Mannose-binding Lectin Research Articles

P-1364. Cefiderocol Activity against Pseudomonas aeruginosa Clinical Isolates Carrying Metallo-β-lactamase Genes in United States and European Hospitals (2020–2023)

Abstract Background Cefiderocol (FDC) is a siderophore cephalosporin that uses the iron transport systems of Gram-negative bacteria to optimize cell entry. FDC is stable to hydrolysis by serine and metallo-β-lactamases (MBL). FDC and comparator activities were analyzed against P. aeruginosa (PSA) carrying MBL genes, as part of the SENTRY Antimicrobial Surveillance Program. Methods 9,573 PSA were collected from 36 sites in the US and 43 sites in Europe (EU) in 2020–2023. Susceptibility (S) testing used broth microdilution with cation-adjusted Mueller-Hinton broth (CAMHB) for comparators and iron-depleted CAMHB for FDC. CLSI/EUCAST breakpoints were used for FDC; whereas CLSI were applied for comparators (EUCAST for colistin [COL]). Isolates with MIC ≥4 mg/L (nonS by CLSI) for imipenem or meropenem were screened for β-lactamase genes. Results Carbapenem-nonS PSA comprised 23.4% (2,236/9,573) of isolates, with 22.3% (980/4,400) and 24.3% (1,256/5,173) originating from US and EU sites, respectively (Table). 5.5% (124/2,236) of PSA carried MBL, and these PSA were mostly from EU (94.4%). FDC (98.3–99.4%S) had MIC50 of 0.12 mg/L and MIC90 of 0.5 mg/L against carbapenem-nonS PSA from the US and EU, whereas other agents had lower S (80.9–90.2%), except for COL (99.7–99.8%S). Aztreonam-avibactam inhibited only 48.4% and 57.6% of carbapenem-nonS PSA from the US and EU at MIC of ≤8 mg/L, respectively. FDC (MIC50/90, 0.25/2 mg/L; 94.4–96.0%S) had activity against the MBL-carrying PSA subset; in contrast, other agents had off-scale MIC90 (i.e. >8 mg/L), except for COL (100%S). All PSA carrying blaIMP and blaVIM were susceptible to FDC (MIC90/100, 1/2 mg/L), whereas higher FDC MIC (MIC50/90, 2/16 mg/L; 57.1–64.3%S) were noted against blaNDM-carrying PSA. Conclusion FDC showed potent activity against carbapenem-nonS PSA clinical isolates from US and EU hospitals, including isolates carrying MBL genes, whereas newly launched BL/BLI didn’t show activity. FDC should be considered as an important option for the treatment of infections caused by these resistant subsets for which antibiotic treatment option are limited. Disclosures Rodrigo E. Mendes, PhD, GSK: Grant/Research Support

P-1367. Changing Epidemiology of Carbapenemase-producing Carbapenem-resistant Enterobacterales (CRE) in Taiwan

Abstract Background Rapid spread of carbapenemases (CP) among Enterobacterales require prompt identification to enable timely and appropriate treatment. This study aimed to determine the accuracy of NG-Test CARBA 5 for rapid detection of CP and to describe the epidemiology of carbapenem-resistant Enterobacterales (CRE) in Taiwan.Fig 1.Increasing Prevalence of Carbapenemase-producing Carbapenem-resistant Enterobacterales (CRE) in Taiwan (2018-2023) Methods 316 isolates of CRE were collected from a medical center, Kaohsiung Veterans General Hospital in Taiwan during 2018 to 2023, of which 30.4% were CP producers. The NG-Test CARBA5, PCR for blaKPC, blaVIM-2, blaIMP, blaNDM, and blaOXA-48-like genes were performed on 101 strains. Sequencing and phylogenetic analysis for blaKPC and blaNDM was done.Table 1.Performance of Rapid NG-Test Carba 5 compared to PCR for detecting carbapenemase genes in clinical isolates of carbapenem-resistant Enterobacterales (CRE) in Taiwan (N=101) Results A significant increase in the prevalence of CP-producing CRE was observed during this period from 9.9% before 2020 to 29.0% in 2020-2021 and 48.6% in 2022-2023 (OR for trend: 2.46, 95% CI: 1.78-3.38, p< 0.001). CP genes was detected by PCR in 100%, however, the NG-Test CARBA 5 failed in 9 strains, with a detection rate of 91.1%. The agreement between the 2 methods were high (94.4 % for CR-Escherichia coli, 90.6 % for CR-Klebsiella pneumoniae, 87.5 % for CR-Citrobacter freundii and 81.8 % for CR-Enterobacter spp). The major CP genes in CRE was blaKPC 38.6%, blaNDM 34.7%, blaIMP7.6% and blaOXA-48-like 6%. Metallo-β-lactamase (MBL) genes became prevalent over time and accounted for 54.5% of CP genes, which was mainly found in CR-E.coli. Highest expression of CP genes blaKPC and blaOXA-48 was in CR-K.pneumoniae (52.9% and 27.5%, blaNDM was in CR-E.coli (55.6%), and blaIMP in CR-Enterobacter spp. (68.2%). The most common genotype of blaNDM was blaNDM-1 (24/35, 68.6%), following by blaNDM-5 (9/35, 25.7%) and blaNDM-4 (2/35, 5.7%). All 33 blaKPC strains were KPC-2 type.Fig 2.Distribution of Carbapenemase (CP) genes in clinical isolates of CP-producing CRE in Taiwan (N=101) Conclusion Our study demonstrated that the NG-Test CARBA 5 was useful for rapid detection of CP genes, and the rising prevalence of MBL genes in Taiwan is a cause of concern due to limited treatment options. Disclosures All Authors: No reported disclosures

