Pathological and molecular studies on mycobacteriosis of milkfish Chanos chanos in Taiwan.

Abstract

investigated in milkfish Chanos chanos, which had a cumulative mortality of up to 66.7% over the course of 1 yr. Gross reddish- or greyish-white nodules appeared on the peritoneal surface, spleen, kidney, liver and gastrointestinal (GI) tract. Epithelioid granulomas with the formation of Langhan's type giant cells were the prominent histopathological changes. Despite large numbers of acid-fast bacilli in the granulomas, neither caseous necrosis nor dystrophic calcification were observed. Using degenerate primers that targeted the heat shock protein 65 kDa gene of Mycobacterium spp., a 441 bp product was amplified. When compared with published sequences, our products were identical to those of Mycobacterium abscessus Type II (GenBank accession number AY603554). This is the first report of M. abscessus infection in milkfish.