The effect of environmental pollutants and food processing on the development of antibiotic resistance

Abstract

Aim. The purpose of this study was to determine how various compounds known to be positive mutagens, contribute to the development of mutations leading to ciprofloxacin resistance in Salmonella enterica subsp. enterica serotype Typhimurium. The molecular mechanism of ciprofloxacin resistance in treated strains was investigated. Methods. A modified version of the incorporation plate test was used for quantitative determination of ciprofloxacin resistant mutants and for assessment of the mutation frequency induced by the positive mutagens in different concentrations. An AS-PCR-RFLP for monitoring of gyrA mutations was applied. Results. Mutation frequency, expressed as number of antibiotic resistant colonies per 10 8 viable cells, was much higher after exposure of bacterial cells to 3-(5-nitro-2-furyl) acrylic acid and 2-nitrofluorene. All isolated cultures retain decreased susceptibility to antibiotic after multiple passages in antibiotic-free medium. 2-nitrofluorene was the best inducer of mutations in gyrA and in regulation genes affecting suppression of synthesis of outer membrane porins. 3-(5-nitro-2-furyl) acrylic acid gives rise to overproduction of efflux pump. Conclusions. The data suggest that antibiotic resistance may not be only a consequence of misuse of antibiotics. A polluted environment as well as food processing could contribute to this unwanted process.

Sewage sludge as a source of triclosan-resistant bacteria

“…Their metabolites are subsequently directed into the municipal wastewaters that fl ow through the sewage system to WWTPs. ATB residues resist the process of degradation in spite of the well-developed process of wastewater treatment (including biological degradation of drugs under anaerobic conditions in sludge towers) and consequently can accumulate in sludge Birošová and Mikulášová, 2014). Studies pointed out the problem of cross-resistance in triclosan-resistant isolates which are also ATB resistant (Birošová et al, 2009;Middleton and Salierno, 2013).…”