P-1363. Cefiderocol Activity against Clinical Enterobacterales Isolates Carrying Metallo-β-lactamase Genes in United States and European Hospitals (2020–2023)

Abstract Background Cefiderocol (FDC) is a siderophore cephalosporin that uses the iron transport systems of Gram-negative bacteria to optimize cell entry. FDC is stable to hydrolysis by serine (e.g. ESBLs, KPC, and OXA-type carbapenemases) and metallo-β-lactamases (MBL). FDC and comparator activities were analyzed against Enterobacterales (ENT) carrying MBL genes, as part of the SENTRY Antimicrobial Surveillance Program. Methods 32,052 ENT were collected from 35 sites in the US and 42 sites in the European (EU) regions during 2020–2023. Susceptibility (S) testing used broth microdilution with cation-adjusted Mueller-Hinton broth (CAMHB) for comparators and iron-depleted CAMHB for FDC. CLSI (same as the FDA) breakpoints were used for FDC; whereas CLSI were applied for comparators, except for colistin (EUCAST). ENT with MIC ≥2 mg/L (nonS based on CLSI criteria) for imipenem or meropenem were screened for β-lactamase genes. Results Carbapenem-nonS isolates comprised 2.9% (944/32,052) of the population, of which 1.4% (207/15,147) and 4.4% (737/16,905) originated from US and EU sites, respectively. FDC (94.6–96.6%S) had equivalent MIC90 of 4 mg/L against all carbapenem-nonS isolates, and the US and EU subsets, whereas other agents had S ≤86.5% (Table). FDC had MIC50/90 of 2/4 mg/L against isolates carrying MBL genes, including the blaNDM and blaVIM-1 subsets; in contrast, various other agents had off-scale MIC90 values (i.e. >8 mg/L). FDC MIC90 of 8 mg/L were obtained against isolates carrying blaNDM-5. Conclusion FDC showed potent activity against carbapenem-nonS ENT and those subsets of isolates carrying MBL genes. This potent FDC activity is presented against a particular subset of resistant ENT, for which antibiotic treatment options are limited. FDC should be considered as an important option for the treatment of infections caused by these resistant organisms. Disclosures Rodrigo E. Mendes, PhD, GSK: Grant/Research Support

Probing the interaction of mannose-binding lectin with healthy and sickle cell anemia red blood cells and its role in cellular biomechanics.

Mannose-binding lectin (MBL) is an important glycoprotein of the human innate immune system. Furthermore, individuals with sickle cell anemia (SCA) and MBL deficiency seem more susceptible to vaso-occlusive crises, suggesting an MBL role on HbSS red blood cells (RBCs). This study investigated the interaction of MBL with HbA (healthy) and HbSS RBCs using optical tweezers (OT) and atomic force microscopy (AFM). OT was employed to measure the RBC overall elasticity, while AFM was applied to assess the local stiffness and roughness of the cell membrane. Osmotic fragility assays were also performed. Additionally, cationic quantum dots (QDs) were applied to evaluate the membrane charges of HbSS RBCs. Results using QDs indicated that HbSS RBCs have a less negatively charged surface than HbA RBCs, potentially due to a reduced sialic acid content. Osmotic fragility assays showed that MBL enhanced the resistance of RBCs to lysis, while OT and AFM indicated a decrease in their elastic capacity following MBL incubation. Moreover, OT and membrane roughness results suggested a greater interaction of MBL with HbSS RBCs. We believe this study provided insights into the MBL interaction with HbSS RBCs, inciting further investigations to better understand its involvement in SCA pathophysiology in vivo.

Recognition of Staphylococcus aureus by the pattern recognition molecules langerin, mannan-binding lectin, and surfactant protein D: the influence of capsular polysaccharides and wall teichoic acid.

