Adhesion and biocides inactivation of Salmonella on stainless steel and polyethylene

Abstract

The adhesion of Salmonella (S.) strains to stainless steel and polyethylene and their inactivation by biocides used in food industry was investigated. Coupons of stainless steel and polyethylene were immersed in bacterial suspensions of S. Enteritidis, S. Typhimurium, and S. Bredeney during 15, 30, and 60 minutes, and submitted to different concentrations of peracetic acid (PAA), sodium hypochlorite (NaOCl), and quaternary ammonium (Quat) sanitizers. Hydrophobicity of the surfaces was evaluated by contact angle measurements using the sessile drop method and bacterial adhesion was accompanied through bacterial counts and scanning electron microscopy (SEM). Results indicated that the three serovars of Salmonella presented similar adhesion to both materials (5.0 to 6.5 log cfu cm -2 ). The time of exposure did not influence the counts of adhered cells on both surfaces, however SEM revealed larger clusters of S.Enteritidis on both materials, not found for the other serovars. S. Enteritidis presented lower sessile drop angle on polyethylene, indicating hydrophilic properties of this material. The biocides were not able to inactivate all the microorganisms adhered on both surfaces. At least 1 log cfu cm -2 of all serovars tested remained viable after the exposure to different biocide concentrations. In general, higher counts of survivors were observed on polyethylene disinfected with different concentrations of biocides. S. Bredeney e S. Typhimurium were more resistant than S. Enteritidis to PAA, whilst S. Enteritidis presented smaller reduction rates to NaOCl. This last biocide was able to reduce Salmonella counts in approximately 3.0 to 4.0 log cm -2 . When adhered to polyethylene, the serovars S. Typhimurium and S. Enteritidis were more resistant to Quat than S. Bredeney in all concentrations tested, and the numbers of S. Enteritidis remained almost unaltered. On stainless steel disinfected by Quat, S. Bredeney presented higher numbers of survivors.

Exposure of Escherichia coli ATCC 12806 to Sublethal Concentrations of Food-Grade Biocides Influences Its Ability To Form Biofilm, Resistance to Antimicrobials, and Ultrastructure

“…Thus, for TSB with and without compounds, important differences in biofilm formation ability were observed between groups of cells (nonadapted or adapted to TSP, SNI, or SHY), even though no substantial differences in bacterial concentrations were found. These results agree with findings from other authors, who found that the number of attached cells remained constant over the period of incubation (31,32). It has been suggested that after a few hours of incubation, the surface reaches a saturation level where larger numbers of planktonic cells do not entail larger numbers of attached cells (7).…”

Investigation of rpoS and dps Genes in Sodium Hypochlorite Resistance of Salmonella Enteritidis SE86 Isolated from Foodborne Illness Outbreaks in Southern Brazil

“…Malheiros et al (20) also found that Salmonella Enteritidis SE86 had a greater capacity for acid adaptation and thermal resistance than did other Salmonella serovars after exposure to sublethal pH. Tondo et al (36) found that Salmonella Enteritidis SE86 was more resistant to sodium hypochlorite than were other Salmonella serovars; however, in our study resistance of Salmonella Enteritidis SE86 to sodium hypochlorite was similar to that of other Salmonella Enteritidis serovars from other countries. Several researchers have reported very low genetic diversity among Salmonella Enteritidis strains (8,19).…”

Imidazolium salts as antifungal agents: strong antibiofilm activity against multidrug-resistant Candida tropicalis isolates

“…The applied methodology is an adaptation from the literature Tondo et al 2010). Initially, the yeasts were grown in Sabouraud agar for 24 h at 37°C.…”