Melioidosis was confirmed for the first time in New Caledonia in February 1999 in a 46-year-old male nurse who worked at the health center of Ouegoa, a village in the Northern Province. He was admitted to the hospital with fever, acute renal insufficiency, pneumonia, and septic shock. Blood culture grew an oxidase-positive, gram-negative rod, which was initially identified as a Pseudomonas sp. by the local laboratory but later confirmed as B. pseudomallei by the Pasteur Institute when the patient was transferred to the hospital in the capital city, Noumea. He had been treated for tuberculosis 20 years earlier. He required intubation and ventilation, and treatment was begun with a combination of ceftazidime and amikacin. Ten days after admission, when B. pseudomallei infection was confirmed, treatment was changed to the combination of imipenem and trimethoprim/sulfamethoxazole. Numerous cutaneous abscesses cultured B. pseudomallei, and he slowly recovered.
The second case came from the same location of Ouegoa but not from the same tribe. The patient was a 43-year-old man with diabetes mellitus and chronic renal failure who required a kidney transplant in 2001. He was taking the immunosuppressant medication tacrolimus when "B. gladioli" septicemia was diagnosed in April 2002. Two months later, he was admitted to the hospital with pneumonia, and blood cultures grew B. pseudomallei. He made a full recovery after therapy with a combination of ceftazidime and trimethoprim/sulfamethoxazole.
In July 2003, a 58-year-old man, living in Poum,  50 km from Ouegoa, was admitted with fever, pneumonia, and renal impairment. This man had tuberculosis in 1993 and was a smoker and alcoholic. Treatment was with amoxicillin/clavulanate for 24 hours followed by a combination of cefotaxime, ofloxacin, and metronidazole for 48 hours. He was transferred to Noumea with severe hypoxemia from bilateral pneumonia and hepatocellular insufficiency. A gram-negative bacillus was isolated from bronchial secretions. Therapy was changed to a combination of ceftazidime and ciprofloxacin, and he slowly improved. The organism was identified as B. pseudomallei 7 days after the patient's transfer to Noumea. A lung lobectomy was performed after 2 months for persisting pulmonary infection, and B. pseudomallei was cultured from the surgical specimen. The patient continued to receive trimethoprim/sulfamethoxazole on a long-term basis.
In June 2004, a 67-year-old woman with a history of diabetes mellitus came to the hospital with abscesses on her thigh, from which B. pseudomallei was cultured. She was otherwise healthy and recovered fully after receiving therapy for melioidosis. She lives in Poindimie, about 200 km southeast of Ouegoa.
The bacterium, also called Whitmore bacillus, is an oxidase-positive, gram-negative rod. It is commonly misidentified, sometimes as various species of the Pseudomonas genus. The bacterium grows aerobically on most agar media and usually produces clearly visible colonies within 24 hours at 37 C. In our cases, B. pseudomallei was identified with API 20NE and API 32GN (API system SA, Lyon, France). Two of the isolates were sent to the Centre d'Identification Moleculaire des Bacteries of Pasteur Institute in Paris, where the identity was confirmed by amplifying and sequencing the 16S rRNA gene. These strains were also defined by multilocus sequence typing (MLST) at Imperial College, London, and compared with isolates from Australia and Thailand. Both strains were new sequence types. When a minimum evolution analysis was performed on the concatenated sequences of the 2 strains and compared with Australian and Thai strains on the MLST website (http://bpseudomallei.mlst.net/), the New Caledonian strains clustered well within groups of Australian sequence types (Figure). Furthermore, 1 of the strains was a single-locus variant (i.e., 6 of 7 alleles identical) of a strain from the east coast of Australia. This comparison suggests that New Caledonian B. pseudomallei strains are linked to Australian strains. New Caledonia is a fragment of the ancient continent of Gondwana and subsequently separated from Australia and New Zealand. The diverse but distinct phylogeny of strains of B. pseudomallei in Southeast Asia and Australia may reflect geographic isolation over long periods.