Search Results (498)

This review explores the biofilm architecture and drug resistance of Enterococcus faecalis in clinical and environmental settings. The biofilm in E. faecalis is a heterogeneous, three-dimensional, mushroom-like or multilayered structure, characteristically forming diplococci or short chains interspersed with water channels for nutrient exchange and waste removal. Exopolysaccharides, proteins, lipids, and extracellular DNA create a protective matrix. Persister cells within the biofilm contribute to antibiotic resistance and survival. The heterogeneous architecture of the E. faecalis biofilm contains both dense clusters and loosely packed regions that vary in thickness, ranging from 10 to 100 µm, depending on the environmental conditions. The pathogenicity of the E. faecalis biofilm is mediated through complex interactions between genes and virulence factors such as DNA release, cytolysin, pili, secreted antigen A, and microbial surface components that recognize adhesive matrix molecules, often involving a key protein called enterococcal surface protein (Esp). Clinically, it is implicated in a range of nosocomial infections, including urinary tract infections, endocarditis, and surgical wound infections. The biofilm serves as a nidus for bacterial dissemination and as a reservoir for antimicrobial resistance. The effectiveness of first-line antibiotics (ampicillin, vancomycin, and aminoglycosides) is diminished due to reduced penetration, altered metabolism, increased tolerance, and intrinsic and acquired resistance. Alternative strategies for biofilm disruption, such as combination therapy (ampicillin with aminoglycosides), as well as newer approaches, including antimicrobial peptides, quorum-sensing inhibitors, and biofilm-disrupting agents (DNase or dispersin B), are also being explored to improve treatment outcomes. Environmentally, E. faecalis biofilms contribute to contamination in water systems, food production facilities, and healthcare environments. They persist in harsh conditions, facilitating the spread of multidrug-resistant strains and increasing the risk of transmission to humans and animals. Therefore, understanding the biofilm architecture and drug resistance is essential for developing effective strategies to mitigate their clinical and environmental impact. Full article

Insects and their bacterial endosymbionts form intricate ecological relationships, yet their role in host–pathogen interactions are not fully elucidated. The small brown planthopper (Laodelphax striatellus), a polyphagous pest of cereal crops, acts as a key vector for rice stripe virus (RSV), a significant threat to rice production. This study aimed to compare the endosymbiont community structures of nonviruliferous and RSV-viruliferous L. striatellus populations using 16S rRNA gene sequencing with high-throughput sequencing technology. Wolbachia was highly dominant in both groups; however, the prevalence of other endosymbionts, specifically Rickettsia and Burkholderia, differed markedly depending on RSV infection. Comprehensive microbial diversity and composition analyses revealed distinct community structures between nonviruliferous and RSV-viruliferous populations, highlighting potential interactions and implications for vector competence and virus transmission dynamics. These findings contribute to understanding virus-insect-endosymbiont dynamics and could inform strategies to mitigate viral spread by targeting symbiotic bacteria. Full article

Objectives: Burkholderia cepacia complex (Bcc), a Gram-negative organism, is a well-recognized cause of hospital outbreaks, often linked to a contaminated shared source, such as multidose medications. In this study, we report an outbreak of Bcc infections in a tertiary care hospital, associated with the intrinsic contamination of a prepared solution used in interventional radiology (IR) procedures. Additionally, we provide a detailed explanation of the interventions implemented to control and interrupt the outbreak. Methods: Records from the infection control committee from 1 January 2023 to 31 October 2024 were screened to identify cases with Bcc growth in cultured blood, urine, or respiratory samples. Clinical and laboratory data were collected in March 2025. Bacterial identification was performed using conventional methods and MALDI-TOF (Bruker Daltonics, Bremen, Germany). Controls were matched to cases by ward, date of initial growth, and duration of hospitalization. Demographic and clinical data of these patients were systematically collected and analyzed. Microbiological cultures were obtained from environmental objects of concern and certain medications. Results: A total of 82 Burkholderia species were identified. We enrolled 77 cases and 77 matched controls. The source of contamination was identified in ready-to-use intravenous medications (remifentanil and magnesium preparations) in the IR department. These preparations were compounded in advance by the team and were used repeatedly. Although the outbreak originated from contaminated IV medications used in IR, secondary transmission likely affected 28 non-IR patients via fomites, shared environments, and possible lapses in isolation precautions. The mortality rate among the cases was 16.9%. Infection with Bcc was associated with prolonged intensive care unit stays (p = 0.018) and an extended overall hospitalization duration (p < 0.001); however, it was not associated with increased mortality. The enforcement of contact precautions and comprehensive environmental decontamination successfully reduced the incidence of the Bcc outbreak. No pathogens were detected in cultures obtained after the disinfection. Conclusions: The hospital transmission of Bcc is likely driven by cross-contamination, invasive medical procedures, and the administration of contaminated medications. Implementing stringent infection control measures such as staff retraining, updated policies on medication use, enhanced environmental decontamination, and strict adherence to isolation precautions has proven effective in curbing the spread of virulent and transmissible Bcc. Full article

