Evaluation of antimicrobial strategies against biomaterial-associated infections: impact of the surrounding environmental conditions

Dissertação de mestrado em Bioengenharia

Estrategias para el mejoramiento de la producción de maní mediante la inoculación de microorganismos biofertilizantes y controladores de enfermedades fúngicas. Strategies to the Improvement of the peanut productivity through of inoculation with microorganism biofertilizers and controllers of fungal diseases.

El cultivo de maní es de gran importancia en la provincia de Córdoba. En los últimos años, la pérdida de rendimiento del cultivo en la región centro debido a la degradación de los suelos, la incidencia de enfermedades causadas por hongos y la erosión hídrica y eólica ha desplazado el área de siembra hacia el sur de la provincia. La hipótesis planteada en este proyecto es que la diversidad de bacterias que habitan la rizósfera y/o los tejidos de maní constituye una fuente para la selección de aquéllos que, por sus propiedades fisiológicas y metabólicas, permitan mejorar el rendimiento del cultivo, actuando como biocontroladores de fitopatógenos o biofertilizantes. Los objetivos propuestos son: 1) Evaluar y caracterizar la actividad antifúngica en una población previamente seleccionada de microorganismos del suelo del área manisera de Córdoba para su utilización en el desarrollo de prácticas sustentables tendientes a optimizar la producción de dicho cultivo mediante funciones biocontroladoras. 2) Seleccionar bacterias nativas nodulantes de maní competitivas y eficientes en la fijación y asimilación de nitrógeno en maní para ser utilizadas como un inoculante potencial. La metodología a utilizar consistirá en ensayos de interacción planta-microorganismos usando técnicas moleculares y bioquímicas. Los estudios sobre el conocimiento de la biodiversidad del suelo en el área manisera aportarán herramientas para una transición hacia una agricultura sustentable, generándose un catálogo de bacterias simbióticas y de vida libre que muestran actividad PGPR y que podrían ser empleadas como biofertilizantes o biocontroladoras de fitopatógenos. Ello podría constituir un importante impulso en la economía regional, la cual se basa principalmente en la explotación agrícola.

Studies in search of a suitable experimental insect model for xenodiagnosis of hosts with Chagas' disease. 1 - Comparative xenodiagnosis with nine triatomine species of animals with acute infections by Trypanosoma cruzi

In search of a suitable vector species for xenodiagnosis of humans and animals with chronic Chagas' disease we first investigated the reactions of different vector species to acute infection with Trypanosoma cruzi. Vector species utilized in this study were: Triatoma infestans, Rhodnius prolixus and Triatoma dimidiata, all well adapted to human habitats; Triatoma rubrovaria and Rhodnius neglectus both considered totally wild species; Panstrongylus megistus, Triatoma sordida, Triatoma pseudomaculata and Triatoma brasiliensis, all essentially sylvatic but some with domiciliary tendencies and others restricted to peridomestic biotopes with incipient colonization of human houses after successful eradication of T. infestans. Results summarized in Table IV suggest the following order of infectivity among the 9 studied vector species: P. megistus with 97.8% of infected bugs, T. rubrovaria with 95% of positive bugs a close second followed by T. Pseudomaculata with 94.3% and R. neglectus with 93.8% of infected bugs, almost identical thirds. R. prolixus, T. infestans and T. dimidiata exhibited low infection rates of 53.1%, 51.6% and 38.2% respectively, coupled with sharp decreases occuring with aging of infection (Fig. 1). The situation was intermediate in T. brasiliensis and T. sordida infection rates being 76.9% and 80% respectively. Results also point to the existence of a close correlation between prevalence and intensity of infection in that, species with high infection rates ranging from 93.8% to 97.8% exhibited relatively large proportions of insects (27.3% - 33.5%) harbouring very dense populations of T. cruzi. In species with low infection rates ranging from 38.2% to 53.1% the proportion of bugs demonstrating comparable parasite densities was at most 6%. No differences attributable to blood-meal size or to greater susceptibility of indigenous vector species to parasites of their own geographical area, as suggested in earlier...

Leishmania infections in Lutzomyia longipalpis (Diptera: Psychodidae) on the Island of Sao Luis, Maranhao State, Brazil

Dissection of Lutzomyia longipalpis, captured in the São Luis focus of visceral Leishmaniasis revealed a 1.8% promastigote infection rate.

The histopathology of Scomber japonicus infection by Nematobothriun scombri (Trematoda: Didymozoidae) and of larval anisakid nematode infections in the liver of Pagrus pagrus

The histopathology induced by Nematobothrium scombri (Trematoda) in Scomber japonicus and of larval anisakid nematodes in Pagrus pagrus is described. Nematodes larvae occurred within the liver capsule and N. scombri occurred within nodules in the opercula. The fishes were collected off the coast of Rio de Janeiro State.

