Vigilância e diagnóstico de Salmonella spp. em pisciculturas de peixes redondos nativos (Colossoma macropomum)

Abstract

Brazil has great potential for aquaculture. However, fish can also be a cofactor of foodborne illness (FBD) outbreaks. Salmonellosis is caused by bacteria of the genus Salmonella of interest to public health worldwide due to its morbidity and control difficulties. Salmonella spp. it has great physiological adaptation capable of surviving in soil and water allowing contamination and dissemination between animals and handlers in the fish processing industry. In Brazilian legislation, Salmonella spp. is prohibited and when detected, the entire batch must be discarded and the industry must under go a cleaning process. Characterized by infection by non-typhoidal species of the genus Salmonella, although they do not naturally belong to the aquatic habitat or microbiota of fish, fish farming systems in tanks can offer conditions that provide contamination and concentration of the microbial load of this pathogen, and as a result, persist after stages of processing and industrial improvement, remaining as a microbiological risk when not completely eliminated. In Chapter 1, a systematic review of the microbiological diagnoses of Salmonella spp. in aquaculture between 2000-2020. Among the results presented, the isolation method by culture was the most widespread, supported by more precise techniques such as PCR. The most prevalent Salmonella serovars reported were S. Typhimurium, S. Weltevreden and S. Newport. The information produced characterizes the occurrence of Salmonella spp. in the aquaculture sector bringing an overview of recent years. Future research focusing on control and prevention strategies for Salmonella spp. in fish production are necessary and should be encouraged. In Chapter 2, a study was conducted to verify the occurrence of Salmonella spp. in tambatinga farms (Colossoma macropomum x Piaractus brachypomus) and to draw a susceptibility profile to antimicrobials of isolates from 25 fish farms distributed in eight municipalities belonging to the Baixada Cuiabana region in Mato Grosso, from November 2021 to June 2022. both 184 samples (fish, pond water and soil, feed and faeces) from 25 farms were evaluated for presumptive detection of Salmonella spp. by the microbiological method based on ISO 6579-1, and confirmed after polymerase chain reaction (PCR) targeting the hilA gene and reading after electrophoresis in agarose gel. Of the fish farms 88% (22/25) were diagnosed with Salmonella spp. in at least one of the samples. Some risk factors, such as the free access of animals outside aquaculture production (domestic, poultry, production, wild) to the breeding tanks, were identified and suggest a potential source of contamination. The results demonstrate a high prevalence, being a silent problem, since the fish in the rearing phase harbors a pathogen of interest in public health without manifesting symptoms of apparent infection.