Assessment of Microbiological Quality of Fresh Vegetables and Oysters Produced in Buenos Aires Province, Argentina

Abstract

Fresh vegetables and shellfish are prone to microbial contamination through irrigation or breeding with sewage-pollutedwaters, as well as by infected food handlers. In this work, we studied the presence of human and bovine polyomavirusesand human norovirus in fresh lettuces, strawberries and oysters produced in Buenos Aires province, Argentina. In oysters,we also investigated F-specific RNA bacteriophages, indicator Escherichia coli (E. coli) and pathogen bacteria of concern(Salmonella spp., Vibrio spp.). Within vegetables, we found viral contamination of human origin given the presence ofhuman-associated polyomaviruses -MCPyV, HPyV6, JCPyV, and SV40- in lettuce and strawberry samples (16 and 10%,respectively), probably coming from irrigation waters and food handling. Among oysters, human (MCPyV, 4.2%) and bovine(BPyV1, 8.4%) polyomaviruses were detected even with low counts of E. coli. Bacteriophages (n = 3) and Salmonella spp.(n = 1) were also found, while Vibrio spp. was not detected. These results may indicate that the contamination in oysters comesfrom human and animal excreta, probably present in breeding waters. Norovirus was not detected in any food sample. Toour knowledge, this is the first description of SV40 in lettuces and MCPyV and BPyV1 in oysters. The detection of differentviral contaminants encourages further studies to evaluate the need for including viral indicators in microbiological standards.The identification of possible sources and routes of contamination using viral markers during routine microbiologicalcontrols, such as the polyomaviruses used in this work, would be useful to focus attention on the most hazardous stages ofthe food production chain.