Melioidosis presenting as lymphadenitis: a case report.

BACKGROUND: Melioidosis is an infection caused by the facultative intracellular gram-negative bacterium; Burkholderia pseudomallei. It gives rise to protean clinical manifestations and has a varied prognosis. Although it was rare in Sri Lanka increasing numbers of cases are being reported with high morbidity and mortality. Here we report a case of melioidosis presenting with lymphadenitis which was diagnosed early and treated promptly with a good outcome.

CASE PRESENTATION: A 53-year-old Sinhalese woman with diabetes presented with fever and left sided painful inguinal lymphadenitis for one month. She had undergone incision and drainage of a thigh abscess three months previously and had been treated with a short course of antibiotics. There was no record that abscess material was tested microbiologically.She had neutrophil leukocytosis and elevated inflammatory markers. Initial pus culture revealed a scanty growth of "Pseudomonas sp." and Escherichia coli which were sensitive to ceftazidime and resistant to gentamicin.Due to the history of diabetes, recurrent abscess formation and the suggestive sensitivity pattern of the bacterial isolates, we actively investigated for melioidosis. The bacterial isolate was subsequently identified as B. pseudomallei by polymerase chain reaction and antibodies to melioidin antigen were found to be raised at a titre of 1:160.The patient was treated with high dose intravenous ceftazidime for four weeks followed by eradication therapy with cotrimoxazole and doxycycline. As the patient was intolerant to cotrimoxazole, the antibiotics were changed to a combination of co-amoxyclav and doxycycline and continued for 12 weeks. The patient was well after 6 months without any relapse.

CONCLUSIONS: Melioidosis is an emerging infection in South Asia. It may present with recurrent abscesses. Therefore it is very important to send pus for culture whenever an abscess is drained. However, it should be noted that the reporting laboratory may be unfamiliar with this bacterium and the isolate may be misidentified as Pseudomonas or even E. coli. Melioidosis should be suspected when an isolate with the typical antibiotic sensitivity pattern of ceftazidime sensitivity and gentamicin resistance is cultured, especially in a patient with diabetes. This will expedite diagnosis and prompt treatment leading to an excellent prognosis.