Hasil untuk "Microbiology"

N. Tietz

J. G. Kusters, A. H. V. van Vliet, E. Kuipers

G. Barrow, R. Feltham

Yan Yang, Xue Li, Lang Sun et al.

ABSTRACT Carbapenem-resistant Pseudomonas aeruginosa (CRPA) is a global threat, but the mechanism of non-carbapenemase carbapenem resistance is still unclear. In the current study, we investigated the contributions of point mutations in mexR, oprD, and ftsI to carbapenem resistance in P. aeruginosa during in vivo evolution studies with consecutive clinical isolates. Real-time qPCR and Electrophoretic Mobility Shift Assay demonstrated that MexR (Gln55Pro) mutation increased MexAB efflux pump genes expression by altering MexR’s binding capacity, leading to a four- to eight-fold increase in meropenem MIC in the Pae d1 Green ∆mexR and PAO1∆mexR mutants. The OprD (Trp415*) truncation affected porin structure, and the constructed mutant Pae d1 Green oprD Trp415* increased meropenem MIC by 16-fold (from 0.25 to 4 µg/mL). The contribution of ftsI mutation to meropenem resistance was confirmed by clinical linkage analysis and was estimated to cause a two-fold increase in meropenem MIC by comparing the resistant clinical isolate with the Pae d1 Green oprD Trp415*∆mexR double mutant. The study found that the oprD Trp415* allele alone accounts for the imipenem MIC in clinical isolates, while the ∆mexR and ftsI Arg504Cys alleles do not contribute to imipenem resistance. In conclusion, we identified and explored the contributions of mexR, oprD, and ftsI mutations to high level non-carbapenemase carbapenem resistance in P. aeruginosa. These findings highlight the interplay of different mutations in causing non-carbapenemase carbapenem-resistance in P. aeruginosa.IMPORTANCEThe emergence of carbapenem-resistant Pseudomonas aeruginosa (CRPA) poses a significant global health threat, complicating treatment options for infections caused by this pathogen. Understanding the mechanisms behind non-carbapenemase carbapenem resistance is critical for developing effective therapeutic strategies. This study provides crucial insights into how specific point mutations in key genes-mexR, oprD, and ftsI-contribute to carbapenem resistance, particularly the MexR (Gln55Pro) mutation’s effect on efflux pump expression and the OprD (Trp415*) truncation’s impact on porin structure. The findings elucidate the complex interplay of these mutations, highlighting their roles in conferring high-level resistance, and underscore the imperative for continued research to inform therapeutic strategies against CRPA infections.

Nawfal Hasan Siam, Nayla Nuren Snigdha

Coccinia grandis (L.) Voigt (ivy gourd) is popularly consumed in South Asia for food and therapeutic purposes. C. grandis acts as a remedy for various ailments, such as hypertension, diabetes, cancer, ulcers, diarrhea, jaundice, inflammation, fever, bronchitis, burns, skin eruptions, insect bites, allergies, eye infections, and urinary disorders. Researchers have identified phytoconstituents in diverse chemical classes from this species, including alkaloids, flavonoids, coumarins, esters, ethers, fatty acids, fatty alcohols, terpenoids, and phenolic compounds. Comprehensive research conducted in vitro and in vivo has confirmed the properties of the plant as antidiabetic, anticancer, antiparasitic, antimicrobial, hepatoprotective, analgesic, antipyretic, anti-Alzheimer's, anticataract, antileishmanial, anti-anaphylactic, anti-histaminic, and wound-healing agent, as well as being advantageous for cardiovascular health. Most pharmacological findings are derived from studies on the extracts and the subsequent phytoconstituents from this plant species. Nevertheless, the specific phytoconstituents underlying these biological effects and the mechanisms of action involved are yet to be fully identified. Toxicological evaluations indicate that C. grandis is generally safe, although high doses can cause dose-dependent hepatotoxicity. Moreover, the clinical trials focusing on the antidiabetic effects of C. grandis demonstrate promising effects in managing glucose dysregulation. This review aims to provide a comprehensive update on C. grandis, expanding on previous studies by incorporating a broader ethnomedicinal scope, a more extensive phytochemical profile with detailed chemical structures, and additional clinical trial data. Unlike prior publications, this review emphasizes C. grandis as a functional food, highlighting its potential in chronic disease management. By integrating these aspects, this study offers a more in-depth analysis of the therapeutic potential and future applications of this plant. The functional food aspect of C. grandis, rich in bioactive compounds, supports its role in preventing and managing chronic diseases as a regular vegetable.

