Search Results (1,364)

Background: Shikonins are natural naphthoquinones that exhibit a range of biological activities. They are typically extracted using nonpolar solvents; however, green extraction approaches remain underexplored. Methods: Phytochemical profiling of E. vulgare root extracts was performed using HPLC-ESI-QTOF-MS/MS and quantitative analysis using HPLC-PDA. Shikonin extraction was performed using VNADESs based on thymol, camphor, menthol and benzyl alcohol. The feasibility of removing the VNADES from the extracts via freeze-drying was assessed. The cytotoxic, antioxidant, anti-inflammatory and antimicrobial activities of the hexane extract and the selected VNADES-based extract (TBa 2:8) were compared. Results: Eight shikonin derivatives were identified in the extracts. VNADES extracts contained comparable amounts of shikonin to hexane extracts; however, freeze-drying resulted in significant shikonin content loss. TBa 2:8 extract exhibited noticeably lower cytotoxicity than the hexane extract while its antioxidant potential depended on the assay applied. In contrast to the hexane extract, TBa 2:8 demonstrated the ability to reduce intracellular ROS and NO levels. However, the hexane extract exhibited stronger antimicrobial activity. Conclusions: VNADES systems enable efficient extraction of shikonin derivatives with performance comparable to hexane. Although the resulting extracts exhibit multidirectional biological activity, it remains challenging to remove the VNADESs effectively without losing the shikonins. Full article

Neonatal infections remain a leading cause of morbidity and mortality worldwide, particularly among preterm and low-birth-weight infants and in low- and middle-income countries. This burden has intensified with the global increase in multidrug-resistant (MDR) bacteria, especially in neonatal intensive care units, where prolonged hospitalization, invasive interventions, and exposure to broad-spectrum antibiotics promote colonization, transmission, and invasive infection. In this narrative review, we explore the epidemiology and microbiological characteristics of MDR bacterial infections in newborns, alongside their associated risk factors, diagnostic challenges, treatment outcomes, and prevention strategies. Across different settings, Gram-negative pathogens, particularly Klebsiella pneumoniae, Escherichia coli, and Acinetobacter baumannii, account for a substantial proportion of severe neonatal infections, whereas methicillin-resistant Staphylococcus aureus remains important in selected units. The risk of MDR infection is driven by a complex interplay of factors, ranging from maternal and perinatal exposures to the inherent immunological vulnerability of newborns, hospital-based transmission, antibiotic selection pressure, and structural deficiencies in healthcare infrastructure. Diagnosis remains challenging because clinical presentations are nonspecific and culture-based methods are constrained by low blood volumes, prior antimicrobial exposure, and delayed turnaround times. Treatment is increasingly complicated due to resistance to standard empirical regimens, substantial regional variation in susceptibility profiles, and limited neonatal pharmacokinetic and safety data for reserve agents. Current evidence mainly supports surveillance-informed empirical therapy, susceptibility-guided treatment adjustment, antimicrobial stewardship, and strict infection prevention measures. Future progress will require neonatal-specific clinical trials, harmonized surveillance systems, stronger molecular epidemiology, and more equitable access to microbiological diagnostics and effective treatment. Full article

Acinetobacter baumannii, a prominent opportunistic pathogen in healthcare settings, causes severe infections and poses significant challenges for clinical treatment. This study investigates the synergistic effects of α-pinene combined with meropenem (MEM) on A. baumannii biofilm formation and lung injury in mice, aiming to develop new strategies to combat persistent infections and antibiotic resistance. α-pinene combined with MEM exhibited strong synergistic antibacterial activity against carbapenem-resistant A. baumannii (CRAB 5E9). The combination significantly inhibited biofilm formation, extracellular polymer production, surface motility, and quorum sensing. The expression of key genes such as ompA, bfmR, bap, csuAB, abaI, and abaR was reduced by up to 61%. In vivo, the treatment alleviated weight loss, decreased the bacterial load in lung tissue, and reduced lung inflammation. Furthermore, it significantly suppressed proteins involved in the inflammatory response and the MAPK pathway, including TLR4, NF-κB, NLRP3, TRAF6, ERK2, p38 MAPK, JNK, and TNF-α. The combination of α-pinene and MEM synergistically inhibits A. baumannii biofilm formation and alleviates the inflammatory response in a mouse model, offering a potential therapeutic approach for combating A. baumannii infections. Full article

