Assessing the Occurrence of Salmonella spp. in the Peel and in the Pulps of Avocado (Persea americana) and Custard Apple (Annona squamosa)

Introduction: In recent years an increase in occurrence of cases and outbreaks of foodborne illness associated with the consumption of fruit have been reported. Among the pathogens that can contaminate tropical fruits, Salmonella has been the pathogen most frequently associated with foodborne disease. Avocado and custard apple are exotic and/or tropical fruits produced in Brazil, whose consumption and exports have increased in recent years. This increase has been related to due to their exotic flavors, variety of nutrients, antioxidants compounds and consumers’ search for healthier foods. Despite this, there are no data on the microbial ecology of these fruits regarding pathogenic bacteria such as Salmonella. This fact is of great concern, since it is known that the low acid fruits constitute optimal substrates for the multiplication of microorganisms, especially pathogens. 

Purpose: To assess the incidence of Salmonella spp. in avocado and custard apple marketed/produced in Brazil; and characterize phenotypically and genotypically the Salmonella strains isolated from these fruits.

Methods: A total of 400 samples of fruits (n = 200 for each fruit), acquired in sales centers (supermarkets and/ or production centers) located in the city of Campinas, SP, Brazil, were analyzed for the presence of Salmonella according to ISO 6579:2002. Both the peel and pulp of each fruit (avocado and custard apple) were analyzed separately. The results further characterized by serotyping and pulsed field gel electrophoresis (PFGE).

Results: Of the 400 samples analyzed, 3 samples of custard apple acquired in the same local were positive for Salmonella. The strains were isolated from the pulp of the fruits and identified as SalmonellaTyphimurium. The three isolates presented 100% similarity, according to PFGE patterns.

Significance: The results showed that tropical fruits such as custard apple can harbor pathogens in their inner tissues, offering risk to public health.