Developing δ15N and δ13C isoscapes using whole blood from Magellanic penguins, Spheniscus magellanicus.

RATIONALE: Understanding the migration of marine animals is hindered by the limitations of traditional tracking methods. It is therefore crucial to develop alternative methods. Stable isotope-based tracking has proven useful for this task, although it requires detailed isoscapes in the focal area. Here, we present predator-based isoscapes of the coastal zone of the Patagonian Shelf Large Marine Ecosystem (PSLME), which offers a novel tool for geolocation. METHODS: Whole-blood samples from breeding Magellanic penguins nesting at 11 colonies were used to create δ15N and δ13C isoscapes. Isotopic values were assigned to random positions inside their corresponding foraging area. Spatial analysis and data interpolation resulted in δ15N and δ13C isoscapes for the coastal zone of the PSLME, which were validated through cross-validation. RESULTS: The isoscapes mean standard error ranged from 0.05 to 0.41 for δ15N and from 0.07 to 0.3 for δ13C, similar to the error range of the mass spectrometer used for measuring isotope ratios. Predictive surfaces reflected the latitudinal trends, with δ13C and δ15N values increasing northwards. δ13C values showed a strong latitudinal gradient, while δ15N values had two distinct domains, with higher values in the north. The error surface indicated the highest certainty within 130 km from the shore and within the reported Magellanic penguin foraging areas. CONCLUSIONS: Both isoscapes revealed strong spatial variation. The δ13C isoscape showed a latitudinal gradient, consistent with patterns in other oceans. The δ15N isoscape clearly separated northern and southern colonies, likely influenced by nitrogen sources. The error obtained fell within the measurement error ranges, adding credibility to the models.

Methicillin-Resistant Staphylococcus aureus and Coagulase-Negative Staphylococcus from School Dining Rooms in Argentina.

Methicillin-resistant Staphylococcus aureus (MRSA) constitutes an important cause for concern in the field of public health, and the role of the food chain in the transmission of this pathogen and in antimicrobial resistance (AMR) has not yet been defined. The objectives of this work were to isolate and characterize coagulase-positive Staphylococcus (CoPS) and coagulase-negative Staphylococcus (CoNS), particularly S. aureus, from school dining rooms located in Argentina. From 95 samples that were obtained from handlers, inert surfaces, food, and air in 10 establishments, 30 Staphylococcus strains were isolated. Four isolates were S. aureus, and the remaining ones (N = 26) belonged to 11 coagulase-negative species (CoNS). The isolates were tested for susceptibility to nine antibiotics. The presence of genes encoding toxins (luk-PV, sea, seb, sec, sed, and see), adhesins (icaA, icaD), and genes that confer resistance to methicillin (mecA) and vancomycin (vanA) was investigated. The resistance rates measured for penicillin, cefoxitin, gentamicin, vancomycin, erythromycin, clindamycin, levofloxacin, trimethoprim-sulfamethoxazole, and tetracycline were 73%, 30%, 13%, 3%, 33%, 17%, 13%, 7%, and 7% of the isolates, respectively. Seventeen AMR profiles were detected, and 11 isolates were multidrug resistant (MDR). Seven methicillin-resistant Staphylococcus isolates were detected in the hands of handlers from four establishments, two of them were MRSA. Two S. aureus isolates presented icaA and icaD, another one, only icaD. The gene vanA was found in two isolates. In relation to S. aureus, resistance to vancomycin but not to gentamicin was detected. School feeding plays a key role in the nutrition of children, and the consumption of food contaminated with MRSA and vancomycin-resistant S. aureus (VRSA) can be a serious threat to health. In particular, it was detected that the handlers were the source of MRSA, VRSA, MR-CoNS (methicillin-resistant coagulase-negative Staphylococcus), and MDR isolates. The results obtained indicate that the vigilance of this pathogen in school dining rooms should be extreme.

The Clinical Impact of Thoracic Endovascular Aortic Repair in the Management of Thoracic Aortic Diseases.