Background: Chryseobacterium indologenes, an environmental bacterium, is increasingly recognized as an emerging nosocomial pathogen, particularly in Asia, and is often characterized by multidrug resistance. Objectives: This study aimed to investigate the genomic features of clinical C. indologenes isolates from Maharaj Nakorn Chiang Mai Hospital, Thailand, to understand their mechanisms of multidrug resistance, virulence factors, and mobile genetic elements (MGEs). Methods: Twelve C. indologenes isolates were identified, and their antibiotic susceptibility profiles were determined. Whole genome sequencing (WGS) was performed using a hybrid approach combining Illumina short-reads and Oxford Nanopore long-reads to generate complete bacterial genomes. The hybrid assembled genomes were subsequently analyzed to detect antimicrobial resistance (AMR) genes, virulence factors, and MGEs. Results: C. indologenes isolates were primarily recovered from urine samples of hospitalized elderly male patients with underlying conditions. These isolates generally exhibited extensive drug resistance, which was subsequently explored and correlated with genomic determinants. With one exception, CMCI13 showed a lower resistance profile (Multidrug resistance, MDR). Genomic analysis revealed isolates with genome sizes of 4.83–5.00 Mb and GC content of 37.15–37.35%. Genomic characterization identified conserved resistance genes (bla_IND-2, bla_CIA-4, adeF, vanT, and qacG) and various virulence factors. Phylogenetic and pangenome analysis showed 11 isolates clustering closely with Chinese strain 3125, while one isolate (CMCI13) formed a distinct branch. Importantly, each isolate, except CMCI13, harbored a large genomic island (approximately 94–100 kb) carrying significant resistance genes (bla_OXA-347, tetX, aadS, and ermF). The absence of this genomic island in CMCI13 correlated with its less resistant phenotype. No plasmids, integrons, or CRISPR-Cas systems were detected in any isolate. Conclusions: This study highlights the alarming emergence of multidrug-resistant C. indologenes in a hospital setting in Thailand. The genomic insights into specific resistance mechanisms, virulence factors, and potential horizontal gene transfer (HGT) events, particularly the association of a large genomic island with the XDR phenotype, underscore the critical need for continuous genomic surveillance to monitor transmission patterns and develop effective treatment strategies for this emerging pathogen. Full article

Microbiological contamination of healthcare workers’ gowns represents a critical risk for the transmission of healthcare-associated infections (HAIs). Despite their use as protective equipment, gowns can act as reservoirs of antibiotic-resistant bacteria, favouring the spread of pathogens between healthcare workers and patients. The presence of these resistant bacteria on healthcare workers’ gowns highlights the urgent need to address this risk as part of infection control strategies. The aim of this work was to assess the microbiological risks associated with the contamination of healthcare staff gowns with Gram-negative bacteria, including the ESKAPE group, and their relationship with antimicrobial resistance. An observational, cross-sectional, prospective study was conducted in 321 hospital workers. The imprinting technique was used to quantify the bacterial load on the gowns, followed by bacterial identification by MALDI-TOF mass spectrometry. In addition, antimicrobial resistance profiles were analysed, and tests for carbapenemases and BLEE production were performed. The ERIC-PCR technique was also used for molecular analysis of Pantoea eucrina clones. Several Gram-negative bacteria were identified, including bacteria of the ESKAPE group. The rate of microbiological contamination of the gowns was 61.05% with no association with the sex of the healthcare personnel. It was observed that critical areas of the hospital, such as intensive care units and operating theatres, showed contamination by medically important bacteria. In addition, some strains of P. eucrina showed resistance to carbapenemics and cephalosporins. ERIC-PCR analysis of P. eucrina isolates showed genetic heterogeneity, indicating absence of clonal dissemination. Healthcare personnel gowns are a significant reservoir of pathogenic bacteria, especially in critical areas of Hospital Juárez de México. It is essential to implement infection control strategies that include improving the cleaning and laundering of gowns and ideally eliminating them from clothing to reduce the risk of transmission of nosocomial infections. Full article

