Co-Selection of Heavy Metal and Antibiotic Resistance in Soil Bacteria from Agricultural Soils in New Zealand

Abstract

Accumulation of trace elements (including heavy metals) in soil from usage of superphosphate fertilisers induces resistance of soil bacteria to trace elements of environmental concern (TEoEC) and may co-select for resistance to antibiotics (Ab). This study aimed to investigate selection of co-resistance of soil bacteria to Cd, Zn and Hg, and Ab in soils with varied management histories. Genetic diversity of these bacteria and horizontal transfer of Cd resistance genes (cadA and czcA) were also investigated. Soils with either pastoral and arable management histories and either high levels of Cd and Zn, or indigenous bush with background levels of these TEoEC from the Waikato region, New Zealand were sampled. Plate culturing with a range of TEoEC and Ab concentrations, Pollution Induced Community Tolerance (PICT) assay, antibiotic sensitivity, terminal restriction fragment length polymorphism (TRFLP) and horizontal gene transfer (HGT) analyses were employed to investigate co-selection of TEoEC and Ab resistance. Higher levels of bacterial resistance to TEoEC and Ab correlated with higher levels of TEoEC in soil. Bacterial community structures were altered in soils with high TEoEC levels. Cd resistance genes were transferred from donor bacterial isolates, to recipients and the transconjugants also had resistance to Zn and/or Hg and a range of Ab.

Heavy Metal and Antibiotic Resistance in Bacteria from a Wastewater Treatment Plant

“…This was reinforced by the bacteria's multiple antibiotic resistance indices, which were>2, suggesting exposure of the isolates to antibiotic contamination (Matyar et al, 2014). Similarly, the bacteria resistance to both heavy metals and antibiotics in the wastewater confirms that resistance factors for heavy metals and antibiotics are coselected in heavy metal-contaminated systems or habitats exposed to anthropogenic pressure (Timoney et al, 1978;Bhattacherjee et al, 1988;Baker-Austin et al, 2006;Heydari et al, 2022).…”

Prevalence of Antibiotics and Cr, Cd, Cu Metals Co-resistant Coliforms in Refuse Dumpsites and Air of Surrounding Buildings in a Nigerian Urban Setting

“…This inference is supported by the results of the correlation analyses. Several reports have indeed indicated that this co-selection phenomenon has often been triggered by the presence of metals [4,[64][65][66][67][68][69]. This is an alarming discovery as the potential spread to residential areas via bioaerosols is indicated by the presence of resistant coliforms in the indoor and outdoor air of nearby homes and shops.…”

Heavy metal co-resistance with antibiotics amongst bacteria isolates from an open dumpsite soil

“…In Europe, the cost is placed at £ 1.4 billion yearly while in developing countries, estimates are hard to come by as health care is largely privately funded [ 9 ]. More complicated is the fact that these ARGs have been shown to co-evolve with heavy metal resistance genes [ 10 , 11 ].…”

“…Antibiotic resistance genes occur naturally in various environments in low abundance. However, studies have shown that their abundance increase in the presence of several pollutants such as heavy metals, crude oil and sewage [ 10 , 11 , 18 ]. Where this happens, these ARG can move from one microorganism to another via horizontal and vertical mechanisms triggering multi-drug resistance and compounding clinical outcomes of infectious diseases.…”

“…Where this happens, these ARG can move from one microorganism to another via horizontal and vertical mechanisms triggering multi-drug resistance and compounding clinical outcomes of infectious diseases. Furthermore, these ecosystems can act as reservoirs for ARG crossing over from environmental into clinical settings [ 11 , 19 ]. There are concerns that ecosystems polluted with metals such as open dumpsites used in the management of solid wastes in developing countries are becoming more common these days [ 20 , 21 ].…”