PURPOSE: Thoracic endovascular aortic repair (TEVAR) has been described to be superior to an open surgical approach, and previous studies have found superiority in TEVAR by reducing overall morbidity and mortality rates. This study aimed to describe the outcomes of TEVAR for patients with thoracic aortic disease at a high complexity. MATERIALS AND METHODS: Descriptive study, developed by a retrospective review of a prospectively collected database. Patients aged above 18 years who underwent TEVAR between 2012 and 2022 were included. Patient demographics, perioperative data, surgical outcomes, morbidity, and mortality were described. Statistical and multivariate analyses were made. Statistical significance was reached when p values were <0.05. RESULTS: A total of 66 patients were included. Male patients were 60.61% and the mean age was 69.24 years. Associated aortic diseases were aneurysms (68.18%), ulcer-related (4.55%), intramural-related hematoma (7.58%), trauma-related pathology (1.52%), and aortic dissection (30.30%). The mean hospital stay was 18.10 days, and intensive care unit was required for 98.48%. At 30 days, the mortality rate was 10.61% and the reintervention rate was 21.21%. Increased intraoperative blood loss (p=0.001) and male sex (p=0.04) showed statistical relationship with mortality. Underweight patients have 6.7 and 11.4 times more risk of complications and endoleak compared with higher body mass index values (p=0.04, 95% confidence interval [CI]=0.82-7.21) and (p=0.02, 95% CI=1.31-12.57), respectively. CONCLUSION: Thoracic endovascular aortic repair seems to be a feasible option for patients with thoracic aortic pathologies, with adequate rates of mortality and morbidity. Underweight patients seem to have an increased risk of overall morbidity and increased risk for endoleak. Further prospective studies are needed to prove our results. CLINICAL IMPACT: Obesity and BMI are widely studied in the surgical literature. According to our study, there is a paradox regarding the outcomes of patients treated with TEVAR in terms of postoperative complications and mortality related to the body mass index. And shouldn't be considered as a high-risk feature in terms of postoperative morbidity and mortality in this procedure.

Occurrence and genetic characterization of Shiga toxin-producing Escherichia coli on bovine and pork carcasses and the environment from transport trucks.

Shiga toxin-producing Escherichia coli (STEC) are foodborne pathogens causing severe diseases. The ability of STEC to produce disease is associated with Shiga toxin (Stx) production. We investigated the occurrence of STEC on bovine and pork carcasses and walls of trucks where they were transported, and we characterized virulence genes and serotypes of STEC strains. We compared the whole genomic sequencing of a STEC O157:H7 strain isolated from a bovine carcass in this work and a STEC O157:H7 strain isolated from a child with HUS, both isolated in 2019. We studied the relationship between these isolates and others collected in the database. The results show a 40% of STEC and two different serogroups were identified (O130 and O157). STEC O157:H7 were isolated from bovine carcasses and harbored stx2, eae, ehxA, katP, espP, stcE, ECSP_0242/1773/2687/2870/2872/3286/3620 and were classified as lineage I/II. In STEC non-O157 isolates, three isolates were isolated from bovine carcasses and harbored the serogroup O130 and one strain isolated from pork carcasses was O-non-typeable. All STEC non-O157 harbored sxt1 gene. The analysis from the whole genome showed that both STEC O157:H7 strains belonged to the hypervirulent clade 8, ST11, phylogroup E, carried the allele tir 255 T > A T, and they were not clonal. The analysis of information allows us to conclude that the STEC strains circulate in pork and bovine carcasses arriving in transport. This situation represents a risk for the consumers and the need to implement an integrated STEC control in the food chain.

Outcomes after Frey's procedure for chronic pancreatitis: a 8-year single-center experience in Colombia.

