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BACKGROUND: Melioidosis is considered rare in the United States. Laboratories may misidentify cultures of the causative bacteria Burkholderia pseudomallei or dismiss them as culture contaminants. A fatal case of melioidosis was diagnosed in Ohio one month after culture results were initially reported as Bacillus species. An investigation was conducted to identify a potential source of infection and assess risk in patient contacts.
METHODS: The investigation involved abstracting patient charts; interviewing physicians and contacts; genetically characterizing the patient isolate; performing B. pseudomallei-antibody indirect hemagglutination assay (IHA) on household contacts and pets to assess seropositivity (titer ≥ 1:40); and collecting household plant, soil, liquid, and insect samples for B. pseudomallei culturing and real-time PCR testing.
RESULTS: At the patient’s February 2013 admission for febrile illness, physician interviews and chart reviews revealed that rapid biochemical identification system results for one out of four blood cultures were positive and B. pseudomallei identified. All four March re-admission blood cultures were B. pseudomallei positive. Although the patient never traveled internationally, the isolate genotype was consistent with Southeast Asian-origin isolates. Ten family members and seven pets tested were seronegative for B. pseudomallei exposure. All environmental samples were negative by real-time PCR, and cultures were negative.
CONCLUSIONS: No source for the patient’s infection was identified. Negative IHA results indicate that there was no infection in household members. Although typed to Southeast Asia, this case represents the fifth reported locally-acquired non-laboratory melioidosis case in the contiguous U.S., providing more evidence that melioidosis may be considered an emerging infection in the U.S. The diagnosis of melioidosis should be considered in patients even without travel history to known endemic areas.