Jorge Emilio Salazar Flórez, Katerine Marín Velasquez, Luz Stella Giraldo Cardona et al.

Background: Early detection of severe dengue (SD) is crucial in preventing life-threatening complications. Despite its importance, comprehensive knowledge about these early indicators is still limited. This study aimed to identify predictors of SD in a hyperendemic region of Colombia. Methods: A cross-sectional analysis was conducted using data from 2018 to 2022, encompassing 233 patients. By utilizing the 2009 World Health Organization dengue classifications, cases were differentiated between severe dengue (SD) and non-severe dengue (non-SD). Among these, 47 were confirmed as SD. Associations between clinical, demographic, and laboratory data and disease severity were examined using Fisher’s exact tests or the Mann–Whitney U test (<i>p</i> < 0.05). Profiles for SD and non-SD cases were established through multiple correspondence analysis, and a logistic regression-based predictive model was validated using training and test sets. The model’s performance was evaluated using the area under the receiver operating characteristic curve (AUC-ROC), accuracy, sensitivity, F1-score, and precision. Results: Differences in place of residence, comorbidities, type of infection, and signs and symptoms were observed between the severe dengue (SD) and non-severe dengue (non-SD) groups. Median levels of platelets, white blood cells (WBC), aspartate aminotransferase (AST), and alanine aminotransferase (ALT) were found to be higher in the SD group compared to the non-SD group. Neutrophils, leukocytes, platelets, AST, and primary infection were significant predictors of SD. The model demonstrated an area under the receiver operating characteristic curve (AUC) of 0.91 (95% CI, 0.85–0.96). Conclusions: The developed predictive model provides significant assistance to clinicians in assessing SD risk and optimizing triage, which is particularly crucial during dengue outbreaks.

Maritza Lizeth Álvarez-Ainza, Pedro Alejandro Fong-Coronado, Eduardo Ruiz-Bustos et al.

IntroductionEnterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp. are microorganisms referred as the ESKAPE group pathogens. These microorganisms have generated great concern in health institutions around the world since most of them have resistance to multiple antibiotics and cause most infections associated with healthcare, as well as community infections. The aim of this study was the analysis of antibiotic resistance in microorganisms of the ESKAPE group, recovered from clinical samples in 11 health institutions from Hermosillo and Ciudad Obregón in the State of Sonora, México, during the period from 2019 to 2020.MethodsA cross-sectional, descriptive, observational, and temporality epidemiological study was carried out. A comparative and statistical analysis of antibiotic resistance was carried out using the chi-square test, and small values were analyzed using Fisher’s exact test p ≤ 0.05.Results and discussionAll the ESKAPE group microorganisms showed significant differences in antibiotic resistance percentages between both cities. High resistance percentages for some antibiotics, like cephalosporins and ciprofloxacin were detected for Klebsiella pneumoniae and Acinetobacter baumannii.

Badriyah S Alotaibi, Abida Kalsoom Khan, Zelal Kharaba et al.

David M. Rutkowski, Vincent Vincenzetti, Dimitrios Vavylonis et al.

Abstract Polarized exocytosis induced by local Cdc42 GTPase activity results in membrane flows that deplete low-mobility membrane-associated proteins. A reaction-diffusion particle model comprising Cdc42 positive feedback activation, hydrolysis by GTPase-activating proteins (GAPs), and flow-induced displacement by exo/endocytosis shows that flow-induced depletion of low mobility GAPs promotes polarization. We modified Cdc42 mobility in Schizosaccharomyces pombe by replacing its prenylation site with 1, 2 or 3 repeats of the Rit C-terminal membrane-binding domain (ritC), yielding alleles with progressively lower mobility and increased flow-coupling. While Cdc42-1ritC cells are viable and polarized, Cdc42-2ritC polarize poorly and Cdc42-3ritC are inviable, in agreement with model’s predictions. Deletion of Cdc42 GAPs restores viability to Cdc42-3ritC cells, verifying the model’s prediction that GAP deletion increases Cdc42 activity at the expense of polarization. Our work demonstrates how membrane flows are an integral part of Cdc42-driven pattern formation and require Cdc42-GTP to turn over faster than the surface on which it forms.

