Isolation and identification by partial sequencing of the 18S ribosomal gene of free-living amoebae from necrotic tissue of Basiliscus plumifrons (Sauria : Iguanidae)

A 3-year-old Basiliscus plumifrons developed a necrotic lesion on the tail resulting from nodules of unknown etiology. Investigation of necrotic tissu e revealed several gram-negative bacteria as well as three different specie s of free-living amoebae. The amoebae were identified by morphological char acters as belonging to the genera Acanthamoeba, Echinamoeba, and Naegleria, respectively. Partial sequencing of the 18S ribosomal gene was performed f or reliable systematic determination. Two of the isolates showed thermotole rance. No isolate was growable in conventional liquid media, but the Acanth amoeba strain readily grew on a human cell line (HEp2). It remains unclear whether the amoebae fed on the coexisting bacteria or on host tissue.