Objectives: This study evaluated the diagnostic performance of the lateral flow immunochromatographic assay (RESIST-ACINETO, Coris BioConcept) for the rapid detection of the major carbapenemases in Acinetobacter baumannii. Methods: Blood culture isolates collected between 2014 and 2024 with meropenem MIC ≥ 4 mg/L were retrieved, re-identified by MALDI-TOF MS, and susceptibility was confirmed by broth microdilution. Carbapenemase genes (bla_OXA-23, bla_OXA-40, bla_NDM) were detected using multiplex PCR, which served as the reference standard. All isolates were tested using the RESIST ACINETO assay, and diagnostic accuracy parameters were calculated. Results: A total of 114 isolates were recovered and confirmed as A. baumannii. Among 93 carbapenem-non-susceptible isolates, 97.8% (91/93) were correctly identified by the assay. The test showed 99.1% sensitivity and 99.1% specificity, with most positive results appearing within 3–10 min. Two discrepant results were observed (one false positive, one false negative), while all meropenem-susceptible isolates tested negative. Conclusions: The RESIST ACINETO assay provides rapid, accurate detection of carbapenemases in A. baumannii, significantly reducing turnaround time compared with conventional workflows. Its performance supports integration into routine diagnostics to enhance timely resistance confirmation and infection-control interventions. Full article

Carbapenem-resistant Acinetobacter baumannii (CRAB) is classified as a critical priority pathogen by the World Health Organization, and new therapeutic alternatives are urgently needed. In this study, we performed genomic mining of 27,531 A. baumannii genomes and identified 5144 prophage-derived endolysin candidates. Four highly prevalent candidates (E1–E4) were recombinantly expressed and functionally evaluated against A. baumannii. Among them, E1 exhibited the strongest bactericidal activity against reference strains ATCC 19606 and CMCC 25001, with a minimum inhibitory concentration in the micromolar range. E1 effectively disrupted preformed biofilms (>60% reduction) and remained stable under a broad range of temperatures (4–60 °C), pH values (6–8), and NaCl concentrations (up to 500 mM). Structural analysis indicated that E1 adopts a canonical lysozyme-like fold with key residues for peptidoglycan binding, and its lytic activity in vitro relied on 1 mM EDTA-mediated outer membrane permeabilization. In a murine peritoneal infection model, combination therapy with E1 and meropenem (each at 1 × MIC) significantly increased the survival rate to 66.7% and reduced bacterial loads in blood and multiple organs. This study demonstrates that prophage-derived endolysin E1 acts synergistically with meropenem against A. baumannii, supporting E1 as a promising candidate for developing combination therapies against CRAB. Full article

Chicken manure and its potential to contaminate water systems through the dispersal of pathogenic bacteria are major concerns in environmental and public health. In this study, a metagenomic analysis was employed to systematically identify and compare bacterial assemblages in chicken manure (CM) and in a contaminated sample of chicken manure wastewater (CMW). Whole DNA was extracted from CM and CMW, followed by whole-genome shotgun sequencing; data analysis was done using online Galaxy software (ver. 26.0.1.dev1). Metagenomic analysis reveals a complex One Health challenge. Data showed that CM and CMW are different in their microbiota, as indicated by a distinct separation of beta diversity values and limited overlapping of species between sample types. In the current study, we found a greatly significant common functional set of adapted bacterial masses, including major pathogenic bacterial groups as well as opportunistic and environmental bacterial species, indicative of a direct contamination from CM and CMW. Notably, in both CM and CMW, a plethora of opportunistic, enteric, and environmental pathogens like Escherichia coli, Salmonella enterica, and Acinetobacter baumannii were found, coupled with an indication of a direct functional flow between both ecosystems as tangled reservoirs. Chicken manure samples showed differences in taxonomic composition and inferred functional profiles at the time of sampling: CM1 was pathogen-enriched, CM2 exhibited strong nitrogen-supportive metabolism, CM3 was dominated by fiber-degrading decomposers, and CM4 showed high methane-producing potential with environmental risk. Such findings underscore the raising of chickens as a potential source of harmful bacteria for the environment. It is important to note that this study represents a preliminary investigation with certain limitations, including the absence of biological replicates, lack of temporal sampling, and limited capacity to infer dynamic ecological interactions. Yet this metagenomic report is more about describing the taxonomy and functional potential of the bacteria, rather than discussing the actual ecological processes of these microorganisms in the environment. Future studies will be required to explore these aspects. Full article

