Toxoplasma gondii infection damages the perineuronal nets in a murine model.

BACKGROUND: Behavioral and neurochemical alterations associated with toxoplasmosis may be influenced by the persistence of tissue cysts and activation of an immune response in the brain of Toxoplasma gondii-infected hosts. The cerebral extracellular matrix is organised as perineuronal nets (PNNs) that are both released and ensheath by some neurons and glial cells. There is evidences to suggest that PNNs impairment is a pathophysiological mechanism associated with neuropsychiatric conditions. However, there is a lack of information regarding the impact of parasitic infections on the PNNs integrity and how this could affect the host's behavior. OBJECTIVES: In this context, we aimed to analyse the impact of T. gondii infection on cyst burden, PNNs integrity, and possible effects in the locomotor activity of chronically infected mice. METHODS: We infected mice with T. gondii ME-49 strain. After thirty days, we assessed locomotor performance of animals using the open field test, followed by evaluation of cysts burden and PNNs integrity in four brain regions (primary and secondary motor cortices, prefrontal and somesthetic cortex) to assess the PNNs integrity using Wisteria floribunda agglutinin (WFA) labeling by immunohistochemical analyses. FINDINGS AND MAIN CONCLUSIONS: Our findings revealed a random distribution of cysts in the brain, the disruption of PNNs surrounding neurons in four areas of the cerebral cortex and hyperlocomotor behavior in T. gondii-infected mice. These results can contribute to elucidate the link toxoplasmosis with the establishment of neuroinflammatory response in neuropsychiatric disorders and to raise a discussion about the mechanisms related to changes in brain connectivity, with possible behavioral repercussions during chronic T. gondii infection.

Effect of toxoplasmic infection on the biodistribution of a brain radiopharmaceutical.

Purpose: This study evaluated if Toxoplasma gondii infection and the drug-associated infection modifies the brain radiopharmaceutical Ethylene Cystine Diethylester Dihydrochloride (99mTc-ECD) biodistribution in mice.Materials and methods: A total of 18 mice were divided into 3 groups. Control group (C) received distilled water and 99mTc-ECD; Infected group (I) received T. gondii strain and 99mTc-ECD; Infected and Treated group (IT), in addition to infection, received association of Pyrimethamine and Sulfadiazine and 99mTc-ECD. The T. gondii strain used in this study was TgCkRrRN3. Forty minutes after administration of the 99mTc-ECD, all animals were euthanized, and blood and brain samples were isolated. The counting of the radioactivity percentage per gram of tissue (%ATI/g) was calculated, and statistical analysis was performed by t-test, with a level of significance of p < .05.Results: There was a significant increase in %ATI/g between groups C and I on brain (0.35 ± 0.02 and 0.45 ± 0.04; p = .041) and on blood (0.80 ± 0.09 and 1.14 ± 0.31; p = .049). A significant decrease in %ATI/g occurred between groups C and IT on blood (0.80 ± 0.09 and 0.54 ± 0.08; p = .001) and on brain (0.35 ± 0.02 and 0.22 ± 0.04; p = .049).Conclusions: Combined therapy of anti-Toxoplasma drugs in infected mice reduced the uptake of 99mTc-ECD, probably due to its binding to plasma proteins.

The influence of salt intake on the course of experimental toxoplasmosis in outbred or inbred mouse strains