BACKGROUND: Chronic pancreatitis is an inflammatory disease characterized by irreversible morphological changes due to chronic pancreatic fibrosis. The treatment goals are to relieve pain, preserve function, and prevent further pathological consequences. Endoscopic treatment, surgery, or both are options for untreatable pain or suspected malignancy. Frey procedure is a reasonable surgical intervention because of its hybrid character, combining resection and drainage. Unfortunately, there is limited information about the outcomes of this procedure in Latin America, and few cases described in Colombia. This study aims to describe the experience of a pancreatic surgery reference center in the management of patients undergoing Frey's surgery for chronic pancreatitis. METHODS: A retrospective review of a prospectively collected database of patients who underwent a Frey procedure due to chronic pancreatitis between January 2014 to February 2022 in a hospital in Bogotá, Colombia, was made. A demographic, clinical, and postoperative outcome description was performed. Mann-Whitney Willcoxon test was performed between operative variables and long-term outcomes. RESULTS: Eighteen patients met the inclusion criteria. 55.5% of patients were male. Chronic pancreatitis etiology in most cases (83.3% n = 15) was idiopathic. The median duration of symptoms and chronic pancreatitis diagnosis before surgery was 6.15 months (IQR 5;97). Overall morbidity was 38.88%. One patient died at 30 days of follow-up. The median follow-up time was 42.5 (IQR 19;65 months). The median pain reduction was 3 points according to the visual analog score. Six patients were diagnosed with malignant conditions after surgery (mean 27.8 ± 7.5 months). Wirsung's duct size was statistically related with malignancy presentation after Frey's procedure (Z = 2.54; P = 0.01). CONCLUSION: According to our data, Frey's procedure remains safe and feasible, with acceptable outcomes in terms of pain relief and pancreatic function. The study confirms the importance of a longstanding follow-up due to an inherent risk of pancreatic malignancy. Our data suggest that pancreatic duct size could be related with the malignancy diagnosis after Frey's procedure; however, further prospective studies with a larger sample size would be helpful to confirm these results.

First report of the distribution of Locus of Adhesion and Autoaggregation (LAA) pathogenicity island in LEE-negative Shiga toxin-producing Escherichia coli isolates from Argentina.

Shiga toxin-producing Escherichia coli (STEC) are important foodborne pathogens that can cause severe disease. The ability to adhere to epithelial cells is an important virulence trait and pathogenicity islands (PAIs) play an important role. Recently, researchers identified a member of the Heat-resistant agglutinin family and characterized this antigen named Hemagglutinin from Shiga toxin-producing E. coli (Hes). More importantly, they showed that hes and other genes such as iha, pagC and agn43 were integrated in each of the four modules present in the new PAI named Locus of Adhesion and Autoaggregation (LAA) whose presence is associated with severe disease linked to with LEE-negatives STEC. The distribution of LAA among STEC strains isolates from different origins between 2000 and 2015 from cattle, the farm environment, and food and harboring diverse virulence was investigated. The STEC strains were characterized by PCR to detect three modules of LAA and agn43 (as marker of module IV), and phylogenetic groups were determined. LAA was found in 46% of LEE-negative STEC corresponding to serogroups O91, O174, O113, O171, O178, O130 and others. The presence of this PAI is associated with strains harboring stx2 (56%) and belonging to phylogroup B1 (91%). LAA is a novel pathogenicity island associated with strains isolated from Hemolytic Uremic Syndrome cases. Therefore, the results of this study contribute to a better understanding regarding the pathogenicity of this emergent subset of STEC strains harboring LAA as a predictor of virulence of LEE-negative STEC strains.

Babesiosis prevalence in malaria-endemic regions of Colombia.

