Análisis epidemiológico y molecular de la virulencia y la antibiorresistencia en Acinetobacter baumannii

Tesis inédita de la Universidad Complutense de Madrid, Facultad de Veterinaria, Departamento de Bioquímica y Biología Molecular IV, leída el 21/12/2016Acinetobacter baumannii is a highly versatile nosocomial pathogen that is implicated in several nosocomial infections among critically ill patients and results in high mortality rates. These infections include ventilator associated pneumonia, bloodstream infections, urinary tract infections, and burn wound infections. Multi-Drug Resistant (MDR), and especially Carbapenem Resistant Acinetobacter baumannii (CRAB) isolates are also sharply increasing in frequency, forcing clinicians to revert to the use of colistin. This organism has numerous intrinsic resistance mechanisms, virulence determinants, and an elastic genome that allows it to acquire resistance to almost all antimicrobial agents rather easily. The acquisition of oxacillinases (OXAs) is one of the most common mechanisms of acquiring carbapenem resistance. Moreover, some clinically important International Clones (ICs) with MDR profiles are disseminated all over the world. A. baumannii is known to differentially express virulence determinants and few studies hint at their relationship with antimicrobial resistance. However, this relationship is not extensively investigated. In this Doctoral Thesis, the relationship between clonality, virulence, and antimicrobial resistance is investigated in two sets of clinical isolates obtained from Spain and Lebanon, two countries in which the rate of CRAB isolates is notoriously high. Our aim is providing clinicians and infection control specialists with tools that could be used to assess the infecting strain based on initial clinical data that could improve the chances of successful therapy and limit the spread of MDR and CRAB isolates. Additionally, it is our aim to better understand the interaction between virulence and antibiotic resistance...Acinetobacter baumannii es un patógeno nosocomial versátil implicado en importantes infecciones como la neumonía asociada a ventilación mecánica, infecciones del torrente sanguíneo, del tracto urinario, de heridas y de quemaduras en pacientes críticamente enfermos. Se han encontrado elevadas tasas de resistencia a muchos grupos de antibióticos en esta especie, incluyendo carbapenemas. La adquisición de resistencias se debe a su genoma elástico. Por ejemplo, la adquisición de OXAs es uno de los mecanismos más comunes en A. baumannii en su resistencia a carbapenemas, y las cepas resistentes a este antibiótico están asociadas con algunos clones internacionales. A. baumannii expresa factores de virulencia de una manera diferente en las diferentes cepas y algunos estudios muestran una relación entre virulencia y antibiorresistencia, que aún no está muy desarrollada. En esta Tesis Doctoral, se investiga la relación entre clonalidad, virulencia, y antibiorresistencia en cepas aisladas en España y el Líbano, dos países de la cuenca Mediterránea. Nuestro objetivo con este estudio es apoyar a los expertos en el control de infecciones, y proporcionar las herramientas necesarias para combatir la propagación de cepas resistentes a diferentes antibióticos. Además, con todo ello intentamos comprender mejor la compleja relación entre virulencia y resistencia antibiótica. Cincuenta y nueve cepas de A. baumannii fueron aisladas del HU-LP (España) y 90 del SGH-UMC (Líbano). Se identificaron las cepas utilizando tiras API, amplificando por PCR genes de OXA-51, y mediante análisis por MALDI-TOF MS. Se analizó la resistencia antibiótica de las cepas según la guía de CLSI, se determinó la clonalidad por PFGE y se realizó la amplificación diferencial de genes “housekeeping”. Los genes de carbapenemasas se detectaron por PCR y la formación de biofilms, hemólisis, movilidad, actividad proteolítica, y tiempos de generación se detectaron fenotípicamente. A continuación, se llevó a cabo la secuenciación del operón pmrCAB y el genoma de cepas resistentes a colistina. Además, se investigaron los patrones de formación de biofilms, después de cultivar las cepas en soportes de acero inoxidables, mediante recuento de las células adheridas y microscopía confocal...Sección Deptal. de Bioquímica y Biología Molecular (Veterinaria)Fac. de VeterinariaTRUEunpu

Analyze TCP Protocol Performance in Satellite Communications

This research is mainly about the influence of protocols on the performance of Satellite Communication. It is widely recognized that satellite communications are affected by some peculiar problems, which penalize heavily the performance and efficiency of the Transmission Control Protocol (TCP). In fact, wireless satellite channels are usually characterized by link-asymmetry and higher Round Trip Time and Bit Error Rate in comparison to wired links. It means that TCP, which was developed for wired channels, exhibits often poor performance in a satellite scenario (unfair bandwidth allocation, low throughput and long file-transfer delay).We have studied and compared many TCP variants recently proposed. In particular we have compared TCP-Reno standard implementation with TCP-SACK, TCP-Westwood, TCP-Vegas and TCP-Tibet. We tested the different protocols on a simulated satellite scenario, with the support of NS2, a well-know network simulator platform, annotating the advantages and drawbacks of various protocols in order to improve the transmission of IP data packets over satellite channels. Keywords: Satellite link, Performance analysis, TCP behaviors

Prethodna terapija vitaminom C štiti od niklom izazvane nefrotoksičnosti u miševa

