Georgia . All cases had no history of traveling abroad from the United States . Melioidosis signs and symptoms are varied and nonspecific , and may include pneumonia , abscess formation , and blood infections .
Ultimately , the source of in infections for these four cases was found to be an aromatherapy room spray imported from India .
An Update : Texas Case Investigation
In a strange twist to the Texas case and after it was learned that an aromatherapy product was the source of the outbreak with the prior mentioned four cases , the Texas Department of State Health Services ( DSHS ) discovered that the Texas patient ’ s family owned a healthy raccoon as a pet . The family reported to the DSHS that the raccoon had broken a bottle of the aromatherapy spray and walked in and through the liquid .
About two weeks after this exposure , April 3 , 2021 , the family ’ s pet raccoon displayed acute neurologic symptoms consistent with neurologic melioidosis and died of unknown cause three days later . The raccoon carcass was wrapped in a cloth robe and buried on the family ’ s property . Importantly , the aromatherapy bottle ( ATS2021 ) linked to the outbreak contained the strain which exhibits a genetic variant , the bimABm allele , which is a virulence factor associated with neurologic melioidosis .
Modeling studies regarding environmental conditions for B . pseudomallei suggest that certain regions of Texas have soil and climate that are favorable for this dangerous pathogenic bacteria . To be conservative and cautious about introducing and establishing this bacteria in soil where it was not thought to be endemic , staff from Texas DSHS , Environmental Protection Agency ( EPA ) and CDC visited the family ’ s property in Texas on April 19 , 2022 , to ascertain B . pseudomallei contamination and to decontaminate the burial site . Thirty-two environmental samples were collected in and around the burial site and property . The raccoon carcass was buried at approximately one foot , and 12 tissue samples were collected during field necropsy .
Following sample collection , EPA staff members immediately decontaminated the carcass and excavated soil within a two-foot circumference of the carcass in germicidal bleach ( 8.25 percent sodium hypochlorite , diluted 1:3 with water ) overnight for approximately 15 hours . All samples were tested for B . pseudomallei by PCR and culture at CDC . A portion of four of the 12 tissue samples were formalin-fixed by the Dallas County Health and Human Services Laboratory in Texas and tested for B . pseudomallei by immunohistochemistry ( IHC ) at CDC .
Laboratory Results
Swabs collected from the raccoon ’ s intraorbital tissue tested positive by PCR for the presence of B . pseudomallei DNA ; however , viable B . pseudomallei was not cultured . All other tissue samples tested negative by PCR or IHC . Contamination of the environment was not detected via no PCR and culture evidence of the pathogen .
The positive PCR result for B . pseduomallei from the raccoon tissue reaffirmed the suspicion that the racoon likely died of acute neurological melioidosis . Per the findings , it is the first reported presumed melioidosis case documented in a raccoon and the first animal case linked to this outbreak . While the pathogen could not be cultured and sequenced , the pet raccoon was most likely infected by the outbreak strain given the animal ’ s exposure history and that B . pseudomallei has never been isolated from a soil sample in Texas .
While this disease it not usually seen in animal to human transmission , it has been documented and shown to infect a wide range of animal life ( fish , reptiles , and mammals ). Thankfully , no evidence of environmental contamination by B . pseudomallei from the buried carcass was found . This is important in preventing a foothold for B . pseudomallei in soil where the pathogen is not known to be endemic .
Important Reminders
As many of you know , I have discussed many forms of antimicrobial resistance ( AMR ) in this column . Surfaces and biofilms intersect with AMR . Animals , including wildlife , livestock , and pets of all kinds can also be important “ carriers or vectors ” of pathogens . Appropriate precautions for importation and movement of animals , vegetation , or other similar products should be followed . Likewise , hand hygiene and other disinfection ( or sterilization ) of surfaces and products may be appropriate .
Rodney E . Rohde , PhD , MS , SM ( ASCP ) CM SVCM , MBCM , FACSc , serves as chair and professor of the Clinical Laboratory Science Program at Texas State University . Follow him on Twitter @ RodneyRohde / @ TXST _ CLS , or on his website : http :// rodneyerohde . wp . txstate . edu /