Jean-Yves Ekra, Eliakunda Michael Mafie, Henri Sonan et al.

The resistance of trypanosomes to the doses of trypanocide administered by farmers to their animals acts as a real brake on efforts to control to combat African trypanosomiasis. Thus, in-depth knowledge of the use of these different molecules and their resistance profiles will be necessary to establish an integrated strategy to combat African trypanosomiasis. To achieve these objectives, a participatory survey among farmers and a resistance diagnosis of trypanosome strains identified in three regions of northern Côte d’Ivoire (Bagoué, Poro and Tchologo) was carried out using the PCR-RFLP technique, followed by sequencing of genes of interest. This study made it possible to identify three molecules that are commonly used by 85% (63/74) of farmers. In descending order of use, we identified Isometamidium chloride (43%), Diminazene aceturate (28%) and Homidium bromide (14%). Three species of trypanosomes, <i>Trypanosoma congolense</i>, <i>Trypanosoma. theileri</i> and <i>Trypanosoma vivax</i>, were identified in farms, and only one strain had the adenosine transporter gene (<i>Trypanosoma congolense</i>), but this strain was sensitive to the Diminazene aceturate molecule. Comparison of the sequence of this trypanosome strain showed that it is different to the Kenyan strain diagnosed as resistant to the Diminazene aceturate molecule. This study shows that a variety of trypanocides are used by farmers, and that the resistance profile of the strains to the Diminazene aceturate molecule could not be observed. However, it is important to further investigate the other molecules encountered in Côte d’Ivoire.

Mura Francesco, Benedetti Francesca, Kratter Matilde et al.

Xianwu Pang, Jinghua Huang, Kailing Tang et al.

The high proportion of AIDS cases and mortality rates in Guangxi underscores the urgency to investigate the influence of HIV-1 genetic diversity on disease progression in this region. Newly diagnosed HIV-1 patients were enrolled from January 2016 to December 2021, and the follow-up work and detection of CD4+T lymphocytes were carried out every six months until December 2022. Multivariate logistic regression was used to analyze the factors affecting pre-treatment CD4+T lymphocyte counts, while local weighted regression models (LOESS) and generalized estimating equation models (GEE) were conducted to assess factors influencing CD4+T Lymphocyte Recovery. Cox regression analysis was utilized to examine the impact of subtypes on survival risk. Additionally, HIV-1 env sequences were utilized for predicting CXCR4 and CCR5 receptors. The study encompassed 1867 individuals with pol sequences and 281 with env sequences. Our findings indicate that age over 30, divorced/widowed, peasant, heterosexual infection, CRF01_AE, long-term infection, and Pre-treatment Viral load &gt;10000 copies/ml were factors associated with higher risk for pre-treatment CD4+T lymphocyte decline. Specifically, male gender, age over 30, heterosexual infection (HETs), long-term infection, CRF01_AE, and Pre-treatment CD4 T cell counts below 350/µL were identified as risk factors impeding CD4+T lymphocyte recovery. Pre-treatment CD4+T lymphocyte counts and recovery in individuals infected with CRF01_AE were lower compared to CRF07_BC and CRF55_01B. Additionally, CRF01_AE and CRF08_BC subtypes exhibited higher mortality rates than CRF07_BC, CRF55_01B, and other subtypes. Notably, CRF01_AE demonstrated the highest percentage of CXCR4 affinity ratios. This research unveils the intricate influence of HIV-1 gene diversity on CD4+T lymphocyte dynamics and clinical outcomes. It highlights the multifaceted nature of HIV infection in Guangxi, providing novel insights into subtype-specific disease progression among HIV-infected individuals in this region.

