Efficacy of leptospiral commercial vaccines on the protection against an autochtonous strain recovered in Brazil

Abstract In swine and bovines, leptospirosis prevention and control is carried out via vaccination of susceptible animals using bacterins. However, the efficiency of leptospirosis vaccines has been questioned. This work aimed to investigate the potency of five leptospirosis vaccines sold commercially in Brazil, challenging the animals with one autochthonous strain of Leptospira, Canicola serovar, denoted LO4, isolated from swine. The standard protocol was followed, and renal carriers of Leptospira were identified among the surviving animals by culture and PCR. Of the five vaccines tested, only two proved effective. None of the surviving animals was positive by culture; however, one animal was positive by PCR. Three of the five vaccines sold commercially in Brazil for the immunization of swine or bovines failed the test of the efficacy to protect the vaccinated animals following challenge with an autochthonous Leptospira strain, Canicola serovar. The two vaccines provided protection against the renal carrier state in the surviving animals. The criteria used to produce leptospirosis bacterins sold commercially in Brazil must be reviewed. The industry should support researches on leptospiral vaccinology to improve the quality of the present vaccines and discover new immunogenic strains, because it is known that vaccination is one of the most important tools to increase the reproduction rates in livestock.

Heterogenic colonization patterns by Leptospira interrogans in Rattus norvegicus from urban slums

Abstract We evaluated the renal colonization by Leptospira interrogans in Rattus norvegicus (rats), as it is the major natural reservoir of urban leptospirosis. We caught 72 R. norvegicus, out of which 32 were found to be positive for L. interrogans by immunofluorescence assay. From these rats, we selected 17 and divided them into six groups based on the mass-age/sex. We performed the immunohistochemistry test against L. interrogans in the kidney sections of the rats and systematically counted the colonized tubules (CTs) in 20 fields. The proportion of positive fields varied from 5% to 95%. The number of CTs in 20 fields varied from 0.5 to 85.5. These differences were not related to age or sex of the animals. The characterization of leptospiral colonization patterns in the natural reservoirs is important to better understand the host-pathogen interactions in leptospirosis.

Cutaneous vasculitis and renal involvement in Mycoplasma pneumoniae infection

No abstract available.

Using a top predator as a sentinel for environmental contamination with pathogenic bacteria: the Iberian wolf and leptospires

The Iberian wolf (Canis lupus) is the top predator in the Iberian environments in which it lives, feeding on a wide range of species, thus encountering a wide range of disease agents. Therefore, the wolf can serve as sentinel of environmental contamination with pathogens. We investigated the exposure of free-living wolves to 14 serovars of Leptospira interrogans sensu lato. Kidney samples from 49 wolves collected from 2010-2013 in northwestern Spain were analysed by culture, direct immunofluorescence and polymerase chain reaction. Tissue fluids were analysed for antibodies by a microscopic agglutination test. Ten wolves (observed prevalence: 20%, 95% confidence interval = 11-33%) showed evidence of contact with leptospires, eight through direct detection and nine through serology (7 wolves were positive according to both techniques). Titres below the cut-off level were also detected in seven cases. Serovars confirmed were Canicola (n = 4), Icterohaemorrhagiae (n = 3) and Sejroë, Ballum and Grippotyphosa (n = 1 each), indicating that wolves were infected with serovars for which dogs, rodents and ungulates, are the natural hosts and supporting the utility of the wolf and other large predators as environmental sentinels for pathogens.

Genotipificación y evaluación de la dinámica de infección de un aislamiento colombiano de Leptospira santarosai en el modelo experimental en hámster / Genotyping and evaluation of infection dynamics in a Colombian isolate of Leptospira santarosai in hamster as an experimental model