Carbapenem-resistant Acinetobacter baumannii infections pose a significant challenge due to their severity and the poor prognoses they often result in, particularly in cases where there are risk factors present. The United States (US) Centers for Disease Control and Prevention (CDC) identified carbapenem-resistant Acinetobacter baumannii (CRAB) infections as a threat to human health. The World Health Organization (WHO) has classified it as a top priority for research. In 2023, the US FDA approved sulbactam–durlobactam for treating certain A. baumannii infections. As of 2024, this combination is designated as the preferred treatment strategy by the Infectious Diseases Society of America (IDSA) for infections due to carbapenem-resistant A. baumannii. In this therapeutic review, the preclinical and clinical data relevant to this regulatory decision were analyzed. This in-depth analysis will provide a comprehensive overview of the complex subject matter. It should be observed that carbapenem-based combination therapy is indicated for carbapenem-resistant A. baumannii. Full article

Carbapenems comprise a class of β-lactam antibiotics with broad-spectrum hydrolytic activity and are often reserved as last-line agents for the treatment of serious multidrug-resistant (MDR) bacterial infections. Clinically important nosocomial MDR Gram-negative bacteria (GNB) include Klebsiella pneumoniae, Pseudomonas aeruginosa, and Acinetobacter baumannii. Carbapenem resistance among these organisms is predominantly mediated by the production of β-lactamases called carbapenemases, such as K. pneumoniae carbapenemase (KPC), New Delhi metallo-β-lactamase (NDM), imipenemase (IMP), Verona integron-encoded metallo-β-lactamase (VIM), and selected oxacillinase (OXA)-type carbapenemases. These enzymes degrade carbapenems, significantly compromising their clinical efficacy. To address escalating antimicrobial resistance, novel next-generation β-lactamase inhibitors (BLIs), partnered with established β-lactams (BLs), have been approved or are currently under development to inhibit carbapenemase activity. The present narrative review aims to synthesize the most current information on the major carbapenemases and discusses recently approved and investigational BL/BLI combination therapies in terms of their mechanisms of action, spectrum of activity, gaps in coverage, and available clinical and in vitro evidence. Development of resistance to novel BL/BLI combinations is also examined. Comparative analysis of inhibitory spectra and microbiological coverage indicates a continued need for metallo-β-lactamase inhibitors with direct pan-inhibitory activity, pathogen-specific BL/BLI regimens for carbapenem-resistant A. baumannii, and carbapenemase-targeted agents effective in the context of non-enzymatic resistance mechanisms. Treatment-emergent resistance to novel BL/BLIs and limitations in activity profiles underscore the critical need for continued innovation in pipeline development, vigilant global and local surveillance of carbapenemase epidemiology, and robust antimicrobial stewardship strategies to aid in preserving the efficacy of the antibacterial drug armamentarium. Full article

