Enterobacteriaceae Research Articles

Water source, latrine type, and rainfall are associated with detection of non-optimal and enteric bacteria in the vaginal microbiome: a prospective observational cohort study nested within a cluster randomized controlled trial

BackgroundLess than one-third of sub-Saharan Africans have access to improved water sources. In US, Indian, and African studies, Bacterial vaginosis (BV) is increased among women with poor water, sanitation, and hygiene (WASH). We examined water source, sanitation (latrine type), and rainfall in relation to the vaginal microbiome (VMB).MethodsIn a cluster randomized controlled trial of menstrual cups and cash transfer, we measured the impact of cups on VMB via 16S rRNA gene amplicon sequencing in a subset of 436 adolescent girls. We analyzed how self-reported water source and latrine type at home related to VMB over 18-months, examining community state type I (CST-I, L. crispatus dominant) vs. other CST; alpha diversity; targeted taxa (coliform and other water-related pathogens); and non-targeted taxa via machine learning approaches. Mixed effects multivariable longitudinal models were adjusted for intervention arm, age, socioeconomic status, sexual activity, and cluster-level school WASH and rainfall (in millimeters).ResultsAdjusting for all covariates in all models: (1) the odds of CST-I were increased among participants with piped water (vs. pond), and decreased with traditional pit latrine vs. flush toilet. (2) Alpha diversity varied by water source and latrine type without consistent trends. (3) Coliform bacteria relative abundance (RA) was higher among participants with traditional pit or ventilated improved pit latrines vs. flush toilet, and higher among participants relying on stream vs. pond water. Streptococcus agalactiae RA was higher among participants with non-flush toilets, while Bacteroides fragilis RA was lower with non-flush toilets. (4) Key taxa from non-targeted analyses associated with water source and latrine type included typical vaginal bacteria, opportunistic pathogens, and urinary tract pathobionts. (6) Increased rainfall was associated with decreased odds of CST-I.Trial registrationClinicalTrials.gov NCT03051789, February 14, 2017.

Monitoring the properties of 1,2,4-triazole derivatives for the development of original antimicrobial drugs

Aim. A comprehensive study on the antimicrobial properties of new 1,2,4-triazole derivatives using the tools of in silico and in vitro studies. Materials and methods. Computer search techniques were used to find a compound with a strong antibacterial activity; in silico molecular docking (receptors for class A (PDB id: 1n9b) and class A SHV-1 (PDB id: 2zd8) beta-lactamase) and in vitro studies on 16 types of microorganisms. Then, the in silico analyzed compounds were tested in vitro for antimicrobial activity. After preparing solutions of different concentrations, the culture growth was measured on a zonal scale for detecting sizes of microbial growth inhibition zones after 24 hours (Antibiotic Zone Scale-C, model RW297, India) and a TpsDig2 software (2016, F. James Rohlf). Statistical analysis of the study results was carried out using the Statistica 13 software (StatSoft Inc., USA). Results. From the results of molecular docking, a strong binding affinity to class A enzymes has been found in compounds 2, 7, so they could be effective in the treatment of infection caused by K. pneumoniae. The ascending order of the predicted binding affinity through the calculated score for TEM and SHV enzymes was as follows: compound 4 < compound 3 < compound 1 < compound 7 < compound 2. According to our results, the studied chemical compounds 1–4, 7 inhibited the growth of many microbial species of the Enterobacteriaceae, Morganellaceae, Pseudomonadaceae, Enterococcaceae, Staphylococcaceae and Bacillaceae families. Conclusions. For the first time, studies on the complex inhibitory effect of chemical compounds 1–4, 7 were conducted using 16 bacterial strains. Evident antibacterial effects of the studied compounds have been established: compound 1 against 13, compound 2 – 9, compound 3 – 10, compound 4 – 7, compound 7 – 10 out of 16 tested polyresistant bacterial strains.

