Free-floating extracellular DNA (exDNA) in different wastewaters: Status quo on exDNA-associated antimicrobial resistance genes

Non-Canonical Aspects of Antibiotics and Antibiotic Resistance

“…However, both transformation and transduction may easily rival conjugation as a means for AR gene spread. With the millions of copies per milliliter of extracellular DNA encoding carbapenemases being dumped into wastewater [ 213 ]; the fact that fragmented (≥20 bp) and damaged DNA can be acquired by transformation [ 214 ]; that transformation can occur in unexpected places, such as the phylloplane of edible vegetables [ 215 ]; and AR genes being routinely found in phages (even towards the “last resort” antibiotic colistin [ 216 ])—from the fecal “phageome” of healthy humans [ 217 ], food samples [ 218 ] (up to the point that the liver of farm chickens can be considered as a reservoir of AR genes [ 219 ]). Furthermore, genomic islands shared by distantly related bacteria were likely mobilized between them by phages [ 220 ].…”

“… Biofilms exposed to even low-concentration antibiotics in aquatic environments, such as water bodies and WWTPs, serve as hotspots for all sorts of mutations and HGT events, becoming reservoirs of AR bacteria and genes [ 308 ]. Between 860 and 14,500 tons of extracellular DNA are discharged into water bodies per year, some containing around 10 7 copies per milliliter of genes such as the carbapenemase gene bla NDM-1 [ 213 ]. The risk of such AR genes being acquired by transformation-competent bacteria, even if small, is inevitable.…”

“…Between 860 and 14,500 tons of extracellular DNA are discharged into water bodies per year, some containing around 10 7 copies per milliliter of genes such as the carbapenemase gene bla NDM-1 [ 213 ]. The risk of such AR genes being acquired by transformation-competent bacteria, even if small, is inevitable.…”