Introducción. Es necesario desarrollar modelos de estudio de la leptospirosis. Objetivo. Genotipificar un aislamiento de Leptospira proveniente de una persona con síndrome de Weil y evaluar, con el modelo experimental en Mesocricetus auratus , su dinámica de infección. Materiales y métodos. Se hizo la genotipificación por análisis de las secuencias génicas rrs 16S y lipL32 . Se determinó la dosis letal media en hámster inoculada por vía intraperitoneal. Se identificaron los patrones de química clínica, la duración de la leptospiremia, la leptospiruria y la histopatología, comparados con el mismo modelo inoculado con la cepa de Leptospira interrogans (Fiocruz L1-130). Resultados. Mediante análisis molecular se determinó que el aislamiento correspondía a la especie patógena Leptospira santarosai . La bacteria se recuperó a partir de tejido de riñón y de pulmón, y se detectó por medio de PCR lipL32 en el tercer día después de la infección. La proteína C reactiva aumentó en el quinto día después de la infección (3,25 mg/dl; valor normal: 0,3 mg/dl) con una disminución en el día 18 (2,60 mg/dl; valor normal: 0,8 mg/dl). Los biomarcadores de urea mostraron alteraciones indicativas de falla renal aguda (día 5 después de la infección: 49,01 mg/dl y día 18: 53,71 mg/dl). La histopatología mostró neumonía intersticial con diferentes grados de hemorragia, así como nefritis intersticial. Conclusión. Se identificó la presencia de la especie L. santarosai con capacidad patógena comparable con la cepa Fiocruz L1-130 de L. interrogans , de reconocida virulencia y tropismo pulmonar, en cuanto a los aspectos histopatológicos de tropismo a pulmón y riñón. Nunca antes se había evaluado en un modelo experimental un aislamiento de origen local bajo estos criterios biológicos.

Introduction: Is necessary to develop models for the study of leptospirosis. Objective: To genotype a Colombian strain of Leptospira isolated from a human with Weil´s syndrome and to evaluate its infection dynamics in the hamster experimental model. Materials and methods: Genotyping was performed by amplification and sequence analysis of the rrs 16S and lipL32 genes. The median lethal dose was determined in intraperitoneally inoculated hamsters. The patterns of clinical chemistry, the duration of leptospiremia, leptospiruria and pathological findings were studied and compared in the same animal model infected with L. interrogans (Fiocruz L1-130). Results: Molecular typing revealed that the isolate corresponded to the pathogenic species L. santarosai, which was recovered from hamsters´ kidneys and lungs and detected by lipL32 PCR from day 3 post-infection in these organs. There was a marked increase of C-reactive protein in animals at day 5 post-infection (3.25 mg/dl; normal value: 0.3 mg/dl) with decreases by day 18 (2.60 mg/dl: normal value: 0.8 mg/dl). Biomarkers of urea showed changes consistent with possible renal acute failure (day 5 post-infection: 49.01 mg/dl and day 18 post-infection: 53.71 mg/dl). Histopathological changes included interstitial pneumonia with varying degrees of hemorrhage and interstitial nephritis. Conclusion: The pathogenic species L. santarosai was identified in Colombia. Its pathogenicity as determined by tropism to lung and kidney was comparable to that of L. interrogans Fiocruz L1-130, well known for its virulence and pulmonar tropism. The biological aspects studied here had never before been evaluated in an autochthonous isolate.

Cross-protection between experimental anti-leptospirosis bacterins

We investigated the existence of cross-protection between two anti-leptospirosis monovalent experimental bacterins produced with two strains of Leptospira serogroup Pomona: Fromm strain of serovar Kennewicky, isolated from pigs in the United States, and strain GR6 of serovar Pomona isolated from pigs in Brazil. Both were added of aluminum hydroxide as an adjuvant. Experimental bacterins were tested with the hamster potency test in order to assess protection provided against the disease and against the establishment of kidney infection. Controls were polyvalent commercial vaccine produced with Leptospira strains isolated outside Brazil, which included a representative of Pomona serovar, or Sorensen solution added of aluminum hydroxide adjuvant. The challenge was performed with cross-strains of serogroup Pomona tested in accordance with international standards established for the potency test. After 21 days of the challenge, survivors were killed to evaluate the condition of Leptospira renal carrier. Experimental bacterins protected hamsters against homologous and heterologous strains, demonstrating the existence of cross-protection. The commercial vaccine protected the hamsters challenged with both strains, but there was a high proportion of animals diagnosed as renal carriers when the challenge was performed with strain GR6, isolated from pigs in Brazil.

