Intestinal cryptosporidiosis in renal transplant recipients: Prevalence, species detection and comparative evaluation of SSU rRNA and Cryptosporidium oocyst wall protein genes

Context: Cryptosporidiosis is intestinal opportunistic infection commonly occurring in immunocompromised patients including renal transplant (RT) recipients receiving continuous immunosuppressive therapy. Knowledge about species of Cryptosporidium-infecting RT recipients is necessary to know about mode of its transmission (anthroponotic or zoonotic). Various genes such as small subunit rRNA (SSU rRNA) and Cryptosporidium oocyst wall protein (COWP) genes may help in species identification though their sensitivity and specificity are highly variable. Subjects and Methods: A total of 993 and 575 stool samples were examined for Cryptosporidium by microscopy from 358 RT recipients and 200 healthy controls, respectively. Stool samples of RT recipients and healthy controls were subjected to polymerase chain reaction (PCR) followed by restriction fragment length polymorphism (RFLP) for species identification. Results: Cryptosporidium was more commonly detected amongst RT recipients than healthy controls (30/358, 8.4% vs. 0/200, respectively; P < 0.001). The infection was more common amongst patients with diarrhoea than those without (26/162, 16.1% vs. 4/145, 2.8%; P < 0.001). Cryptosporidium parvum was identified in 10/30 (33.3%) and Cryptosporidium hominis in 20/30 (66.7%) samples. SSU gene PCR-RFLP proved to be more sensitive (100%) than COWP (90%); however, specificity of both was same (100%). Conclusions: Cryptosporidiosis is common amongst RT recipients, particularly those with diarrhoea. C. hominis is the most common species in the studied population. SSU rRNA PCR was more sensitive molecular method for the differentiation of Cryptosporidium species.