Comparison by electron microscopy of intracellular events and survival of Burkholderia pseudomallei in monocytes from normal subjects and patients with melioidosis
Puthucheary, S.D.; Nathan, S.A.
Singapore Medical Journal 47(8): 697-703
2006
ISSN/ISBN: 0037-5675 PMID: 16865211 Document Number: 597269
Introduction: Burkholderid pseudomattei (B. pseudomailei) has been shown to persist intracellularly in patients with melioidosis, until reactivated by decreasing immunocompetence. We have previously demonstrated by transmission electron microscopy, the internallsation of B. -pseudomallei, by human macrophages and the occurrence of phagosome-lysosorn e fusion.Methods: Phagocytosis and electron microscopy were used to compare the rate of, phagosome-lysosome fusion and the intracellular survival of B. pseudomallei using monocytes obtained from five patients with melioidosis and five normal healthy adults.Results: Ingested bacilli were seen in various stages of degradation, with a few remaining viable within phagolysosomes, and the proliferation of these viable bacteria was observed. Phagocytosis of B. pseudomallei by normal macrophages was two-fold higher than uptake by the melioiclosis macrophages (p-value is less than 0.001). Three times more phagolysosomes were present in the normal macrophages, indicating that fusion occurred slowly and inefficiently in the melioiclosis macrophages (p-value is less than 0.00 1), resulting in higher number of organisms -within the melloidosis macrophages (p-value is less than 0.001). Both variables were inversely related to each other.Conclusion: Our observations suggest that phagolysosome fusion occurred slowly and inefficiently in monocytes of patients with melloidosis, leading to an increased number of intracellular organisms compared to monocytes obtained from healthy donors.