BACKGROUND & OBJECTIVES: : The presence of Babesia spp in humans, bovine cattle and ticks (the transmitting vector) has not been well characterized in Colombia. Babesia infection in humans can be overlooked due to similarity of the disease symptoms with malaria specially in the regions where malaria is endemic. The aim of the present work was to study the frequency of Babesia infection in humans, bovines and ticks in a malaria endemic region of Colombia, and explore the possible relationship of infection with host and the environmental factors. METHODS: : A cross-sectional study was carried out between August 2014 and March 2015 to determine the frequency of B. bovis and B. bigemina infection in a sample of 300 humans involved in cattle raising, in 202 bovines; and in 515 ticks obtained from these subjects, using molecular (PCR), microscopic and serological methods. In addition, the demographic, ecological and zootechnical factors associated with the presence of Babesia, were explored. RESULTS: : In the bovine population, the prevalence of infection was 14.4% (29/202); the highest risk of infection was found in cattle under nine months of age (OR = 23.9, CI 8.10-94.30, p = 0.0). In humans, a prevalence of 2% (6/300) was found; four of these six cases were positive for B. bovis. Self-report of fever in the last seven days in the positive cases was found to be associated with Babesia infection (Incidence rate ratio = 9.08; CI 1.34-61.10, p = 0.02). The frequency of B. bigemina infection in the collected ticks was 18.5% (30/162). INTERPRETATION & CONCLUSION: : The study established the presence of Babesia spp in humans, bovines and ticks. The most prevalent species responsible for babesiosis in humans and bovines was B. bovis, while B. bigemina was the species most frequently found in the tick population. The results contribute to the knowledge of the epidemiology of babesiosis in the country and can provide guidelines for the epidemiological surveillance of this non-malarial febrile illness in humans as well as cattle.

Virulence traits and different nle profiles in cattle and human verotoxin-producing Escherichia coli O157:H7 strains from Argentina.

Verotoxin-producing E. coli (VTEC) O157:H7 is the dominant serotype isolated from patients with HUS and, Argentina has the highest rate of HUS in the world. Molecular typing had allowed to identify subpopulations related to the origin and virulence of O157:H7 strains. Our aim was to perform a genetic characterization of 43 O157:H7 strains isolated in Argentine mostly from cattle and humans in order to establish the potential public health risk. For it, we used a combination of molecular subtyping methods in order to identify clade 8_rhsA (C3468G), LSPA-6 and virulence profiles and, a cytotoxicity assay on Vero cell. All isolates carried the clade 8 SNP variant and 98% of them belonged to lineage I/II (2% lineage II). Isolates were grouped into eleven nle profiles, 46% were positive for all nle genes, while the remaining isolates, except two, showed incomplete OI-71, particularly lacked nleF. All isolates showed the plasmid profile ehxA-espP-katP-stcE and harbored ehaA, elfA, iha and lpfA variants lpfA1-3 and lpfA2-2 and, ECSP_0242. The frequencies of the remaining ECSP genes were 95% ECSP_2687, 88% ECSP_3286, 86% ECSP_3620, 53% ECSP_2870/2872 and 44% ECSP_1733. All O157:H7 strains, except the isolate identified as lineage II, were cytotoxic on Vero cells. Among Argentinean strains, most genetic markers occur at equal relative frequencies among clinical and bovine isolates, showing diversity mostly in nle genes profiles. The belonging of the isolates to hypervirulent clade 8 and lineage I/II, the high prevalence of nle and putative virulence factors genes, would allow assigning most O157:H7 strains of this region a high risk to public health.

Delayed gastric emptying after pancreatoduodenectomy: an analysis of risk factors.

BACKGROUND: Delayed gastric emptying (DGE) is a frequent complication after pancreatoduodenectomy. Preoperative factors are limited and controversial. This study aims to identify associated factors related to this complication in the Colombian population. METHODS: A retrospective review of a prospectively collected database was conducted. All patients over 18 years of age who underwent pancreaticoduodenectomy were included. Associations with DGE syndrome were evaluated with logistic regression analysis, Odds ratio, and b-coefficient were provided when appropriate. RESULTS: 205 patients were included. Male patients constituted 54.15% (n = 111). 53 patients (25.85%) were diagnosed with DGE syndrome. Smoking habit (OR 17.58 p 0.00 95% CI 7.62-40.51), hydromorphone use > 0.6 mg/daily (OR 11.04 p 0.03 95% CI 1.26-96.66), bilirubin levels > 6 mg/dL (OR 2.51 p 0.02 95% CI 1.12-5.61), and pancreatic fistula type B (OR 2.72 p 0.02 CI 1.74-10.00). DISCUSSION: Smoking history, opioid use (hydromorphone > 0.6 mg/Daily), type B pancreatic fistula, and bilirubin levels > 6 mg/dL should be considered as risk factors for DGE.

