Abstract:

A 64-year-old female patient, who is a farmer, was admitted to the hospital for intermittent pain and discomfort in the lower back. The patient was positive for human immunodeficiency virus (HIV) antigen/antibody test. Blastocystis hominis and Giardia lamblia flagellate cysts were found by microscopic examination for the normal saline smear of the fecal sample. The B. hominis cysts were round, oval, and varying in size, with 1 to 2 granular nuclei. Vacuoles were seen in the middle of the iodine-stained parasites with irregular, shiny, crescent-like edges between the vacuoles and the cell membrane. Many small bright spots were seen in the vacuoles. The G. lamblia flagellate cysts are oval in shape, with thick cyst walls. There is a clear gap between the cyst and the parasite. The iodine stains the inner axis of the cyst with 2 to 4 nuclei. The nuclei are located on both sides of the axis. Four purplish red nuclei were evident in the cyst after hematoxylin staining. Nested PCR amplified a 511 bp band from patient fecal DNA, which was 99% identical to the sequence TSA417 of G. lamblia (GenBank accession number AF065606). The ribosomal small subunit gene was amplified by PCR with the specific primers of BhRDr and RD5 of B. hominis, and a band of approximately 600 bp was amplified. The sequencing suggested it was B. hominis ST1 type. Combined with the patient’s epidemiological history of drinking unboiled water, using dry-toilet, breading cats and dogs, etc., the diagnosis of HIV co-infection with B. hominis and G. lamblia was made. After 4 days of treatment with metronidazole (0.2 g/time, 3 times/d), the patient’s symptoms were relieved, and the patient was discharged.

Key words: Blastocystis hominis, Giardia lamblia, Cavity type, Human immunodeficiency virus