Histopathological kidney alterations in rats naturally infected with Leptospira / Alteraciones histopatológicas en ratas naturalmente infectadas con Leptospira

Introduction: Histopathological changes by Leptospira in naturally infected rodent reservoirs have been poorly described. Objective: The aim of the current study is to describe renal histopathology associated with leptospirosis infection of naturally infected rodents captured in the urban area of the city of Medellin, Colombia. Materials and methods: We performed hematoxilin-eosin (H-E) on kidney samples collected from 254 captured rodents. The positive samples were processed by Warthin Starry (W-S) staining and PCR- LipL 32. Results: Fifty one rodent kidneys showed H-E histopathological changes that consisted of inflammatory infiltrate with lympho-plasmocitary cells and histiocytes. We performed W-S staining and PCR- LipL 32 to 67 kidney samples, including the 51 that had shown detectable changes by H-E and 16 (8%) of 203 rodents with negative results. Eight of the samples that tested positive for H-E (15.7%) were also positive for W-S staining. All negative for H-E were also negative for W-S staining. Of the W-S positive samples also tested for culture only three tested positive for both. Additionally, 47 (92.1%) samples positive for H-E were positive for PCR; while eleven of the 16 (68.8%) negative for H-E were positive for PCR. The samples positive for PCR were subsequently tested for culture and 11 (23.4%) were positive. Seven samples were positive for PCR and W-S and three were positive for PCR, W-S and culture. All of the PCR- LipL 32 fragments were sequenced and showed specific amplicons for L. interrogans . Conclusions: The Leptospira infection was confirmed in all of the animals tested. The only histological kidney lesion attributable to leptospiral infection in the reservoir was interstitial nephritis.

Introducción. Los hallazgos histopatológicos ocasionados por Leptospira spp. han sido poco estudiados en poblaciones de roedores naturalmente infectados. Objetivo. Describir la histopatología renal asociada con las infecciones naturalmente adquiridas en un grupo de roedores capturados en el área urbana de Medellín, Colombia. Materiales y métodos. Se llevaron a cabo coloraciones de hematoxilina y eosina de los riñones de 254 roedores recolectados en el área de estudio. Las muestras positivas se procesaron con la coloración de Warthin-Starry y mediante reacción en cadena de la polimerasa (PCR)-LipL32. Results. Se observaron cambios histopatológicos con hematoxilina y eosina en 51 riñones de roedores, que consistieron en infiltrado inflamatorio con linfoplasmocitos e histiocitos. Se utilizó coloración de Warthin-Starry y PCR-LipL32 en 67 muestras de riñón que incluyeron las 51 muestras que tuvieron cambios detectables por hematoxilina y eosina y 16 de 203 (8 %) muestras con resultados negativos. Ocho de las muestras positivas por hematoxilina y eosina (15,7 %) también fueron positivas por la coloración de Warthin-Starry. Las muestras negativas por hematoxilina y eosina (8 %) también fueron negativas con la coloración de Warthin-Starry. Tres de las ocho muestras positivas por esta última, también lo fueron por cultivo. Además, 47 (92,1 %) muestras positivas por hematoxilina y eosina fueron positivas por PCR. Del grupo de 16 negativos por hematoxilina y eosina, 11 (68,8 %) fueron positivos por PCR. De las muestras positivas por PCR, 11 también lo fueron por cultivo (23,4 %). Siete muestras fueron positivas por PCR y Warthin-Starry y tres lo fueron por PCR, Warthin-Starry y cultivo. Todos los fragmentos de la PCR-LipL32 fueron secuenciados y mostraron secuencias específicas de L. interrogans . Conclusiones. Se confirmó la infección por Leptospira y la única lesión presente en el reservorio atribuible fue la nefritis intersticial.

Molecular serovar characterization of Leptospira isolates from animals and water in Colombia / Caracterización molecular de serovariedades de Leptospira spp. aisladas de muestras de animales y agua en Colombia

Introduction: Leptospirosis is a bacterial disease transmitted directly or indirectly from animals to humans that may result in severe hemorrhagic, hepatic/renal and pulmonary disease. There are 20 known Leptospira species and hundreds of serovars, some of which belong to different species. It is essential to identify pathogenic Leptospira serovars and their potential reservoirs to prepare adequate control strategies. Objective: To characterize the Leptospira serovars isolated from rodents, dogs, pigs and water samples in Colombia. Materials and methods: Leptospira organisms were isolated and cultured, and pathogenic strains were identified using a polymerase chain-reaction (PCR). Leptospira DNA and Salmonella Braenderup H9812 (molecular weight standard) DNA were cleaved using NotI and subjected to pulsed-field gel electrophoresis (PFGE). The PFGE patterns were analyzed based on bacterial strain-typing criteria and Dice coefficients (DCs) between these isolates and over 200 Leptospira organisms isolated from other parts of the world. Results: All of the isolates were pathogenic strains, and five were genetically characterized. The P275 (84% DC) and P282 (95% DC) pig isolates were related to the Leptospira interrogans Pomona serovar; the I15 (DC: 100%) rat isolate was identical to the Leptospira interrogans Icterohameorrhagiae or Copenhageni serovars, while the C67 (64% DC) dog and A42 (60% DC) water isolates were not related (< 73.7% DC) to any of the 200 reference serovars; the closest serovars were the Leptospira noguchii Nicaragua and Orleans serovars, respectively. Conclusion: This was the first molecular characterization of Colombian Leptospira spp isolates; these isolates will be used to develop a Colombian diagnostic panel.