Introduction: In recent years, antimicrobial resistance (AMR) rates have increased significantly in bacterial pathogens, particularly extended beta-lactam resistance. This study aimed to investigate resistome and phylogenomics of Escherichia coli (E. coli) strains isolated from various sources in Jimma, Ethiopia. Methods: Phenotypic antibiotic resistance patterns of E. coli isolates were determined using automated Kirby–Bauer disc diffusion and minimum inhibitory concentration (MIC). Isolates exhibiting phenotypic resistance to beta-lactam antibiotics were further analyzed with a DNA microarray to confirm the presence of resistance-encoding genes. Additionally, multilocus sequence typing (MLST) of seven housekeeping genes was conducted using PCR and Oxford Nanopore-Technology (ONT) to assess the phylogenetic relationships among the E. coli isolates. Results: A total of 611 E. coli isolates from human, animal, and environmental sources were analyzed. Of these, 41.6% (254) showed phenotypic resistance to at least one of the tested beta-lactams, 96.1% (244) thereof were confirmed genotypically. More than half of the isolates (53.3%) had two or more resistance genes present. The most frequent ESBL-encoding gene was CTX-M-15 (74.2%; 181), followed by TEM (59.4%; 145) and CTX-M-9 (4.1%; 10). The predominant carbapenemase gene was NDM-1, detected in 80% (12 out of 15) of carbapenem-resistant isolates. A phylogenetic analysis revealed clonality among the strains obtained from various sources, with international high-risk clones such as ST131, ST648, ST38, ST73, and ST405 identified across various niches. Conclusions: The high prevalence of CTX-M-15 and NDM-1 in multidrug-resistant E. coli isolates indicates the growing threat of AMR in Ethiopia. The discovery of these high-risk clones in various niches shows possible routes of transmission and highlights the necessity of a One Health approach to intervention and surveillance. Strengthening antimicrobial stewardship, infection prevention, and control measures are crucial to mitigate the spread of these resistant strains. Full article

Hemotrophic mycoplasmas (HMs) are cell wall-less, small and uncultivable pathogens, which can cause infections in pigs with no to severe clinical signs and can contribute to significant economic losses in the pig industry. In addition to the known mechanical transmission routes of HMs (e.g., via blood-contaminated instruments or lesions from ranking fights), transmission to pigs by arthropod vectors such as Stomoxys calcitrans is being discussed. To date, there is scant available data concerning the transmission of HMs by stable flies. The objective of this study is to gain more data concerning the occurrence of HMs in Stomoxys calcitrans. Therefore, quantitative real-time PCR was conducted on different stable fly samples (surface washings and whole flies). We found Mycoplasma (M.) suis in 5.2% of crushed flies and 4.2% of fly wash solutions, and M. parvum was detected in 5.2% of flies and 9.4% of fly wash solutions. ‘Candidatus (Ca.) M. haemosuis’ was not detected in any sample. The mean bacterial loads were 2.0 × 10² M. suis/fly, 9.3 × 10² M. suis/fly wash solution and, for M. parvum, 2.4 × 10³ M. parvum/fly and 2.1 × 10³ M. parvum/fly wash solution. This molecular occurrence of porcine HMs in blood-sucking flies and reasonable bacterial loads in the two- to three-digit range demonstrate that these flies serve as mechanical vectors in stables and are, therefore, of epidemiological importance. Full article

