Meta-Analysis on the Global Prevalence of Tetracycline Resistance in Escherichia coli Isolated from Beef Cattle

Abstract

Antimicrobial resistance (AMR) is an emerging global concern, with the widespread use of antimicrobials in One Health contributing significantly to this phenomenon. Among various antimicrobials, tetracyclines are extensively used in the beef cattle industry, potentially contributing to the development of resistance in bacterial populations. This meta-analysis aimed to examine the association between tetracycline use in beef cattle and the development of tetracycline resistance in Escherichia coli isolates. A comprehensive search was conducted using multiple databases to gather relevant observational studies evaluating tetracycline use and tetracycline resistance in Escherichia coli isolates from beef cattle. The rate of tetracycline resistance from each study served as the effect measure and was pooled using a random-effects model, considering possible disparities among studies. The meta-analysis of 14 prospective longitudinal studies resulted in a 0.31 prevalence of tetracycline resistance in Escherichia coli in non-intervention (no exposure), contrasting numerically elevated resistance rates in the intervention (exposed) groups of 0.53 and 0.39 in those receiving tetracyclines via feed or systemically, respectively. Despite the observed numerical differences, no statistically significant differences existed between intervention and non-intervention groups, challenging the conventional belief that antimicrobial use in livestock inherently leads to increased AMR. The findings of this study underscore the need for additional research to fully understand the complex relationship between antimicrobial use and AMR development. A considerable degree of heterogeneity across studies, potentially driven by variations in study design and diverse presentation of results, indicates the intricate and complex nature of AMR development. Further research with standardized methodologies might help elucidate the relationship between tetracycline use and resistance in Escherichia coli isolated from beef cattle.

Keywords: antimicrobial resistance; fecal samples; in-feed administration; indicator organism; treatment.

Figure 1

Article collection and screening steps followed and a few included studies.

Figure 2

Venn diagram depicting the overlap of unique article titles retrieved from three different databases: PubMed, Web of Science, and Scopus, along with the articles that were included in the final selection.

Figure 3

Prevalence of tetracycline resistance in Escherichia coli isolates obtained from beef cattle without antimicrobial intervention. Samples were collected upon the entry of cattle into the feedlots (‘Entry’) and at the time of their exit (‘Control’). NOTE: Some of the studies classified under the ‘Control’ subgroup were part of case-control studies (n = 7) [24,25,26,27,28,29,30], while others originated from cohort observational studies (n = 6) [31,32,33,34,35,36].

Figure 4

Prevalence of tetracycline resistance in Escherichia coli isolates sourced from beef cattle subjected to antimicrobial intervention. The tetracycline was administered sub-therapeutically via either feed (indicated as ‘Feed’; n = 7) [24,25,26,28,29,30,37] or an injection (denoted as ‘Inj’; n = 3) [27,28,34]. To examine the dynamics of tetracycline resistance following an intervention, samples were collected at various time points post-administration.