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Healthcare-associated infections caused by Staphylococcus, particularly Staphylococcus aureus, represent a high risk for human and animal health. Staphylococcus can be easily transmitted through direct contact with individual carriers or fomites, such as medical and non-medical equipment. The risk increases if S. aureus strains carry antibiotic resistance genes and show a phenotypic multidrug resistance behavior. The aim of the study was to identify and characterize methicillin resistant coagulase-positive staphylococci (MRSA) and coagulase-negative staphylococci (MRCoNS) in equine patients and environmental sources in an equine hospital to evaluate the genetic presence of multidrug resistance and to understand the dissemination risks within the hospital setting. We explored 978 samples for MRSA and MRCoNS using Oxacillin Screen Agar in an equine hospital for racehorses in Chile, which included monthly samples (n = 61-70) from equine patients (246) and hospital environments (732) in a one-year period. All isolates were PCR-assessed for the presence of methicillin resistance gene mecA and/or mecC. Additionally, we explored the epidemiological relatedness by Pulsed Field Gel Electrophoresis (PFGE) in MRSA isolates. Phenotypic antibiotic resistance was evaluated using the Kirby-Bauer disk diffusion method. We estimated the unadjusted and adjusted risk of acquiring drug-resistant Staphylococcus strains by employing logistic regression analyses. We identified 16 MRSA isolates and 36 MRCoNS isolates. For MRSA, we detected mecA and mecC in 100% and 87.5 % of the isolates, respectively. For MRCoNS, mecA was detected among 94% of the isolates and mecC among 86%. MRSA and MRCoNS were isolated from eight and 13 equine patients, respectively, either from colonized areas or compromised wounds. MRSA strains showed six different pulse types (i.e., A1-A3, B1-B2, C) isolated from different highly transited areas of the hospital, suggesting potential transmission risks for other patients and hospital staff. The risk of acquiring drug-resistant Staphylococcus species is considerably greater for patients from the surgery, equipment, and exterior areas posing higher transmission risks. Tackling antimicrobial resistance (AMR) using a One Health perspective should be advocated, including a wider control over antimicrobial consumption and reducing the exposure to AMR reservoirs in animals, to avoid cross-transmission of AMR Staphylococcus within equine hospitals.

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Staphylococcus aureus is a Gram-positive bacterium that causes intramammary infections and bulk tank milk (BTM) contamination in dairy operations around the world in spite of on-farm application of preventive measures. The study was conducted on a 30-cow dairy farm in the Ñuble Region of Chile. For BTM culture and somatic cell count (SCC) analysis, three consecutive BTM samples were collected. Samples for bacterial culture (n = 16) were collected from macroscopic adherence on previously washed, sanitized, and dry milking equipment surfaces in direct contact with milk during milking or cooling. A total of 48 S. aureus isolates from BTM, milking equipment, and cows' quarters with intramammary infections were analyzed by pulsed-field gel electrophoresis (PFGE). Selected milking equipment pieces were removed for biofilm visualization using scanning electron microscopy (SEM). S. aureus was isolated from all three BTM samples; the average SCC for the three BTM samples was 1,429,333 cells/mL. Fourteen of the 16 samples of milking equipment (87.5%) were culture positive for S. aureus. Biofilms were visualized by SEM in all four removed milking equipment pieces. Microorganisms observed by SEM in those biofilms were mainly coccus-shaped bacteria, and microbiological culture of these biofilms yielded viable S. aureus isolates in all samples. All pulsotypes observed among S. aureus isolates from BTM were indistinguishable from those in milking equipment surfaces. All PFGE pulsotypes observed among S. aureus isolates from biofilms on rubber liners were indistinguishable from isolates from intramammary infections in cows. Our findings suggest that milking equipment films may act as source of S. aureus contamination for BTM and cows during milking, thus compromising the microbiological quality of milk used for manufacturing dairy products.

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We analyze the evolutionary dynamics of ninety carbapenem-resistant Acinetobacter baumannii (CRAB) isolates collected between 1990 and 2015 in Chile. CRAB were identified at first in an isolate collected in 2005, which harbored the ISAba1-blaOXA-69 arrangement. Later, OXA-58- and OXA-23-producing A. baumannii strains emerged in 2007 and 2009, respectively. This phenomenon was associated with variations in the epidemiology of OXA-type carbapenemases, linked to nosocomial lineages belonging to ST109, ST162, ST15 (CC15) and ST318 (CC15).

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Background: The 6-minutes walking test (6WT) is the ideal submaximal test for the evaluation and follow-up of patients with chronic respiratory diseases. There are no reference values (RV) for Chilean children using the American Thoracic Society guidelines. Aim: To generate 6WT reference values for Chilean children aged 6 to 14 years. Material and Methods: 6MW was evaluated in 192 healthy children (100 women) aged between 6 and 14 years. The test was carried out in a 30 m long indoor flat surface. Children also answered a survey about health problems and their weight and height were recorded. Results: The distance walked by women and men was 596.5 ± 57 and 625 ± 59.7 m respectively (p < 0.05). There was a significant correlation between the distance walked and height (r = 0.58), age (r = 0.56), weight (r = 0.54) and reserve heart rate (r = 0.21). Conclusions: These results can be used as reference values for the 6WT in Chilean children aged 6 to 14 years. They are similar to those reported abroad.