Many environmental factors contribute to an effective immune response against Toxoplasma gondii (Tg) infection, among which diet is important in triggering the immune response of the host to infection. Emerging reports suggest that salt intake undermines the regulatory mechanisms mediated by innate and adaptive immune cells. Unfortunately, the impact of an Intermediate Salt Diet (ISD) on the pathogenesis and immune response to toxoplasmosis remains unclear. The purpose of this study was to evaluate the susceptibility profile to an ISD (NaCl 2%) of two mouse strains (outbred Swiss and inbred C57BL6) infected by the ME49 strain of Tg. Our data confirm an antagonistic susceptibility to oral Tg infection among the two mouse strains. Sodium intake induced the highest mortality in C57BL6 compared to Swiss mice in the infected groups. A simultaneous ISD with the infection did not induce significant differences in body weight in either mouse strains. Both mouse strains showed an antagonistic response to a sodium intake diet on the number of parasite brain cysts. An increased number of brain cysts in C57BL6 ISD-Tg animals were noted while Swiss ISD-Tg animals presented a decrease in the number of brain cysts compared to NSD-Tg (Normal Salt Diet) for both mouse strains. Furthermore, sodium intake caused a significant reduction in the specific humoral immune response against Tg in inbred C57BL6 mice. Thus, our data reveal that an ISD affects the humoral immune response in the murine model and influences the course of Tg infection.

Frequência e perfil de resistência de Klebsiella spp. em um hospital universitário de Natal/RN durante 10 anos / Frequence and resistance profile of Klebsiella spp. isolates in a university hospital in Natal/RN during a ten-year period

INTRODUÇÃO: As espécies de Klebsiella spp. podem causar vários tipos de infecções, principalmente hospitalares, e têm merecido destaque pelos seus variados e emergentes mecanismos de resistência. OBJETIVOS: Determinar a frequência de isolamento e a caracterização do perfil de resistência de Klebsiella spp. em um hospital universitário durante um período de 10 anos e, ainda, avaliar a tendência para o crescimento dessa resistência. Material e método: Fez-se um estudo descritivo e retrospectivo a partir de dados coletados nos livros de registro do Laboratório de Microbiologia Clínica do hospital investigado, correspondentes ao período de janeiro de 1999 a dezembro de 2008. RESULTADO: A frequência de isolamento de Klebsiella spp. foi de 13,4 por cento com predominância em uroculturas (56,4 por cento). Houve aumento significativo na resistência para a maioria dos antimicrobianos testados ao longo do período analisado com tendência para o crescimento da mesma. Nesse período, isolou-se 23 por cento de Klebsiella spp. com fenótipo produtor de betalactamases de amplo espectro (ESBL). DISCUSSÃO: O isolamento de Klebsiella spp. resistente a antimicrobianos em amostras de origem clínica e a detecção da tendência do crescimento da resistência, inclusive às drogas de reserva terapêutica, são motivos de grande preocupação. Nesse hospital, a implantação de métodos de triagem e de confirmatórios para os mecanismos de resistência de Klebsiella spp. poderiam auxiliar no diagnóstico e no tratamento das infecções causadas por esse microrganismo. CONCLUSÃO: A tendência de crescimento na resistência aos antibióticos detectada neste estudo reforça a importância de monitoramentos contínuos. Estes elucidam características locais, orientando para melhores medidas de controle.

INTRODUCTION: Klebsiella spp. species can cause several infections, particularly nosocomial ones. Furthermore, its multiple emerging resistance mechanisms have been widely described. OBJECTIVES: To determine the isolation frequency and resistance profile of Klebsiella spp. at a university hospital during a ten-year period as well as to assess the increase in its resistance. Material and method: A retrospective and descriptive study was carried out based on data collected from the record books of the Laboratory of Clinical Microbiology of the investigated Hospital from January 1999 to December 2008. RESULTS: The isolation frequency of Klebsiella spp. was 13.4 percent, predominantly in urine cultures (56.4 percent). There was a significant increase in resistance to most antimicrobials tested over the analyzed period; 23 percent of Klebsiella spp. with ESBL phenotype was isolated over this period. DISCUSSION: Multi-resistant Klebsiella spp. isolates from clinical samples as well as its growing trend in resistance mechanisms, including to reserve drugs, are cause for great concern. The implementation of screening and confirmatory methods of bacterial resistance could aid in the diagnosis and treatment of infections caused by this microorganism. CONCLUSION: The increase in resistance to antibiotics reinforces the importance of continuous monitoring, which elucidates local characteristics and allows more suitable control measures.