Purpose: The objective of this study was to investigate the microbiological quality of six types of fresh produce obtained from three retail stores located on the Eastern Shore of Maryland.
Methods: A total of 414 samples representing basil, cilantro, lettuce, scallion, spinach and parsley were analyzed for total aerobic bacteria (APC), total coliforms, Escherichia coli, and three pathogenic bacteria (Escherichia coli O157:H7, Listeria monocytogenes, and Salmonella) using standard methods. Presumptive pathogenic isolates were confirmed using BAX Polymerase Chain Reaction.
Results: All samples were positive for APC, 39% positive for total coliforms and only 10% positive for E. coli. Mean log CFU/g for APC in the six produce types ranged from 7.49 to 8.06. The rate of detection of total coliforms and E. coli in the six produce types ranged from 22%-45% and 8.7%-17%, respectively. There was a statistically significant difference with respect to rate of detection of total coliforms across retail stores, but not with respect to abundance of APC or rate of detection of E. coli. Escherichia coli O157:H7 and L. monocytogenes were detected in one spinach sample each, while one parsley and one cilantro sample were positive for Salmonella.
Significance: Although the results of this study provided some indices of sanitary and/or spoilage level, no relationship existed among the APC, total coliforms, E. coli, and the presence of pathogenic bacteria in the samples tested. The results of this study provide a baseline for further studies in the area to evaluate the microbiological quality of produce both sold and produced locally, as well as, to help develop risk management policies in the US.