MOLECULAR DETECTION OF MYCOBACTERIA IN FILLETS OF NILE TILAPIA (OREOCHROMIS NILOTICUS) FOR HUMAN CONSUMPTION

Abstract

Fifty fillets of Nile tilapia (Oreochromis niloticus) from a fish market in a municipality of Sao Paulo State, Brazil, were analyzed for the prevalence of Mycobacterium spp. After fish collection, the fillets were individually stored and identified in hermetic sterile plastic bags, placed in a thermal box with ice and taken to the laboratory. Muscle samples (20 mg) were obtained and evaluated by standard PCR (Polymerase Chain Reaction). The results showed the presence of Mycobacterium spp. in 100% of the samples (50/50). Sanger sequencing revealed the presence of Mycobacterium gordonae in all samples. Even though M. gordonae is generally viewed as having low pathogenic potential in humans, the literature reports infection in immunosuppressed patients, such as in lungs, soft tissues, cornea, peritoneal cavity and, less frequently, disseminated disease, and bacteremia. Thus, the considerably high number of this organism found in this study in a popular dish like tilapia fillets is of great concern. The changes in feeding habits of the population, such as the increase of consumption of raw fish must draw attention of fish farmers and surveillance committees given that suggestive macroscopic lesions are usually absent in the products. Moreover, it is necessary to assess the potential role of Mycobacterium gordonae as infection agent when ingested through food for both immunosuppressed and immunocompetent persons.