b Shiga toxin-producing Escherichia coli O157:H7 (STEC) is by far the most prevalent serotype associated with hemolytic uremic syndrome (HUS) although many non-O157 STEC strains have been also isolated from patients with HUS. The main virulence factor of STEC is the Shiga toxin type 2 (Stx2) present in O157 and non-O157 strains. Recently, another toxin, named subtilase cytotoxin (SubAB), has been isolated from several non-O157 strains and may contribute to the pathogenesis of HUS. Here, we have demonstrated that an O113:H21 STEC strain expressing SubAB and Stx2 inhibits normal water absorption across human colon and causes damage to the surface epithelium, necrosis, mononuclear inflammatory infiltration, edema, and marked mucin depletion. This damage was less marked, but nevertheless significant, when purified SubAB or E. coli O113:H21 expressing only SubAB was assayed. This is the first study showing that SubAB may directly participate in the mechanisms of diarrhea in children infected with non-O157 STEC strains. Shiga toxin-producing Escherichia coli (STEC) strains colonize the human colon and may cause systemic complications such as hemolytic uremic syndrome (HUS) (1, 2). HUS develops in 5 to 10% of children several days after bloody diarrhea and is a systemic disease characterized by thrombotic microangiopathy, hemolytic anemia, thrombocytopenia, and acute renal failure. HUS is the most common cause of acute renal failure in children and the second leading cause of chronic renal failure in children younger than 5 years old (3, 4). STEC O157:H7 is by far the most prevalent serotype associated with HUS although non-O157 STEC strains have been also isolated from children with HUS (5, 6). The main virulence factor of STEC is the Shiga toxin type 2 (Stx2) present in O157 and non-O157 strains (7,8). Unlike O157:H7 strains, some non-O157 STEC strains, among them O113:H21, lack the locus of enterocyte effacement (LEE) but encode additional proteins in order to adhere to intestinal epithelial cells (9). Recently, it has been reported that certain LEE-negative STEC strains produce another cytotoxin, named subtilase cytotoxin (SubAB), which may contribute to the pathogenesis of HUS. SubAB is toxic for eukaryotic cells, and its mechanism of action involves highly specific A-subunit-mediated proteolytic cleavage of the essential endoplasmic reticulum chaperone BiP (10, 11). To date, the in vivo effects of SubAB have only been examined in mice. Gut colonization with recombinant E. coli expressing subAB genes did not cause diarrhea but produced a dramatic weight loss over a 6-day period (11). Interestingly, intraperitoneal injection of purified SubAB caused microangiopathic hemolytic anemia, thrombocytopenia, and renal impairment, characteristics typical of Stxinduced HUS (12). These findings raise the possibility that SubAB directly contributes to pathology in humans infected with STEC strains that produce both Stx and SubAB.The purpose of the present study was to examine the physiological and morphological effects of STE...
The aim of this study was to set up a simple protocol to concentrate SARS-CoV-2 from sewage, which can be implemented in laboratories with minimal equipment resources. The method avoids the need for extensive purification steps and reduces the concentration of potential inhibitors of RT-qPCR contained in sewage. The concentration method consists of a single step, in which a small volume (40 mL) of sewage sample is incubated with polyaluminum chloride (PAC)(0.00045 N Al 3+ final concentration). Virus particles adsorbed to the precipitate are collected by low-speed centrifugation, after which the recovered pellet is resuspended with a saline buffer. PAC concentrated samples are stable for at least one week at 4 °C. Therefore, they may be sent refrigerated to a diagnosis center for RNA extraction and RT-qPCR for SARS-CoV-2 RNA detection if the lab does not have such capabilities. The PAC concentration method produced an average shift of 4.5-units in quantification cycle (Cq) values compared to non-concentrated samples, indicating a 25-fold increase in detection sensitivity. The lower detection limit corresponded approximately to 100 viral copies per ml. Kappa index indicated substantial agreement between PAC and polyethylene glycol (PEG) precipitation protocols (k = 0.688, CI 0.457-0.919). This low-cost concentration protocol could be useful to aid in the monitoring of community circulation of SARS-CoV-2, especially in low- and middle-income countries, which do not have massive access to support from specialized labs for sewage surveillance.