Nickel is an abundant carcinogenic and nephrotoxic metal whose activity leads to renal impairment. Previous studies have shown a protective effect of simultaneous vitamin C administration on acute and chronic nickel toxicity. However, very little research relating to the effect of vitamin C pretreatment in preventing nickel-induced acute nephrotoxicity is available. Therefore, the present study aimed to determine the efficiency of vitamin C (VC) pretreatment in preventing acute renal toxicity of nickel. Mice were pretreated orally with vitamin C (16.6 mg kg-1 body weight, b.w.) for seven consecutive days, prior to intraperitoneal (i.p.) administration of nickel chloride at different doses (3, 5, and 10 mg Ni kg-1 b.w.) for an exposure period of 24 hours. Thereafter, animals were killed and kidney tissue and blood samples were taken for histological examination and biochemical marker analyses. Vitamin C pretreatment alone did not alter the levels of serum kidney markers (creatinine, urea, and uric acid). However, treatment with Ni alone showed a significant increase in the levels of serum creatinine, urea, and uric acid with marked necrotic epithelial cells and infiltration by inflammatory cells in kidney sections as compared to the control group. Pretreatment with vitamin C and treatment with Ni at all doses tested for 24 hours showed a significant decrease in the levels of serum creatinine, urea, and uric acid, as well as an improvement in histological changes compared to those previously seen in the group treated with Ni alone. It is concluded that vitamin C pretreatment effectively improved renal function and tissue damage caused by nickel.Nikal je sveprisutan kancerogeni i nefrotoksični metal čije djelovanje dovodi do oštećenja bubrežne funkcije. Rezultati prethodnih istraživanja dokazali su zaštitni učinak istodobne terapije vitaminom C na akutnu i kroničnu toksičnost izazvanu niklom. Međutim, vrlo je malo istraživanja o učinku prethodne terapije vitaminom C radi sprječavanja niklom izazvane akutne nefrotoksičnosti. Stoga se ovim ispitivanjem nastojala utvrditi učinkovitost prethodne terapije vitaminom C (VC) u sprječavanju akutne bubrežne toksičnosti izazvane niklom. Prije intraperitonealnog (IP) ubrizgavanja različitih doza (3, 5 i 10 mg Ni kg-1 tjelesne težine) nikal klorida u razdoblju izlaganja od 24 sata, miševi su sedam dana uzastopce dobivali oralnu terapiju vitaminom C (16,6 mg kg-1 tjelesne težine). Nakon toga životinje su usmrćene, a bubrežno tkivo i uzorci krvi uzeti su radi histološke obrade i analize biokemijskih markera. U miševa koji su dobivali samo terapiju vitaminom C, serumske razine bubrežnih markera (kreatinin, urea i mokraćna kiselina) nisu bile promijenjene. Međutim, tretiranje samo niklom dovelo je do značajnog povećanja razina kreatinina, ureje i mokraćne kiseline te do značajnog broja nekrotičnih epitelnih stanica i infiltracije upalnih stanica u presjecima bubrega u usporedbi s kontrolnom skupinom. Prethodna terapija vitaminom C i tretiranje niklom u svim navedenim dozama tijekom 24 sata doveli su do značajnog smanjenja razina kreatinina, ureje i mokraćne kiseline u serumu te do poboljšanja histoloških promjena u usporedbi sa skupinom koja je tretirana samo niklom. Zaključuje se da prethodna terapija vitaminom C učinkovito poboljšava bubrežnu funkciju i oštećenje tkiva uzrokovano niklom

Toxicity of Amoxicillin and Erythromycin to Fish and Mosquito

This study characterized the toxicity of Amoxicillin (AM), Erythromycin (ER) and Endosulfan (EN) to fish and mosquito larvae obtained from a certified fish farm and from Wadi Gaza. The acute toxicity tests were determined by calculating mortality percentage of fish and mosquitoes through a gradient concentration of the tested compounds. Mortality percentage, exposure time, LC50 and LT50 were taken as indicators of toxicity. The results showed that AM was the potent compound against fish with LC50 value lower that EN. Toxicity to fish is in the following order: AM > EN > ER whereas the toxicity to mosquitoes is in the following order: ER > EN > AM. Fish are more sensitive to AM than mosquitoes whereas mosquitoes are more sensitive to ER than fish. The interesting outcome of the study is the calculated LC50 values are far below the concentration found in different water systems. Mixture toxicity of the tested antibiotics indicates antagonistic effect on both fish and mosquitoes

An Evaluation of Clean the World, Las Vegas Volunteer Program

Background Student evaluation team, AVID Advising, conducted an evaluation of a not for profit organization, Clean the World, Las Vegas Volunteer Program from February 2015 through August 2015. The pre-­‐ valuation consisted of an analysis of the organization’s growth since opening its Las Vegas doors in 2012, staff responsibilities, and their volunteer program. As a result of the pre-­‐ valuation, AVID Advising and Clean the World Las Vegas Manager, Kevin Williams determined an evaluation on the existing volunteer program would be most beneficial to the organization. Purpose The primary purpose of this evaluation is to provide Clean the World, Las Vegas with both short and long term recommendations based on the identified needs of their current volunteer program. Methodology To obtain qualitative and quantitative information about the volunteer program, information was collected via interviews with Clean the World, Las Vegas staff members, found in benchmarks studies, and through surveys ADIV Advising developed and distributed to current volunteers. Findings The volunteer survey respondents were able to provide important critical feedback regarding the volunteer program; survey data and commen