In this study, we found that the deletion of the gene evfG in the type VI secretion system (T6SS) gene cluster significantly affected the motility of porcine extraintestinal pathogenic Escherichia coli (ExPEC) strain PCN033. Furthermore, the bacterial motility assay showed that ΔevfG mutants exhibited reduced motility compared to the parental strain. Transmission electron microscopy (TEM) showed a significant reduction in the number of flagella in the mutant ΔevfG when compared with PCN033. To further explore the reasons why the deletion of evfG affects the motility of PCN033, transcriptomic and metabolomic analyses were conducted. The omics analyses showed that 134 differentially accumulated metabolites and 2236 differentially expressed genes were identified between the mutant ΔevfG and the parental strain PCN033. The metabolome profile and functional annotation analyses indicated that the impaired motility of ΔevfG was connected to the downregulation of the expression levels of genes associated with the energy metabolism pathway and flagellar assembly. Our study provides a new insight into the diminished PCN033 motility induced by evfG deletion. Moreover, the candidate genes and metabolites regulated by the gene evfG in the T6SS, which was involved in the motility of PCN033, were reported in this study. Full article

Background: Canine pyoderma and otitis externa are prevalent bacterial skin infections in veterinary practice, frequently complicated by the emergence of multidrug-resistant (MDR) pathogens. Objectives: To investigate the frequency, antimicrobial resistance (AMR) profiles, and frequency of MDR bacterial isolates from dogs with pyoderma or otitis externa in Hong Kong. Methods: A retrospective study of bacterial isolates from 215 clinical samples collected from dogs presenting with pyoderma (n = 63) or otitis externa (n = 152) at veterinary clinics across Hong Kong between 2018 and 2022. Bacterial isolates were identified and subjected to antimicrobial susceptibility testing against 13 antimicrobial classes. Results: Staphylococcus spp., particularly S. pseudintermedius, were the most commonly isolated species, followed by Pseudomonas spp. and Proteus spp. High resistance rates were observed for orbifloxacin (61.3% in pyoderma; 76.7% in otitis externa), doxycycline (59.3%; 69.2%), clindamycin (62%; 68.9%), and enrofloxacin (50%; 55.5%). Most isolates were sensitive to ofloxacin, ticarcillin–clavulanate, tobramycin, ciprofloxacin, cefpodoxime, cefuroxime, and cefixime. MDR was detected in 67.5% of pyoderma and 66.8% of otitis externa isolates. Gram-negative bacteria exhibited significantly higher MDR rates than Gram-positive isolates. The multiple antibiotic resistance (MAR) index averaged 0.41 for pyoderma and 0.52 for otitis externa isolates. We found no significant associations between MDR and non-modifiable risk factors (i.e., age, sex, breed, and reproductive status). Conclusions: These findings highlight the critical need for prudent antimicrobial use and continuous surveillance of AMR trends in companion animals. A higher focus should be placed on topical antiseptic therapy, with oral antibiotics used only in exceptional cases and after susceptibility testing. From a One Health perspective, the potential transmission of MDR bacteria between companion animals and humans underscores the importance of a coordinated approach to antimicrobial stewardship across both veterinary and human medicine. Full article

The COVID-19 pandemic prompted widespread adoption of intensified hand hygiene practices, raising concerns about their medium-term impact on the skin microbiome. This study investigates alterations in the hand microbiome of healthy adults during the pandemic compared to pre-pandemic periods in Majorca, Spain. A total of 30 volunteers (16 women, 14 men; mean age 44.1 ± 8.8 years) were sampled between 2014 and 2021. Palm swabs were collected following WHO guidelines, alongside measurements of skin pH, temperature, and handwashing frequency. Bacterial DNA was extracted and analyzed via 16S rRNA (V3-V4) metagenomic sequencing to assess microbial diversity and composition. Results revealed a significant decline in microbial diversity during the COVID-19 period, accompanied by a marked shift in the community structure. The Firmicutes phylum dominated, with Bacillales increasing from 30.7% to 84.1%, primarily driven by a surge in Staphylococcus species (e.g., S. pasteuri). Conversely, S. hominis and Actinomycetales nearly disappeared. No significant associations were observed with gender or handwashing frequency. The skin temperature increased during the pandemic, while the pH remained stable. The Staphylococcus/Bacillus ratio shifted significantly, favoring Staphylococcus dominance. These findings, derived from a geographically limited population in Majorca, Spain, demonstrate that stringent hygiene measures during COVID-19 reduced microbial diversity and restructured hand microbiome composition. The study underscores the necessity for balanced hygiene strategies that mitigate pathogen transmission while preserving beneficial microbial communities critical to skin health. Full article