The gut microbiome and resistome of yellow perch (Perca flavescens) living in Minnesota lakes under varying anthropogenic pressure

Anthropogenic activities can significantly impact wildlife in natural water bodies, affecting not only the host's physiology but also its microbiome. This study aimed to analyze the gut microbiome and antimicrobial resistance gene profile (i.e., the resistome) of yellow perch living in lakes subjected to different levels of anthropogenic pressure: wastewater effluent-impacted lakes and undeveloped lakes. Total DNA and RNA from gut content samples were extracted and sequenced for analysis. Results indicate that the gut resistome and microbiome of yellow perch differ between lakes, perhaps due to varying anthropogenic pressure. The resistome was predominated by macrolide resistance genes, particularly the MLS23S group, making up 53 % of resistome sequences from effluent-impacted lakes and 73 % from undeveloped lakes. The colistin resistance gene group (mcr) was detected in numerous samples, including variants associated with Aeromonas and the family Enterobacteriaceae. The gut microbiome across all samples was dominated by the phyla Proteobacteria, Firmicutes, and Actinobacteria, with the opportunistic pathogens Plesiomonas shigelloides and Aeromonas veronii more abundant in effluent-impacted lakes. Metagenomic analysis of wild fish samples offers valuable insights into the effects of anthropogenic pressures on microbial communities, including antimicrobial resistance genes, in water bodies.

Enterobacteriaceae community dynamics in sleepy lizards: Richness, prevalence and co‐occurrence over time

AbstractAnimal gut microbiomes can be very diverse, and enteric bacteria can profoundly affect the physiology of their host. The gut microbiome can be related to host health and digestion, which ultimately contribute to host body condition. However, we have a limited understanding of the co‐occurrence patterns of gut bacteria in their host, and how co‐occurrence and bacterial diversity change over time. This notion is especially important to animals living in groups as bacteria can transmit through social interactions. We investigated the co‐occurrence patterns of gut bacteria in a lizard host. We repeatedly collected cloacal swabs from 87 sleepy lizards (Tiliqua rugosa) from two different study sites over their activity season. We determined the richness and prevalence of 82 enteric bacterial strains and used a probabilistic model to investigate their co‐occurrence. At both study sites, richness and prevalence generally increased over time. We suggest that the lizards acquire strains throughout their activity season by moving through the landscape and inspecting conspecific scats. Lizards continuously tongue‐flick while moving, and thereby ingest bacteria when they move through areas where other animals defaecated. Temperature, rainfall and diet change seasonally, influencing lizard activity, and may influence the observed increase in enterobacterial richness and prevalence. Further, albeit with some exceptions, most strain pairs did not occur significantly more often or less often than expected by chance. This finding shows a lack of structured co‐occurrence, which may imply that most bacterial strains did not facilitate or inhibit each other. The absence of a co‐occurrence pattern could also be driven by random encounters of bacteria shed by other lizards within the habitat. Our results suggest that behaviour (movement patterns, tongue‐flicking), activity patterns and environmental factors collectively drive the temporal pattern of the gut bacterial community in sleepy lizards and potentially other wild reptiles.

High antimicrobial resistance rates and multidrug resistance in Enterobacteriaceae isolates from poultry in Souk Ahras region, Algeria

Background and Aim: The spread of antimicrobial resistance (AMR) in the Enterobacteriaceae family represents a major global health problem for humans and animals. This study aimed to determine AMR levels and highlight the different resistance profiles of Enterobacteriaceae isolates collected from healthy broiler chickens in eastern Algeria. Materials and Methods: A total of 200 cloacal swabs of healthy broilers from several poultry farms located in the Souk Ahras region (eastern Algeria) were collected. Samples were inoculated on MacConkey agar, and the isolated bacteria were identified using the API 20E system. Antimicrobial susceptibility testing was conducted using the disk diffusion method in accordance with the Clinical and Laboratory Standards Institute guidelines. The broth microdilution method was used to determine the minimum inhibitory concentration of colistin (CT). Results: Two hundred and forty-one isolates of commensal Enterobacteriaceae were recovered, including: Escherichia coli (n = 194; 80.5%), Proteus mirabilis (n = 21; 8.71%), Escherichia fergusonii (n = 8, 3.32%), Salmonella spp. (n = 7, 2.9%), Enterobacter cloacae (n = 4, 1.66%), Klebsiella pneumoniae (n = 3, 1.25%), Serratia spp. (n = 3, 1.25%), and Kluyvera spp. (n = 1, 0.41%). High resistance rates were observed toward erythromycin (100%), doxycycline (96.68%), trimethoprim-sulfamethoxazole (95.85%), ciprofloxacin (94.19%), ampicillin (90.04%), kanamycin (78.01%), and amoxicillin-clavulanic acid (69.71%). However, moderate-to-low resistance rates were observed for CT (25.31%), ceftazidime (12.45%), and cefotaxime (8.71%). Interestingly, only two extended-spectrum beta-lactamase (ESBL)-producing E. coli isolates were detected. All isolates (100%) were multidrug-resistant (MDR), among which 58.92% were resistant to six and seven antibiotics. Forty AMR profiles were identified, reflecting a wide diversity of resistance with combinations of three to ten antibiotics. Conclusion: Our findings revealed alarming rates of AMR, highlighting the need to take measures to combat the phenomenon of AMR to protect animals and public health. Keywords: Algeria, antibiotic resistance, Enterobacteriaceae, multidrug resistance, poultry.