The innate immune system plays a critical role in the rapid recognition and elimination of pathogens through pattern recognition receptors (PRRs). Among these PRRs are the C-type lectins (CTLs) langerin, mannan-binding lectin (MBL), and surfactant protein D (SP-D), which recognize carbohydrate patterns on pathogens. Each represents proteins from different compartments of the body and employs separate effector mechanisms. We have investigated their interaction with the Gram-positive opportunistic pathogen Staphylococcus aureus, a bacterium whose cell wall contains two key glycopolymers: capsular polysaccharide (CP) and wall teichoic acid (WTA). Using a langerin-expressing cell line and recombinant langerin, MBL, and SP-D, we demonstrated that langerin, MBL, and SP-D all recognize nonencapsulated S. aureus. However, the bacterium may produce CP that effectively shields S. aureus from recognition by all three CTLs. Experiments utilizing mutant S. aureus strains confirmed that WTA is a ligand for MBL, but that langerin likely interacts with an additional unknown ligand. A competition assay revealed that MBL and SP-D inhibit langerin's interaction with S. aureus, highlighting the intricate redundancy and cooperation within the innate immune system. This study highlights the dynamic interplay of langerin, MBL, and SP-D in recognizing specific surface structures on S. aureus and provides insight into how this pathogen evades innate immune recognition.

A possible association between low MBL/lectin pathway functionality and microbiota dysbiosis in endometriosis patients.

Endometriosis (EM) is a chronic inflammatory disorder with multifactorial etiologies (i.e., genetics and environmental factors, hormonal and immunological changes, and microbiome alterations). The complement system is one of the most frequently dysregulated pathways in EM. Mannose-binding lectin (MBL), a carbohydrate pattern recognition molecule, is the first described recognition subcomponent of the complement lectin pathway (LP). Here, we unveiled the interplay among MBL polymorphisms, plasma levels, LP functionality, and microbiota as potential contributors to EM pathogenesis. A cohort of 38 EM patients and 20 healthy controls was enrolled and the levels and functionality of the lectin pathway were assessed via ELISA assays. MBL genetic variants and the endometrial and vaginal microbiome were investigated and correlated. High MBL levels were related to the disease severity, although not accountable to the MBL2 genotype. MBL and MASP-2 were present in the uterine mucosa but appeared to have no function at the endometriotic lesion. EM patients with LP functional deficit displayed pathogenic bacterial species more frequently in the endometrial microbiome. Moreover, women affected by EM showed a higher frequency of rare gene variants in the estrogen pathway genes, potentially affecting MBL plasma levels. A lower functionality of LP in the uterine mucosa may contribute to an unbalanced bacterial environment that could activate endometrial cells. Not only the genotype and the inflammatory condition, but also the estrogen pathway can cause altered MBL levels, thus contributing to changes in the LP functionality.

Metabolic labeling and targeted modulation of adipocytes.

Adipocytes play a critical role in energy storage and endocrine signaling and are associated with various diseases such as cancer and diabetes. Facile strategies to engineer adipocytes have long been pursued for elucidating adipocyte biology and developing adipocyte-based therapies. Herein, we report metabolic glycan labeling of adipocytes and subsequent targeted modulation of adipocytes via click chemistry. We show that azido tags expressed on the surface of adipocytes can persist for over 4 days. By conjugating dibenzocyclooctyne (DBCO)-cargos onto azido-labeled adipocytes via click chemistry, the cargos can be retained on the adipocyte membrane for over 12 hours. We further show that signaling molecules including adiponectin, calreticulin, mannose-binding lectin 2, and milk fat globule-EGF factor 8 protein can be conjugated to adipocytes to orchestrate their phagocytosis by macrophages. The azido-labeled adipocytes grafted into mice can also mediate targeted conjugation of DBCO-cargos in vivo. This adipocyte labeling and targeting technology will facilitate the development of adipocyte-based therapies and provides a new platform for manipulating the interaction between adipocytes and other types of cells.

Activation of the Complement Lectin Pathway by Iron Oxide Nanoparticles and Induction of Pro-inflammatory Immune Response by Macrophages

Aims: Nanoparticles are important agents for targeted drug delivery to tissues or organs, or even solid tumour in certain instances. However, their surface charge distribution makes them amenable to recognition by the host immune mechanisms, especially the innate immune system, which interferes with their intended targeting, circulation life, and eventual fate in the body. We aimed to study the immunological response of iron oxide nanoparticles (Fe-NPs) and the role of the complement system in inducing an inflammatory cascade. Background: The complement system is an important component of the innate immune system that can recognise molecular patterns on the pathogens (non-self), altered self (apoptotic and necrotic cells, and aggregated proteins such as beta-amyloid peptides), and cancer cells. It is no surprise that clusters of charge on nanoparticles are recognised by complement subcomponents, thus activating the three complement pathways: classical, alternative, and lectin. Objective: This study aimed to examine the ability of Fe-NPs to activate the complement system and interact with macrophages in vitro. Methods: Complement activation following exposure of macrophage-like cell line (THP-1) to Fe-NPs or positive control was analysed by standard protocol. Real-time PCR was used for mRNA-level gene expression analysis, whereas multiplex cytokine array was used for proteinlevel expression analysis of cytokines and chemokines. Results: Fe-NPs activated all three pathways to a certain extent; however, the activation of the lectin pathway was the most pronounced, suggesting that Fe-NPs bind mannan-binding lectin (MBL), a pattern recognition soluble receptor (humoral factor). MBL-mediated complement activation on the surface of Fe-NPs enhanced their uptake by THP-1 cells, in addition to dampening inflammatory cytokines, chemokines, growth factors, and soluble immune ligands. Conclusion: Selective complement deposition (via the lectin pathway in this study) can make pro-inflammatory nanoparticles biocompatible and render them anti-inflammatory properties.

