Researchers at the University of Leon in Spain have discovered that sub-lethal doses of some biocides in common use in the food industry could both enhance the ability of bacteria to form biofilms and increase their resistance to certain antibiotics.
The team investigated the effect of increasing sub-inhibitory concentrations of trisodium phosphate, sodium nitrite and sodium hypochlorite on laboratory strains of E. coli. They found that the exposed cultures showed an increased tolerance to the biocides, particularly sodium nitrite and sodium hypochlorite, and were also more likely to form persistent biofilms on surfaces.
Exposure to biocides was also found to be associated with a reduced susceptibility to a range of antibiotic compounds, notably aminoglycosides, cephalosporins and quinolones. Sodium nitrite caused the greatest effect with resistance to 14 out of 29 antibiotics increasing. The researchers conclude that the use of biocides at sub-inhibitory levels could be a risk to public health.
The results of the study will be published in the journal Applied and Environmental Microbiology next month, but a draft copy of the manuscript can be found here.