Endovascular approach of hepatic artery pseudoaneurysm after Whipple procedure: Case report and literature review.

INTRODUCTION AND IMPORTANCE: Pseudoaneurysms after pancreatoduodenectomy are an uncommon complication, but they are associated with life-threatening outcomes in up to 50 % due to the development of postoperative bleeding. They usually result as a consequence of local inflammatory processes, such as pancreatic fistula or intra-abdominal collections. The cornerstones of treatment are thus intraoperative management and early identification of the complication. CASE PRESENTATION: We present a 62-year-old female patient in postoperative pancreatoduodenectomy due to a periampullary tumor, that presented upper gastrointestinal bleeding which required multiple transfusions. During hospitalization, the patient presented a refractory hypovolemic shock to conservative measures. It was documented intra-abdominal hemorrhage due to hepatic artery pseudoaneurysm that required endovascular management with common hepatic artery embolization, with successful bleeding control. CLINICAL DISCUSSION: Pseudoaneurysms are the result of tissue damage after surgery. The usual clinical presentation is upper gastrointestinal bleeding unresponsive to conservative treatment that results in hemodynamic instability due to hypovolemic shock. Prevention is currently based on preoperative and intraoperative measures such as nutritional repletion, vessel protection, adequate hemostasis, and prevention and treatment of pancreatic leak and abdominal infection. Once documented, treatment can be endovascular or surgical. CONCLUSION: The formation of pseudoaneurysms after pancreaticoduodenectomy is an uncommon and challenging complication. Early diagnosis, risk factor detection and a combined multidisciplinary approach lead to better outcomes, avoiding open surgical procedures that can increase morbidity and mortality rates.

Anisakidae parasites in frozen fish fillets intended for human consumption. / Parásitos anisákidos en filetes de pescado congelado destinados a consumo humano

INTRODUCTION: Anisakiasis is a human parasitic disease caused by the consumption of raw fish or shellfish containing larvae of the Anisakidae family. It is currently considered an emerging disease of public health interest. OBJECTIVE: To identify the presence of larvae of the Anisakidae family in samples of frozen raw fish fillets intended for human consumption in markets in Medellín and its metropolitan area in Antioquia, Colombia. MATERIALS AND METHODS: A cross-sectional study was carried out, in which larvae of the Anisakidae family were detected and identified in frozen raw fish fillets from three representative markets in Medellín and its metropolitan area. A total of 384 ready for consumption fillets were analyzed (197 sawfish, 137 salmon, 37 tuna, and 13 hake), using the pressing and ultraviolet light method. Taxonomic keys were used to identify the collected parasites and to establish its genus. Conventional PCR and Sanger sequencing was performed to determine the species. RESULTS: Four larvae were found in 4 of the 384 (1.04%) fillets (CI95% 1.04 ± 1.01%). The species of fish in which the larvae were found was sawfish (Scomberomorus spp.) and the genus and species of the larvae was established as Anisakis pegreffii. CONCLUSIONS: According to the study, the presence of Anisakis parasites in frozen raw fish fillets in the influence area is evident.

