Impact of point sources on antibiotic resistance genes in the natural environment: a systematic review of the evidence

Abstract

There is a growing concern about the role of the environment in the dissemination of antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARG). In this systematic review, we summarize evidence for increases of ARG in the natural environment associated with potential sources of ARB and ARG such as agricultural facilities and wastewater treatment plants. A total of 5247 citations were identified, including studies that ascertained both ARG and ARB outcomes. All studies were screened for relevance to the question and methodology. This paper summarizes the evidence only for those studies with ARG outcomes (n = 24). Sixteen studies were at high (n = 3) or at unclear (n = 13) risk of bias in the estimation of source effects due to lack of information or failure to control for confounders. Statistical methods were used in nine studies; three studies assessed the effect of multiple sources using modeling approaches, and none reported effect measures. Most studies reported higher ARG concentration downstream/near the source, but heterogeneous findings hindered making any sound conclusions. To quantify increases of ARG in the environment due to specific point sources, there is a need for studies that emphasize analytic or design control of confounding, and that provide effect measure estimates.

Antibiotic Resistance Genes in Freshwater Trout Farms in a Watershed in Chile

“…There is evidence that ARGs can be found in the environment, but quantifying the attribution to specific point sources, such as fish farms, is lacking (Williams‐Nguyen et al, 2016). Given the findings of our previous systematic review (Bueno et al, 2017), which highlighted major limitations in the study design of many environmental AMR studies, this investigation focused on the design of the study and appropriate data analysis methods to inform attribution conclusions (Singer et al, 2006). …”

“…Once in the aquatic environment, gene exchange can occur between bacteria, including environmental bacteria, and ARGs can then be further disseminated through the natural environment (Baquero et al, 2008, Bengtsson‐Palme et al, 2017; Waseem et al, 2017). There is a lack of quantitative studies attributing environmental ARG abundance to specific sources such as fish farms (Williams‐Nguyen et al, 2016; Bueno et al, 2017). To characterize and manage the potential impact of these farms on the development and dissemination of ARGs in the environment, it is necessary to quantify their specific contribution.…”

Systematic Review: Impact of point sources on antibiotic‐resistant bacteria in the natural environment

“…This systematic review was conducted as described previously (Bueno et al., ). Briefly, a systematic review of the literature was conducted following a protocol using the population, exposure, comparator, outcome and study design (PECOS) framework (Williams‐Nguyen, Bueno, et al.…”

“…The review team comprised six people with expertise in antimicrobial resistance, epidemiology, veterinary medicine and systematic review methodology. Three databases (PubMed©, Commonwealth Agricultural Bureaux (CAB Abstracts©) and Scopus©) were searched on 14 October 2014 from inception date using specific search strategies as shown below and as previously reported (Bueno et al., ). The PubMed© controlled‐vocabulary search string was as follows: “drug resistance, microbial”[Mesh] AND (“water pollutants”[Mesh] OR “environment”[MeSH Terms] OR “soil”[MeSH Terms] OR “water”[MeSH Terms] OR “water pollution”[MeSH Terms] OR “air pollution”[MeSH Terms] OR “air pollutants”[MeSH Terms] OR “animals, wild”[MeSH Terms]) AND (“Animals”[MeSH Terms] OR “humans”[MeSH Terms] OR “animal feed”[MeSH Terms] OR “manure”[MeSH Terms] OR “aquaculture”[MeSH Terms] OR “waste water”[MeSH Terms] OR “sewage”[MeSH Terms] OR “hospitals”[MeSH Terms] OR “hospitals, animal”[MeSH Terms] OR “cities”[MeSH Terms]) NOT “therapeutics”[MeSH Terms] NOT “drug discovery”[MeSH Terms] NOT “aids”[All Fields] NOT “hiv”[All Fields] NOT “influenza”[All Fields]. …”

Modelling microbial infection to address global health challenges

“…Although most models of antibiotic resistance have focused on transmission in healthcare settings, the importance of antibiotic resistance in natural, agricultural and urban settings has been increasingly recognized [77][78][79][80][81][82][83] . For example, a metapopulation model of antimicrobial-resistant Clostridium difficile simulated its transmission within and between hospitals, long-term care facilities and the community.…”