Commensal and Pathogenic Bacteria Associated with Farmed Rainbow Trout (Oncorhynchus mykiss Walbum) and Aquaculture Environment

The bacterial microflora associated with farmed rainbow trout (Oncorhynchus mykiss Walbaum) and its aquaculture environment was characterized. The counts of commensal, indicator and pathogenic bacteria were determined and bacterial colonies were characterized. The mean mesophilic counts were 4.5 log CFU g -1 and 7.6 log CFU g -1 in skin with muscle and intestine respectively. Significantly high densities of faecal coliform, E. coli and Enterococci was detected in pond sediment, fish intestine and feed when compared to pond water and trout tissues. A total of 110 randomly selected isolates from TSA were identified and characterized. Of the mesophiles, 70–75% were aerobic Gram-negative bacteria, both motile and non-motile, and members of the Enterobacteriaceae family. The skin microflora of trout was dominated by Gram-negative aerobic rods belonging to Enterobacteriaceae, Aeromonadaceae, Pseudomonas/ Shewanella, Moraxella, Acinetobacter and Flavobacterium. Psychrotrophic bacterial isolates of the genera Pseudomonas, Morganella, Hafnia were identified in trout. Pathogenic bacteria such as Clostridium botulinum, Yersinia enterocolitica could not be detected. However, Aeromonas hydrophila, A. veronii biovar sobria, A. veronii biovar veronii were prevalent in farmed trout. Presence of bacterial pathogens in the trout farm envisages a strict hygienic handling and processing of fish from such culture systems for ensuring public health safety.

Affinity Capture Using Ligand and Polymer-Functionalized Iron Oxide, Gold and Iron-Gold Nanocomposites to Target Enteric Bacteria

Affinity Capture Using Ligand and Polymer-Functionalized Iron Oxide, Gold and Iron-Gold Nanocomposites to Target Enteric Bacteria

The transcriptional response to low temperature is weakly conserved across the Enterobacteriaceae.

We studied how different species of bacteria from the same Family (Enterobacteriaceae) change the expression of their genes in response to a decrease in temperature. Using de novo-generated parallel RNA-seq data sets, we found that the six species in this study change the level of expression of many of their genes in response to a shift from human body temperature (37°C) to a temperature that might be found out of doors (15°C). Surprisingly, there were very few genes that change expression in all six species. This was due in part to differences in gene content, and in part due to shared genes with distinct expression profiles between the species. This study is important to the field because it illustrates that closely related species can share many genes but not use those genes in the same way in response to the same environmental change.

