Microbial species diversity and antibiotic-resistant Enterobacteriaceae spread on dairy farms

Introduction . Bacterial communities significantly affect the overall productivity of agricultural establishments, as animal health, milk production, and food quality and safety depend on them. Zoonotic bacteria not only have a negative impact on animal health, but also pose a risk to public health, so monitoring of the microbial species diversity on dairy farms to determine the predominant pathogen species and antibiotic resistance profiles is essential. Objective . Study of bacterial species diversity on a dairy farm and monitoring of antibiotic resistance spread in Escherichia coli and Proteus mirabilis isolates in order to enable timely development of measures containing the spread of antibiotic-resistant microorganisms. Materials and methods . To achieve this goal, microorganisms were identified by MALDI-ToF mass spectrometry and antibiotic susceptibility of the isolated cultures was determined using the disc diffusion test. Results . The species diversity of microorganisms isolated from samples of cattle limb wound exudates, feces, and feed was established. Opportunistic and pathogenic Escherichia coli and Proteus mirabilis turned out to be the predominant microorganisms, and their antibiotic resistance profiles were determined. One of the Escherichia coli isolates was found to be multi-resistant; only a combination of amoxicillin and clavulanic acid proved effective in inhibiting the growth of this culture. A large proportion of Proteus mirabilis isolates were resistant to drugs included in the group of fluoroquinolones and sensitive to all other tested antibacterial agents. Conclusion . The factors influencing the microbial species diversity in wound exudate, feces and feed were reported. Determination of Enterobacteriaceae antibiotic resistance profiles will allow for the rotation of antibacterial drugs on the studied livestock farms.