INTRACELLULAR PROTOZOAN INFECTION IN SMALL-INTESTINAL BIOPSIES OF PATIENTS WITH AIDS - LIGHT AND ELECTRON-MICROSCOPIC EVALUATION

Small intestinal biopsies of 21 patients with acquired immunodeficienc y syndrome (AIDS) with light microscopic findings diagnostic or suspic ious for parasite infection were investigated by transmission electron microscopy (TEM). TEM allowed us to identify and specify the genus an d species of involved parasites in 16 out of the 21 cases: 7 Cryptospo ridium parvum, 5 Enterocytozoon bieneusi and 4 Isospora belli. Cryptos poridium was easily identified on light microscopy (LM), and only slig htly influenced by parasite burden in all the 7 cases; TEM confirmed L M diagnosis and made it possible to characterize the parasites as C. p arvum. The identification of Microsporidium on LM in our cases was rel ated to the burden of parasite; its presence was certainty identified in 2 cases and suspected in 3. TEM allowed to identify these parasites as E. bieneusi. Intracytoplasmic coccidia could be detected with cert ainty in semithin sections in all 4 cases, but TEA was always needed t o specify the infectious agent as I. belli. In 5 cases the suspicious of protozoan infection on LM (3 microsporidia, 1 intracytoplasmic cocc idia and 1 Cryptosporidium) was not confirmed by TEM. Our data suggest that TEM is an appropriate diagnostic tool in this field of pathology and necessary in most of the cases.