To the Editor: Melioidosis refers to infection caused by the facultative intracellular gram-negative bacterium Burkholderia pseudomallei. The clinical manifestations of melioidosis span a wide spectrum, from asymptomatic exposure or localized cutaneous infection to septic shock with multiorgan failure. Melioidosis usually occurs in residents of or travelers to disease-endemic areas in northern Australia and Southeast Asia; however, an increasing number of confirmed melioidosis cases are being reported from the Caribbean. We report a case of melioidosis acquired in Trinidad and Tobago.

In February 2014, a 17-year-old male student was admitted to a tertiary care hospital in Vancouver, British Columbia, Canada, with catecholaminergic polymorphic ventricular tachycardia and electrical storm. He had a 9-month history of dry cough that was unresponsive to multiple and prolonged courses of treatment for community-acquired pneumonia. During the 6 months before his admission, the patient had hemoptysis and radiologic evidence of pneumonia that were treated with courses of cephalosporins without resolution of symptoms. Bronchoscopy and culture of lavage samples had revealed infection with Staphylococcus aureus and an organism most closely related to Actinomyces graevenitzii .

The patient had no history indicative of risk factors for recurrent sinusitis or pneumonia (e.g., cystic fibrosis, chronic granulatomous disease, Job syndrome), and no risk factors for tuberculosis or infection with dimorphic fungi. He was up to date on his vaccinations and had no pets. He was born in Jamaica, had moved to Canada at age 4, and had not traveled anywhere other than Trinidad and Tobago, Canada, and England. He had traveled to visit family in Trinidad for 2 months during the rainy season in 2012, at which time he also visited Tobago.

On day 5 of hospital admission, the patient became febrile (39.6°C), and an infectious diseases specialist was consulted. Examination revealed that the patient was clinically stable but emaciated at 45 kg. His oxygen saturation while breathing room air was 98%. Physical examination, including cardiorespiratory examination, was unremarkable. Laboratory results showed a normal hemoglobin concentration of 133 g/L; elevated leukocyte count of 22.8 × 10⁹ cells/L; neutrophils 19.4 × 10⁹ cells/L; normal platelet count of 295 × 10⁹/L; and normal creatinine of 54 μmol/L. Test results for HIV-1 and blood cultures were negative. Computed tomography scan showed dilated bronchi and dense consolidation of the right and left lower lobes. Piperacillin/tazobactam was started for presumed hospital-acquired pneumonia.

The patient underwent diagnostic bronchoscopy with bronchoalveolar lavage. Gram staining of specimens showed occasional gram-negative bacilli, and aerobic cultures grew gram-negative bacilli. Further testing with the Vitek 2 (bioMérieux, Laval, Quebec, Canada) (96%) and RapID NF (Oxoid, Nepean, Ontario, Canada) (99.9%) systems identified B. pseudomallei, but matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (Vitek MS, bioMérieux) did not. Phenotypic confirmation was performed at the provincial public health and reference laboratory. Antimicrobial drug susceptibility testing performed by broth microdilution according to Clinical and Laboratory Standards Institute recommendations (1) and by Etest (bioMérieux) showed susceptibility to amoxicillin/clavulanic acid, ceftazidime, imipenem, doxycycline, and trimethoprim/sulfamethoxazole. The patient’s condition improved after 2 weeks of intravenous meropenem, and antimicrobial therapy was changed to oral trimethoprim/sulfamethoxazole.

The B. pseudomallei isolate was sent to the Public Health Agency of Canada’s National Microbiology Laboratory for molecular typing. Query of 7 standard multilocus sequence typing loci (http://bpseudomallei.mlst.net/) identified the isolate as a novel multilocus sequence type. The sequence type (1,1,2,1,5,6,1) closely resembled that of B. pseudomallei previously isolated from the Caribbean (2).

Although melioidosis was first described in the Caribbean in 1947 (3), most case reports of the disease in the area are from the past 2 decades. This case report suggests progression of the range of melioidosis to include Trinidad and Tobago. A recent study documented the presence of B. pseudomallei in soil samples and high seroprevalence rates among contacts of persons with melioidosis in Puerto Rico (4). If examined, this pattern of regional melioidosis endemicity may also be found on other Caribbean islands.

Increased clinical awareness of and improved surveillance for B. pseudomallei infection may partly explain emergence. Nonetheless, underascertainment probably occurs in rural areas with limited access to advanced diagnostic support and in urban areas when B. pseudomallei infection is not suspected because of lack of travel to classic disease-endemic areas. Because B. pseudomallei is a Biosafety Level 3 agent, when infectious disease specialists consider melioidosis in their differential diagnoses, they should alert the microbiology laboratory to confirm species identification and ensure that staff use proper biosafety measures.

A total of 19 cases of melioidosis acquired in the Caribbean have been reported (Table). Nine of these were travel related, suggesting that melioidoisis may be emerging as a travel health issue. Travelers with known risk factors for melioidosis, such as diabetes mellitus and chronic lung disease, should be informed of their increased infection risk. Physicians should include B. pseudomallei in the differential diagnosis of travelers with pneumonia or sepsis who are returning from the Caribbean, particularly when they have a history of travel during the rainy season, soil-contaminated wounds, or known risk factors for melioidosis.

Top

Related Links

• More Letter Articles