SAFETY OF BLACK SOLDIER FLY LARVAE: MICROBIAL AND HEAVY METAL RISKS

Black soldier fly larvae (BSFL) are considered a sustainable protein source and an effective means of recycling organic waste. They are rich in nutrients, including proteins and lipids, making them suitable for animal feed and potentially for human consumption. In addition to their nutritional benefits, BSFL also have environmental benefits, i.e., reducing waste and greenhouse gas emissions. However, concerns about their safety persist, particularly regarding contamination by pathogenic microorganisms, toxins, and heavy metals. The aim of our study was to investigate the effect of different feedstuffs on heavy metal accumulation and on the microcenosis (Enterobacteriaceae, aerobic bacterial endospores, microscopic filamentous fungi) of BSFL. BSFL were fed four feed treatments (I: egg pasta cooked in whole milk; II: cooked rice with peas; III: poultry feed; and IV: cooked couscous, boiled eggs, and raw carrot peels). The results of our study showed that feed variants significantly affect the microbial safety of BSFL. Using MALDI-TOF, we identified 13 species of family Enterobacteriaceae in BSFL, including facultative pathogenic species Enterobacter cloacae, Klebsiella aerogenes, Klebsiella pneumoniae, Morganella morganii, and Proteus mirabilis. Our research confirmed that BSFL fed different feed variants under experimental laboratory conditions contained heavy metals, including cadmium, copper, manganese, molybdenum, nickel, lead, and zinc. Cadmium concentrations in BSFL ranged from 0.12 to 0.18 mg.kg-1, with the highest values measured in BSFL in variant IV.

Ethnic foods of Northeast India: insight into the light of food safety

BackgroundTraditional and fermented foods are widely consumed by the ethnic population of Northeast India. These foods are not only very nutritious, easily available, and reasonably priced, but also boost immunity and protect from various seasonal infections and have been reported through several investigations. However, pathogens transmitted by these foods have never been reported. The process of preparation and preservation of fermented traditional foods involves various steps that can prompt contamination risks. Using the Indian Council of Medical Research (ICMR)-FoodNet surveillance data, we report the profile of enteric bacteria and mycotoxin-producing fungal pathogens identified in traditional and fermented food items and their importance in public health.MethodsFood samples were collected from rural areas of Assam, Arunachal Pradesh, Tripura, and Sikkim. Bacterial and fungal pathogens were tested as per the standard operating procedure at respective ICMR-FoodNet laboratories and MycoNet laboratory at Assam. Samples were collected under six broad categories: milk products, edible insects, non-vegetarian, legumes/cereals, veggies, and alcoholic beverages. Data compilation was done centrally through a digital data portal. Quality assurance was done by the ICMR-National Institute for Research in Bacterial Infections (NIRBI), Kolkata.ResultA total of 1227 samples were collected, among which 78 samples (6.8%) were positive for enteric pathogens, with Bacillus cereus being the most prevalent one (n = 59). Furthermore, 71 fungal isolates were detected from different food categories. The most common mycotoxin-producing fungal genera include Aspergillus [A. fumigatus (n = 7)], Rhizopus [R. arrhizus (n = 13)], and Penicillium (n = 2).ConclusionTraditional foods have immense social, and cultural value and popularity among locals. However, processing, fermentation, and preservation of these foods without any preservatives and refrigerators, increases the possibility of contamination and growth by pathogenic organisms. It is crucial to understand the contamination risk involved during preparation so that the safety of these traditional foods can be ensured and local delicacies can be relished without any fear of foodborne infections and outbreaks, particularly when consumed by masses during festivals.

Extreme drought shapes the gut microbiota composition and function of common cranes (Grus grus) wintering in Poyang Lake.

Extreme weather events driven by climate change profoundly affect migratory birds by altering their habitats, food sources, and migration routes. While gut microbiota is believed to play a role in helping birds adapt to environmental changes, research on how extreme weather impacts their gut microbiota and how these microbial communities respond to such conditions has been limited. 16S rRNA gene sequencing was utilized to investigate the gut microbiota of common cranes (Grus grus) wintering at Poyang Lake from 2020 to 2023, with a particular focus on their response to extreme drought conditions on both inter-annual and monthly timescales. The results revealed that extreme drought conditions substantially impact gut microbiota, with inter-annual water-level fluctuations exerting a more pronounced impact on microbial community structure than that of inter-monthly fluctuations. Notably, a significant decline in bacterial diversity within the gut microbiota of common cranes was observed in the extreme drought year of 2022 compared with other years. Monthly observations indicated a gradual increase in gut microbial diversity, coinciding with relatively minor water-level changes. Key taxa that responded to drought included the Enterobacteriaceae family and Bifidobacterium and Lactobacillus species. Additionally, functional genes related to carbohydrate metabolism, the phosphotransferase system, and the two-component systems were significantly enriched during the extreme drought year. These functions may represent adaptive mechanisms by which the gut microbiota of common cranes respond to drought stress. This research provides novel insights into the temporal variability of gut microbiota in wintering waterbirds, underscoring the significant impact of climatic fluctuations on microbial communities. The findings highlight the importance of understanding the ecological and functional responses of gut microbiota to extreme weather events, which is crucial for the conservation and management of migratory bird populations in the face of climate change.

