under the microscope
By Rodney E . Rohde , PhD , MS , SM ( ASCP ) CMSV CM , MBCM , FACSc
Fish Aquariums : A Transmission Source
In
September 2021 , I reported on a Burkholderia pseudomallei ( melioidosis ) outbreak consisting of four cases from Georgia , Kansas , Minnesota and Texas . 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 an extended time then 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
During those formative years of my professional career , I will always remember the critical and sometimes lifesaving advice to not forget about doing a deep dive on a patient history .” symptoms are varied and nonspecific , and may include pneumonia , abscess formation , and blood infections .
All four melioidosis cases initially presented with symptoms ranging from cough and shortness of breath to weakness , fatigue , nausea , vomiting , intermittent fever , and rash on the trunk , abdomen , and face . Two cases , one fatal , had several risk factors for melioidosis , including COPD and cirrhosis . The other two cases had no known risk factors for melioidosis . Genomic analysis of the strains strongly suggested a common source ( e . g ., imported product or animal ). The source is unknown to date despite environmental sampling , serological testing , and family interviews .
The Centers for Disease Control and Prevention ( CDC ) recently reported a 56-year-old woman , hospitalized on Sept . 20 , 2019 , likely acquired melioidosis via novel transmission of B . pseudomallei from a freshwater home aquarium in the December 2021 issue of Emerging Infectious Diseases . The Maryland woman is the first known person to have this severe tropical infection by this new transmission route .
The patient history showed diabetes and rheumatologic disease . She was hospitalized because of fever , cough , and chest pain with onset two days earlier . Her ongoing medications indicated immunosuppressives ( methotrexate , azathioprine , and prednisone ) until one month before she became symptomatic . Multiple blood cultures were taken on days 1-4 which grew B . pseudomallei , without evidence of endocarditis or intravascular seeding .
Other clinical data presented a thoracic radiograph on day 0 consistent with pneumonia . A non-contrast computed tomography ( CT ) scan on day 3 showed air space consolidation in the right lower lobe consistent with pneumonia . Other notable clinical laboratory results at presentation included an increased leukocyte count of 22,800 cells / μL ( reference range 4,500 to 11,000 cells / μL ) and a decreased sodium level of 125 mmol / L ( reference range 135μL145 mmol / L ).
Despite weeks of meropenem ( Merrem ), she developed evidence of a lung abscess , and trimethoprim / sulfamethoxazole ( Bactrim ) was added . Ultimately , the patient required a 12-week course of antibiotics for eradication therapy and resolution .
I started my career in public health at the Texas Department of State Health Services as a public health microbiologist and molecular epidemiologist in the Zoonosis Control Division . During that decade , I had the opportunity to spend two sessions with the CDC in the Rabies Laboratory as a visiting scientist . During those formative years of my professional career , I will always remember the critical and sometimes life-saving advice to not forget about doing a deep dive on a patient history . The melioidosis case in Maryland is significant to that advice .
CDC epidemiologist Patrick Dawson , PhD , first author of the report , told Medscape Medical News that although outbreak investigators always ask about pet ownership , they have not explicitly asked about fish . In this case , the patient did not volunteer exposure to the fish . If I am being honest , I am not sure I would have either . Typically , physicians and epidemiologists know to ask about exposures from animals , the environment ( e . g ., soil , water , etc .) and travel . While we know fish can be a source of different microbial infections , since this patient had not mentioned it , the epidemiologists and others did not think about .
However , when there was a visit to patient ’ s home , “ one of the first things they saw was a few aquariums ,” Dawson said . Seeing the water and knowing “ that most freshwater tropical fish in the U . S . are imported from Southeast Asia ” led them to culture specifically for B . pseudomallei , which can be difficult for the microbiology lab to identify .
The investigative epidemiology team discovered she had bought her fish six months earlier . Through environmental sampling at the local pet store , they did not discover the bacteria there . Eventually , the team worked with the national brand to find where the fish originated . Ultimately , an exact matching isolate could not be identified after so many months had passed , but they found a positive PCR for B . pseudomallei in a water sample from imported fish in Los Angeles .
Advice for the public :
●Wash your hands before and after contact with an aquarium ●If you have cuts or wounds , wear gloves while working with an aquarium or cleaning fish ●If immunocompromised ( including younger children ), don ’ t handle fish or aquariums
●Aquatic zoonoses ( infections from water ) are important because an estimated 11.5 million U . S . households have pet fish , totaling about 139 million freshwater fish .
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 /