We demonstrate here a widespread distribution of genes mediating efflux-based resistance to quaternary ammonium compounds (QACs) in staphylococci from unpasteurized milk from 127 dairy cattle herds and 70 dairy goat herds. QAC resistance genes were identified in 21% of the cattle herds (qacA/B, smr, qacG, and qacJ) and in 10% of the goat herds (qacA/B and smr). Further examination of 42 QAC-resistant bovine and caprine isolates revealed the following genes: qacA/B (12 isolates) was present in four different species of coagulase-negative staphylococci (CoNS), smr (27 isolates) was detected in eight different CoNS species and in Staphylococcus aureus on a previously reported plasmid (pNVH99), qacG (two isolates) was detected on two plasmids (pST94-like) in Staphylococcus cohnii and Staphylococcus warneri, and qacJ (two isolates) was found in Staphylococcus hominis and Staphylococcus delphini on a plasmid (pNVH01) previously found in equine staphylococci. Isolation of indistinguishable pulsed-field gel electrophoresis (PFGE) CoNS types from tank milk and mammary quarter milk samples in a dairy cattle herd suggested that these QAC-resistant staphylococci were of intramammary origin. Indistinguishable or closely related PFGE types of bovine QAC-resistant CoNS were observed in different herds. One particular bovine S. warneri PFGE type was isolated repeatedly from samples collected during a 30-month period in a herd, showing long-term persistence. In conclusion, it seems that the widespread distribution of staphylococci carrying QAC resistance genes in Norwegian dairy cattle and goat herds is the result of both the intra- and interspecies spread of QAC resistance plasmids and the clonal spread of QAC-resistant strains.

Widespread Distribution of Disinfectant Resistance Genes among Staphylococci of Bovine and Caprine Origin in Norway

The textile and leather industry produces large amounts of wastewater that contains high levels of chemicals and other pollutants, incorporated during the processing stages We evaluated the efficacy of green synthesized iron oxide (α-Fe2O3) and magnesium oxide (MgO) nanoparticles (NPs) for wastewater treatment of crude textile and tannery effluents Green synthesis of α-Fe2O3-NPs and MgO-NPs was conducted using the newly obtained Aspergillus carbonarious strain D-1 The optimization of the physicochemical parameters for the biosynthesis of NPs, including incubation periods, contact time, pH, temperature, and precursor concentrations, were assessed The characterization of NPs obtained under optimal conditions was evaluated using UV–visible spectroscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD) patterns, dynamic light scattering (DLS), and Fourier Transform Infrared (FT-IR) Spectroscopy The optimal concentration for efficient textile/tannery wastewater decolorization was determined to be 100 mg NPs after eight hours for α-Fe2O3-NPs and after four hours for MgO-NPs Under these conditions, chemical oxygen deman (COD), pH value, total dissolved solids (TDS), total suspended solids (TSS), and conductivity were greatly reduced as compared to control for crude textile wastewater GC–MS analysis of NPs-treated textile wastewater revealed that some major compounds were greatly diminished, bio-transformed, or completely degraded MgO and α-Fe2O3 NPs exhibited a high capacity to reduce the COD of tannery wastewater by 975% and 950%, respectively Hematite NPs exhibited higher removal capacity for TDS, TSS, and conductivity compared to MgO-NPs MgO and hematite NPs exhibited high capacities to remove Cr, with MgO redcing Cr by 8706 and hematite NPs reducing Cr by 754% MgO-NPs were more effective than α-Fe2O3-NPs at removing Pb, Ni, and Cd

Catalytic degradation of wastewater from the textile and tannery industries by green synthesized hematite (α-Fe2O3) and magnesium oxide (MgO) nanoparticles

Antimycin-type depsipeptides: discovery, biosynthesis, chemical synthesis, and bioactivities

Antimicrobial resistance among staphylococci of animal origin is based on a wide variety of resistance genes. These genes mediate resistance to many classes of antimicrobial agents approved for use in animals, such as penicillins, cephalosporins, tetracyclines, macrolides, lincosamides, phenicols, aminoglycosides, aminocyclitols, pleuromutilins, and diaminopyrimidines. In addition, numerous mutations have been identified that confer resistance to specific antimicrobial agents, such as ansamycins and fluoroquinolones. The gene products of some of these resistance genes confer resistance to only specific members of a class of antimicrobial agents, whereas others confer resistance to the entire class or even to members of different classes of antimicrobial agents, including agents approved solely for human use. The resistance genes code for all three major resistance mechanisms: enzymatic inactivation, active efflux, and protection/modification/replacement of the cellular target sites of the antimicrobial agents. Mobile genetic elements, in particular plasmids and transposons, play a major role as carriers of antimicrobial resistance genes in animal staphylococci. They facilitate not only the exchange of resistance genes among members of the same and/or different staphylococcal species, but also between staphylococci and other Gram-positive bacteria. The observation that plasmids of staphylococci often harbor more than one resistance gene points toward coselection and persistence of resistance genes even without direct selective pressure by a specific antimicrobial agent. This chapter provides an overview of the resistance genes and resistance-mediating mutations known to occur in staphylococci of animal origin.

Antimicrobial Resistance among Staphylococci of Animal Origin

N-(4-{[4-(1H-Benzoimidazol-2-yl)-arylamino]-methyl}-phenyl)-benzamide derivatives as small molecule heparanase inhibitors.

The present study was conducted from July to August 2018 on milk samples taken at dairy farms in the Northern Province and Kigali District of Rwanda in order to identify Staphylococcus spp. associated with bovine intramammary infection. A total of 161 staphylococcal isolates originating from quarter milk samples of 112 crossbred dairy cattle were included in the study. Antimicrobial susceptibility testing was performed and isolates were examined for the presence of various resistance genes. Staphylococcus aureus isolates were also analyzed for the presence of virulence factors, genotyped by spa typing and further phenotypically subtyped for capsule expression using Fourier Transform Infrared (FTIR) spectroscopy. Selected S. aureus were characterized using DNA microarray technology, multi-locus sequence typing (MLST) and whole-genome sequencing. All mecA-positive staphylococci were further genotyped using dru typing. In total, 14 different staphylococcal species were detected, with S. aureus being most prevalent (26.7%), followed by S. xylosus (22.4%) and S. haemolyticus (14.9%). A high number of isolates was resistant to penicillin and tetracycline. Various antimicrobial and biocide resistance genes were detected. Among S. aureus, the Panton-Valentine leukocidin (PVL) genes, as well as bovine leukocidin (LukM/LukF-P83) genes, were detected in two and three isolates, respectively, of which two also carried the toxic shock syndrome toxin gene tsst-1 bovine variant. t1236 was the predominant spa type. FTIR-based capsule serotyping revealed a high prevalence of non-encapsulated S. aureus isolates (89.5%). The majority of the selected S. aureus isolates belonged to clonal complex (CC) 97 which was determined using DNA microarray based assignment. Three new MLST sequence types were detected.

Vedaste Nyirimbuga

Papers

Characterization of Antibiotic and Biocide Resistance Genes and Virulence Factors of Staphylococcus Species Associated with Bovine Mastitis in Rwanda