Effect of Fiber Drink Consumption Containing Glucomannan and Isomaltooligosaccharide on Digesta Profile and Gut Microbiota

Dietary fibers have long been recognized for their numerous health benefits, including supporting gut health, aiding in weight management, and reducing the risk of cardiovascular disease. Glucomannan, derived from konjac and porang tubers, has gained attention for its diverse health-promoting properties. However, its application in beverages is limited due to its high viscosity. Combining glucomannan with isomaltooligosaccharide (IMO) is suggested to synergistically enhance functionality, particularly improving gastrointestinal health. This study investigates the functional effects of porang glucomannan and isomaltooligosaccharide-containing fiber drinks (GIFD) on body weight, feed intake, digesta profiles (digesta weight, moisture content, pH) and gut microbiota using in vivo method. Twenty-four male Sprague Dawley rats were divided into 4 groups, including control, inulin, and 2 doses of glucomannan and isomaltooligosaccharide fiber drink (GIFD). Rats were fed with AIN-93M. Adaptation was carried out for 5 days followed by 28 days of intervention. Results indicate that GIFD consumption led to reduced feed intake, likely due to increased satiety effects and glucomannan’s gel-forming ability, resulting in lower body weight gain compared to other groups. While GIFD did not significantly alter digesta weight and moisture contents, it significantly decreased pH values. Analysis of short-chain fatty acids (SCFAs) showed a shift in propionic acid levels, suggesting a beneficial effect on weight control. Moreover, GIFD treatment reduced abundance percentages of enteric bacteria like E. coli and Clostridium, possibly due to increased SCFA production. However, GIFD consumption did not significantly alter sIgA concentration, although there was a trend towards increased levels in GIFD-2, suggesting potential immunomodulatory effects. Overall, it was indicated that porang glucomannan and IMO-containing fiber drinks has the potential to be used as beverages to support body weight regulation and to help maintaining digestive tract health. HIGHLIGHTS Glucomannan and isomaltooligosaccharide-containing fiber drinks (GIFD) reduced feed intake. Consumption of GIFD induced the shift of molar proportion of SCFAs suggesting beneficial health effect. GIFD treated groups showed lower abundance percentages of coli and Clostridium compared to control. GIFD is potential to be developed as weight management product. GRAPHICAL ABSTRACT

Metagenomics insights into bacterial diversity and antibiotic resistome of the sewage in the city of Belém, Pará, Brazil.

The advancement of antimicrobial resistance is a significant public health issue today. With the spread of resistant bacterial strains in water resources, especially in urban sewage, metagenomic studies enable the investigation of the microbial composition and resistance genes present in these locations. This study characterized the bacterial community and antibiotic resistance genes in a sewage system that receives effluents from various sources through metagenomics. One liter of surface water was collected at four points of a sewage channel, and after filtration, the total DNA was extracted and then sequenced on an NGS platform (Illumina® NextSeq). The sequenced data were trimmed, and the microbiome was predicted using the Kraken software, while the resistome was analyzed on the CARD webserver. All ecological and statistical analyses were performed using the. RStudio tool. The complete metagenome results showed a community with high diversity at the beginning and more restricted diversity at the end of the sampling, with a predominance of the phyla Bacteroidetes, Actinobacteria, Firmicutes, and Proteobacteria. Most species were considered pathogenic, with an emphasis on those belonging to the Enterobacteriaceae family. It was possible to identify bacterial groups of different threat levels to human health according to a report by the U.S. Centers for Disease Control and Prevention. The resistome analysis predominantly revealed genes that confer resistance to multiple drugs, followed by aminoglycosides and macrolides, with efflux pumps and drug inactivation being the most prevalent resistance mechanisms. This work was pioneering in characterizing resistance in a sanitary environment in the Amazon region and reinforces that sanitation measures for urban sewage are necessary to prevent the advancement of antibiotic resistance and the contamination of water resources, as evidenced by the process of eutrophication.

