What is the evidence that point sources of anthropogenic effluent increase antibiotic resistance in the environment? Protocol for a systematic review

Abstract

Herein we describe a protocol for a systematic review of the evidence on whether point sources of anthropogenic effluent are associated with an increase in antibiotic resistance in the adjacent environment. The review question was based on the Population, Exposure, Comparator, Outcome, Study Design (PECOS) framework as follows: Is the prevalence or concentration of antibiotic resistant bacteria or resistance genes (O) in soil, water, air or free-living wildlife (P) higher in close proximity to, or downstream from, known or suspected sources of anthropogenic effluent (E) compared to areas more distant from or upstream from these sources (C)? A comprehensive search strategy was created to capture all relevant, published literature. Criteria for two stages of eligibility screening were developed to exclude publications that were not relevant to the question, and determine if the study used a design that permitted estimation of an association between a source and levels of resistance. A decision matrix was created for assessment of risk of bias to internal validity due to sample selection bias, information bias, and confounding. The goal of this protocol is to provide a method for determining the state of knowledge about the effect of point sources on antibiotic resistance in the environment.

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

“…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. ; Williams‐Nguyen, Sallach, et al. ).…”

“…An exclusion criterion that was not reported in the original protocol (Williams‐Nguyen, Bueno, et al. ; Williams‐Nguyen, Sallach, et al. ) was added and asked: “Does the study use microbial source tracking techniques?”.…”

“…An additional question not reported a priori in the protocol (Williams‐Nguyen, Bueno, et al. ; Williams‐Nguyen, Sallach, et al. ) was added at this screening stage and asked: “Does the study implicitly or explicitly define a point source to which a comparison is made?”.…”

“…A qualitative rubric of low, high and unclear was assigned to each study for the potential risk of bias in the reported effect measure or other outcome variable due to selection bias, information bias and confounding (Williams‐Nguyen, Bueno, et al. ; Williams‐Nguyen, Sallach, et al. ).…”

“…The first step to assess these risks is to quantify the relative contribution of specific point sources on increases in ARB and ARG in the natural environment. Despite an increase in research in this field, the relative impact of specific types of point sources on levels of ARB and ARG in the environment is still unclear and is an area of ongoing scientific investigation (Williams‐Nguyen, Bueno, Sargeant, Nault, & Singer, ; Williams‐Nguyen, Sallach, et al. ; Wooldridge, ; Woolhouse, Ward, van Bunnik, & Farrar, ).…”