Inhibitory Activity of Silver Nanoparticles and Sodium Hypochlorite against Biofilm Produced by Salmonellae Isolated from Poultry Farms

Salmonella typhimurium and Salmonella enteritidis are among the predominant Salmonella serotypes in the Egyptian poultry farms. Salmonella has the ability to build up biofilms on a variety of surfaces. The antibiofilm activities of silver nanoparticles (AgNPs) and sodium hypochlorite (NaOCL) on prevention and controlling of biofilm by Salmonella spp. was estimated. Silver nanoparticles exhibited bactericidal activity against both S. typhimurium and S. enteritidis with MIC value at 15 µg/ml, while, that of NaOCL was 1600 µg/ml. AgNPs (25 ug/ml) could inhibit biofilm formation at percentages of 84.96% and 78.85% against S. typhimurium and S. enteritidis, respectively. A percentage of 87 % biofilm removal by AgNPS after 3 h contact with the built-up biofilm produced by S. typhimurium and S. enteritidis was recorded. NaOCL (2200 µg/ml) exhibited inhibition percentages of biofilm formation at 83.89% and 75.76% against S. typhimurium and S. enteritidis, respectively. While, biofilm removal percentages after 2 h contact between NaOCL (2200 µg/ml) with the formed biofilm by S. typhimurium and S. enteritidis were 87.42% and 89.37%, respectively. It can be concluded that AgNPs and NaOCl were able to promote a significant reduction of biofilm formation by S. typhimurium and S. enteritidis. Also, AgNPs and NaOCl effectively oppress the mature biofilms formed and the antibiofilm efficiency increased with the increase of contact time with the biofilms.