Disinfection of Clostridioides difficile on spinach with epigallocatechin-based antimicrobial solutions and sodium hypochlorite.

The removal of C. difficile inoculated on fresh spinach leaves washed with antimicrobial solutions was investigated. In addition, the effect of washing solutions on the total aerobic mesophilic bacteria (TAMB) and Enterobacteriaceae in the fresh spinach was examined. The fresh spinach was washed through immersion in different concentrations (MIC, 2xMIC, and 4xMIC) of the natural disinfectant solution (NDS) consisting of EDTA, borax, and epigallocatechin gallate (EGCG) content developed in our laboratory and green tea extract-acetic acid (GTE-AA) for varying contact times (5 and 15 min). Different concentrations (50, 100, and 200 ppm) of sodium hypochlorite (NaOCl) and tap water as the control group were used to compare the effectiveness of the NDS. In addition, the effects of washing on the color, texture, and total phenol content of the spinach were determined. No statistical difference was observed in the washing of the spinach leaves with NDS prepared at 2xMIC and 4xMIC concentrations, while inhibition of C. difficile ranged between 2.11 and 2.32 logs. The highest inhibition was observed in the application of 50 ppm NaOCl for 15 min with a decrease of 2.88 logs in C. difficile spores. The GTE-AA and NDS decreased the number of TAMB by 2.27-3.08 log and, 3.21-3.66 log, respectively. Washing spinach leaves with natural disinfectant for 5 min caused a decrease of 2.58 logs in Enterobacteriaceae load, while washing with 50 ppm NaOCl for 15 min reduced Enterobacteriaceae load by 4 logs. Tap water was ineffective in reducing any microbial load. No difference was detected in the color parameters of the spinach through all washes. Although all antimicrobial washes made a difference in the texture of the spinach, the greatest loss in firmness was observed in the spinach washed with NaOCl. Washing spinach with epigallocatechin-based wash solutions can remove C. difficile in possible C. difficile contamination, thereby reducing the environmental load of C. difficile. Epigallocatechin-based disinfectants can be an alternative to chlorine-based disinfectants in improving the microbial quality of vegetables.

Carbapenem resistance and biofilm formation status of Enterobacterales isolated from raw milk via molecular versus phenotypic methods.

Antibiotic resistance genes can easily be transferred between bacteria in the biofilm. In the dairy industry, many bacterial species forming biofilms on the surfaces of equipment are widely reported. The experiments reported in this research paper aimed to investigate the carbapenem resistance and biofilm formation properties of Enterobacterales isolates which are spoilage microorganisms obtained from raw milk. In addition, the study determined that whether there was a relationship between the biofilm formation ability or the protein spectra of these isolates. In this study, ninety-two Enterobacterales isolates collected from 173 raw milk samples were investigated. Initially, the isolates were identified as Citrobacter braakii (n = 18), Citrobacter freundii (n = 12), Enterobacter asburiae (n = 1), Enterobacter cloacae (n = 3), Escherichia coli (n = 10), Hafnia alvei (n = 18), Klebsiella oxytoca (n = 1), Serratia fonticola (n = 24), Serratia liquefaciens (n = 4), and Serratia marcescens (n = 1) using MALDI-TOF MS. As a result, carbapenem resistance was determined in 6.5% of the isolates by CIM test, MHT, and the disk diffusion methods, but none of them had blaOXA-48, blaKPC, blaNDM-1, blaOXA23, blaOXA-58, blaOXA-51, blaVIM, and blaIMP genes. This may be due to the effect of other resistance mechanisms such as porin loss or increased flow pump activity. Furthermore, biofilm formation (weak and moderate) was detected in 97.8% of the Enterobacterales isolates. The mass spectra of the moderate biofilm producer isolate of Serratia spp. and the mass spectra of the weak biofilm producers of E.coli presented similarities.