Presence of acid-fast bacteria in wild and cultured silver mullets (Mugil curema VAL., 1836) from Margarita Island Venezuela

Twenty specimens of silver mullet (Mugil curema Val., 1836) from the La Res tinga coastal lagoon complex in Margarita Island, Venezuela, and 20 specime ns of the same species cultured in sea water ponds at Boca de Rio, in the s ame locality, were examined for the presence of acid-fast bacteria. Samples from the faeces and intestinal contents, kidney, fiver and spleen were tre ated by Petroff method. Smears were taken from the centrifuged sediment and stained by a modified Ziehl-Neelsen technique, and the sediment was cultur ed on tubes of Lowenstein-Jensen medium. Acid-fast bacteria were detected i n smears from five (25%) of the wild mullets, and five (25%) of the culture d mullets. Three strains of mycobacteria were isolated from the wild fish a nd one strain from the cultured fish. These four strains were identified as Mycobacterium chelonei subsp. abscessus, M. chelonei subsp. chelonei, M. f ortuitum and M. scrofulaceum. The strains were isolated from the faeces and spleens of the infected fish. The presence of mycobacteria as the aetiolog ical agents of tuberculosis in grey mullets and other fish species is discu ssed in relation to the importance of these organisms as potential human pa thogens. It is recommended that populations of mullets used as a source of seed or spawning stock for aquaculture operations be carefully monitored to detect the possible occurrence of latent and/or patent acid-fast bacterial infections.