Introducción. La leptospirosis es una infección bacteriana transmitida directa o indirectamente de animales a humanos, la cual puede resultar en una enfermedad hemorrágica grave, hepática o renal y pulmonar. Hay 20 especies de Leptospira conocidas y cientos de serovariedades, algunas de las cuales pertenecen a diferentes especies. Es esencial identificar las serovariedades patógenas y sus reservorios potenciales para enfocar estrategias de control. Objetivo. Caracterizar las serovariedades de Leptospira aisladas de muestras de roedores, perros, cerdos y agua en Colombia. Materiales y métodos. Las cepas de leptospiras aisladas fueron identificadas como patógenas usando la reacción en cadena de la polimerasa (PRC). Sus ADN y el ADN de Salmonella Braenderup H9812 (marcador de peso molecular) fueron cortados con NotI y corridos en electroforesis de campo pulsado. Los patrones de la ECP se analizaron con base en los criterios de tipificación para cepas bacterianas y el coeficiente de Dice, cuando se compararon con 200 cepas aisladas en otras partes del mundo. Los perfiles de ADN con un coeficiente de Dice entre 73,7 % y 100 % se consideraron pertenecientes a la misma especie. Resultados. Todos los aislamientos fueron cepas patógenas y cinco se caracterizaron genéticamente. El aislamiento P275 (coeficiente de Dice: 84 %) y el P282 (coeficiente de Dice: 95 %) de cerdos, se relacionaron con Leptospira interrogans de serovariedad Pomona; el aislamiento de rata (I15) fue indistinguible de Leptospira interrogans de serovariedades Icterohaemorrhagiae o Copenhageni (coeficiente de Dice: 100 %), mientras que los aislamientos de perro (C67) y agua (A42) no se relacionaron (coeficiente de Dice <73,7 %) con ninguna de las 200 cepas de referencia; las más cercanas fueron Leptospira noguchii de serovariedades Nicaragua (coeficiente de Dice: 63 %) y Orleans (coeficiente de Dice: 60 %). Conclusiones. Esta fue la primera caracterización molecular de serotipos de aislamientos colombianos, los cuales serían los primeros miembros de un panel diagnóstico colombiano.

Comparison of two PCR methods for detection of Leptospira interrogans in formalin-fixed and paraffin-embedded tissues

In this study we compared two polymerase chain reaction (PCR) methods using either 16S ribosomal RNA (rRNA) or 23S rRNA gene primers for the detection of different Leptospira interrogans serovars. The performance of these two methods was assessed using DNA extracted from bovine tissues previously inoculated with several bacterial suspensions. PCR was performed on the same tissues before and after the formalin-fixed, paraffin-embedding procedure (FFPE tissues). The 23S rDNA PCR detected all fresh and FFPE positive tissues while the 16S rDNA-based protocol detected primarily the positive fresh tissues. Both methods are specific for pathogenic L. interrogans. The 23S-based PCR method successfully detected Leptospira in four dubious cases of human leptospirosis from archival tissue specimens and one leptospirosis-positive canine specimen. A sensitive method for leptospirosis identification in FFPE tissues would be a useful tool to screen histological specimen archives and gain a better assessment of human leptospirosis prevalence, especially in tropical countries, where large outbreaks can occur following the rainy season.

Aplicação dos modelos experimentais de camundongos transgênicos e ratos no estudo da interação leptospira-hospedeiro / Application of experimental models of transgenic mice and rats in the study of Leptospira-host interaction

