Antibiotic-Resistant Bacteria Found in Spinach and Soil After Zinc Treatment

Jenn Hoskins
24th August, 2024

Antibiotic-Resistant Bacteria Found in Spinach and Soil After Zinc Treatment

Image Source: Natural Science News, 2024

Key Findings

  • Researchers from the University of Galway and Teagasc Food Research Centre studied antimicrobial-resistant bacteria in soils and spinach with and without zinc amendment
  • They found 20 antimicrobial-resistant Enterobacterales in soil and spinach, with Serratia fonticola being the most common species
  • Zinc amendment did not affect the presence of antimicrobial-resistant Enterobacterales in the samples
Antimicrobial resistance (AMR) is a growing concern in food production environments, where bacteria can develop resistance to antibiotics, making infections harder to treat. The University of Galway, Ireland, and Teagasc Food Research Centre, Dublin, Ireland, conducted a study to examine the presence and characteristics of antimicrobial-resistant Enterobacterales in soils and spinach grown in soils with and without zinc amendment[1]. The study involved collecting 160 samples (92 soil and 68 spinach) from two locations. Some plots were amended with zinc, a heavy metal known to influence bacterial physiology and resistance. Samples were cultured on selective agars to detect extended-spectrum beta-lactamase-producing Enterobacterales (ESBL), carbapenem-resistant Enterobacterales, and ciprofloxacin-resistant Enterobacterales. Additionally, the total Enterobacterales were enumerated, and isolates were identified using MALDI-TOF, a technique for identifying bacteria based on their protein profile. Antimicrobial susceptibility testing followed EUCAST (2021) and CLSI (2020) criteria. Selected isolates underwent whole genome sequencing (WGS) to identify resistance genes. Zinc concentration in soil samples was measured using Inductively Coupled Plasma Atomic Emission Spectrometry. The results showed that 20 antimicrobial-resistant Enterobacterales were isolated from soil (8) and spinach samples (12). Serratia fonticola was the dominant species, followed by Escherichia coli, Citrobacter freundii, Morganella morganii, and Enterobacter cloacae. The WGS confirmed that 14 S. fonticola isolates were ESBL producers harboring the blaFONA gene, which confers resistance to beta-lactam antibiotics. Additionally, genes encoding for zinc resistance and multidrug efflux pumps, which can target both antimicrobials and heavy metals, were identified. Surprisingly, the presence of zinc did not influence the AMR Enterobacterales in soil or spinach samples. This study builds on previous research highlighting the interplay between heavy metals and AMR. For instance, a review of 73 studies revealed that heavy metals like zinc and copper can impact the abundance and dissemination of antimicrobial resistance genes (ARGs) in the primary food production environment[2]. This review emphasized the role of mobile genetic elements (MGEs) in spreading ARGs and metal resistance genes (MRGs), suggesting a complex relationship between heavy metals and AMR. Moreover, zinc's role in bacterial physiology and pathogenesis has been previously documented. Zinc is essential for the proper functioning of various bacterial proteins and enzymes. For example, in Salmonella enterica, zinc deficiency led to a significant reduction in motility and biofilm formation, which are critical for bacterial survival and virulence[3]. This underscores zinc's multifaceted role in bacterial behavior and resistance mechanisms. The findings from the University of Galway and Teagasc Food Research Centre suggest that zinc amendment in soil does not necessarily influence the presence of AMR Enterobacterales in the environment. This contrasts with earlier studies that indicated heavy metals could select for resistant bacteria[2]. However, the study also identified genes for zinc resistance and multidrug efflux pumps, highlighting the complex genetic landscape of resistance. In conclusion, while heavy metals like zinc play a crucial role in bacterial physiology and can influence AMR, their impact may vary depending on the environmental context. This study provides valuable insights into the presence and characteristics of AMR in food production environments, emphasizing the need for continued research to fully understand the intricate relationships between heavy metals and antimicrobial resistance.

AgricultureBiotechPlant Science

References

Main Study

1) Characterization of antimicrobial resistant Enterobacterales isolated from spinach and soil following zinc amendment.

Published 21st August, 2024

https://doi.org/10.1016/j.envpol.2024.124774

Related Studies

2) Evaluating the impact of heavy metals on antimicrobial resistance in the primary food production environment: A scoping review.

https://doi.org/10.1016/j.envpol.2023.121035

3) Zinc is required to ensure the expression of flagella and the ability to form biofilms in Salmonella enterica sv Typhimurium.

Journal: Metallomics : integrated biometal science, Issue: Vol 8, Issue 10, Oct 2016


Related Articles

An unhandled error has occurred. Reload 🗙