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

E. coli paplitimas mažmeninės prekybos realizuojamose kepenėlėse, jų atsparumas antimikrobinėms medžiagoms

Tyrimų tikslas – ištirti E. coli paplitimą mažmeninės prekybos realizuojamose vištų kepenėlėse, kaip viename iš populiariausių vištienos subproduktų, ir nustatyti šių bakterijų atsparumą antimikrobinėms medžiagoms. Iš skirtingų mažmeninės prekybos vietų surinkti įvairių Lietuvos gamintojų šviežių žalių vištų kepenėlių mėginiai (240 mėginių) ir atlikti E. coli bakteriologiniai tyrimai. Iš mėginių išskirtas vienas šimtas E. coli padermių (41,7 proc.) ir nustatytas jų atsparumas antimikrobinėms medžiagioms. Tyrimams taikytas mikroskiedimų metodas plokštelėse, naudojant 14 skirtingų antimikrobinių medžiagų. Rezultatai vertinti pagal ribines jautrumo reikšmes, nurodytas Europos antimikrobinio jautrumo tyrimų komiteto (EUCAST) duomenų bazėje. Nustatyta, jog dažniausiai tirtosios E. coli padermės pasižymėjo atsparumu streptomicinui (100 proc.), ampicilinui (60 proc.), nalidikso rūgščiai (50 proc.), ciprofloksacinui (47 proc.) ir tetraciklinui (45 proc.). Atsparių amikacinui padermių nenustatyta. Nustatytas retas atsparumas cefoksitinui (2 proc.), ceftiofurui (7 proc.), chloramfenikoliui (10 proc.), amoksicilino ir klavulano rūgšties kombinacijai (15 proc.). Mažiausios slopinamosios koncentracijos, didesnės nei plokštelėse esančios antimikrobinių medžiagų koncentracijos, nustatytos visoms tirtoms medžiagoms, išskyrus amikaciną. Rasta daug E. coli padermių, kurioms inaktyvuoti reikėjo didelio MSK ampicilino, nalidikso rūgšties, sulfonamidų ir tepraciklino kiekio. Tyrimų duomenys rodo potencialią riziką vartotojams (užsikrėsti atspariomis bakterijomis ar jų perduodamais atsparumo veiksniais per maisto gamybos grandinę), nes šios antimikrobinės medžiagos naudojamos tiek žmonių, tiek ir veterinarinėje medicinojeThe objective of this study was to estimate the prevalence and the antimicrobial resistance of E. coli that contaminates raw chicken liver as one of the most popular poultry sub-product sold in retail markets. Two hundred and forty samples of fresh raw chicken liver were obtained from national poultry producers in different retail marketing sites and tested for the presence of E. coli. One hundred E. coli strains (41.7%) were isolated and tested for antimicrobial susceptibility. The MICs of 14 antimicrobial agents were determined for each of the isolates using the broth microdilution method with custom-made microtitre plates. EUCAST cut-off values were used for the interpretation of susceptibility of isolated bacteria to antimicrobial agents. The most frequent resistances were demonstrated to streptomycin (100 %), ampicillin (60%), nalidixic acid (50%), ciprofloxacin (47%) and tetracycline (45%). No resistant strains were found to amikacin. Law percentage of resistant strains was recorded to cefoxitin (2%), ceftiofur (7%), chloramphenicol (10%) and amoxicillin/clavulanic acid (15%). MIC’s values above dilution ranges were found to all antimicrobials except amikacin. The highest numbers of resistant strains that demonstrated resistance to the highest concentrations of antimicrobial agents were found to ampicillin, nalidixic acid, sulphonamides and tetracycline. The data demonstrate potential risk during food preparation for consumers in the context of resistant E. coli as abovementioned antimicrobial agents are used in veterinary and human medicine as wellLietuvos sveikatos mokslų universitetasMatematikos ir statistikos katedraVytauto Didžiojo universiteta

Antimicrobial Properties of CuO Particles Deposited on a Medical Mask

Medical face masks help to reduce the transmission of pathogens, however, the number of infections caused by antimicrobial-resistant pathogens continues to increase. The aim of this study was to investigate the antimicrobial effect of an experimental medical mask layer coated with copper oxide using an environmentally friendly non-thermal physical vapour deposition approach. Pure CuO nanoparticles were successfully deposited on the middle layer of a face mask. The particles were distributed in different size clusters (starting from less than 100 nm dots going up to about 1 µm cluster-like structures). The CuO clusters did not form uniform films, which could negatively influence airflow during use of the mask. We investigated the antimicrobial properties of the experimental mask layer coated with CuO NPs using 17 clinical and zoonotic strains of gram-negative, gram-positive, spore-forming bacteria and yeasts, during direct and indirect contact with the mask surface. The effectiveness of the coated mask layer depended on the deposition duration of CuO. The optimal time for deposition was 30 min, which ensured a bactericidal effect for both gram-positive and gram-negative bacteria, including antimicrobial-resistant strains, using 150 W power. The CuO NPs had little or no effect on Candida spp. yeasts

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

Otpornost na antibiotike bakterija Enterococcus spp. izdvojenih iz stoke u Litvi.