A leptospirose é uma zoonose de importância global. Em nosso meio, a doença associa-se às condições de saneamento precário e pobreza. Sua patogenia permanece pouco compreendida sendo ainda necessário o desenvolvimento de modelos experimentais que esclareçam os mecanismos de disseminação e colonização da leptospira nos tecidos do hospedeiro, bem como a avaliação de determinantes da susceptibilidade e resistência do hospedeiro à doença. Diversos modelos experimentais já foram utilizados no estudo da leptospirose e, especificamente, dois deles foram pouco explorados, incluindo o modelo do rato (Rattus norvegicus), principal hospedeiro de leptospiras patogênicas e protótipo de resistência à doença aguda letal, e o modelo murino, que oferece a vantagem de amplas possibilidades para estudos genéticos e imunológicos. Foi estabelecido o modelo de colonização, avaliação das lesões associadas a este processo e tempo de persistência das leptospiras nos rins. O modelo de ratos foi utilizado para o estudo da cinética de disseminação de leptospiras do primeiro até o nono dia da infecção experimental. Além disso, foram realizados estudos comparativos das lesões renais observadas em ratos de laboratório com aquelãs presentes em ratos da mesma espécie capturados em Salvador, com e sem evidência microbiológica de infecção. Foi avaliado ainda o papel de citocinas através da infecção experimental de camundongos selvagens e com deficiências genéticas específicas. Os animais transgênicos usados foram da linhagem C57BL6, deficientes para os genes do receptor Rp55 do fator de necrose tumoral alfa (TNFRKO) ou do interferon gama (IFNKO), e BALB/c deficientes para o gene da interleucina 4. Os resultados comprovam a reprodutibilidade da infecção renal persistente e resistência de ratos à doença aguda letal. A disseminação é ampla nos tecidos até o quinto dia da infecção sendo seguida por persistência seletiva nos rins, semelhante ao que é descrito em outros modelos de animais susceptíveis à leptospirose. Uma neftite intersticial discreta é o único achado que pode ser atribuível à infecção por leptospiras, visto que é a única reprodutível experimentalmente. A deficiência específica dos genes estudados tem pouco efeito sobre o curso da infecção experimental em camundongos. A maior gravidade da nefrite intersticial nos animais C57BL6 TNFRKO sugere que esta é uma lesão residual provavelmente secundária ao menor controle da disseminação precoce de leptospiras na ausência desta via da imunidade inata. A linhagem C57BL6 apresenta alterações inflamatórias renais com maior freqüência do que a BALB/c. Isto indica que camundongos C57BL6 devem ser priorizados em estudos genéticos na leptospirose experimental por permitir um segundo desfecho a ser avaliado, além da sobrevida.

Recent clinical overview of renal and perirenal abscesses in 56 consecutive cases

BACKGROUND/AIMS: The aim of this study was to examine the recent clinical trends and antibiotic susceptibilities of the causative microorganisms in renal and perirenal abscesses, and to elucidate the factors associated with treatment strategies. METHODS: We retrospectively analyzed 56 patients who were diagnosed with renal and perirenal abscesses at our hospital from January 2000 to September 2007. RESULTS: The mean age of the patients was 53.5 years, and a female predominance of patients (75%) was observed. Diabetes mellitus (44.6%) was the most common predisposing condition. The mean duration of symptoms before diagnosis was 11.6 days, and fever (75%) was the most common symptom. Escherichia coli (44%) and Klebsiella pneumoniae (28%) were common pathogens, and the rates of susceptibility of E. coli isolates to ampicillin, cephalothin, cefotaxime, trimethoprim-sulfamethoxazole, ciprofloxacin, gentamicin, and imipenem were 18.2%, 27.3%, 72.7%, 72.7%, 63.6%, 63.6%, and 100%, respectively. Abscesses were classified according to the location as follows: renal abscess (n=31, 55.4%) and perirenal abscess +/- renal abscess (n=25, 44.6%). In the renal abscess group, the infection rate of gram-negative organisms was higher than in the perirenal abscess group. Patients were also divided according to the treatment modality: antibiotics only (n=20, 35.7%) and percutaneous intervention or surgery (n=36, 64.3%). Patients who had a perirenal abscess or a large renal abscess required more invasive treatment. CONCLUSIONS: This study revealed somewhat different results from those of previous studies. Clinical and microbial differences were observed between the renal and perirenal abscess groups. Abscess location and the size of the renal abscess were the factors associated with treatment strategies.