The Effects of Fat Content on the Shelf-Life of Vacuum-Packed Red Meat.

When stored at chill temperatures, vacuum-packed (VP) lamb has a much shorter shelf-life than VP beef, primarily due to its higher pH, which could be linked to the higher fat content. The higher pH would create more favourable conditions for the growth of spoilage bacteria, resulting in a shorter shelf-life of meat. To determine the effects of fat on meat shelf-life as it relates to pH, a series of shelf-life trials at 2 °C were conducted using VP beef and lamb mince with varying fat contents (i.e., control with ~5%, 20%, and 50%) as a model system to red meat primal cuts. The results showed that higher fat content reduced the shelf-life of VP beef mince by 24% and lamb mince by 12.5%. This reduction was accompanied by significantly (p < 0.05) decreased glucose and lactic acid levels. Throughout storage, a higher fat content in beef and lamb mince generally resulted in a higher pH by 0.1 (p < 0.05) compared to the respective controls. Higher fat content mince also had faster lactic acid bacteria growth rates (by up to 0.13 Log10 CFU/g/day) and higher maximum populations of presumptive enteric bacteria up to 1.3 Log10 CFU/g (p < 0.05). These results suggest that fat content can negatively influence the shelf-life of VP red meat through lowering glucose and lactic acid levels, raising the pH, and increasing LAB growth rate and maximum population levels of presumptive enteric bacteria.

Dietary pattern and the corresponding gut microbiome in response to immunotherapy in Thai patients with advanced non-small cell lung cancer (NSCLC)

Gut microbiota is considered a key player modulating the response to immune checkpoint inhibitors (ICI) in cancer. The effects of dietary pattern on this interaction is not well-studied. A prospective multicenter cohort of 95 patients with advanced non-small cell lung cancer (NSCLC) undergoing ICI therapy were enrolled. Stool shotgun metagenomic sequencing was performed. Three-day dietary patterns before ICI were assessed. Patients were categorized as hyperprogressive disease (HPD) if they exhibited a time to treatment failure of less than 2 months. All others were categorized as non-hyperprogressive disease (non-HPD). The correlation between dietary patterns, gut microbiome, and response to ICI therapy was analyzed. In the multivariate analysis, a high abundance of Firmicutes unclassified and the Ruminococcaceae family correlated with a significantly diminished progression-free survival (PFS) with an HR of 2.40 [P = 0.006] and 4.30 [P = 0.005], respectively. More specifically, within the subset of NSCLC patients treated solely with ICI therapy, a high abundance of Intestinimonas and the Enterobacteriaceae family were associated with substantially reduced PFS with an HR of 2.61 [P = 0.02] and HR 3.34 [P = 0.005], respectively. In our comprehensive dietary pattern analysis, the HPD group showed increased consumption of cholesterol, sodium, and fats beyond recommended levels compared to the non-HPD group. This group also displayed a tendency towards higher food pattern scores characterized by a high intake of fat and dairy products. Our study revealed a distinct association between the gut microbiome composition and treatment outcomes. The overall composition of diet might be related to ICI therapeutic outcomes.

Bacterial contamination of autologous blood salvaged during deceased donor liver transplantation: a prospective observational study.

Decompensated cirrhotic patients experience severely increased intestinal permeability and bacterial translocation. Thus, autologous blood salvaged during deceased donor liver transplantation (DDLT) may be contaminated with enteric bacteria. We aimed to evaluate bacterial contamination of autologous blood salvaged during DDLT and its association with post-transplant bacteremia. In 30 patients undergoing DDLT, bacterial culture was performed in salvaged autologous blood samples: one before graft reperfusion (non-leukoreduced) and two after graft reperfusion (non-leukoreduced and leukoreduced). The primary outcome was bacterial contamination of salvaged autologous blood. Seven of 30 patients (23.3%) were positive for bacteria (3 enteric/4 non-enteric) before graft reperfusion while 11 patients (36.7%) were positive (5 enteric/6 non-enteric) after graft reperfusion. Six of 7 patients who were positive for bacteria before graft reperfusion were positive after graft reperfusion with the same bacteria. Only 4 of 11 contaminated blood samples were converted to negative after leukoreduction. Post-transplant bacteremia risk was insignificantly greater in patients who received autologous blood with bacteria than in patients without bacteria (30.0% vs. 5.0%, P = 0.06). We found contamination of salvaged autologous blood with enteric bacteria throughout DDLT and incomplete performance of leukoreduction, indicating high bacterial load. The potential association between contaminated autotransfusion and post-transplant bacteremia warrants further validation in a larger prospective study.Clinical trial notation: This study was registered at the Clinical Research Information Service (CRiS; https://cris.nih.go.kr ; No. KCT0007223; principal registration investigator: Sangbin Han, date of registration: April 25, 2022).