Thymoma, immunodeficiency, and herpes simplex virus infections.

Hypogammaglobulinemia develops in 3 to 6% of patients with thymoma and this association is commonly referred to as thymoma with immunodeficiency (formerly Good syndrome). Recurrent infections with encapsulated bacteria and opportunistic infections associated with disorders of both humoral and cell mediated immunity frequently occur in this rare primary, adult-onset immunodeficiency. We report a case of thymoma with immunodeficiency complicated by disseminated herpes simplex virus (HSV) infection and review five additional cases of HSV-related infections reported since 1966 in patients presenting with thymoma with immunodeficiency. Patients presented with epiglottitis, keratitis, recurrent genital herpes, ulcerative dermatitis, and acute hepatitis. Four of the six cases had a fatal outcome, two of which were directly attributable to HSV infection. Since the risk of invasive opportunistic infections is high and the presentation atypical, lymphocyte count and total serum immunoglobulin should be measured regularly in all patients presenting with thymoma with immunodeficiency.

Host factors and genetic susceptibility to infections due to intracellular bacteria and fastidious organisms.

While genetic polymorphisms play a paramount role in tuberculosis (TB), less is known about their contribution to the severity of diseases caused by other intracellular bacteria and fastidious microorganisms. We searched electronic databases for observational studies reporting on host factors and genetic predisposition to infections caused by intracellular fastidious bacteria published up to 30 May 2014. The contribution of genetic polymorphisms was documented for TB. This includes genetic defects in the mononuclear phagocyte/T helper cell type 1 (Th1) pathway contributing to disseminated TB disease in children and genome-wide linkage analysis (GWAS) in reactivated pulmonary TB in adults. Similarly, experimental studies supported the role of host genetic factors in the clinical presentation of illnesses resulting from other fastidious intracellular bacteria. These include IL-6 -174G/C or low mannose-binding (MBL) polymorphisms, which are incriminated in chronic pulmonary conditions triggered by C. pneumoniae, type 2-like cytokine secretion polymorphisms, which are correlated with various clinical patterns of M. pneumoniae infections, and genetic variation in the NOD2 gene, which is an indicator of tubal pathology resulting from Chamydia trachomatis infections. Monocyte/macrophage migration and T lymphocyte recruitment defects are corroborated to ineffective granuloma formation observed among patients with chronic Q fever. Similar genetic polymorphisms have also been suggested for infections caused by T. whipplei although not confirmed yet. In conclusion, this review supports the paramount role of genetic factors in clinical presentations and severity of infections caused by intracellular fastidious bacteria. Genetic predisposition should be further explored through such as exome sequencing.

Diagnostic et traitement des infections d'implants orthopédiques [Update on implant related infections in orthopaedic surgery. Diagnosis and treatment]

Infections associated with implants are increasingly important in modem medicine. Biofilms are the cause that these infections are more difficult to diagnose and to cure. Particularly low-grade infections are difficult to distinguish from aseptic failure, because they often present with early loosening and persisting pain. For an accurate diagnosis, clinical signs and symptoms, laboratory markers of infection, microbiology, histology and imaging examinations are needed. The treatment goal is eradication of infection and an optimal functional result. Successful treatment requires adequate surgical procedure combined with long-term antimicrobial therapy, ideally with an agent acting on biofilms.

Characteristics of infections associated with external ventricular drains of cerebrospinal fluid.

OBJECTIVES: Manifestations of external ventricular drain (EVD) - associated infections overlap with those of the underlying neurosurgical conditions. We analyzed characteristics of EVD-associated infections. METHODS: We included patients aged ≥18 years with EVD-associated infections from 1997 to 2008, using modified CDC criteria for nosocomial infections. Hospital charts were reviewed retrospectively and the in-hospital outcome was evaluated. RESULTS: Forty-eight patients with EVD-associated infections were included (median age, 52 years, range 20-74 years). The median EVD-indwelling time was 7 days (range, 1-39 days) and EVD-associated infection occurred 6 days after insertion (range, 1-17 days). In 23% of patients, meningitis occurred 1-10 days after EVD removal. Fever >38 °C was present in 79% of patients, but Glasgow Coma Scale (GCS) scores were reduced in only 29%, and headache, vomiting and/or neck stiffness were present in only 31%. The median cerebrospinal fluid (CSF) leukocyte count was higher at onset of EVD-associated infection than at EVD insertion (175 × 10(6)/l versus 46 × 10(6)/l, p = 0.021), but other CSF parameters did not differ significantly. The most commonly implicated organisms were coagulase-negative staphylococci (63%) and Propionibacterium acnes (15%). CONCLUSIONS: Fever and increased CSF leukocytes should raise the suspicion of EVD-associated infection, which may occur up to 10 days after removal of EVD.