According to the World Health Organization, carbapenem-resistant Enterobacteriaceae (CRE) belong to the highest priority group for the development of new antibiotics. Argentina-WHONET data showed that Gram-negative resistance frequencies to imipenem have been increasing since 2010 mostly in two CRE bacteria: Klebsiella pneumoniae and Enterobacter cloacae Complex (ECC). This scenario is mirrored in our hospital. It is known that K. pneumoniae and the ECC coexist in the human body, but little is known about the outcome of these species producing KPC, and colonizing or infecting a patient. We aimed to contribute to the understanding of the rise of the ECC in Argentina, taking as a biological model both a patient colonized with two KPC-producing strains (one Enterobacter hormaechei and one K. pneumoniae) and in vitro competition assays with prevalent KPC-producing ECC (KPC-ECC) versus KPC-producing K. pneumoniae (KPC-Kp) high-risk clones from our institution. A KPC-producing E. hormaechei and later a KPC-Kp strain that colonized a patient shared an identical novel conjugative IncM1 plasmid harboring blaKPC-2. In addition, a total of 19 KPC-ECC and 58 KPC-Kp strains isolated from nosocomial infections revealed that high-risk clones KPC-ECC ST66 and ST78 as well as KPC-Kp ST11 and ST258 were prevalent and selected for competition assays. The competition assays with KCP-ECC ST45, ST66, and ST78 versus KPC-Kp ST11, ST18, and ST258 strains analyzed here showed no statistically significant difference. These assays evidenced that high-risk clones of KPC-ECC and KPC-Kp can coexist in the same hospital environment including the same patient, which explains from an ecological point of view that both species can exchange and share plasmids. These findings offer hints to explain the worldwide rise of KPC-ECC strains based on the ability of some pandemic clones to compete and occupy a certain niche. Taken together, the presence of the same new plasmid and the fitness results that showed that both strains can coexist within the same patient suggest that horizontal genetic transfer of blaKPC-2 within the patient cannot be ruled out. These findings highlight the constant interaction that these two species can keep in the hospital environment, which, in turn, can be related to the spread of KPC.
The aim of this study was to set up a simple protocol to concentrate SARS-CoV-2 from sewage, which can be implemented in laboratories with minimal equipment resources. The method avoids the need for extensive purification steps and reduces the concentration of potential inhibitors of RT-qPCR contained in sewage. The concentration method consists of a single step, in which a small volume of sewage sample is incubated with polyaluminum chloride (PAC). Virus particles adsorbed to the precipitate are collected by low-speed centrifugation, after which the recovered pellet is resuspended with a saline buffer. The PAC concentration method produced an average shift of 4.4-units in Cq values compared to non-concentrated samples, indicating a 25-fold increase in detection sensitivity. The lower detection limit corresponded approximately to 100 copies per ml. Kappa index indicated substantial agreement between PAC and PEG precipitation protocols (k=0.688, CI 0.457-0.919). PAC concentrated samples can be processed immediately for RNA purification and qPCR or sent refrigerated to a diagnosis center, where SARS-CoV-2 detection should be performed in the same way as for clinical samples. This low cost protocol could be useful to aid in the monitoring of community circulation of SARS-CoV-2, especially in low- and middle-income countries, which do not have massive access to support from specialized labs for sewage surveillance.
In this article we analyze the debates and political disputes in the Second International about the Jewish Question as a national question. We focus on different political organizations of various zones of Eastern Europe: The Russian Empire, where we address the relations between the Bund and the rest of Russian Social Democracy; the polish zone of the Empire (Congress Poland), where we analyze the relations between the Bund, Polish Social Democracy and the Polish Socialist Party (PPS); finally, we focus on the Province of Galitzia, in that moment a part of Austria, to assess the struggle between the Polish Social Democratic Party of Austria (part of the All-Austrian party) and the Jewish activists that, coming from this party, broke with it to create a Jewish party of bundist orientation. In all the examined cases we combine an analysis of the positions that these different organizations developed over time about the Jewish national question, framed in their general disputes and debates. We focus in their positions about the existence of a Jewish nationality, their position on the future of Jewish population (assimilationist, neutralist, nationalist, etc.) and the relationship of these questions with a general position on the national question. This work focuses in analyzing the regions where different positions on the convenience of a separate Jewish socialist organization emerged, a factor that stimulated the whole debate on the Jewish National Question. We finish by analyzing the struggle that some socialist Jewish organizations fought to be recognized by the Second International and the international connections between the different postures.
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