Microbial Diversity and Antimicrobial Resistance Profile in Microbiota From Soils of Conventional and Organic Farming Systems

Soil is one of the biggest reservoirs of microbial diversity, yet the processes that define the community dynamics are not fully understood. Apart from soil management being vital for agricultural purposes, it is also considered a favorable environment for the evolution and development of antimicrobial resistance, which is due to its high complexity and ongoing competition between the microorganisms. Different approaches to agricultural production might have specific outcomes for soil microbial community composition and antibiotic resistance phenotype. Therefore in this study we aimed to compare the soil microbiota and its resistome in conventional and organic farming systems that are continually influenced by the different treatment (inorganic fertilizers and pesticides vs. organic manure and no chemical pest management). The comparison of the soil microbial communities revealed no major differences among the main phyla of bacteria between the two farming styles with similar soil structure and pH. Only small differences between the lower taxa could be observed indicating that the soil community is stable, with minor shifts in composition being able to handle the different styles of treatment and fertilization. It is still unclear what level of intensity can change microbial composition but current conventional farming in Central Europe demonstrates acceptable level of intensity for soil bacterial communities. When the resistome of the soils was assessed by screening the total soil DNA for clinically relevant and soil-derived antibiotic resistance genes, a low variety of resistance determinants was detected (resistance to β-lactams, aminoglycosides, tetracycline, erythromycin, and rifampicin) with no clear preference for the soil farming type. The same soil samples were also used to isolate antibiotic resistant cultivable bacteria, which were predominated by highly resistant isolates of Pseudomonas, Stenotrophomonas, Sphingobacterium and Chryseobacterium genera. The resistance of these isolates was largely dependent on the efflux mechanisms, the soil Pseudomonas spp. relying mostly on RND, while Stenotrophomonas spp. and Chryseobacterium spp. on RND and ABC transporters

Microbial and antimicrobial resistance profiles of microbiota in common carps (Cyprinus carpio) from aquacultured and wild fish population

In this study we analyzed differences in microbial composition and antimicrobial resistance profiles in common carp living in two different environments: fish ponds, where carp have been kept under the same growing conditions over the last 50 years, and from the wild. The results demonstrated that wild fish carry a great variety of bacterial species (448 species with a prevalence of at least 0.01% from the total number of reads). Aquacultured individuals harbored 2.56 times fewer species in their gut. Significant microbial differences were observed in all taxonomic ranks, including bacterial classes and phyla. Besides bacterial variety, it was determined that aquacultured fish harbored more bacteria that are considered pathogens or opportunistic pathogens, such as Moraxellaceae, Flavobacteriaceae, and Staphylococcaceae. The frequency of antimicrobial resistance in bacterial indicators was more common in aquacultured fish than in wild fish, therefore fish farming may be a potential source of environmental contamination with antimicrobial resistant bacteria

A Study on the Stability and Antimicrobial Efficacy of a Newly Modeled Teat Dip Solution Containing Chlorhexidine

Despite much focus on mastitis as an endemic disease, clinical and subclinical mastitis remains an important problem for many herds. Reducing the usage of antibiotics for mastitis treatment allows the risks to be minimized related to the development of antimicrobial resistance and the excretion of antibiotics into the environment. The aim of the study was to determine the physico-chemical properties, stability and antimicrobial effect of a newly formulated biocide for post-milking udder hygiene containing a thickener made from hydroxypropyl guar gum, an antiseptic chlorhexidine digluconate and teat skin-friendly components including glycerol, Mentha Arvensis herbal oil and Aesculus hippocastanum extract. Hydroxypropyl guar gum was used as a thickener to provide the physical parameters and to retain the viscosity at 1438 mPa.s. The physical and chemical properties of the product, including the 12-month stability, were tested in long-term and accelerated stability studies. The product was effective against the primary mastitis pathogens, including Staphylococcus aureus, Streptococcus uberis, Escherichia coli, Candida albicans and Aspergillus niger