Genotypic detection of metallo-Beta-Lactamases among multidrug resistant Klebsiella pneumoniae isolated from urine samples of UTI patients

Metallo-beta-lactamases producing bacteria are of public health concern, owning to the fact that bacteria that harbour genes for their production are notably resistant to several antibiotics. This study was carried out to genotypically investigate the prevalence of MBL-production in multidrug resistant K. pneumoniae isolated from urine samples of UTI patients attending a tertiary teaching hospital in Awka, Anambra State, Nigeria. Two hundred (200) mid-stream urine samples were collected from UTI patients, and were analyzed using standard microbiological procedures. Antibiotic susceptibility testing (AST) of the isolates was carried out using Kirby-Bauer disc diffusion method and combination disc test was employed to phenotypically screen the isolates for MBL production. The genotypic screening was performed by Polymerase chain reaction (PCR), using specific primers. Fifty-one (51) K. pneumoniae isolates were recovered from the urine samples. AST revealed that the isolates exhibited high resistance to Amoxicllin-clavulanic acid (100%), Ampiclox (98.04%), Imipenem (98.04%), Cefotaxime (96.08%), Cefuroxime (96.08%), Nitrofurantoin (70.59%), and were relatively susceptible to Ofloxacin (54.91%), Gentamycin (50.98%) and Levofloxacin (47.06%). A 79.02% of the K. pneumoniae isolates showed resistance to more than two classes of antibiotics, thus termed multidrug resistance strains. Of the 38 (41.76%) isolates of K. pneumoniae that were resistant to imipenem, 19 (20.88%) were confirmed as MBL-producers phenotypically, while 19 (20.88%) were non-MBL producers. Genotypically, blaVIM (21.98%) was the most detected MBL gene, followed by blaOXA-48 (18.68%) and blaIMP (15.38%). This study revealed the prevalence of multidrug resistant and MBLs producing K. pneumoniae in urine samples of the selected UTI patients.

Plasma acute phase proteins as potential predictors of intra-amniotic inflammation and infection in preterm premature rupture of membranes.

We aimed to investigate the potential of altered levels of various acute phase proteins (APPs) in the plasma, either used alone or in combination with ultrasound-, clinical-, and conventional blood-based tests, for predicting the risk of intra-amniotic inflammation (IAI), microbial invasion of the amniotic cavity (MIAC), histologic chorioamnionitis (HCA), and funisitis in women with preterm premature rupture of membranes (PPROM). A total of 195 consecutive pregnancies involving singleton women with PPROM (at 23 + 0-34 + 0 weeks) who underwent amniocentesis and from whom plasma samples were obtained at amniocentesis were retrospectively included in this study. Amniotic fluid (AF) was cultured to assess the MIAC and analyzed for interleukin (IL)-6 levels to define IAI (AF IL-6 level of ≥2.6 ng/mL). The plasma concentrations of hepcidin, mannose-binding lectin (MBL), pentraxin-2, retinol-binding protein 4 (RBP4), serum amyloid A1 (SAA1), and serpin A1 were determined using ELISA. Ultrasonographic cervical length (CL), neutrophil-to-lymphocyte ratio (NLR), and C-reactive protein levels were measured. IAI/MIAC was defined as IAI, MIAC, or both. Multivariate logistic regression analyses showed the following: (1) elevated plasma levels of hepcidin and SAA1 and decreased levels of RBP4 in the plasma were independently associated with IAI/MIAC and (2) decreased plasma RBP4 levels were independently associated with funisitis; however, (3) none of the plasma APPs investigated were associated with acute HCA when adjusted for baseline covariates. Using stepwise regression analysis, noninvasive prediction models comprising plasma RBP4 levels, CL, NLR, and gestational age at sampling were proposed, which provided a good prediction of IAI/MIAC and funisitis (area under the curve: 0.80 and 0.72, respectively). Hepcidin, RBP4, and SAA1 were identified as potential APP biomarkers in the plasma predictive of IAI/MIAC or funisitis in patients with PPROM. In particular, combination of these APP biomarkers with ultrasound-, clinical-, and conventional blood-based markers can significantly support the diagnosis of IAI/MIAC and funisitis.

