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Updated: Dec 31, 2025
Isolation and Identification of Waterborne Antibiotic-Resistant Bacteria and Molecular Characterization of their Antibiotic Resistance Genes
Published on: March 3, 2023
Methicillin-resistant Staphylococcus aureus and glycopeptide-resistant enterococci in fecal samples of birds from
Jolanta Kutkowska1, Anna Turska-Szewczuk2, Marek Kucharczyk3
1Department of Genetics and Microbiology, Maria Curie-Skłodowska University, Akademicka 19, 20-033, Lublin, Poland. jolanta.kutkowska@poczta.umcs.lublin.pl.
Background:
The incidence of human infection and colonization with methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE) has increased in the recent years. Environmental sources, including bird droppings, might play an important role as resistance reservoirs.
Results:
Fresh fecal samples were collected from rooks and wild-living birds during the autumn-winter period of 2016/2017, and tested for the presence of bacteria associated with human diseases. Besides bacteria representing the genera Enterococcus, Campylobacter, Escherichia, and Staphylococcus, Enterobacter, Citrobacter, Proteus, Hafnia, and Pseudomonas were also identified. The susceptibility of S. aureus and Enterococcus spp. isolates to methicillin, and vancomycin and teicoplanin, respectively, was analyzed to assess the avian wildlife as a reservoir of MRSA and VRE strains. Twenty-two percent of all S. aureus isolates were methicillin-resistant. These strains were screened by polymerase chain reaction (PCR), using the most widely used primer sets specific for the mecA gene. Twenty percent of all Enterococcus strains were phenotypically vancomycin-resistant. The presence of van resistance genes in these strains was investigated by PCR using vanA and vanB gene-specific primers. A good correlation between mecA gene detection and disc diffusion data was observed, while some discrepancy was noted between the PCR data and the vancomycin/teicoplanin phenotypic resistance pattern. The incidence of strains resistant to methicillin and glycopeptide antibiotics in wild-living birds was twice that in rooks.
Conclusions:
The study suggests that rooks from urban areas and passerine birds from the natural habitat carry antibiotic-resistant Enterococcus spp. and S. aureus strains, probably reflecting the presence of such isolates in the environmental food sources.
Insights
Wild birds, including rooks, carry antibiotic-resistant bacteria like methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE). Bird droppings may serve as environmental reservoirs for these resistant strains, potentially impacting human health.
Area of Science:
- Microbiology
- Environmental Science
- Public Health
Background:
- Rising incidence of human infections caused by methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE).
- Environmental sources, such as bird droppings, are potential reservoirs for antibiotic-resistant bacteria.
Purpose of the Study:
- To investigate avian wildlife as a potential reservoir for MRSA and VRE strains.
- To analyze the prevalence of antibiotic-resistant bacteria in wild-living birds and rooks.
Main Methods:
- Fecal samples from rooks and wild birds were collected and tested for bacterial presence.
- Susceptibility of Staphylococcus aureus and Enterococcus spp. isolates to methicillin, vancomycin, and teicoplanin was analyzed.
- Polymerase chain reaction (PCR) was used to detect mecA, vanA, and vanB genes.
Main Results:
- Twenty-two percent of S. aureus isolates were methicillin-resistant (MRSA).
- Twenty percent of Enterococcus strains were vancomycin-resistant (VRE).
- Antibiotic resistance incidence was twice as high in wild-living birds compared to rooks.
Conclusions:
- Urban rooks and natural habitat passerine birds harbor antibiotic-resistant Enterococcus spp. and S. aureus.
- These findings suggest environmental food sources may harbor antibiotic-resistant isolates.
- Avian wildlife represents a potential reservoir for MRSA and VRE, highlighting environmental surveillance importance.
