Chitosan disrupts biofilm formation and promotes biofilm eradication in Staphylococcus species isolated from bovine mastitis.

Staphylococci are the main pathogens associated with hard-to-control intramammary infections in dairy cattle, and bacterial biofilms are suspected to be responsible for the antimicrobial resistance and persistence of this disease. Biofilms have the ability to resist to higher levels of antibiotics and reduce their efficacy. It is thus necessary to develop strategies targeted to bacterial biofilm infections. Chitosan is a polysaccharide with a proven broad spectrum of antimicrobial activity against fungi and bacteria. The aim of this study was assess the effect of low molecular weight (LMW) chitosan against biofilm hyperproducer Staphylococcus spp. (S. aureus and S. xylosus) strains usually involved in chronic bovine mastitis, and to test their efficacy in biofilm formation and eradication. The results obtained showed that LMW chitosan is able to inhibit S. aureus and S. xylosus planktonic growth in a dose-dependent manner and reduce bacterial viability. LMW chitosan inhibits biofilm formation, reduces biofilm viability and disrupts established biofilm. These results indicate the inhibitory effects of chitosan on biofilm formation, and these effects are observed at lower concentrations for S. xylosus. Our studies show the potential of this biopolymer to be used as an effective antibiofilm agent able to act upon staphylococcal infections.

Draft Genome Sequence of Bacillus cereus CITVM-11.1, a Strain Exhibiting Interesting Antifungal Activities.

Bacillus cereus is a gram-positive, spore-forming bacterium possessing an important and historical record as a human-pathogenic bacterium. However, several strains of this species exhibit interesting potential to be used as plant growth-promoting rhizobacteria. Here, we report the draft genome sequence of B. cereus strain CITVM-11.1, which consists of 37 contig sequences, accounting for 5,746,486 bp (with a GC content of 34.8%) and 5,752 predicted protein-coding sequences. Several of them could potentially be involved in plant-bacterium interactions and may contribute to the strong antagonistic activity shown by this strain against the charcoal root rot fungus, Macrophomina phaseolina. This genomic sequence also showed a number of genes that may confer this strain resistance against several polluting heavy metals and for the bioconversion of mycotoxins.

Chitosan and cloxacillin combination improve antibiotic efficacy against different lifestyle of coagulase-negative Staphylococcus isolates from chronic bovine mastitis.

Bovine mastitis affects the health of dairy cows and the profitability of herds worldwide. Coagulase-negative staphylococci (CNS) are the most frequently isolated pathogens in bovine intramammary infection. Based on the wide range of antimicrobial, mucoadhesive and immunostimulant properties demonstrated by chitosan, we have evaluated therapy efficiency of chitosan incorporation to cloxacillin antibiotic as well as its effect against different bacterial lifestyles of seven CNS isolates from chronic intramammary infections. The therapeutic effects of combinations were evaluated on planktonic cultures, bacterial biofilms and intracellular growth in mammary epithelial cells. We found that biofilms and intracellular growth forms offered a strong protection against antibiotic therapy. On the other hand, we found that chitosan addition to cloxacillin efficiently reduced the antibiotic concentration necessary for bacterial killing in different lifestyle. Remarkably, the combined treatment was not only able to inhibit bacterial biofilm establishment and increase preformed biofilm eradication, but it also reduced intracellular bacterial viability while it increased IL-6 secretion by infected epithelial cells. These findings provide a new approach to prophylactic drying therapy that could help to improve conventional antimicrobial treatment against different forms of bacterial growth in an efficient, safer and greener manner reducing multiresistant bacteria generation and spread.

Evaluation of the biofilm forming ability and its associated genes in Staphylococcus species isolates from bovine mastitis in Argentinean dairy farms.

Staphylococcus aureus and coagulase-negative staphylococci (CNS) are important causes of intramammary infection in dairy cattle, and their ability to produce biofilm is considered an important virulence property in the pathogenesis of mastitis. However, the published date on mechanisms and factors involved in infection persistence in the mammary gland remains unclear. The aim of this study was to investigate whether the main Staphylococcus species involved in bovine intramammary infections possess specific characteristics that promote colonization of the udder. We evaluated the biofilm-forming ability and distribution of adhesion- and biofilm-associated genes of Staphylococcus spp. isolated from bovine mastitis infected animals in Argentinean dairy farms. For this purpose, the phenotypic biofilm formation ability of 209 Staphylococcus spp. from bovine mastitis was investigated. All isolates produced biofilm in vitro, being 35,0% and 45,0% of the 127 S. aureus or 51,0% and 29,0% of the 82 CNS strong and moderate biofilm producers respectively. All S. aureus samples were PCR-positive for icaA, icaD, clfA, clfB and fnbpA genes, 76.3% were positive for fnbpB gene and 11.0% were positive for bap gene. In CNS isolates, the positive rates for icaA and icaD were 73.2%, while for clfA, clfB, fnbpA fnbpB and bap genes the percentage were lower. The results demonstrate that in Staphylococcus spp. biofilm formation, the polysaccharide and the adhesion- and biofilm-associated genes are of overall importance on bovine mastitis in Argentina. Therefore, future works should focus on these pathogenic specific factors for the development of more effective therapies of control, being essential to consider the ability of isolates to produce biofilm.

Arterial stiffness and endothelial function in obese children and adolescents and its relationship with cardiovascular risk factors.

BACKGROUND: Obesity is related to an increase in the rates of cardiovascular disease. OBJECTIVE: To establish the impact of obesity on vascular function (endothelial function and arterial stiffness) in children and adolescents and its relationship to cardiovascular risk factors. METHODS: In obese (OB) children and adolescents, endothelial function and arterial stiffness were evaluated by a pulse plethysmography method (reactive hyperemia and index of digital volume waveforms, respectively). Data were compared with the non-obese (non-OB) group (body mass index >10th to <97th percentile). Anthropometric parameters, body fat percentage, fasting glucose, lipid profile, insulinemia, HOMA-IR and hemodynamic parameters were determined in both groups. RESULTS: Body mass index, weight, waist circumference, body fat, insulinemia and HOMA-IR were significantly higher in the OB group. The OB group showed impaired endothelial function (15.8 ± 0.2%, n = 37) compared to the non-OB group (41.4 ± 5%, n = 20; p < 0.001) and increased arterial stiffness. Endothelial function was only negatively correlated with waist circumference and HOMA-IR in the OB group, whereas a positive correlation was found between insulinemia and HOMA-IR. CONCLUSIONS: This study shows that impaired vascular function is already present in OB children and adolescents. The fact that obesity is associated with some markers of cardiovascular risk suggests the importance of early lifestyle interventions in this population to prevent cardiovascular disease.