Shelby E. Gantt, Patrick M. Erwin

Abstract Sponges perform important ecosystem functions, host diverse microbial symbiont communities (microbiomes), and have been increasing in density on Caribbean coral reefs over the last decade. Sponges compete for space in coral reef communities through both morphological and allelopathic strategies, but no studies of microbiome impacts during these interactions have been conducted. Microbiome alterations mediate spatial competition in other coral reef invertebrates and may similarly impact competitive outcomes for sponges. In this study, we characterized the microbiomes of three common Caribbean sponges (Agelas tubulata, Iotrochota birotulata, and Xestospongia muta) observed to naturally interact spatially in Key Largo, Florida (USA). For each species, replicate samples were collected from sponges in contact with neighbors at the site of contact (contact) and distant from the site of contact (no contact), and from sponges spatially isolated from neighbors (control). Next‐generation amplicon sequencing (V4 region of 16S rRNA) revealed significant differences in microbial community structure and diversity among sponge species, but no significant effects were observed within sponge species across all contact states and competitor pairings, indicating no large community shifts in response to direct contact. At a finer scale, particular symbiont taxa (operational taxonomic units at 97% sequence identity, OTUs) were shown to decrease significantly in some interaction pairings, suggesting localized effects for specific sponge competitors. Overall, these results revealed that direct contact during spatial competition does not significantly alter microbial community composition or structure of interacting sponges, suggesting that allelopathic interactions and competitive outcomes are not mediated by microbiome damage or destabilization.

Aamer Alchalaby, Semaa AL-Abedi

The present study's objective was to evaluate the inhibitory activity of the Probiotics Lactobacillus acidophilus and Bifidobacterium (obtained from the Agriculture Research Directorate, Ministry of Science and Technology, Iraq) and a suspension of a mixture between the two mentioned probiotics with two types of Gram-negative bacteria (Pseudomonas spp and Proteus spp) and one type of Gram-positive bacteria (Streptococcus spp) in vitro. The required tests were completed to verify the probiotics' purity, and the bacterial isolates used in the current investigation were assessed using biochemical assays and selected culture medium (culture and microscopic features). In addition, the inhibitory efficacy of the investigated Probiotics in different Gram positive and negative bacteria was evaluated by drug susceptibility testing (disc diffusion test as well as agar well diffusion test). Our data of the current study confirmed an excellent inhibitory activity of each Bifidobacterium (B) and the mixture of the two probiotics (MLB) via measuring the inhibition area, they had 25, 22mm, 28,-30 mm inhibition zone for Pseudomonas spp, 23, 25 mm, 26-27mm inhibition zone for Proteus species spp, and 22,20 mm, 33,29 mm inhibition quarter for Streptococcus species, by way of the usage of disc and agar well diffusion methods respectively. Where it was once weak inhibition activity of Lactobacillus acidophilus (L)on Pseudomonas spp, 0-3 mm and Streptococcus species 1-7 mm by the usage ofthe disc and agar well diffusion respectively. On the other, hand, Probiotic(Lactobacillus acidophilus) had available zone of inhibition on the Proteus sppbacteria, which were 24, 24 mm through the disc and agar well diffusion respectively. In conclusion: the Probiotics were found to have good and active inhibitory action on Gram-positive microorganism (Streptococcus) and gram-negative microorganism (Pseudomonas and Proteus) in vitro by way of using disc and agar well diffusion test, and the combination of the two probiotics MBL of present study, had more potent inhibitory action than each one of the studied separate probiotics.

Anjali Garg, Neelja Singhal, Manish Kumar

Matthew Combs, Ashley L. Marcinkiewicz, Alan P. Dupuis et al.

