Bottled Water May Harbor Antibiotic Resistance Genes

Bottled Water Under the Microscope: A Hidden Reservoir of Resistance Genes?

For decades, bottled natural mineral water has been considered microbiologically safe for human consumption. But new research reveals a potential hidden risk: the presence of antibiotic resistance genes (ARGs) and virulence-related genes (VRGs) in bottled water samples.

Using next-generation sequencing (NGS), scientists analyzed microbial communities in four popular bottled water brands and discovered genes that may contribute to antimicrobial resistance (AMR) and potential virulence in environmental bacteria.

Key Findings: What the Study Revealed

1. Detection of Antibiotic Resistance Genes

The study identified several ARGs, including:

TEM-116 (beta-lactam resistance)
APH(3’’)-Ib and APH(6)-Id (aminoglycoside resistance)
dfrB3 (trimethoprim resistance)

Some of these genes confer resistance to clinically important antibiotics, raising questions about how such genes enter water ecosystems.

2. Virulence-Related Genes Identified

A total of 14 virulence genes were detected, such as:

acpXL: present in all samples, linked to bacterial membrane function
esxN: involved in secretion systems often linked to pathogenicity

3. Diverse Microbial Communities

The microbial diversity differed across water sources:

Betaproteobacteria dominated three brands
Bacteroidota dominated the fourth brand, sourced from volcanic aquifers

Such diversity suggests that geological factors and bottling environments influence microbial composition.

Why It Matters: Public Health Implications

Although no immediate threat to human health was identified, the presence of ARGs and VRGs in bottled water raises concerns:

Horizontal gene transfer could enable these genes to spread to pathogenic bacteria.
Bottled water labeling laws often focus on detecting only a limited set of pathogens, overlooking potential genetic risk factors.

The study emphasizes the need for broader surveillance and advanced molecular screening to safeguard water safety standards.

Future Directions: Rethinking “Microbiologically Pure”

Researchers recommend:

Routine genomic testing for ARGs and VRGs in water safety regulations
Advanced purification technologies targeting genetic material, not just microbial cells
Global surveillance efforts to track emerging AMR hotspots in water systems

Conclusion: A Wake-Up Call for Water Safety Standards

While bottled natural mineral water remains microbiologically safe by current standards, this study highlights the urgent need to include genetic risk factors in water quality assessments.

The rise of antimicrobial resistance demands holistic monitoring approaches, integrating genomics, ecology, and public health to ensure the safety of one of our most essential resources—drinking water.

Reference

Radocchia, G., Brunetti, F., Marazzato, M., Scribano, D., Nencioni, L., Palamara, A. T., Schippa, S., & Pantanella, F. (2025). Antibiotic-resistance and virulence-related genes in commercially bottled natural mineral waters. BMC Microbiology, 25(1), 583. https://doi.org/10.1186/s12866-025-04336-2