Histopathological Changes and Clinical Responses of Buruli Ulcer Plaque Lesions during Chemotherapy: A Role for Surgical Removal of Necrotic Tissue?

The tropical necrotizing skin disease Buruli ulcer (BU) caused by Mycobacterium ulcerans is associated with extensive tissue destruction and local immunosuppression caused by the macrolide exotoxin mycolactone. Chemotherapy with a combination of rifampicin and streptomycin for 8 weeks is the currently recommended treatment for all types of BU lesions, including both ulcerative and non-ulcerative stages (plaques, nodules and edema). Our histopathological analysis of twelve BU plaque lesions revealed extensive destruction of sub-cutaneous tissue. This frequently led to ulceration during antibiotic treatment. This should not be mistaken as a failure of the antimycobacterial chemotherapy, since we found no evidence for the persistence of active infection foci. Large necrotic areas were found to persist even after completion of antibiotic treatment. These may disturb wound healing and the role of wound debridement should therefore be formally tested in a clinical trial setting

Characteristic histopathological features of tissue surgically excised to support wound healing.

<p>Histological sections were stained either with Haematoxylin-Eosin (HE) (A–C), Ziehl-Neelsen (counterstain methylenblue) (ZN) (L) or with antibodies against cell surface or cytoplasmic markers (counterstain haematoxylin) (D–K). A: Overview over an excised tissue specimen still harbouring large necrotic areas with fat cell ghosts and oedema. B: Overview over an excised tissue specimen presenting with mixed infiltration in the former necrotic region. C: Necrosis and oedema of the dermis of an excised non-ulcerative lesion. D: CD14 (D1) and N-elastase (D2) staining revealing a clear border between infiltration with intact CD14 positive macrophages (D1) and neutrophilic debris inside the necrotic area (D2). Infiltrated tissue areas contained large numbers of CD68 positive macrophages (E) and large numbers of CD3 positive cells (F). These belonged mainly of the CD8 (G) and not of the CD4 (H) subset. Langhans and foreign body giant cells (I) and B-cell cluster (J) were present in the majority of the samples. Accumulations of N-elastase positive cells (K) were occasionally found. AFB were rare, had a beaded appearance and intracellular location (L).</p

Characteristic histopathological features of tissue samples taken before start of antibiotic treatment.

<p>Histological sections were stained either with Haematoxylin-Eosin (HE) (A, C–E), Ziehl-Neelsen (counterstain methylenblue) (ZN) (B) or with antibodies against cell surface or cytoplasmic markers (counterstain haematoxylin) (F–H). A: Punch biopsy with large necrotic areas, fat cell ghosts and oedema but relatively intact epidermis and dermis. B: a band of extracellular AFBs is present in a deep layer of the necrotic subcutis. C: epidermis and dermis. D: necrotic region with fat cell ghosts. E: few infiltrating cells around a blood vessel. F: N-elastase staining revealed the presence of neutrophilic debris inside the necrotic regions. G: few intact neutrophils and H: CD68 positive infiltrating macrophages were found.</p

Characteristics of the 12 Buruli ulcer plaque patients.

<p>*the mean duration from start of treatment to ulceration was 30 days (11–53 days) for those five patients for which beginning of ulceration could be exactly recorded.</p

Characteristic histopathological features of tissue samples taken 26–34 days after start of antibiotic treatment.

<p>Histological sections were stained either with Haematoxylin-Eosin (HE) (A, B, H), Ziehl-Neelsen (counterstain methylenblue) (ZN) (C) or with antibodies against cell surface or cytoplasmic markers (counterstain haematoxylin) (D–G, I). A: Punch biopsy with large necrotic areas, fat cell ghosts and oedema but relatively intact epidermis and dermis. B: Higher magnification of necrotic tissue with large numbers of fat cell ghosts. C: Small numbers of intra and extracellular beaded AFB. D: N-elastase positive intact neutrophils were rare. E: More intact CD68 positive macrophages and F: CD3 positive T-cells were observed in the dermal tissue. Additionally, small CD20 positive B-cell cluster (G), few granulomas (H) and langhans giant cells (I) were found in only few of the samples.</p

Severe Multifocal Form of Buruli Ulcer after Streptomycin and Rifampin Treatment: Comments on Possible Dissemination Mechanisms

Buruli ulcer (BU), a disease caused by Mycobacterium ulcerans, leads to the destruction of skin and sometimes bone. Here, we report a case of severe multifocal BU with osteomyelitis in a 6-year-old human immunodeficiency virus (HIV)-negative boy. Such disseminated forms are poorly documented and generally occur in patients with HIV co-infection. The advent of antibiotic treatment with streptomycin (S) and rifampin (R) raised hope that these multifocal BU cases could be reduced. The present case raises two relevant points about multifocal BU: the mechanism of dissemination that leads to the development of multiple foci and the difficulties of treatment of multifocal forms of BU. Biochemical (hypoproteinemia), hematological (anemia), clinical (traditional treatment), and genetic factors are discussed as possible risk factors for dissemination