ABSTRACT Host association—the selective adaptation of pathogens to specific host species—evolves through constant interactions between host and pathogens, leaving a lot yet to be discovered on immunological mechanisms and genomic determinants. The causative agents of Lyme disease (LD) are spirochete bacteria composed of multiple species of the Borrelia burgdorferi sensu lato complex, including B. burgdorferi (Bb), the main LD pathogen in North America—a useful model for the study of mechanisms underlying host-pathogen association. Host adaptation requires pathogens’ ability to evade host immune responses, such as complement, the first-line innate immune defense mechanism. We tested the hypothesis that different host-adapted phenotypes among Bb strains are linked to polymorphic loci that confer complement evasion traits in a host-specific manner. We first examined the survivability of 20 Bb strains in sera in vitro and/or bloodstream and tissues in vivo from rodent and avian LD models. Three groups of complement-dependent host-association phenotypes emerged. We analyzed complement-evasion genes, identified a priori among all strains and sequenced and compared genomes for individual strains representing each phenotype. The evolutionary history of ospC loci is correlated with host-specific complement-evasion phenotypes, while comparative genomics suggests that several gene families and loci are potentially involved in host association. This multidisciplinary work provides novel insights into the functional evolution of host-adapted phenotypes, building a foundation for further investigation of the immunological and genomic determinants of host association. IMPORTANCE Host association is the phenotype that is commonly found in many pathogens that preferential survive in particular hosts. The Lyme disease (LD)-causing agent, B. burgdorferi (Bb), is an ideal model to study host association, as Bb is mainly maintained in nature through rodent and avian hosts. A widespread yet untested concept posits that host association in Bb strains is linked to Bb functional genetic variation conferring evasion to complement, an innate defense mechanism in vertebrate sera. Here, we tested this concept by grouping 20 Bb strains into three complement-dependent host-association phenotypes based on their survivability in sera and/or bloodstream and distal tissues in rodent and avian LD models. Phylogenomic analysis of these strains further correlated several gene families and loci, including ospC, with host-specific complement-evasion phenotypes. Such multifaceted studies thus pave the road to further identify the determinants of host association, providing mechanistic insights into host-pathogen interaction.

Philip Bell‐Doyon, Jérôme Laroche, Kristin Saltonstall et al.

Abstract Epiphytes face several constraints regarding nutrient acquisition: They are disconnected from soil minerals and they have to mainly rely on nutrients leached by precipitation and microbes. The cycad, Zamia pseudoparasitica Yates, is the only known strictly epiphytic gymnosperm, and it is endemic to Panamanian rainforests. Cycads have evolved specialized coralloid roots that host endophytic cyanobacteria specialized in nitrogen fixation. We collected coralloid roots from plants in the Omar Torrijos National Park, Provincia de Coclé. DNA was extracted from fresh inner coralloid roots, and the bacteriome was described using two molecular markers: rbcL‐rbcX (targeting cyanobacteria) and 16S (all bacteria). Sixteen samples were sequenced for rbcL‐rbcX yielding sequences belonging to a monophyletic group within the order Nostocales. One hundred and sixty‐five amplicon sequence variants (ASVs) were found in at least two of our 27 samples amplified for 16S. Nostocales, Rhizobiales, and Acetobacterales were the three most diverse and abundant orders of bacteria found within the coralloid roots, and the candidate phylum WPS‐2 was also found in many samples. We performed a de novo assembly from a single culture of the endophytic cyanobacteria. A phylogenomic analysis of the isolate places the cyanobacterium in a sister clade to mostly symbiotic taxa from mosses, liverworts, and lichens. Additionally, the isolate has genes putatively involved in symbiotic signaling, hormogonium differentiation, ammonium transport, nitrogen fixation, heterocyst differentiation, sulfate transport, and secondary metabolites. Although dominated by organisms with the capacity to fix nitrogen, coralloid roots are also inhabited by a diverse community of other taxa which may also play biologically important roles.

Shaohua Gu, Tianjie Yang, Zhengying Shao et al.

