Incidence, Virulence Potential and Genotypic Diversity of Fungi Associated with Ready-to-eat Street-vended Foods in Gaborone, Botswana

Abstract

Fungi have recently come to the fore as important etiologic agents of infectious diseases, especially in
immunocompromised patients. While the role of food as an avenue of spread of foodborne fungal disease
remains unclear, the virulence potential and genetic diversity associated with street food fungi remains to
be determined. Therefore, the present study sought to investigate the occurrence of fungi in various foods
sold by ambulatory and stationary street vendors at three geographical areas of Gaborone (BBS Mall, Train
Station and Bus Rank) from October 2018 to March 2019. From a total of 685 ready-to-eat street foods
cultured, 480 (70.1%) tested positive for fungi. Statistical analyses revealed that the detection of different
fungal species was neither influenced by the three sampling areas studied in Gaborone nor the six food
commodities analysed (p = 0.001). Out of the 28 strains pooled thereafter, virulence studies by activities
of protease and lipase as well as biofilm formation suggested virulence potential of various fungi such as
Candida albicans and Aspergillus fumigatus. Assessment of genetic diversity of the pooled 28 isolates
detected some genetic differentiation of the fungi studied herein especially Candida albicans, Aspergillus
fumigatus, Rhodotorula glutinis and Aspergillus niger. The unprecedented levels of incidence of fungi in
food, virulence potential and high genetic diversity warrant further investigations on source tracking of
food-borne fungi and evaluation of the reasons of high genetic diversity to protect the vulnerable population
consuming these ready-to-eat foods.