Background: Colistin (Col) resistance and heteroresistance in extensively drug-resistant (XDR) Acinetobacter baumannii severely limit therapeutic options. We investigated the activity and mechanism of human albumin nanoparticles (haNPs) as colistin potentiators against genetically characterized clinical isolates. Methods: Sixteen clinical isolates were analyzed. Col MICs were determined by broth microdilution, and heteroresistance by population analysis profiling. Potentiation of Col activity was assessed using both Col-loaded haNPs (Col/haNPs) and free Col co-administered with empty haNPs, alongside the proton motive force (PMF) uncoupler carbonyl cyanide 3-chlorophenylhydrazone (CCCP). Assays included checkerboard synergy (FICI), membrane potential analysis (DiOC₂(3)), intracellular Col quantification (UPLC–MS/MS), zeta potential measurements, transmission electron microscopy (TEM), protein leakage, and ROS detection. Results: Heteroresistance was detected in 9/16 isolates. Col/haNPs reduced Col MICs by 4–64-fold in resistant strains and shifted MICs to ≤2 mg/L in most heteroresistant isolates. Empty haNPs displayed no intrinsic antibacterial activity yet selectively potentiated Col, with strong synergy (FICI down to 0.035). Membrane depolarization and increased intracellular Col accumulation under haNP-treated conditions paralleled the effects of CCCP, indicating that haNPs elicit a CCCP-like functional response. These findings are compatible with perturbation of membrane energetics and possible downstream effects on PMF-dependent transport processes. TEM and surface charge analyses supported direct nanoparticle–envelope interaction and progressive membrane disruption. Conclusions: haNPs enhance Col activity across genetically diverse A. baumannii isolates, with particularly strong effects in heteroresistant strains. The combined effects of PMF modulation, increased intracellular drug availability, and envelope interaction provide a mechanistic rationale for the use of albumin-based nanoparticles, either as Col carriers or in combination with free drug, to overcome Col resistance and heteroresistance. Full article

Antimicrobial resistance is a serious global public health concern, with Acinetobacter baumannii recognized as one of the most problematic multidrug-resistant (MDR) pathogens. This Gram-negative bacterium is highly persistent in the environment, possesses a remarkably adaptable cell envelope, and forms biofilms. As the effectiveness of conventional antibiotics declines, alternative strategies are being actively explored, particularly membrane-targeting approaches based on synthetic copolymers. These compounds mimic antimicrobial peptides, offer enhanced stability and structural tunability, and have a lower propensity to develop resistance. Recent advances in polymer chemistry have led to the design of antibacterial polymers with activity against MDR A. baumannii. Some of these act synergistically with existing antibiotics, restoring bacterial susceptibility or disrupting biofilms. However, their non-degradability remains a concern due to its potential implications for body/environment accumulation and related toxicity and/or selection of resistant strains. This review examines the biology of the A. baumannii cell envelope, its resistance mechanisms, and treatment limitations, while emphasizing the promise of membrane-active copolymers. By bridging materials science and microbiology, these approaches offer promising strategies for combating World Health Organization priority pathogens. Full article