Agaricus bisporus mannose-binding protein stimulates the innate immune cells

Purpose: A lectin-like protein from the mushroom Agaricus bisporus has been shown to slightly increase the proliferation of RAW 264.7 cells. Following its identification as a mannose-binding lectin, henceforth called A. bisporus mannose-binding protein (Abmb), the protein is hypothesized to stimulate the innate immune cells response. The present work was aimed to substantiate that hypothesis. Furthermore, this study complements Abmb exploration as a potential agent for anti-breast cancer, which its treatment is hampered with compromised immunity of patient receiving chemotherapy. Method: Abmb’s effect on the phagocytic activity of the macrophage was measured with FACS. Nitric oxide production was checked using Griess test while expression of the cytokines in the RAW 264.7 cells was analysed at gene and protein level using PCR and FACS, respectively. Abmb’s effect on the expression of surface markers of the human immune cells in the peripheral blood mononuclear cells was checked with specific antibodies for targeted cluster differentiation and analysed using FACS. Result: Abmb increased the phagocytic activity of the macrophage and NO production. Abmb increased the expression of cytokines i.e. tumour necrosis factor (TNF)-α, interleukin (IL)-6, and IL-10. With the peripheral blood mononuclear cells, Abmb activated dendritic and Natural Killer cells, but not the B- or T-cells. Conclusion: Abmb increased the activity of the macrophage cells and activated the immune cells that are related to the innate immune system, particularly the cellular immunity.

Pitavastatin, Procollagen Pathways, and Plaque Stabilization in Patients With HIV

In a mechanistic substudy of the Randomized Trial to Prevent Vascular Events in HIV (REPRIEVE) randomized clinical trial, pitavastatin reduced noncalcified plaque (NCP) volume, but specific protein and gene pathways contributing to changes in coronary plaque remain unknown. To use targeted discovery proteomics and transcriptomics approaches to interrogate biological pathways beyond low-density lipoprotein cholesterol (LDL-C), relating statin outcomes to reduce NCP volume and promote plaque stabilization among people with HIV (PWH). This was a post hoc analysis of the double-blind, placebo-controlled, REPRIEVE randomized clinical trial. Participants underwent coronary computed tomography angiography (CTA), plasma protein analysis, and transcriptomic analysis at baseline and 2-year follow-up. The trial enrolled PWH from April 2015 to February 2018 at 31 US research sites. PWH without known cardiovascular diseases taking antiretroviral therapy and with low to moderate 10-year cardiovascular risk were eligible. Data analyses were conducted from October 2023 to February 2024. Oral pitavastatin calcium, 4 mg per day. Relative change in plasma proteomics, transcriptomics, and noncalcified plaque volume among those receiving treatment vs placebo. Among 558 individuals (mean [SD] age, 51 [6] years; 455 male [82%]) included in the proteomics assessment, 272 (48.7%) received pitavastatin and 286 (51.3%) received placebo. After adjusting for false discovery rates, pitavastatin increased abundance of procollagen C-endopeptidase enhancer 1 (PCOLCE), neuropilin 1 (NRP-1), major histocompatibility complex class I polypeptide-related sequence A (MIC-A) and B (MIC-B), and decreased abundance of tissue factor pathway inhibitor (TFPI), tumor necrosis factor ligand superfamily member 10 (TRAIL), angiopoietin-related protein 3 (ANGPTL3), and mannose-binding protein C (MBL2). Among these proteins, the association of pitavastatin with PCOLCE (a rate-limiting enzyme of collagen deposition) was greatest, with an effect size of 24.3% (95% CI, 18.0%-30.8%; P < .001). In a transcriptomic analysis, individual collagen genes and collagen gene sets showed increased expression. Among the 195 individuals with plaque at baseline (88 [45.1%] taking pitavastatin, 107 [54.9%] taking placebo), changes in NCP volume were most strongly associated with changes in PCOLCE (%change NCP volume/log2-fold change = -31.9%; 95% CI, -42.9% to -18.7%; P < .001), independent of changes in LDL-C level. Increases in PCOLCE related most strongly to change in the fibro-fatty (<130 Hounsfield units) component of NCP (%change fibro-fatty volume/log2-fold change = -38.5%; 95% CI, -58.1% to -9.7%; P = .01) with a directionally opposite, although nonsignificant, increase in calcified plaque (%change calcified volume/log2-fold change = 34.4%; 95% CI, -7.9% to 96.2%; P = .12). Results of this secondary analysis of the REPRIEVE randomized clinical trial suggest that PCOLCE may be associated with the atherosclerotic plaque stabilization effects of statins by promoting collagen deposition in the extracellular matrix transforming vulnerable plaque phenotypes to more stable coronary lesions. ClinicalTrials.gov Identifier: NCT02344290.

Unraveling the impact of SARS-CoV-2 mutations on immunity: insights from innate immune recognition to antibody and T cell responses.