Identificação da Leptospira interrogans sorovar pomona em camundongos geneticamente selecionados, para a alta e baixa produção de anticorpos, através da técnica de imunoperoxidase em tecido renal e isolamento bacteriano em meio de Fletcher / Identification of Leptospira interrogans serovar pomona in mice genetically selected for high and low antibody production, by means of the immunoperoxidase technique in renal tissue and bacterial isolation in Fletcher medium

O presente trabalho teve por objetivo identificar a presença da Leptospira interrogans sorovar pomona em camundongos geneticamente selecionados para a alta e baixa resposta a anticorpos. Todos os animais foram submetidos ao isolamento bacteriano, imunohistoquímica (imunoperoxidase) em cortes de tecido renal e coloração através da hematoxilina-eosina. A técnica de imunoperoxidase apresentou-se pouco mais sensível em relação ao cultivo, entretanto, ambas foram bons parâmetros de identificação do agente. Presença de lesões renais mais intensas ocorreram em períodos em que houve maior número de bactérias isoladas em meio de cultivo. Camundongos da linhagem HIV-A conseguiram eliminar as leptospiras com maior eficiência e rapidez em relação as linhagem LIV-A, entretanto o estudo demonstrou que ambas linhagens da seleção IV-A foram eficientes em controlar o processo infeccioso.

The present work had the objective of identifying the presence of Leptospira interrogans serovar pomona in mice that had been genetically selected for high and low response to antibodies. All the animals were subjected to bacterial isolation, immunohistochemical analysis (immunoperoxidase) in renal tissue sections and hematoxylin-eosin staining. The immunoperoxidase technique was little more sensitive than culturing, but both were good parameters for agent identification. More severe renal lesions were present at times when there were greater numbers of bacteria isolated in culture medium. Mice of the lineage HIV-A were able to eliminate the Leptospira more efficiently and faster than the lineage LIV-A could. However, the study demonstrated that both lineages of the IV-A selection were efficient in controlling the infectious process.

Mucormicosis renal aislada / Isolated renal mucormicosis

La mucormicosis es una infección causada por hongos de la clase Zygomycetes. Existen varias formas de presentación clínica, siendo las más comunes la rinocerebral y la pulmonar. La mucormicosis renal aislada es un tipo de mucormicosis muy poco frecuente hasta el momento; se han reportado 25 casos en la literatura. Se presenta el caso de una paciente con leucemia aguda que desarrolló mucormicosis renal aislada, y se revisa la literatura.

Mucormycosis is an infection caused by a class Zygomycetes fungi. The rhinocerebral and pulmonary are the most common clinical presentations. Renal mucormycosis is a very rare form. To date, only 25 cases have been reported in the literature. We describe the case of a patient with leukemia who developed isolated renal mucormycosis and review the literature.

Efecto del herbicida ácido 2, 4-Diclorofenoxiacético sobre la fimbriación de bacterias uropatógenas / Effect of the herbicide 2, 4-Dichlorophenoxyacetic acid on fimbriation of uropathogenic bacteria

Existen algunos datos epidemiológicos que demuestran que, en poblaciones rurales, la frecuencia de lesiones inflamatorias de origen infeccioso en el riñón es mayor en individuos expuestos a pesticidas. Estudios previos han demostrado que el herbicida 2,4-D altera las propiedades de adherencia bacteriana a riñón, mediada por fimbrias de Escherichia coli uropatógena, si bien aún no se ha estudiado el mecanismo que podría estar involucrado. El 2,4-D demostró capacidad de generar uniones covalentes a proteínas de bacilos gram negativos. Debido a este hallazgo, se hipotetizó que la unión del herbicida a proteínas involucradas en la síntesis, exportación o ensamble de las subunidades fimbriales podía alterar la expresión de las fimbrias. En este trabajo se demuestra una unión covalente del herbicida a proteínas de membrana externa de Escherichia coli uropatógena y paralelamenteuna disminución de la fimbriación, determinada por tres técnicas diferentes: hemoaglutinación, cuantificación de proteínas de superficie y microscopía electrónica. Una conclusión importante está referida a que la exposición accidental detrabajadores rurales al 2,4-D en muy bajas dosis y durante un corto período de tiempo tendría un efecto protector de la pielonefritis por disminución de la fimbriación; mientras que los altos niveles de exposición predispondrían a la recurrencia del proceso infeccioso en el modelo de la pielonefritis ascendente no obstructiva en ratón (Balagué et al 2002). Probablemente los estudios epidemiológicos que asocian exposición a los herbicidas e infección renal estén relacionados con este último tipo de exposiciones.