Introducción. La anisakiasis es una infección producida por parásitos de la familia Anisakidae, transmitida a los humanos por el consumo de pescado o mariscos crudos. En la actualidad, se considera una enfermedad emergente de interés en salud pública. Objetivo. Identificar la presencia de larvas de la familia Anisakidae en muestras de filetes de pescado crudo congelado destinados a consumo humano, en mercados de Medellín y su área metropolitana en Antioquia (Colombia). Materiales y métodos. Se realizó un estudio transversal, en el cual se buscó la presencia de larvas de la familia Anisakidae en filetes de pescado crudo congelado de tres mercados representativos de Medellín y su área metropolitana. Se analizaron 384 filetes listos para el consumo (197 sierras, 137 salmones, 37 atunes y 13 merluzas). Cada filete fue analizado mediante el método de prensado y luz ultravioleta. Los parásitos recolectados se identificaron a partir de claves taxonómicas para establecer el género, así como PCR convencional y posterior secuenciación Sanger, para determinar la especie. Resultados. Se encontraron 4 larvas en 4 de los 384 filetes (1,04 %) (IC95% 1,04 ± 1,01 %). Las larvas encontradas fueron identificadas como Anisakis pegreffi y el tipo de pescado en el cual se encontraron fue la sierra (Scomberomorus spp.). Conclusiones. De acuerdo con el estudio realizado, se evidencia la presencia de parásitos anisákidos en filetes de pescado crudo congelado en el área de influencia.

Trans-gastric and trans-abdominal percutaneous drainage of acute peripancreatic fluid infected collections: A retrospective analysis.

Background: Acute pancreatitis is one of the most common gastrointestinal diseases. Approximately 20% of the patients develop peripancreatic collections. Step-up management it's now the best approach with less rate of morbidity and mortality compared with open or minimally invasive surgery. Percutaneous management could reach a success rate between 50 and 76%. Our study shows the outcomes of trans-gastric versus transabdominal percutaneous drainage in cases of acute peripancreatic fluid infected collections in the absence of interventionist endoscopy. Methods: A retrospective review of a prospectively collected database was conducted. All the patients older than 18 years old that underwent percutaneous drainage between January 2010-December 2021 were included. Analysis and description of outcomes such as mortality, complications, and avoidance of surgical procedures was performed. Results: 18 patients underwent percutaneous drainage. 66.67% of patients were male. Mean age was 52.55 ± 22.06 years. Mean weight was 74.43 ± 15.25 kg. Mean size of peripancreatic collections 118.4 ± 49.12 mm. Wall-off necrosis was present in 33.33%. Trans-gastric approach was performed in 50% of the cases, the rest was trans-abdominal. No mortality was evidenced after 30 days of follow up. After trans-gastric percutaneous drainage, all patients avoided surgical open or laparoscopic procedure. Conclusion: Standardized step-up approach shows increased rates of success in percutaneous drainage of peripancreatic collections. Our case series shows a high rate of success in terms of avoidance any surgical procedure with no mortality after trans-abdominal and trans-gastric percutaneous drainage. Nevertheless, further prospective studies with higher sample size are needed.

[Renal involvement in monoclonal gammopathies]. / Compromiso renal en gammapatías monoclonales.

INTRODUCTION: The kidney is one of the organs most frequently affected by disease processes which produce monoclonal immunoglobins, therefore renal morphological and immunopathological alterations should be clearly recognized. OBJECTIVE: To describe the pathological features of renal involvement in monoclonal gammopathies. MATERIAL AND METHODS: A descriptive, retrospective and cross-sectional study of renal biopsies studied in a single center during a period of 14 years was carried out. RESULTS: 102 cases were included, of which 53% were male patients and the median age was 62.5 years (range 34 - 79). 97% of the biopsies were from native kidneys. The most frequent histopathological diagnosis (31.4%) was myeloma kidney, with kappa being the light chain most frequently deposited (65.6% of cases). AL amyloidosis was the second most common (29.4%) where the lambda chain predominated in 86.6%, followed by light chain deposition disease (20.6%) with the predominance of the kappa chain in 66.6%. CONCLUSIONS: The most frequent renal involvement due to monoclonal gammopathies was myeloma kidney with deposition of kappa light chains, followed by AL lambda amyloidosis; these diseases were found more frequently in patients over 50 years of age.