Throughout the COVID-19 pandemic, the emergence of new viral variants has challenged public health efforts, often evading antibody responses generated by infections and vaccinations. This immune escape has led to waves of breakthrough infections, raising questions about the efficacy and durability of immune protection. Here we focus on the impact of SARS-CoV-2 Delta and Omicron spike mutations on ACE-2 receptor binding, protein stability, and immune response evasion. Delta and Omicron variants had 3-5 times higher binding affinities to ACE-2 than the ancestral strain (KDwt = 23.4 nM, KDDelta = 8.08 nM, KDBA.1 = 4.77 nM, KDBA.2 = 4.47 nM). The pattern recognition molecule mannose-binding lectin (MBL) has been shown to recognize the spike protein. Here we found that MBL binding remained largely unchanged across the variants, even after introducing mutations at single glycan sites. Although MBL binding decreased post-vaccination, it increased by 2.6-fold upon IgG depletion, suggesting a compensatory or redundant role in immune recognition. Notably, we identified two glycan sites (N717 and N801) as potentially essential for the structural integrity of the spike protein. We also evaluated the antibody and T cell responses. Neutralization by serum immunoglobulins was predominantly mediated by IgG rather than IgA and was markedly impaired against the Delta (5.8-fold decrease) and Omicron variants BA.1 (17.4-fold) and BA.2 (14.2-fold). T cell responses, initially conserved, waned rapidly within 3 months post-Omicron infection. Our data suggests that immune imprinting may have hindered antibody and T cell responses toward the variants. Overall, despite decreased antibody neutralization, MBL recognition and T cell responses were generally unaffected by the variants. These findings extend our understanding of the complex interplay between viral adaptation and immune response, underscoring the importance of considering MBL interactions, immune imprinting, and viral evolution dynamics in developing new vaccine and treatment strategies.

Genomic Insights into Host Susceptibility to Periprosthetic Joint Infections: A Comprehensive Literature Review.

Periprosthetic joint infection (PJI) is a multifactorial disease, and the risk of contracting infection is determined by the complex interplays between environmental and host-related factors. While research has shown that certain individuals may have a genetic predisposition for PJI, the existing literature is scarce, and the heterogeneity in the assessed genes limits its clinical applicability. Our review on genetic susceptibility for PJI has the following two objectives: (1) Explore the potential risk of developing PJI based on specific genetic polymorphisms or allelic variations; and (2) Characterize the regulatory cascades involved in the risk of developing PJI. This review focused on clinical studies investigating the association between genetic mutations or variations with the development of PJI. The genes investigated in these studies included toll-like receptors and humoral pattern recognition molecules, cytokines, chemokines, mannose-binding lectin (MBL), bone metabolism molecules, and human leukocyte antigen. Among these genes, polymorphisms in IL-1, MBL, vitamin D receptors, HLA-C, and HLA-DQ might have a relevant impact on the development of PJI. The literature surrounding this topic is limited, but emerging transcriptomic and genome-wide association studies hold promise for identifying at-risk genes. This advancement could pave the way for incorporating genetic testing into preoperative risk stratification, enhancing personalized patient care.

Convergence of plant sterols and host eukaryotic cell-derived defensive lipids at the infectious pathogen-host interface.

Plant sterols (PSs) exhibit intrinsic functions such as antibacterial effects. Their effects simultaneously on both host-mediated and bacteria-mediated pathogenesis are not yet fully understood. We hypothesized that when absorptive cells, defensive cells and detoxer cells are cultured together, their convergent response to an infectious pathogen depends on the molecular mimicry between the ingested sterols and their own defensive lipids. A human triple cell co-culture model incorporating colonocytes, macrophages, and hepatocytes was established. Cocultures were stimulated with Klebsiella pneumoniae 52145 (Kp52145) in the presence of pure plant sterol (β-sitosterol, PS) for 6h. Changes in the structural health markers of the stimulated cocultured cells and their immune response and biochemical markers of pathogenicity were determined. PS significantly inhibited the secretion of cytokines induced by Kp52145. Cell viability was higher in the Kp52145+PS group compared to the Kp52145 alone group. PS decreased Kp52145-induced marker of pathogenicity (SOD), accompanied by reduced levels of interleukin-1β (IL-1β), interleukin-6 (IL-6), mannose binding lectin (MBL), and pentraxin 3 (PTX3) which are the mediators and enzymes associated with the inflammatory response to an infectious-inflamed milieu. PS recovered Kp52145-decreased peroxidase (POX), catalase (CAT), complement component 3 (C3), and high-density lipoprotein cholesterol (HDL-C) values. Convergence of ingested plant sterols and host eukaryotic cell-derived defensive lipids mitigates the disruptive effects of bacterial toxic effector molecules. Structural or immunological similarities (molecular mimicry) between ingested plant sterols and host defensive lipids play an important role in modulating bacterial signalling that occurs at the pathogen-host interface and in the mitigation of infection- and inflammation-driven pathological processes.