Epidemiological data demonstrate, on rural populations, that the frequency of inflammatory lesions in renal tissue is higher for individuals exposed to pesticides. Previous studies demonstrated that the herbicide 2,4-D altered the bacterial adherence properties to renal tissue, mediated by fimbriae in uropathogenic Escherichia coli, but the mechanism involved is still unknown. The acid 2,4-D has the ability to perform covalent bonds to proteins in gram-negative bacteria. Because of this fact, we hypothesized that the 2,4-D acid binds proteins involved in the synthesis, export or ensemble of fimbrial subunits, modifying fimbrial expression. In this work we demonstrated a covalent bond of the herbicide to outer membrane proteins in uropathogenic E. coli and a paralleldecrease of fimbriation, assayed by three different methods: hemmaglutination, surface protein quantification and electronmicroscopy. An important conclusion is that the accidental exposure of rural workers to 2,4-D may have a protective effect by a decrease in fimbriation, when it is used in low doses and during a short period of exposure. But, it must be considered that high doses and several days of exposure had adverse effects, like recurrence of infection, in the mouse model of ascendingpyelonephritis (Balagué et al, 2002). Probably, the epidemiological studies that associate the herbicide exposure with renal infection were due to the last kind of exposure described.

Papel de la Toxina Shiga en el sindrome urémico hemolítico / Role of the Shiga toxin in the hemolytic uremic syndrome

In the last years, infection associated with Shiga toxin-producing Escherichia coli (STEC) and subsequent Hemolitic-Uremic Syndrome (HUS) became relevant as a public health since it was considered as one of the most important emergent patogen present in the food contaminated by cattle feces. STEC infection may be asymptomatic or begins with a watery diarrhea that may or may not progress to bloody diarrhea (hemorrhagic colitis) and HUS. In Argentina, HUS is the most common pediatric cause of acute renal insufficiency and the second cause of chronic renal failure. Up to now, STEC infection lacks of known effective treatment strategies that diminish risk of progression to HUS. The mechanisms by which Shiga toxin (Stx) induce HUS may help to find strategies to prevent or ameliorate HUS. In this article, recent progress that has contributed to understanding the disease pathogenesis of STEC is reviewed. New strategies to prevent further uptake of Shiga from the gut, either during the diarrheal phase or once HUS has developed are discussed.

Candidiosis hepato-renal y de músculos paravertebrales por Candida famata resistente a anfotericina B fluconazol / Hepatosplenorenal and paravertebral muscle infection caused by amphotericin B fluconazole resistant Candida famata

Introducción. Candidiosis sistémica tiene una mortalidad de 60-80 por ciento, aumenta cuando es causada por Candida sp. resistente a los antimicóticos convencionales. Objetivo: presentar la evolución clínica de un caso pediátrico de candidiosis sistémica. Caso clínico. Niña de 3 años de edad con diagnóstico en marzo de 1996 de linfoma no Hodgkin. Con quimioterapia de consolidación y rescate. Ingresó el 12 de junio de 1998 con neutropenia grave, afebril, y cistitis hemorrágica. Se manejó inicialmente con antibióticos de amplio espectro. Al séptimo día, con 6 días febril se inició anfotericina B. Al noveno día se observaron abscesos en dorso de mano izquierda, pliegue de codo y antebrazo derecho. Los cultivos de aspirado de los abscesos, hemocultivo central/periférico, urocultivo y coprocultivo reportaron levaduras. El aislamiento en tubo germinativo fue negativo. El ultrasonido y la tomografía axial computada abdominal reportaron lesiones parenquimatosas en hígado, con múltiples lesiones hipoecoicas en bazo, riñón y músculos paravertebrales. Confirmándose por biopsia de bazo. Mediante API 20 C AUX se identificó Candida famata. La sensibilidad reportó resistencia a anfotericina B 2 µg/mL (normal: £ 1), fluconazol 64 µg/mL (normal: £ 16) y susceptible a 5-fluocitosina 12.5 µg/mL (normal: £ 25). Se adicionó rifampicina y 5-fluocitocina. El control tomográfico demostró disminución del tamaño de los abscesos. Falleció por un evento de choque séptico asociado a Staphylococcus epidermidis. La autopsia reportó persistencia de levaduras. Conclusiones. La respuesta a la anfotericina B es pobre cuando se trata de Candida diferente a Candida albicans.

