Detection of 16S rRNA gene for rapid identification of bacterial pathogens causing peritonitis in patients on continuous ambulatory peritoneal dialysis.

PURPOSE: Peritonitis is the most important complication with high rate of morbidity and mortality in patients on continuous ambulatory peritoneal dialysis (CAPD) despite the success and advances. Rapid and accurate identification of pathogens causing peritonitis in a CAPD patient is essential for early targeted treatment. The aim of the study was to evaluate the role of 16S rRNA gene and ITS region PCR and sequencing in detecting bacterial and fungal pathogens from the dialysate of patients undergoing CAPD. METHODS: Fifty eight peritoneal dialysate from suspected cases of peritonitis on CAPD were subjected to conventional culture as per the ISPD guidelines and automated culture system. A conventional PCR was performed to detect the 16S rRNA gene and ITS region. Sequencing and analysis were performed to identify the etiological agent from the remaining dialysate. RESULTS: Among the 58 dialysate fluid, the etiological agents were identified in 8(14%) samples by conventional culture, 28(48%) by automated culture and 47(81%) by 16S rRNA sequencing and analysis. In 8 samples there was discordance in the results of the culture and 16S rRNA PCR. BLAST search of nine sequences obtained from 16S rRNA PCR revealed that these sequences matched best with uncultured bacterial clones. In eleven samples the sequence failed. CONCLUSION: The molecular tool 16S rRNA gene and ITS region PCR and sequencing cannot be used as a standalone test as it lacks sensitivity to identify some bacterial species due to high genetic similarity in some cases and inadequate database in GenBank. However, it could be used as a supplementary test to the culture method especially in the diagnosis of culture negative peritonitis.

Subcutaneous phaeohyphomycosis in kidney transplant recipients: A series of seven cases.

BACKGROUND: Superficial and deep fungal infections are more frequent in transplant recipients primarily because of the failure of cell-mediated immunity and lesser amount of antigen-presenting Langerhans cells in their epidermis. Here, we report seven cases of post-renal transplant subcutaneous phaeohyphomycosis, all of which manifested within 1 year after transplantation and were unresponsive to prolonged courses of itraconazole. This is the first case series, to our knowledge, of phaeohyphomycosis in transplant recipients in India. METHOD: We performed a retrospective review of cases of phaeohyphomycosis among kidney transplant recipients for type of transplant, immunosuppression, histopathology, and treatment, with prospective follow-up of healed lesion. RESULTS: An overall incidence of 8.3% was noted, with a median duration of approximately 6 months post transplant to the onset of skin lesion. None of the lesions responded to itraconazole alone and 6/7 lesions were surgically excised. Histopathology showed various lesions and culture could isolate Neocytalidium and Exophiala jeanselmi in two cases. CONCLUSION: Dematiaceous fungi are increasingly implicated in cutaneous lesions in transplant recipients. Histopathology and surgical excision are the appropriate tools for diagnosis and treatment, respectively.