Background/Objectives: Central line-associated bloodstream infections (CLABSIs) remain a leading healthcare-associated infection in intensive care units (ICUs), yet independent risk factors and evidence-based catheter duration thresholds have not been defined through analytical study designs in settings with endemic multidrug-resistant organisms (MDROs). Methods: A retrospective case–control study was conducted in the ICU of a tertiary teaching university hospital in western Türkiye (January 2019–December 2024). Cases (n = 74) were patients with confirmed CLABSIs per CDC/NHSN criteria; controls (n = 148) were randomly selected central venous catheter (CVC)-bearing patients without CLABSIs. A reduced multivariate logistic regression model (seven variables; events-per-variable ratio 10.6) identified independent risk factors. Results: In multivariate analysis, catheter duration (adjusted OR: 1.19 per day; 95% CI: 1.13–1.24; p < 0.001), renal replacement therapy (aOR: 3.66; 95% CI: 1.68–7.95; p = 0.001), vasopressor support (aOR: 3.04; 95% CI: 1.50–6.17; p = 0.002), APACHE-II score (aOR: 1.07 per point; 95% CI: 1.02–1.11; p = 0.002), lower Glasgow Coma Scale (aOR: 0.86 per point; 95% CI: 0.78–0.94; p = 0.002), mechanical ventilation (aOR: 2.48; 95% CI: 1.24–4.95; p = 0.010), and total parenteral nutrition (aOR: 2.33; 95% CI: 1.12–4.86; p = 0.024) were independently associated with CLABSI. The model demonstrated good discrimination (C-statistic: 0.864) and calibration (Hosmer–Lemeshow p = 0.425). Kaplan–Meier analysis showed CLABSI-free survival declining from 98.9% at day 7 to 42.9% at day 21 (log-rank p < 0.001); these within-study estimates reflect relative risk patterns given the artificial 1:2 case-to-control ratio. Receiver operating characteristic (ROC) analysis identified day 13 as an exploratory optimal cutoff (AUC: 0.818; 95% CI: 0.762–0.874; sensitivity: 77.0%; specificity: 74.3%). CLABSI-attributable ICU mortality was 20.3% (47.3% vs. 27.0%; p = 0.004). Late-onset CLABSIs (>10 days) were dominated by Gram-negative pathogens (68.3%) versus 35.7% in early-onset infections (Fisher’s exact p = 0.012), with Acinetobacter baumannii as the predominant organism (27.0%; 83.3% carbapenem-resistant). Conclusions: Each additional catheter-day is independently associated with a 19% increment in CLABSI odds, with an exploratory critical threshold at day 13 beyond which enhanced surveillance measures should be considered, pending external validation. Full article

Multidrug-resistant Acinetobacter baumannii is a major nosocomial pathogen for which bacteriophages are being explored as alternative antibacterial agents. In this study, we isolated and characterized AUBFM01, a lytic phage active against MDR A. baumannii, and performed an initial assessment of its interaction with PMA-differentiated THP-1 macrophages. AUBFM01 was evaluated by host range testing, adsorption and one-step growth assays, lytic activity, stability testing, biofilm disruption, whole-genome sequencing, and flow cytometry-based macrophage profiling. The phage showed rapid adsorption, a short latent period of approximately 30 min, and a burst size of about 165 phage particles per infected cell. It remained stable under moderate temperature and near-neutral pH conditions and significantly reduced preformed A. baumannii biofilm biomass in vitro. Genomic analysis identified a 41,354-bp double-stranded DNA genome lacking detectable lysogeny-associated genes, antibiotic resistance determinants, and known bacterial virulence factors. In THP-1 macrophages, AUBFM01 exposure was associated with reduced cell viability and with enrichment of a resting/intermediate-like CD86-defined phenotype among the remaining cells, including after endotoxin reduction. These findings identify AUBFM01 as a lytic anti-Acinetobacter phage with antibiofilm activity and notable macrophage-associated effects that warrant further mechanistic and safety investigation. Full article

Background/Objectives: Accurate determination of colistin (COL) in vitro activity against carbapenem-resistant Acinetobacter baumannii complex (CRAB) isolates remains challenging, as the reference broth microdilution (BMD) method is labor-intensive and not routinely implemented in most clinical laboratories. Semi-automated susceptibility methods for colistin in the clinical laboratory require validation. The present study evaluated the performance characteristics of the recently introduced Vitek^®2 card AST-N440 for COL antimicrobial susceptibility testing (AST) on CRAB isolates compared with a BMD-based reference method (ComASP Colistin). Methods: A total of 176 single-patient CRAB isolates from two distinct tertiary Greek hospitals between 2024 and 2025 were included. COL susceptibility testing was performed using Vitek^®2 AST-N440 and compared with BMD. Minimum inhibitory concentrations (MICs) were interpreted according to EUCAST breakpoints. Method performance was evaluated by calculating categorical (CA) and essential agreement (EA), sensitivity, specificity, positive and negative predictive values (PPV/NPV), and major (ME) and very major error rates (VME) according to ISO 20776-2. Results: Compared with BMD, AST-N440 showed a sensitivity of 89.6% and a specificity of 62.3%, with a PPV and NPV of 81.7% and 76.0%, respectively. The CA (80.1%) and the EA (46.0%) were below ISO acceptance criteria. The VME rate was 10.4%, and the ME rate 37.7%. Identical MIC values were observed in 25.0% of the isolates, while Vitek^®2 reported lower and higher MIC values than BMD in 46.6% and 28.4% of isolates, respectively. Conclusions: The Vitek^®2 AST-N440 card performed suboptimally for COL susceptibility testing in CRAB isolates. Further validation of automated systems for COL AST is needed. Full article

