Efficacy of commercial disinfectants against multidrug-resistant bacteria isolated from fresh vegetables

Fresh vegetables are part of a healthy diet owing to their vitamin, mineral, and bioactive compound content; however, these are sources of microorganisms, such as bacteria. The aim of this study was to evaluate the effectiveness of commercial disinfectants on multidrug-resistant bacteria isolated from broccoli, coriander, and spinach. A total of 108 samples were acquired from open and closed markets and shopping centers in Hidalgo, Mexico. A total of 140 bacteria were isolated, and 117 were identified using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, with a total of 74 Gram-negative and 43 Gram-positive bacteria. The bacterial genera most frequently identified were Enterobacter spp. 46/74 (62.16%), Escherichia spp. 19/74 (25.6%), and Staphylococcus spp. 38/43 (88.3%). According to the resistance profile, Gram-negative bacteria showed a higher percentage of resistance to carbenicillin (CB, 98.65%), cephalothin (CF,100%), and ampicillin (AM, 74.32%), with Multi-Antimicrobial Resistance Index (MARI) value of 0.42-0.58. Gram-positive bacteria were resistant to dicloxacillin (DC, 100%), cephalothin (CF, 100%), and ampicillin (AM, 79.06%) with MARI values of 0.75-1. All bacteria isolates (117) were resistant to at least one beta-lactam. The 20 bacteria with the highest resistance index did not show growth at 100 ppm of sodium hypochlorite (concentration recommended by The Regional International Organization for Agricultural Health OIRSA), or 1 ppm of colloidal silver (concentration of use indicated by the supplier); 10 out of 20 challenged bacteria showed growth. Results demonstrate that colloidal silver has reduced efficacy against bacteria with MARI values of 0.42–1. This study demonstrates the importance of identifying and determining the MARI of bacteria isolated from fresh vegetables, as well as verifying the effectiveness of commercial disinfectants on these microorganisms, to ensure food safety.