Coagulase-negative staphylococci (CNS) are the most prevalent mastitis pathogens. However, virulence characteristics of CNS have not been well determined. The presence of genes for enterotoxins (sea-sej), toxic shock syndrome toxin-1 (tst), the exfoliative toxins (eta, etb), Panton-Valentine leukocidin (pvl) and mecA of CNS species isolated from cows and ewes with subclinical mastitis was investigated in this study. A total of 121 CNS (81 cows, 40 ewes) representing 18 different Staphylococci species were examined by PCR, and 38.1% (33 cows and 13 ewes) of CNS isolates had one or more se genes. The difference between percentages for SE toxin genes of CNS strains isolated from cows (40.7%) and ewes (32.5%) was not statistically significant (P > 0.05; χ(2) = 0.380). It was found that S. simulans isolates had the highest prevalent se genes. Furthermore, the most common SE gene types was seh-sej. In this study, none of the isolates harbored the toxic shock syndrome toxin gene (tsst) and the exfoliative toxin genes (eta, etb). Five cow (6.17%) and three ewe CNS (7.5%) isolates had mecA gene. Three cow (3.7%) and two ewe CNS (5.0%) isolates had pvl gene. In conclusion, the present study showed that CNS species isolated from cows and ewes could serve as potential reservoir of se, mecA, and pvl genes.
In this study, amoxicillin (AMO)-loaded poly(vinyl alcohol)/sodium alginate (PVA/NaAlg) nanoparticles were prepared as a polymer-based controlled release system. The physicochemical properties of the obtained nanoparticles were investigated by XRD, DSC/TGA, particle size analyses and zeta potential measurements. The average particle sizes were in the range from 336.3 ± 25.66 to 558.3 ± 31.39 nm with negative zeta potential values from -41.86 ± 0.55 to -47.3 ± 2.76 mV. The influences of PVA/NaAlg ratio, span 80 concentration, exposure time to glutaraldehyde (GA) and the drug/polymer ratio on AMO release profiles were evaluated. In vitro drug release studies showed a controlled and pH dependent AMO release with an initial burst effect. XRD patterns and DSC thermograms of AMO-loaded nanoparticles revealed that the drug in the nanoparticles was in amorphous form, which was more stable than the crystalline form. The antibacterial activity of the optimal formulation was also investigated. The minimum inhibitory concentration (MIC) values of this formulation had the comparable antibacterial activity with that of pure AMO. These results indicate that the developed nanoparticles could be a promising candidate drug delivery system for AMO.
The aims of this study were to determine the existence of pvl gene, some toxin genes, and mecA gene in Staphylococcus aureus strains isolated from sheep milk and to examine antimicrobial resistance profiles in staphylococci from sheep and goats' milk. The milk samples were collected from 13 different small ruminant farms in Kirikkale province from February to August 2009. A total of 1,604 half-udder milk samples from 857 ewes and 66 half-udder milk samples from 33 goats were collected. Staphylococcus spp. were isolated and identified from the samples. Toxin genes and mecA gene among S. aureus strains were determined by PCR. Antimicrobial susceptibility of staphylococci was examined by the disk diffusion method on Mueller-Hinton agar, and interpreted according to the Clinical Laboratory Standards Institute (CLSI) guidelines. The prevalence of subclinical intramammary infection in both ewes and goats was 5.2%. The most prevalent subclinical mastitis agents were coagulase-negative staphylococci and S. aureus with prevalences 2.8% (n:46) and 1.3% (n = 21), respectively. The prevalence of resistances in isolated Staphylococcus spp. to penicilin G, tetracycline, erythromycin, gentamicin, and enrofloxacin were found as 26.9% (18), 7.5% (5), 6.0% (4), 3.0% (2), and 1.5% (1), respectively. Only 3 of the 21 S. aureus ewe isolates (13.4%) were shown to harbor enterotoxin genes being either seh, sej or sec. However, fourteen (66.6%) of the 21 S. aureus isolates had pvl gene while none of the isolates harbored mecA gene. In conclusion, Staphylococci were shown to be the most prevalent bacteria isolated from subclinical mastitis of ewes and goats and these isolates were susceptible to most of the antibiotics. In addition, S. aureus strains isolated from ewes were harboring few staphylococcal enterotoxin genes. However, Panton-Valentine leukocidin produced by S. aureus could be an important virulence factor and contribute to subclinical mastitis pathogenicity.
Materials and methods Identification and isolation of enterococciTwo hundred and forty cloacal swab samples, which were collected in Cary-Blair transport medium from the slaughterhouses of three different integrated broiler companies in 2011 and 2012, were inoculated onto Slanetz and Bartley agar plates supplemented with vancomycin
IntroductionEscherichia coli strains are important pathogens in animals and humans, and are normal commensals in intestinal tracts. The β-lactam group of antibiotics has been intensely used in human and veterinary medicine as infectious disease treatments (1). Extended-spectrum betalactamases (ESBLs) hydrolyze oxyimino-cephalosporins and give resistance to bacteria against the penicillins, cephalosporins (first, second, and third generations), and aztreonam. They are repressed by β-lactamase inhibitors. ESBLs are classified as β-lactamases containing three main families: TEM (named after the patient Temoneria), SHV (sulfhydryl reagent variable), and CTX-M (active on cefotaxime, first isolated in Munich) (2). The prevalence of CTX-M-type β-lactamase-producing E. coli has increased in poultry over the last decade (3).Increasing prevalence of ESBL-producing E. coli in poultry has become a major zoonotic risk because of possible transmission from broilers to humans (3). In addition, ESBL-producing E. coli strains that may have multidrug resistance (MDR) and cause therapeutic problems have been reported in human and veterinary practice (4). The alarming spread of ESBL-producing Enterobacteriaceae poses a serious public health threat and has attracted the attention of scientists, politicians, and the general public globally. There was no previous study about the presence, prevalence, and molecular epidemiology of ESBL-producing E. coli isolates from broilers in Turkey. The aim of the present study was to investigate the resistance phenotype and genotyping characteristics of ESBL-carrying E. coli strains in healthy broilers in Turkey. Materials and methods Samples, isolations, and identificationFrom January to April 2012, 300 samples were collected from cloacal samples of healthy slaughterhouse broilers in two regions of Turkey. Broiler cloacal samples were obtained from a total of 30 different poultry houses
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