ABSTRACT Interactions between plant pathogens and root-associated microbes play an important role in determining disease outcomes. While several studies have suggested that steering these interactions may improve plant health, such approaches have remained challenging in practice. Because of low iron availability in most soils, competition for iron via secreted siderophore molecules might influence microbial interaction outcomes. Here, we tested if bacterial interactions mediated by iron-scavenging siderophores can be used to predict the disease suppressiveness of microbial consortia against soilborne Ralstonia solanacearum, a bacterial pathogen in the tomato rhizosphere. Iron availability significantly affected the interactions within inoculated consortia and between the consortia and the pathogen. We observed contrasting effects of siderophores and other nonsiderophore metabolites on the pathogen growth, while the siderophore effects were relatively much stronger. Specifically, disease incidence was reduced in vivo when the inoculated consortia produced siderophores that the pathogen could not use for its own growth. Employing siderophore-mediated interactions to engineer functionally robust microbial inoculants shows promise in protecting plants from soilborne pathogens. IMPORTANCE Soil-borne pathogens cause high losses in crop yields globally. The development of environmentally friendly approaches is urgently needed, but is often constrained by complex interactions between root-associated microbes and pathogens. Here, we demonstrate that the interactions within microbial consortia mediated by iron-scavenging siderophores play an important role in reducing pathogen infection and enhancing plant health. This study provides a promising and novel research direction for dealing with a wide range of microbial infections through iron exploitation, which is important for the colonization and infection of both plant and human hosts by pathogens.

Martin Weichert, José Guirao-Abad, Vishukumar Aimanianda et al.

ABSTRACT Many species of pathogenic fungi deploy the unfolded protein response (UPR) to expand the folding capacity of the endoplasmic reticulum (ER) in proportion to the demand for virulence-related proteins that traffic through the secretory pathway. Although Ca2+ plays a pivotal role in ER function, the mechanism by which transcriptional upregulation of the protein folding machinery is coordinated with Ca2+ homeostasis is incompletely understood. In this study, we investigated the link between the UPR and genes encoding P-type Ca2+-ATPases in the human-pathogenic mold Aspergillus fumigatus. We demonstrate that acute ER stress increases transcription of the srcA gene, encoding a member of the sarco/endoplasmic reticulum Ca2+-ATPase (SERCA) family, as well as that of pmrA, encoding a secretory pathway Ca2+-ATPase (SPCA) in the Golgi membrane. Loss of the UPR transcription factor HacA prevented the induction of srcA and pmrA transcription during ER stress, defining these ER/Golgi Ca2+ pumps as novel downstream targets of this pathway. While deletion of srcA alone caused no major deficiencies, a ΔsrcA/ΔpmrA mutant displayed a severe polarity defect, was hypersensitive to ER stress, and showed attenuated virulence. In addition, cell wall analyses revealed a striking reduction in mannose levels in the absence of both Ca2+ pumps. The ΔhacA mutant was hypersensitive to agents that block calcineurin-dependent signaling, consistent with a functional coupling between the UPR and Ca2+ homeostasis. Together, these findings demonstrate that the UPR integrates the need for increased levels of chaperone and folding enzymes with an influx of Ca2+ into the secretory pathway to support fungal growth, stress adaptation, and pathogenicity. IMPORTANCE The UPR is an intracellular signal transduction pathway that maintains homeostasis of the ER. The pathway is also tightly linked to the expression of virulence-related traits in diverse species of human-pathogenic and plant-pathogenic fungal species, including the predominant mold pathogen infecting humans, Aspergillus fumigatus. Despite advances in the understanding of UPR signaling, the linkages and networks that are governed by this pathway are not well defined. In this study, we revealed that the UPR is a major driving force for stimulating Ca2+ influx at the ER and Golgi membranes and that the coupling between the UPR and Ca2+ import is important for virulence, cell wall biosynthesis, and resistance to antifungal compounds that inhibit Ca2+ signaling.

Shakira Johnson, Dan Jones, Amali H. Thrimawithana et al.

Venturia nashicola, the cause of scab disease of Asian pears, is a host-specific, biotrophic fungus. It is restricted to Asia and is regarded as a quarantine threat outside this region. European pear displays nonhost resistance (NHR) to V. nashicola and Asian pears are nonhosts of V. pyrina (the cause of European pear scab disease). The host specificity of these two fungi is likely governed by differences in their effector arsenals, with a subset hypothesized to activate NHR. The Pyrus-Venturia pathosystem provides an opportunity to dissect the underlying genetics of nonhost interactions in this potentially more durable form of resistance. The V. nashicola genome will enable comparisons to other Venturia spp. genomes to identify effectors that potentially activate NHR in the pear scab pathosystem.