Investigating the role of PmrB mutation on Colistin antibiotics drug resistance in Klebsiella Pneumoniae

Klebsiella pneumoniae, a member of the Enterobacteriaceae family, naturally resides in the digestive tracts of both healthy animals and humans. Carbapenem-resistant Klebsiella pneumoniae (CRKP) poses a significant health risk for hospitalized patients worldwide, greatly reducing the effectiveness of commonly used antibiotics. This leaves healthcare providers with limited treatment options, often relying on colistin. PmrB is important for the survival of Klebsiella pneumonia and, a mutation in the PmrB protein is accountable for the development of colistin antibiotic resistance in Klebsiella pneumonia. This is especially important because colistin is a fundamental component in the treatment of pneumonia. Three mutated residues—T157P, G207D, and T246A—are responsible for colistin resistance. The structural alterations and underlying mechanisms in the PmrB protein that cause resistance owing to mutation remain unclear. As a result, this study is focused to the exploration of the putative mechanism of resistance resulting from these mutations, as well as the structure modification of normal and mutant PmrB proteins, using molecular docking and molecular dynamics simulations analysis. Our results demonstrated that the interaction paradigm for the mutants has been altered and thus showing a significant effect upon the hydrogen bonding network. Interestingly, the binding of Colistin with the three mutant demonstrate unstable behavior as compared with WT+Colistin. The proposed drug-resistance mechanism will help to guide the development of PmrB drugs. These finding may give a new framework for developing novel drugs against the mutant version of PmrB.

Neoadjuvant vidutolimod and nivolumab in high-risk resectable melanoma: A prospective phase II trial

Intratumoral TLR9 agonists and anti-PD-1 produce clinical responses and broad immune activation. We conducted a single-arm study of neoadjuvant TLR9 agonist vidutolimod combined with anti-PD-1 nivolumab in high-risk resectable melanoma. In 31 evaluable patients, 55% major pathologic response(MPR) was observed, meeting primary endpoint. MPR was associated with necrosis, and melanophagocytosis with increased CD8+ tumor-infiltrating lymphocytes and plasmacytoid dendritic cells (pDCs) in the tumor microenvironment, and increased frequencies of Ki67+CD8+ Tcells peripherally. MPRs had an enriched pre-treatment gene signature of myeloid cells, and response to therapy was associated with gene signatures of immune cells, pDCs, phagocytosis, and macrophage activation. MPRs gut microbiota were enriched for Gram-negative bacteria belonging to the Bacteroidaceae and Enterobacteriaceae families and the small subgroup of Gram-negative Firmicutes. Our findings support that combined vidutolimod and nivolumab stimulates a broad anti-tumor immune response and is associated with distinct baseline myeloid gene signature and gut microbiota. ClinicalTrials.gov identifier: NCT03618641.

Characteristics of the Gut Microbiota Composition of the Arctic Zone Residents in the Far Eastern Region.