MOLECULAR CHARACTERIZATION OF MBL IN UROPATHOGENIC E. COLI ISOLATED FROM PATIENTS OF TERTIARY CARE HOSPITAL

Background: Antibiotic resistance is on an increasing trend, particularly in gram-negative bacteria. The production of metallo β-lactamase (MBL) puts the health sector at great risk as it further limits the treatment option for MDR strain. MBL is mostly reported in Enterobacteriaceae, which poses resistance to almost all β-lactam antibiotics except monobactam. The current study aims to determine the prevalence, antibacterial sensitivity pattern, and molecular characterization of MBL in Uropathogenic E. coli from clinical samples of hospitalized patients in Khyber Pakhtunkhwa. Methods: From tertiary care hospitals in Peshawar, 250 Urine samples were collected from indoor hospitalized patients. Gold standard microbiological methods were used to identify UPEC from these clinical samples.For that,urine samples was inoculated onto Cysteine Lactose Electrolyte. Deficient (CLED) agar plate, and MacConkey Agar.Positive growth of E.coli identified through Gram staining, colony morphology, Biochemical Tests and E.coli 16srRNA gene amplification .Antibiotic sensitivity was determined by the disc diffusion method on Muller Hinton agar. For the detection of MBL production double disc synergy, and a combination disc test of the antibiotics were used. Furthermore, multiplex PCR was used for the molecular characterization of the MBL (blaIMP, blaVIM, and blaNDM) genes. Results: Of the 250 samples, only 110 samples were confirmed as Uropathogenic E. coli based on colonial morphology, biochemical testing, and molecular level by targeting the 16SrDNA. Female was found more susceptible to UTI compared to male. High prevalence was found in the age group 45-65 years. UPEC was found highly resistance to Ciprofloxacin (90%), followed by Cefotaxime and Ceftriaxone (86%), Ceftazidime and Augmentin (81%), Tazobactam (61%). while the lowest resistance was reported against Meropenum (20%) Imipenem (18%) and Amikacin (37%). PCR-based confirmed prevalence of MBL encoding genes was blaNDM (42%), blaVIM (32%), and blaIMP (26%). Conclusion: The study proposed a higher prevalence of urinary tract infections (UTIs) in females aged group 54-65 years compared to males. An analysis of antibiotic sensitivity revealed Imipenem and Meropenem to be the most effective antimicrobial agents, while Ciprofloxacin, Cefotaxime and Amoxicillin were found to be the less effective. UPEC were found highly resistance to Ciprofloxacin 91%, and ceftazidime 86%, while comparatively less resistance to meropenem, and imipenem,20% and 18% respectively. Genotype BlaNDM of the MBL is highly prevalent (42%) among UPEC.Furthermore, the presence of MBL genes was detected in over 19% of UPEC, and in different combinations.The upraise of the MBLs resistance in uropathogenic E. coli is an alarming sign for clinicians to decide on treatment options for complicated UTIs.

High diversity of strain clonality and metallo-β-lactamases genes among carbapenem-resistant Enterobacterales in Taiwan.

This study aimed to investigate the genetic and clinical characteristics of carbapenem-resistant Enterobacterales (CRE) isolates carrying metallo-β-lactamases (MBLs) genes. A total of 146 non-duplicated isolates of CRE were collected in 2022. Their ceftazidime/avibactam (CZA) susceptibilities were determined using the E test. The phenotypic identification of carbapenemases was conducted using the modified carbapenem inactivation method, followed by sequencing of the five common carbapenemase genes (blaKPC, blaNDM, blaVIM, blaIMP, and blaOXA-48). Multilocus sequence typing of selected Klebsiella pneumoniae, Escherichia coli, and Enterobacter cloacae complex isolates were performed. Among the 146 CRE isolates, 52 (35.6%) were resistant to CZA. MBL-encoding genes were detected in 46 (31.5%) of all tested CRE isolates, with 82.6% (n = 38) of them exhibiting resistance to CZA. Fourteen isolates were resistant to CZA without any detected MBL genes. The most commonly identified MBL genes were blaIMP (n = 20), followed by blaNDM (n = 19), and blaVIM (n = 5). In CZA-R, the most common definite antibiotic before the CZA E test was CZA (n = 18), followed by tigecycline (n = 13), and fluroquinolone (n = 10). The 14-day and 30-day mortality rates were 9.0% (n = 13) and 22.8% (n = 34), and were associated with intensive care unit admission at onset (P = 0.029 and P = 0.001, respectively). The sequence types of CRE isolates carrying MBLs were diverse without major clones. The continuous emergence of MBL gene-encoding CRE with multiple clones has led to reduced CZA susceptibilities and worse outcomes.

Highly sensitive and rapid detection of Vibrio parahaemolyticus using a dual-recognition platform based on functionalized quantum dots and aptamer.