Untreated water bodies are critical ecological niches where environmental conditions can drive the adaptive evolution of bacterial populations, enabling them to acquire new traits such as antibiotic-resistance genes. Escherichia coli is typically a commensal bacterium but can evolve into a pathogenic form, known as Diarrheagenic E. coli, responsible for both intestinal and extraintestinal diseases. This study focuses on the characterization of E. coli isolates from water samples collected from the Matasnillo River and the influence of the Juan Díaz Wastewater Treatment Plant (WWTP). While isolates from the Matasnillo River were classified as commensal, 18% of the isolates from the WWTP belonged to either phylogroups D or B2. Pathotype analysis revealed the presence of Entero-Toxigenic and Entero-Hemorrhagic E. coli in the WWTP. Moreover, Matasnillo River isolates exhibited resistance mainly to the quinolone ciprofloxacin, whereas those from the WWTP influent showed resistance to multiple broad-spectrum antibiotics. Sequencing analysis revealed the prevalence of the transmissible quinolone resistance qnrB19 among the Matasnillo River isolates and mutations conferring resistance to quinolone in gyrA, parC, and parE. These findings highlight the importance of monitoring antibiotic-resistant bacterial contamination in both freshwater and wastewater to mitigate the risk of the spread of resistant pathogens and potential epidemic outbreaks. Full article

Background:Salmonella Typhimurium is a major zoonotic pathogen, in which type 1 fimbriae play a crucial role in intestinal colonization and immune modulation. This study aimed to improve the protective immunity of a previously developed growth-deficient strain—a double auxotroph for D-glutamate and D-alanine—by engineering the inducible expression of type 1 fimbriae. Methods: P_tetA-driven expression of the fim operon was achieved by λ-Red mutagenesis. fimA expression was quantified by qRT-PCR, and fimbriation visualized by transmission electron microscopy. Adhesive properties were evaluated through FimH sequence analysis, yeast agglutination, mannose-binding/inhibition assays, and HT-29 cell adherence. BALB/c mice were immunized orogastrically with IRTA ΔΔΔ or IRTA ΔΔΔ P_tetA::fim. Safety and immunogenicity were assessed by clinical monitoring, bacterial load, fecal shedding, ELISA tests, and adhesion/blocking assays using fecal extracts. Protection was evaluated after challenging with wild-type and heterologous strains. Results: IRTA ΔΔΔ P_tetA::fim showed robust fimA expression, dense fimbrial coverage, a marked mannose-sensitive adhesive phenotype and enhanced HT-29 attachment. Fimbrial overexpression did not alter intestinal colonization or translocation to mesenteric lymph nodes (mLNs). Immunization elicited a mixed IgG1/IgG2a, significantly increased IgA and IgG against type 1 fimbriae-expressing Salmonella, and enhanced the ability of fecal extracts to inhibit the adherence of wild-type strains. Upon challenge (IRTA wild-type/20220258), IRTA ΔΔΔ P_tetA::fim reduced infection burden in the cecum (−1.46/1.47-log), large intestine (−1.35/2.17-log), mLNs (−1.32/0.98-log) and systemic organs more effectively than IRTA ΔΔΔ. Conclusions: Inducible expression of type 1 fimbriae enhances mucosal immunity and protection, supporting their inclusion in next-generation Salmonella vaccines. Future work should assess cross-protection and optimize FimH-mediated targeting for mucosal delivery. Full article

