Ultrastructural morphologic changes in mycobacterial biofilm in different extreme condition.

The aim of this study was to investigate the morphologic and ultrastructural features of biofilms of slow and fast-growing mycobacteria in different stress conditions, presence and absence of oleic acid albumin dextrose catalase (OADC) enrichment and at different temperatures: 30, 37 and 42 °C. Four hundred mycobacterial isolates were taken. The biomass of each biofilm was quantified using a modified microtiter plate assay method. Isolates were divided into those that formed fully established biofilms, moderately attached biofilms and weakly adherent biofilms by comparison with a known biofilm-forming strain. The large quantity of biofilm was produced by Mycobacterium smegmatis at temperature 37 and 42 °C as compared to 30 °C. Mycobacterium fortuitum and M. avium developed large amount of biofilm at 30 °C as compared to 37 and 42 °C. Mycobacterium tuberculosis developed strong biofilm at 37 °C and no biofilm at 30 and 42 °C in Sauton's media. The selected non-tuberculous mycobacteria and H37Rv developed strong biofilm in the presence of OADC enrichment in Sauton's medium. Microscopic examination of biofilms by scanning electron microscopy revealed that poorly adherent biofilm formers failed to colonize the entire surface of the microtiter well. While moderately adherent biofilm formers grew in uniform monolayers but failed to develop a mature three-dimensional structure. SEM analysis of an isolate representative of the group formed fully established biofilms with a textured, multi-layered, three-dimensional structure.

High resolution structural changes of Schwann cell and endothelial cells in peripheral nerves across leprosy spectrum.

A systematic ultrastructure of peripheral nerves across the spectrum of leprosy was studied with an aim to better understanding the pathogenesis of nerve involvement in leprosy using light and electron microscope. The pathogenesis of nerve destruction varies in leprosy considerably along the spectrum. The study has begun to shed new light on some aspects of the infection of Mycobacterium leprae (M. lepare) and phenomenon has opened new avenue of research and possible mechanism of pathogenesis in TT/BT/BL/LL leprosy. In tuberculoid type (TT) and borderline tuberculoid (BT) leprosy, the degenerative changes of Schwann cells (SCs) and presence of perineural and perivascular cuffing by mononuclear cells. The endoneurial blood vessel (EBV) showed thickening of basement membrane with hypertrophy of EC leading to narrowing or complete occlusion of lumen and causing ischemia. However, borderline lepromatous (BL) and lepromatous leprosy (LL) foamy macrophages and vacuolated SC contain numerous small dense materials, irregular in shape and size was prominent and, considered to be degenerated and fragmented M. Leprae. The dense materials were also found in the cytoplasm of vascular EC. It was revealed that besides SC, the EC of EBV frequently harbor M. leprae in LL. The lumen of the EBV was wide open with enlarged nucleus. In the present study, the ultrastructural characteristics suggest that hypersensitivity mechanisms are possibly responsible for nerve damage in TT/BT leprosy. However, the study indicates that the mechanisms of nerve damage in BL/LL are basically different wherein hypersensitivity appears to play a very limited role.