Blastocystis hominis infection in Cuban AIDS patients.

Blastocystis hominis, previously known as a yeast, is being considered a potential pathogenic protozoan by different authors (RR Babb & S Wagener 1989 West J Med 151: 518-519, SMH Qadri et al. 1989 J Clin Microbiol 27: 2407-2409). However, others believe it to be a commensal microorganism (T Sun et al. 1989 Am J Gastroenterol 84: 1543-1547, H Senay & D Mac Pherson 1990 J Infect Dis 162: 987-990). There are many reports that show the possibility of this microorganism to cause gastrointestinal disorders in patients with immunodeficiency diseases (PL Garavelli et al. 1988 Lancet ii: 1364, JM Llibre et al. 1989 Lancet ii: 221, PL Garavelli & M Libanore 1990 Rev Infect Dis 12: 158). We present here the results of a coproparasitological study carried out in Cuban AIDS patients in whom the prevalence of B. hominis infection had never been studied. During the period of September 1994 to January 1995, at least two fecal samples were obtained from 67 adult AIDS patients who were admitted in our hospital due to different diseases; all of them were infected with the human immunodeficiency virus (HIV) and met the Centers for Disease Control (CDC) criteria for AIDS (CDC 1987 MMWR 36: 1-15); the totality of stool samples were examined immediately upon arrival and were processed in the intestinal parasite laboratory at Tropical Medicine Institute “Pedro Kourí” in Havana. Direct wet mount with Lugol’s stain and Ritchie’s concentration technique (LR Ash & TC Orihel 1987 Parasites: a guide to laboratory procedures and identification, ASCP Press, Chicago, 328 pp.) were the selected laboratory procedures. Patients were interviewed according to the same questionnaire and clinical records reviewed by a single observer. Statistical analysis was carried out using proportion test, and the differences were considered to be statistically significant when the P value obtained was less than 0.05. B. hominis was identified in 17 patients (25.4%), only by direct wet mounts with Lugol’s stain. It was found to infect more males (14/17) than females (3/17), in the majority of cases this protozoan was found alone (12/17) and in others it was associated to other intestinal parasites such as Cryptosporidium spp. (2 cases), Giardia lamblia (1 case), Ascaris lumbricoides (2 cases, 1 of them with Enterobius vermicularis) and Entamoeba histolytica (1 case). None of these cases had more than 5 B. hominis microorganisms per field (400X magnification). There were not found statistical significant differences in clinical findings between the group of AIDS patients with B. hominis and the rest of AIDS patients without this intestinal protozoa (P>0.05) (Table).