The World Health Organization (WHO) cites antimicrobial resistance as among the greatest threats to human health. The multidrug-resistant pathogen Acinetobacter baumannii, recognized as a priority pathogen for healthcare and research, is responsible for a diverse array of infections including respiratory tract, soft tissue and wound, and bloodstream infections. Despite this importance, the mechanisms of its pathogenesis remain poorly understood. Conjugation represents a central mechanism for bacterial adaptation and evolution and is responsible for the spread of genes that promote pathogen survival, antibiotic resistance, virulence, and biofilm formation. Our laboratory recently characterized a large group of almost 120 Type IV Secretion System (T4SS)-encoding plasmids in Acinetobacter, distributed globally across 20 countries spanning four continents, and demonstrated that an XDR A. baumannii plasmid from this family was transmissible to another A. baumannii strain. This research investigated the potential diversity of host strains for this representative member plasmid. Using the GC1 lineage strain A. baumannii AB5075-UW harbouring the XDR plasmid p1AB5075 and a series of previously characterized clinical and environmental Acinetobacter strains, conjugative analyses demonstrated transfer of the XDR plasmid to both A. baumannii strains of more genetically divergent sequence types and to non-baumannii Acinetobacter species both inside and outside the Acinetobacter calcoaceticus–baumannii (ACB) complex. Successful recipients included diverse strains of both clinical and environmental origin within the Acinetobacter genus. Collectively, this research could provide insights into an important genetic element for future surveillance. Full article

Background/Objectives: Antibiotic resistance or antimicrobial resistance (AMR) in livestock is a growing global concern that threatens both human and animal health. The overuse and misuse of antibiotics in livestock production have led to an increased propensity for the development of AMR bacterial strains in animals, which can be spread to humans through the consumption of contaminated animal products, direct contact, or environmental exposure. This review aims to summarize the development and transmission of AMR in livestock, explore its underlying mechanisms and impact on human and animal health, and discuss current practices and potential strategies for mitigation and prevention. Methods: For this narrative review, we searched articles on PubMed and Google Scholar using the terms antibiotic resistance, livestock, and environment, alone or in combination. Results: The history of antibiotic use in livestock and its link to increased AMR, along with the involved mechanisms, including the enzymatic breakdown of antibiotics, alterations in bacterial targets, horizontal gene transfer, and efflux pumps, are important. Antibiotics in livestock are used for growth promotion, disease prevention and control, and metaphylactic use. The role of livestock and the environment as reservoirs for resistant pathogens, their impact on human health, chronic infections, allergic reactions, toxicity, and the development of untreatable diseases is important to understand AMR. Conclusions: Given the widespread use of antibiotics and the potential consequences of AMR, collaborative global efforts, increased public awareness, coordinated regulations, and advancements in biological technology are required to mitigate the threat AMR poses to human and animal health. Regulatory solutions and the development of new therapeutic alternatives like antimicrobial peptides and bacteriophage therapy, and preventive measures such as DNA and mRNA vaccines, are future perspectives. Full article

Background: Bacterial lysates are known to modulate the immune response against respiratory infections. However, the effects of the commercial bacterial lysate Pulmonarom^® on dendritic cells—particularly human monocyte-derived dendritic cells (moDCs)—have not been studied. Additionally, limited data are available on the expression of Toll-like receptors (TLRs) and cytokines following stimulation with bacterial lysates. Methods: Human monocytes were isolated from buffy coats and differentiated into moDCs. Pulmonarom^® was lyophilized, quantified, and used to stimulate moDCs. Ultrastructural changes were evaluated using transmission electron microscopy. The expression of TLRs and selected cytokines was analyzed by flow cytometry. Results: Pulmonarom^® stimulation induced morphological changes in moDCs, including an increased number of dendrites and lysosomes. It also led to the upregulation of MHC class II molecules and TLRs 2, 3, 6, and 7. Additionally, the production of IL-4, IL-6, IL-8, and MCP-1 was significantly increased. Conclusions: Pulmonarom^® promotes moDC maturation, characterized by enhanced antigen presentation capabilities and lysosomal activity, along with increased expression of specific TLRs and cytokines. These features suggest a trained immunity phenotype in moDCs, potentially improving their ability to initiate adaptive immune responses against respiratory pathogens. To our knowledge, this is the first study to investigate the immunomodulatory effects of Pulmonarom^® on human moDCs, providing novel insights into its potential as an immunotherapeutic adjuvant. Full article