As one of the most harmful pathogenic bacteria in shrimp aquaculture, Vibrio parahaemolyticus often causes massive mortality in shrimp. Accurate and rapid detection of V. parahaemolyticus in shrimp farming is essential for avoiding huge economic losses caused by related diseases. In this study, we designed a dual-recognition platform for efficient identification and quantification of V. parahaemolyticus. First, the target bacterium was captured with magnetic beads functionalized by aptamers (Apt-MBs), and then, the broad-spectrum fluorescent probe FcMBL@CdSe-ZnS was used to detect the bacterium based on the interactions between fragment crystallizable mannose-binding lectin (FcMBL) and pathogenic bacteria. The proposed dual-recognition strategy centered around aptamers and FcMBL@CdSe-ZnS was applied to definite quantification of V. parahaemolyticus over a wide range of 10-108 CFU/mL with a limit of detection of 4 CFU/mL within 55 min. The feasibility was demonstrated by using the platform to detect V. parahaemolyticus from shrimp intestine, aquaculture water, and seawater.

OsPIPK-FAB, A Negative Regulator in Rice Immunity Unveiled by OsMBL1 Inhibition

Phosphatidylinositol signaling system plays a crucial role in plant physiology and development, phosphatidylinositol phosphate kinases (PIPKs) are one of the essential enzymes responsible for catalyzing the synthesis of phosphatidylinositol bisphosphate (PIP2) within this signaling pathway. However, its mechanism of signal transduction remains poorly exploited in plants. OsMBL1, a jacalin-related mannose-binding lectin in rice, plays a crucial role in plant defense mechanisms, acting as a key component of the pattern-triggered immunity (PTI) pathway. Here, a rice phosphatidylinositol-phosphate kinase FAB (OsPIPK-FAB), a member of the rice PIPKs family, as an interacting protein of OsMBL1 through yeast-two-hybrid (Y2H) screening assay. And this interaction was confirmed by using co-immunoprecipitation (Co-IP) and pull-down assay techniques. Furthermore, we demonstrated that the deletion of OsPIPK-FAB gene in plant enhanced resistance against rice blast while overexpression of OsPIPK-FAB increases sensitivity to the fungal infection. Additionally, through determination and measurement of the plant inositol 1,4,5-trisphosphate (IP3) contents and the plant phosphatidylinositol 4-phosphate 5-kinase (PIP5K) activity, we revealed that OsMBL1 inhibits the PIP5K kinase activity of OsPIPK-FAB as well as the plant IP3 contents in rice. Conclusively, these findings indicated that OsPIPK-FAB serves as a novel and critical component that is negatively involved in PTI activation and was inhibited by OsMBL1.

A single-center analysis of clonal transmission of carbapenem-resistant Acinetobacter baumannii among intensive care unit patients during the COVID-19 pandemic

Carbapenem-Resistant Acinetobacter baumannii (CRAB) outbreak in intensive care units (ICUs) is a significant problem for healthcare facilities. In this study, we aimed to investigate the occurrence of CRAB isolates among ICU-admitted patients during the three waves of the COVID-19 pandemic in Iran using Multiple-Locus Variable Number Tandem-Repeat Analysis (MLVA). We obtained 50 (A) baumannii isolates from tracheal aspirate and blood culture samples. In the disc diffusion method, all isolates were cefotaxime, ceftriaxone, and cefepime-resistant, while 98% (49/50) of isolates were resistant to piperacillin, piperacillin-tazobactam, ceftazidime, and ciprofloxacin. Levofloxacin and tobramycin resistance was found in 76% (38/50) of isolates. In the microbroth dilution test all isolates were resistant to imipenem, 98% (49/50) to meropenem, 68% (34/50) to colistin, and 20% (10/50) to polymyxin (B) Based on the PCR findings, all isolates harbored blaOXA−40, ISAba-1, and int-2 genes. There were no isolates found that have the blaOXA−58, blaOXA−143, blaVEB−1, blaVIM, and int-3 genes. Among Extended-spectrum beta-lactamases (ESBL) genes, blaCTX−M, blaTEM, blaSHV, blaGES, and blaPER−1 have a prevalence of 42% (21/50), 84% (42/50), 58% (29/50), 78% (39/50), and 54% (27/50), respectively. 74% (37/50) of the isolates had the blaOXA−23 gene, while all of the isolates carried the blaOXA−40 gene. Among MBL genes, blaIPM, blaGIM, blaSIM, and blaNDM−1 have a prevalence of 20% (10/50), 8% (4/50), 22% (11/50), and 60% (30/50), respectively. The prevalence of int-1 was documented as 74% (37/50). Accordingly, all isolates were identified as CRAB. The co-existence of blaOXA−23/int-2 and blaOXA−23/isaba-1 was 74% (37/50). The co-existence of blaNDM−1/ISAba-1 was observed in 30 (60%) isolates. Using an 80% similarity threshold on the dendrogram constructed through MLVA typing, all isolates were grouped into two clusters: cluster A with 9 isolates from wave 3, and cluster B with 41 isolates from waves 3, 4, and 5. Our study confirms a clonal transmission of CRAB during the study period and suggests using molecular typing methods like MLVA in healthcare settings to identify dominant clones, antibiotic resistance patterns, and transmission routes. This will help to better manage the emergence and spread of antibiotic-resistant strains in future outbreaks.