Genetic features of verotoxigenic Escherichia coli O157:H7 isolated from clinical cases of Argentina and Chile.

We aimed to compare the genetic diversity existing in VTEC O157:H7 strains isolated from cases of human disease from Argentina and Chile. For it, 76 strains were studied in relation to the distribution of genes encoding virulence factors and subtyped by lineage-specific polymorphisms (LSPA-6), and phylogroups assignment. Our results show the almost exclusive circulation of VTEC O157:H7 isolates belonging to lineage I/II, associated with hypervirulent strains, and to the phylogroup E and, on the other hand, genetic diversity present among Argentinean and Chilean strains analyzed, mainly in relation to putative virulence determinants and nle profiles.

Differential elements of a successful agricultural innovation scaling-up model.

Worldwide, there is currently an increasing demand for an active connection between the generation of innovations and the achievement of their escalation. Between 2015 and 2018 the scaling up of three varieties of yellow potatoes was carried out in Colombia within the framework of the "More Nutritious Potatoes" project, which had results beyond the objectives and goals proposed in a period of 28 months. One of the results of the project was the design of a Scaling-up model of innovations that linked agriculture with nutrition. This article answers the question: Which were the elements of the scaling-up model that allowed the results obtained in the More Nutritious Potatoes Project? To respond, a set of reference criteria was constructed from the literature. These criteria were contrasted with the theoretical project scaling-up model and its subsequent implementation in the field, using focus groups as a methodology and the model design analysis and its execution by the leaders and the evaluator of the project. The project's Scaling-up Model (SM) was found to include all benchmarks, in addition to identify three key elements that made the results possible: (i) the characteristics of the innovation, (ii) the trans-disciplinary work and (iii) facilitating elements of the process. The results of this exercise complement the evaluated scaling-up model and become benchmarks in the design of innovation scaling-up processes.

Differential expression of the virulence gene nleB among Shiga toxin-producing Escherichia coli strains.

Shiga toxin-producing Escherichia coli (STEC) is a zoonotic foodborne pathogen associated with hemolytic uremic syndrome (HUS) that vary in their ability to cause disease in humans. STEC represents a serious problem for public health and Argentina is the country with the highest HUS incidence worldwide. Non-LEE effector (nle) genes, present on pathogenicity islands (PAIs), encode translocated substrates of the type III secretion system (T3SS), which could have an important role in STEC virulence. Particularly, nleB is one of the main effector genes proposed as a virulence marker that is involved in the action of T3SS during the STEC infection. NleB inhibits the inflammatory response of the host cell allowing the bacteria to persist in the first stage of the infection. In order to identify the potential risk of STEC strains for public health, the aim of this study was to evaluate and compare basal nleB transcription of 24 STEC strains belonging to 10 serotypes isolated from cattle, food and patients. The results showed differences in nleB transcription among strains. Some non-O157:H7 strains presented transcription levels above the control, an O157:H7 HUS-producing strain. On the other hand, no significant differences were found in basal transcription levels associated with origin or serotype but differences were found between HUS and non-HUS strains. These differences in nleB transcription may be of importance in STEC pathogenesis and could help to differentiate high and low virulence STEC strains.

Ligand-Efficient Inhibitors of Trichomonas vaginalis Adenosine/Guanosine Preferring Nucleoside Ribohydrolase.

Trichomoniasis is caused by the parasitic protozoan Trichomonas vaginalis and is the most prevalent, nonviral sexually transmitted disease. The parasite has shown increasing resistance to the current 5-nitroimidazole therapies indicating the need for new therapies with different mechanisms. T. vaginalis is an obligate parasite that scavenges nucleosides from host cells and then uses salvage pathway enzymes to obtain the nucleobases. The adenosine/guanosine preferring nucleoside ribohydrolase was screened against a 2000-compound diversity fragment library using a 1H NMR-based activity assay. Three classes of inhibitors with more than five representatives were identified: bis-aryl phenols, amino bicyclic pyrimidines, and aryl acetamides. Among the active fragments were 10 compounds with ligand efficiency values greater than 0.5, including five with IC50 values <10 µM. Jump-dilution and detergent counter screens validated reversible, target-specific activity. The data reveals an emerging SAR that is guiding our medicinal chemistry efforts aimed at discovering compounds with nanomolar potency.