Background: End-stage renal disease (ESRD) is an immunocompromised state that confers a high risk of infection. We aimed to integrate bioinformatics analyses with a clinical cohort to explore the association between ESRD and sepsis. Methods: We retrieved transcriptomic data from the Gene Expression Omnibus and used computational tools, including Gene Set Enrichment Analysis, the eXtreme Gradient Boosting algorithm, and Mendelian randomization, to characterize gene expression changes, biological pathways, and genetic features in ESRD and sepsis. A multicenter retrospective cohort of patients with sepsis due to carbapenem-resistant Acinetobacter baumannii (CRAB) pneumonia in intensive care units (ICUs) was used to compare clinical presentation and outcomes between patients with and without ESRD. Results: Differential gene expression analysis showed widespread transcriptomic dysregulation in ESRD, and functional enrichment analysis revealed perturbations in immune signaling and vesicular transport pathways. Both the innate and adaptive immune systems appeared compromised, with marked depletion of lymphoid lineages in ESRD. An XGBoost machine-learning model derived from immune cell enrichment scores demonstrated a similar immune microenvironment in ESRD and sepsis. Mendelian randomization analysis supported an association between genetic variants predisposing to ESRD and an increased risk of sepsis, using genome-wide association study datasets. In the clinical cohort, patients with ESRD had significantly higher Sequential Organ Failure Assessment (SOFA) scores and in-hospital mortality than patients with normal renal function. Conclusions: ESRD shares similar immune microenvironmental features and genetic signatures with sepsis. These shared characteristics may contribute to the greater sepsis severity and poorer outcomes observed in patients with ESRD. Full article

Background: Carbapenem-resistant Acinetobacter baumannii (CRAB) is a critical pathogen associated with severe hospital infections and high antimicrobial resistance. Despite the global significance of A. baumannii, there are limited data from Costa Rica regarding the resistance rate and genomic characteristics of CRAB. Methods: This study aimed to provide initial and exploratory epidemiological data on infections caused by A. baumannii and CRAB isolated in Costa Rica and to gain insights on the genome of selected strains, focusing on their resistance determinants and phylogenetic relationships. Results: Based on data from five main hospitals in Costa Rica, resistance rate to carbapenems was estimated at 9.8% to imipenem and 6.1% to meropenem. From 190 carbapenem-resistant clinical isolates available in a local collection, seven A. baumannii strains were identified, all showing resistance to carbapenems and carrying the bla_NDM-1 gene. Whole-genome sequencing of two strains yielded two distinct MLST profiles (Pasteur scheme: ST-150 for strain IPAT15 and ST-250 for IPAT72), as well as variations in the number and identity of plasmids, genomic islands, and other elements of the mobilome. Both isolates carried ten antimicrobial resistance genes, which are predicted to be harbored in plasmids for IPAT15, unlike the chromosomal determinants in IPAT72. A pangenome analysis of 878 genomes from a public database identified over 51,000 genes, with only 1338 (2.6%) forming the core genome. Phylogenetic analysis and assignation of international clones (ICs) showed predominance of IC2. Isolates from Costa Rica clustered near IC9 and shared some resistance determinants, but they were not directly assigned to an IC. Conclusions: Overall, this study provides exploratory insights regarding the occurrence of CRAB in Costa Rica using epidemiological and genomic data, with profiles that are comparable to other regions in Latin America and diverse genomic resistance determinants. While this study does not show the whole landscape of CRAB in Costa Rica, these data constitute an initial approach for improving clinical management and public health responses to CRAB infections, to ultimately improve outcomes for patients affected by this pathogen. Full article