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Published on: March 3, 2023
Occurrence of multidrug-resistant Enterococcus faecium isolated from environmental samples
L D R Dos Santos1, J P R Furlan1, I F L Gallo1
1Departamento de Análises Clínicas, Toxicológicas e Bromatológicas, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, São Paulo, Brazil.
Abstract:
Enterococcus species are present in the microbiota of humans and animals and have also been described in the environment. Among the species, Enterococcus faecium is one of the main pathogens associated with nosocomial infections worldwide. Enterococcus faecium isolates resistant to different classes of antimicrobials have been increasingly reported, including multidrug-resistant (MDR) isolates in environmental sources, which is worrying. Therefore, this study aimed to characterize E. faecium isolates obtained from soil and water samples regarding antimicrobial resistance and virulence determinants. A total 40 E. faecium isolates were recovered from 171 environmental samples. All isolates were classified as MDR, highlighting the resistance to the fluoroquinolones class, linezolid and vancomycin. Furthermore, high-level aminoglycoside resistance and high-level ciprofloxacin resistance were detected in some isolates. Several clinically relevant antimicrobial resistance genes were found, including vanC1, ermB, ermC, mefAE, tetM, tetL, ant(6')-Ia, ant(4')-Ia, aph(3')-IIIa and aac(6')-Ie-aph(2″)-Ia. Three virulence genes were detected among the MDR E. faecium isolates, such as esp, gelE and ace. The results of this study contribute to a better understanding of MDR E. faecium isolates carrying antimicrobial resistance and virulence genes in environmental sources and report for the first time in the world the presence of vanC1-producing E. faecium isolated from soil.
Insights
Multidrug-resistant Enterococcus faecium, a significant pathogen, was found in environmental soil and water samples. These resistant bacteria carried concerning antimicrobial resistance and virulence genes, including vanC1, which was newly identified in soil isolates.
Area of Science:
- Microbiology
- Environmental Science
- Infectious Diseases
Background:
- Enterococcus species, including the pathogen Enterococcus faecium, are part of human and animal microbiota and found in the environment.
- Multidrug-resistant (MDR) Enterococcus faecium is a growing concern for nosocomial infections worldwide.
- Environmental reservoirs of MDR E. faecium pose a potential public health risk.
Purpose of the Study:
- To characterize antimicrobial resistance and virulence determinants of E. faecium isolates from environmental soil and water samples.
- To investigate the prevalence of specific antimicrobial resistance and virulence genes in environmental E. faecium.
- To identify novel environmental sources of concerning E. faecium strains.
Main Methods:
- Isolation and identification of Enterococcus faecium from 171 environmental samples (soil and water).
- Antimicrobial susceptibility testing, including resistance to fluoroquinolones, linezolid, vancomycin, aminoglycosides, and ciprofloxacin.
- Molecular detection of key antimicrobial resistance genes (e.g., vanC1, ermB, tetM) and virulence genes (e.g., esp, gelE, ace).
Main Results:
- All 40 recovered E. faecium isolates were multidrug-resistant (MDR).
- High resistance rates were observed for fluoroquinolones, linezolid, and vancomycin. High-level aminoglycoside and ciprofloxacin resistance were also detected.
- Clinically relevant resistance genes (vanC1, ermB, tetM, etc.) and virulence genes (esp, gelE, ace) were identified in the isolates. Notably, vanC1-producing E. faecium was identified in soil for the first time globally.
Conclusions:
- Environmental soil and water harbor MDR Enterococcus faecium strains with significant antimicrobial resistance and virulence potential.
- The presence of vanC1-producing E. faecium in soil represents a novel environmental finding with potential implications for public health.
- Continued surveillance of environmental bacteria is crucial for understanding and mitigating the spread of antimicrobial resistance.
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