NMR-Based Activity Assays for Determining Compound Inhibition, IC50 Values, Artifactual Activity, and Whole-Cell Activity of Nucleoside Ribohydrolases.

NMR spectroscopy is often used for the identification and characterization of enzyme inhibitors in drug discovery, particularly in the context of fragment screening. NMR-based activity assays are ideally suited to work at the higher concentrations of test compounds required to detect these weaker inhibitors. The dynamic range and chemical shift dispersion in an NMR experiment can easily resolve resonances from substrate, product, and test compounds. This contrasts with spectrophotometric assays, in which read-out interference problems often arise from compounds with overlapping UV-vis absorption profiles. In addition, since they lack reporter enzymes, the single-enzyme NMR assays are not prone to coupled-assay false positives. This attribute makes them useful as orthogonal assays, complementing traditional high throughput screening assays and benchtop triage assays. Detailed protocols are provided for initial compound assays at 500 µM and 250 µM, dose-response assays for determining IC50 values, detergent counter screen assays, jump-dilution counter screen assays, and assays in E. coli whole cells. The methods are demonstrated using two nucleoside ribohydrolase enzymes. The use of 1H NMR is shown for the purine-specific enzyme, while 19F NMR is shown for the pyrimidine-specific enzyme. The protocols are generally applicable to any enzyme where substrate and product resonances can be observed and distinguished by NMR spectroscopy. To be the most useful in the context of drug discovery, the final concentration of substrate should be no more than 2-3x its Km value. The choice of NMR experiment depends on the enzyme reaction and substrates available as well as available NMR instrumentation.

Erratum: Jimena Soledad Cadona, et al.; Pathogenicity Islands Distribution in Non-O157 Shiga Toxin-Producing Escherichia coli (STEC). Genes 2018, 9, 81.

We wish to make the following correction to the paper by Soledad-Cadona et al.[...].

Pathogenicity Islands Distribution in Non-O157 Shiga Toxin-Producing Escherichia coli (STEC).

Shiga toxin-producing Escherichia coli (STEC) are foodborne pathogens associated with outbreaks and hemolytic-uremic syndrome. Cattle and meat foods are the main reservoir and infection source, respectively. Pathogenicity islands (PAIs) play an important role in STEC pathogenicity, and non-locus of the enterocyte effacement(LEE) effector (nle) genes present on them encode translocated substrates of the type III secretion system. A molecular risk assessment based on the evaluation of the nle content has been used to predict which STEC strains pose a risk to humans. The goal was to investigate the distribution of the PAIs OI (O-island)-36 (nleB2, nleC, nleH1-1, nleD), OI-57 (nleG2-3, nleG5-2, nleG6-2), OI-71 (nleA, nleF, nleG, nleG2-1, nleG9, nleH1-2) and OI-122 (ent/espL2, nleB, nleE, Z4321, Z4326, Z4332, Z4333) among 204 clinical, food and animal isolates belonging to 52 non-O157:H7 serotypes. Differences in the frequencies of genetic markers and a wide spectrum of PAI virulence profiles were found. In most LEE-negative strains, only module 1 (Z4321) of OI-122 was present. However, some unusual eae-negative strains were detected, which carried other PAI genes. The cluster analysis, excluding isolates that presented no genes, defined two major groups: eae-negative (determined as seropathotypes (SPTs) D, E or without determination, isolated from cattle or food) and eae-positive (mostly identified as SPTs B, C, or not determined).