105 isolates of Enterococcus spp. were selected as representative samples from different herds of pigs (n=25), cattle (n=46) and poultry (n=34). Antimicrobial susceptibility was determined according to epidemiological cut-off values. The highest number of strains demonstrated epidemiological resistance to lincomycin (78%), tetracycline, (65%), flavomycin (59%) and erythromycin (55%). The smallest number of strains was resistant to linezolid (1%) and tigecycline (2%). Six percent of all tested strains were epidemiologically resistant to ciprofloxacin, vancomycin and daptomycin. Cattle isolates showed the most frequent resistance to fl avomycin (71%), lincomycin (54%), tetracycline (45%), streptomycin (40%) and erythromycin (40%). Enterococci isolated from pigs showed the highest resistance to tetracycline and lincomycin (92%), erythromycin (76%), kanamycin (56%) and streptomycin (52%). All strains isolated from poultry were epidemiologically resistant to lincomycin. The most frequent resistance of poultry strains was also demonstrated to tetracycline (72%), erythromycin (63%), streptomycin (50%), flavomycin (48%) and tylosin (47%). However all strains isolated from poultry were susceptible to chloramphenicol, quinupristin/dalfopristin, linezolid and bacitracin.Ukupno je 105 izolata bakterija Enterococcus spp. bilo odabrano kao predstavnici iz različitih uzgoja svinja (n = 25), goveda (n = 46) i peradi (n = 34). Osjetljivost prema antimikrobnim tvarima određivana je na osnovi epidemioloških graničnih vrijednosti. Većina izolata bila je otporna prema linkomicinu (78%), tetraciklinu (65%), flavomicinu (59%) i eritromicinu (55%). Najmanje izolata bilo je otporno prema linezolidu (1%) i tigeciklinu (2%). Šest posto svih pretraženih sojeva bilo je otporno na ciprofloksacin, vankomicin i daptomicin. Izolati iz goveda bili su najčešće otporni na flavomicin (71%), linkomicin (54%), tetraciklin (45%), streptomicin (40%) i eritromicin (40%). Enterokoki izdvojeni iz svinja bili su najotporniji prema tetraciklinu i linkomicinu (92%), eritromicinu (76%), kanamicinu (56%) i streptomicinu (52%). Svi izolati iz peradi bili su otporni prema linkomicinu. Sojevi iz peradi također su bili najčešće otporni prema tetraciklinu (72%), eritromicinu (63%), streptomicinu (50%), flavomicinu (48%) i tilozinu (47%). Međutim svi sojevi izdvojeni iz peradi bili su osjetljivi prema kloramfenikolu, kvinupristinu/dalfopristinu, linezolidu i bacitracinu

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

Antimicrobial Properties of Diamond-Like Carbon/Silver Nanocomposite Thin Films Deposited on Textiles: Towards Smart Bandages

In the current work, a new antibacterial bandage was proposed where diamond-like carbon with silver nanoparticle (DLC:Ag)-coated synthetic silk tissue was used as a building block. The DLC:Ag structure, the dimensions of nanoparticles, the silver concentration and the silver ion release were studied systematically employing scanning electron microscopy, energy dispersive X-ray spectroscopy and atomic absorption spectroscopy, respectively. Antimicrobial properties were investigated using microbiological tests (disk diffusion method and spread-plate technique). The DLC:Ag layer was stabilized on the surface of the bandage using a thin layer of medical grade gelatin and cellulose. Four different strains of Staphylococcus aureus extracted from humans’ and animals’ infected wounds were used. It is demonstrated that the efficiency of the Ag+ ion release to the aqueous media can be increased by further RF oxygen plasma etching of the nanocomposite. It was obtained that the best antibacterial properties were demonstrated by the plasma-processed DLC:Ag layer having a 3.12 at % Ag surface concentration with the dominating linear dimensions of nanoparticles being 23.7 nm. An extra protective layer made from cellulose and gelatin with agar contributed to the accumulation and efficient release of silver ions to the aqueous media, increasing bandage antimicrobial efficiency up to 50% as compared to the single DLC:Ag layer on textile

Serological Variety and Antimicrobial Resistance in Salmonella Isolated from Reptiles

Salmonella enterica is one of the best adapted bacterial pathogens causing infections in a wide variety of vertebrate species. The aim of this study was to investigate the prevalence of Salmonella in different reptile species and to evaluate their serological variety and patterns of antimicrobial resistance. In total, 97 samples from 25 wild and domesticated reptile species were investigated in Lithuania. Serological variety, as well as phenotypical and genotypical resistance to antimicrobials, were investigated. Fifty isolates of Salmonella were obtained from the ninety-seven tested samples (51.5%; 95% CI 41.2–61.2). A significantly higher prevalence of Salmonella was detected in domesticated individuals (61.3%; 95% CI 50.0–71.5) compared with wild ones (18.2%; 95% CI 7.3–38.5). All isolates belonged to a single species, Salmonella enterica. Results demonstrated that reptiles carry a large variety of Salmonella serovars. Thirty-four isolates (68%) of Salmonella were resistant to at least one antimicrobial drug. The most frequent resistance of the isolates was to streptomycin (26%), cefoxitin, gentamicin, tetracycline and chloramphenicol (16%). Genes encoding resistance to tetracyclines, aminoglycosides, sulphonamides and trimethoprim were detected. No integrons that are associated with horizontal gene transfer were found. Data obtained provided knowledge about the adaptation of Salmonella in reptiles. Healthy individuals, irrespective of their origin, often carry Salmonella, including multi-resistant strains. Due to its large serological diversity, zoonotic potential and antimicrobial resistance, Salmonella in reptiles poses a risk to other animals and humans