Prevalence and Characterization of Isolated Escherichia coli from Organic and Conventional Produce Commercialized in Bogota, Colombia

Introduction: In Colombia, implementation of ecologic agriculture has increased due to the security and quality offered to the consumer, and friendly relationship with the environment, society and economy. Escherichia coli O157:H7 is considered one of the most important foodborne illness agents related to fresh produce consumption representing a high risk for consumers. Likewise, every day there are more reports of resistant bacteria transmitted by food. 

Purpose: Characterize and estimate the prevalence of E. coli in organic and conventional fresh produce commercialized in Bogota, and determine the antimicrobial resistance profiles. 

Methods: 69 Isolates of E. coli were obtained from samples of organic and conventional produce (tomato, strawberry, spinach and lettuce) using the INVIMA protocol and multiplex PCR for the detection of stx1 and stx2 genes, and E. coli O157:H7. The resistance profile of the isolates was determined according to the CLSI standards and the statistical analysis was performed using Kruskal-Wallis test. 

Results: Thirty-three isolates of E. coli were obtained from samples of conventional lettuce and spinach; 13 were found to be resistant, of which 4 were multiresistant. Resistance to tetracycline (50%), ampicillin (20%), chloramphenicol (15%) and cefoxitin (5%) was found. E. coli O157:H7 or E. coli carrier of stx1 and stx2 genes were not detected and no significant differences were found in the count of E. coli between organic and conventional products (P = 0.07). 

Significance: These results suggest that organic fresh produce traded in Bogota does not represent a significant risk for human health, although antibiotic resistant and multiresistant isolates are circulating in conventional commercial produce.