Background. In many studies over the past decade, scientists have made a connection between the composition of gut microbiota and human health. A number of publications have shown that gut bacteria are involved in many metabolic and physiological processes of the organism. The composition of the gut microbiome is unique for each person and is formed under the influence of various factors associated with both the individual characteristics of the body and the characteristics of the environment. Different regional characteristics make it necessary for the body to adapt to certain conditions, including temperature fluctuations. Living in areas with low temperatures, such as the Arctic zone, dictates the need for increased energy consumption, which affects the composition of the gut microbiome. Methods. In our study, an extensive questionnaire was conducted among the participants, where many questions were included about the dietary preferences of the study participants, which allowed them us to further divide them into groups according to their diets. Stool samples were collected from participants from 3 groups: Arctic native, Arctic newcomer and the control group. The next step was the isolation of bacterial DNA and sequencing the 16S rRNA gene. The analysis of the results of the diversity of the intestinal microbiota was carried out both with and without taking into account the dietary preferences of the participants. Results. As a result of comparing the intestinal microbiota obtained from residents of the Arctic zone with the gut microbiota of residents of other regions with a milder climate, significant differences are found. These differences may be related to limited food resources and a reduction in the variety of food products characteristic of this Arctic region. t was also found that representatives of the bacterial families Christensenellaceae and Muribaculaceae dominated the control group, both with traditional nutrition and with a dairy-free diet in comparison with the Arctic groups. The control group was dominated by representatives of the Prevotellaceae, Enterobacteriaceae and Comamonadaceae families compared to the Arctic group (with a traditional diet). The results also show that the number of representatives of the families Desulfovibrionaceae (with traditional diet) and Enterobacteriaceae (with milk-free diet) is growing in the Arctic group. Conclusions. In the course of this work, bacterial families characteristic of people living in the Arc-tic zone of the Far Eastern region of the Russian Federation were identified. Poor diet, difficult climatic conditions, and problems with logistics and medical care can have a strong impact on the health of this population. The main type of diet for the inhabitants of the Arctic is the traditional type of diet. They consume a large number of low-cost products, obtainget animal protein from poultry and canned food, and also eat a small number of fresh vegetables and fruits. Such a diet is due to the social status of the study participants and the climatic and geographical features of the region (difficulties in agriculture). With such a diet, we observe a decrease in representatives of the Christensenellaceae, Muribaculaceae, Eubacteriaceae, and Prevotellaceae families and an increase in representatives of the Enterobacteriaceae and Desulfovibrionaceae families among Arctic residents. This imbalance in the futuremay cause, this population may to develop various diseases in the future, including chronic diseases such as obesity, intestinal dysbiosis, inflammatory bowel diseases, and type 2 diabetes.

Assessment of Nitrate Reduction by Microbes in Artificial Groundwater Medium

There are significant reasons for nitrate contamination in groundwater (Delhi, India): sewage, runoff from landfill sites, nitrogenous chemical fertilisers, and pesticides from agricultural lands. The highest recorded concentration of nitrate in Delhi’s groundwater is reported to be 1500 mg/l. Consumption of high nitrate through water may pose serious health problems in humans, especially children (below five years). The study’s primary objective was to isolate and identify nitrate-remediating microbes from the nitrate-contaminated site Okhla Barrage, located on the Yamuna River in Delhi, India. A total of 11 different strains were isolated from this site. Among these four strains exhibited 40%–50% remediation efficiency at a nitrate concentration of 1000 mg/l. Molecular characterisation revealed that these four strains, Enterobacter aerogenes, E. coli K12, &lt;i&gt;Klebsiella oxytoca&lt;/i&gt; and &lt;i&gt;Lelliottia amnigena&lt;/i&gt;, belong to the Enterobacteriaceae family. This study assessed the nitrate remediation potential of isolated microbes in groundwater with 1000 and 1500 mg/l nitrate concentrations. By using a 2% inoculum, the microbes were incubated anaerobically at room temperature for ten days. Nitrate concentrations were monitored every 48 hours. &lt;i&gt;Lelliottia&lt;/i&gt;, &lt;i&gt;E. coli&lt;/i&gt;, and &lt;i&gt;Enterobacter&lt;/i&gt; reduced nitrate (1500 mg/l) by approximately 42%, 24%, and 29%, respectively, while &lt;i&gt;K. oxytoca&lt;/i&gt; showed minimal reduction. &lt;i&gt;L. amnigena&lt;/i&gt; exhibited superior nitrate removal efficiency compared to other strains. According to the reported data, these strains are known to reduce nitrate concentrations of 620 mg/l. However, our findings demonstrate a remarkable nitrate remediation capacity of 1500 mg/l, showcasing a novel contribution to this study. Further detailed analysis for condition optimisation and association of microbe-microbe could be more helpful.