Molecular characterization of Cryptosporidium spp. obtained from fecal samples of immunosuppressed patients from Brazil

Background: Cryptosporidium spp. are pathogenic protozoans that play an important role in developing diseases in the elderly, children, and immunosuppressed individuals. Methods: The objective of this study was to detect and genetically characterize Cryptosporidium spp. in kidney transplanted patients (n = 97 samples; group 1) and immunosuppressed individuals from an outpatient clinic suspected of having Cryptosporidium infection (n = 53 samples; group 2). All fecal samples were analyzed by parasitological stool examination, immunochromatographic test, and real-time polymerase chain reaction (real-time PCR). Cryptosporidium-positive samples were tested using nested PCR for the gp60 gene, followed by sequencing for subtype determination. Results: Parasitological examination was negative in all Group 1, and positive in four Group 2 samples. Real-time PCR revealed Cryptosporidium in 13 samples: four in Group 1 (three C. hominis and one C. parvum) and nine in Group 2 (seven C. hominis, one C. parvum, and one mixed C. hominis/C. parvum). The immunochromatographic test was reactive in 11 samples (four in Group 1 and seven in Group 2). All 11 C. hominis isolates were identified as subtype IbA10G2 and one C. parvum as subtype IIbA15G2R1. All C. hominis belonged to subtype IbA10G2, which is recognized as the most prevalent and pathogenic subtype. Conclusions: This study showed, for the first time, that the presence of Cryptosporidium subtypes is considered more virulent in Brazilian transplanted kidney patients.