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BACKGROUND: The 6-minutes walking test (6WT) is the ideal submaximal test for the evaluation and follow-up of patients with chronic respiratory diseases. There are no reference values (RV) for Chilean children using the American Thoracic Society guidelines. AIM: To generate 6WT reference values for Chilean children aged 6 to 14 years. MATERIAL AND METHODS: 6MW was evaluated in 192 healthy children (100 women) aged between 6 and 14 years. The test was carried out in a 30 m long indoor flat surface. Children also answered a survey about health problems and their weight and height were recorded. RESULTS: The distance walked by women and men was 596.5 ± 57 and 625 ± 59.7 m respectively (p < 0.05). There was a significant correlation between the distance walked and height (r = 0.58), age (r = 0.56), weight (r = 0.54) and reserve heart rate (r = 0.21). CONCLUSIONS: These results can be used as reference values for the 6WT in Chilean children aged 6 to 14 years. They are similar to those reported abroad.

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Tumor progression and angiogenesis are intimately related. To understand the interrelationship between these two processes, real-time imaging can make a major contribution. In this report, fluorescent protein imaging (FPI) and magnetic resonance imaging (MRI) were utilized to demonstrate the effects of selenium on tumor progression and angiogenesis in an orthotopic model of human colon cancer. GEO (well-differentiated human colon carcinoma) cells transfected with green fluorescent protein (GFP) were implanted orthotopically into the colon of athymic nude mice. Beginning at five days post implantation, whole-body FPI was performed to monitor tumor growth in vivo. Upon successful visualization of tumor growth by FPI, animals were randomly assigned to either a control group or a treatment group. Treatment consisted of daily oral administration of the organoselenium compound, methyl-selenocysteine (MSC; 0.2 mg/day × five weeks). Dynamic contrast-enhanced MRI was performed to examine the change in tumor blood volume following treatment. CD31 immunostaining of tumor sections was also performed to quantify microvessel density (MVD). While T1- and T2-weighted MRI provided adequate contrast and volumetric assessment of GEO tumor growth, GFP imaging allowed for high-throughput visualization of tumor progression in vivo. Selenium treatment resulted in a significant reduction in blood volume and microvessel density of GEO tumors. A significant inhibition of tumor growth was also observed in selenium-treated animals compared to untreated control animals. Together, these results highlight the usefulness of multimodal imaging approaches to demonstrate antitumor and anti-angiogenesis efficacy and the promise of selenium treatment of colon cancer.

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BACKGROUND: Colorectal cancer metastases result in a significant number of cancer related deaths. The molecular mechanisms underlying this complex, multi-step pathway are yet to be completely elucidated. In the absence of any transgenic models of colon cancer metastases, an in vivo model system that fulfills the rate limiting steps of metastasis (local invasion and distant colony formation) is needed. The purpose of this study was to characterize the behavior of a human colon cancer cell line, HCT116 in an orthotopic model. MATERIALS AND METHODS: HCT116 cells were transfected with green fluorescence protein and subcutaneously injected into BALB/c nude male mice. Once xenografts were established, they were excised and orthotopically implanted into 32 other male BALB/c nude mice using microsurgical techniques. Animals were serially imaged and euthanized at 6-8 weeks post-implantation. Tissues were procured and processed for hematoxylin and eosin analysis. RESULTS: All 32 animals demonstrated primary tumor growth, invasion and peritoneal spread. Liver metastases were identified in 15/32 (47%), and lung metastases were confirmed in 13/32 (41%). In total, 19/32 (59%) animals demonstrated distant metastatic colony formation. CONCLUSIONS: This orthotopic model of colon cancer fulfills the rate limiting steps of local invasion and distant colony formation in the process of metastases. HCT116 human colon cancer cell line in this in vivo model system provides a tool to dissect the molecular mechanism involved in the metastatic cascade.

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Stilbene-derived optical brighteners can markedly enhance the insecticidal activity of certain baculoviruses. We evaluated the influence of an optical brightener on the rate at which Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) developed resistance to nucleopolyhedrovirus (SfMNPV). Two laboratory colonies of S. frugiperda were inoculated with an LC50 of SfMNPV, in the absence or presence of the optical brightener Tinopal LPW (0.1%), over a period of two and 11 generations, in the first and second experiment, respectively. Compared with the initial susceptibility of the insect colony, resistance ratios of 11- and 12-fold were observed after two generations of treatment with SfMNPV + Tinopal LPW and SfMNPV alone. Similar, but variable degrees of resistance were observed in the long-term experiment with resistance ratios of 8- to 35-fold after seven to 11 generations. The presence of Tinopal LPW alone, or in mixtures with SfMNPV, did not cause any systematic change in insect resistance in either experiment. At the end of the long-term experiment, debilitating effects on pupal weight, adult fecundity, and longevity were observed in the insects exposed to Tinopal LPW alone or in mixtures with SfMNPV, but the pattern of such effects among treatments differed in each generation. We conclude that optical brighteners are unlikely to affect the rate of development of resistance to nucleopolyhedroviruses applied as biological insecticides.

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