A associaçäo entre a toxocaríase humana e os abscessos piogênicos / The association of human toxocariasis and pyogenic abscesses

A associaçäo entre o abscesso hepático e a esquistosomose mansônica foi confirmada por estudos clínicos e experimentais. Outros parasitos, como a larva de Toxocara canis, podem causar alteraçöes imunológicas sistêmicas e estruturais nos órgaos acometidos que favorecem a instalaçäo e o crescimento da bactéria. A piomiosite tropical, o abscesso hepático piogênico e o abscesso renal säo doenças freqüentes nos países tropicais e muitas vezes näo se encontra doença de base que poderia explicá-las. A síndrome de larva migrans visceral é causada pela presença no organismo humano de larvas de vermes que têm outros animais como hospedeiro definitivo sendo a T. canis o agente mais comum. As larvas migram por vários órgäos causando reaçäo inflamatória na forma de granuloma com necrose tecidual. Nesta revisäo discutem-se os possíveis mecanismos de interaçäo entre o hospedeiro, o parasito e a bactéria que podem favorecer a formaçäo de abscessos nos órgäos acometidos pela larva de T. canis e resumem-se alguns resultados preliminares de trabalho clínico-experimental realizado durante os últimos quatro anos para definir o papel deste parasito na patogenia dos abscessos

Estudo da translocaçäo bacteriana após sutura primária de colo com e sem limpeza mecânica: trabalho experimental em cäes / Bacteria translocation study after primary colocolonic suture with and without mechanical purging in dogs

O objetivo do presente trabalho foi investigar a ocorrencia de translocaçäo bacteriana em cäes submetidos a suturas colocólicas primárias, no colo descendente, com e sem limpeza intestinal. Para o estudo, foram utilizados três grupos de oito animais. O Grupo I (obs. de 1 a 8) foi utilizado como grupo-controle. Nesse grupo, os animais foram submetidos à laparotomia sob anestesia geral, exposiçäo das alças intestinais ao ar ambiente da sala cirúrgica pelo período de cinco minutos. No Grupo II (obs. de 9 a 16), realizou-se colotomia e sutura colocólica primária, sem limpeza do conteúdo cólico e fechamento da parede abdominal. No Grupo III (obs. de 17 a 24), realizou-se colotomia, limpeza do reto, limpeza do colo por meio de lavagem mecânica transoperatória retrógrada, seguida de sutura colocólica terminoterminal e fechamento da parede abdominal. Todos os animais foram mantidos em observaçäo pelo período de 24 horas. Após esse período foi realizada a coleta de amostras de sangue e amostras de linfonodo mesentérico, do fígado, baço, rim e pulmäo para realizaçäo de culturas. As culturas foram realizadas em meios específicos para Escherichia coli e Enterococcus faecalis. Os resultados foram: näo ocorreu translocaçäo bacteriana para o sangue portal nos Grupos II e III. Ocorreu translocaçäo bacteriana para os linfonodos, fígado, baço, rim e pulmäo nos Grupos II e III. Observaram-se índices de translocaçäo bacteriana mais elevados no Grupo II do que no Grupo III, porém sem significância estatística. A Escherichia coli foi a bactéria isolada nas culturas positivas dos Grupos II e III

Surveillance of leptospiral carriage by feral rats in Barbados

Rodents, particularly rats, are widely held to be the source of most human cases of leptospirosis. Feral rats were trapped at sites throughout Barbados during two six month surveys: from October to March 1986/87 and from October to March 1994/95. During the first survey, 63 rats were trapped, of which 26 (41) were identified as Rattus rattus and 37 (59) as Rattus norvegicus. In the second study, 100 rats were trapped, of which R. rattus comprised 24(24) and R. norvegicus 76(76). Cultures of blood, urine and kidney were made in EMJH medium. Leptospires were isolated from 12/63 (19) and from 16/100 (16) of the rats during 1986/87 and 1994/95, respectively; 27/28 isolates were recovered from the kidneys or urine or both, while only one isolate was recovered from the blood. During the first study, isolates were identified as serovars copenhageni (11) and arborea (1), while in the second study, serovars copenhageni (9), arborea (5) and bim (1) were identified; one isolate was lost before it could be identified. In the first study, antibodies were detected by microscopic agglutination at a titre of > or = 100 in 26/62 (42) of rats tested, while in the second survey, 5/100 (5) of rats had similar titres. In two surveys, conducted eight years apart, we confirmed that rats in Barbados are commonly infected with leptospires, and that viable organisms are found in the kidneys and urine, evidence of chronic infection and thus excretion of leptospires in rodent urine. Moreover, the predominant serovar isolated was copenhageni, of which Rattus spp. are the worldwide reservoir. There was little evidence that rats act as a reservoir for the serovar bim, the most common cause of human leptospirosis in Barbados.