Virulence factors, antibiotic susceptibility and sequence type distribution of hospital-associated Clostridioides difficile isolates in Israel, 2020-2022.

Biofilm formation and toxin production are some of the virulence factors of Clostridioides difficile (C. difficile), which causes hospital-acquired C. difficile infection (HA-CDI). This work investigated the prevalence and distribution of different strains recovered from HA-CDI patients hospitalized in 4 medical centres across Israel, and characterized strains' virulence factors and antibiotic susceptibility. One-hundred and eighty-eight faecal samples were collected. C. difficile 's toxins were detected by the CerTest Clostridium difficile GDH + Toxin A + B combo card test kit. Toxin loci PaLoc and PaCdt were detected by whole-genome sequencing (WGS). Multi-locus sequence typing (MLST) was performed to classify strains. Biofilm production was assessed by crystal violet. Antibiotic susceptibility was determined using Etest. Fidaxomicin susceptibility was tested via agar dilution. Sequence type (ST) 42 was the most (13.8%) common strain. All strains harboured the 2 toxins genes; 6.9% had the binary toxin. Most isolates were susceptible to metronidazole (98.9%) and vancomycin (99.5%). Eleven (5.85%) isolates were fidaxomicin-resistant. Biofilm production capacity was associated with ST (p < 0.001). In conclusion, a broad variety of C. difficile strains circulate in Israel's medical centres. Further studies are needed to explore the differences and their contribution to HA-CDI epidemiology.

Biofilm formation, antibiotic-resistance and clonal relatedness among clinical isolates of Acinetobacterbaumannii.

In this work, the antibiotic resistance, biofilm formation capability, and clonal relatedness of 50 A. baumannii isolates collected from three hospitals in Ardabil city, Iran, were evaluated. Antibiotic sensitivity and biofilm formation of isolates were determined by disk diffusion and microtiter-plate methods, respectively. Molecular typing of isolates was also performed using repetitive sequence-based PCR (REP-PCR). The majority of isolates were resistant to cephems, aminoglycosides, and carbapenems, with 80 % classified as multi-drug resistant (MDR). While, only isolates collected from blood and tracheal were resistant to colistin. Additionally, 42 isolates (84 %) had biofilm formation capability. According to rep-PCR results, 34 isolates showed similar banding patterns, while 16 isolates had unique banding patterns. Finally, based on the molecular analysis, there was a direct relationship between biofilm formation and the antibiotic resistance of isolates. In other words, MDR isolates had a higher ability to form biofilm.

Engineered Cell Elongation Promotes Extracellular Electron Transfer of Shewanella Oneidensis.

To investigate how cell elongation impacts extracellular electron transfer (EET) of electroactive microorganisms (EAMs), the division of model EAM Shewanella oneidensis (S. oneidensis) MR-1 is engineered by reducing the formation of cell divisome. Specially, by blocking the translation of division proteins via anti-sense RNAs or expressing division inhibitors, the cellular length and output power density are all increased. Electrophysiological and transcriptomic results synergistically reveal that the programmed cell elongation reinforces EET by enhancing NADH oxidation, inner-membrane quinone pool, and abundance of c-type cytochromes. Moreover, cell elongation enhances hydrophobicity due to decreased cell-surface polysaccharide, thus facilitates the initial surface adhesion stage during biofilm formation. The output current and power density all increase in positive correction with cellular length. However, inhibition of cell division reduces cell growth, which is then restored by quorum sensing-based dynamic regulation of cell growth and elongation phases. The QS-regulated elongated strain thus enables a cell length of 143.6 ± 40.3 µm (72.6-fold of that of S. oneidensis MR-1), which results in an output power density of 248.0 ± 10.6 mW m-2 (3.41-fold of that of S. oneidensis MR-1) and exhibits superior potential for pollutant treatment. Engineering cellular length paves an innovate avenue for enhancing the EET of EAMs.

Mechanism of antibacterial resistance, strategies and next-generation antimicrobials to contain antimicrobial resistance: a review.

Antibacterial drug resistance poses a significant challenge to modern healthcare systems, threatening our ability to effectively treat bacterial infections. This review aims to provide a comprehensive overview of the types and mechanisms of antibacterial drug resistance. To achieve this aim, a thorough literature search was conducted to identify key studies and reviews on antibacterial resistance mechanisms, strategies and next-generation antimicrobials to contain antimicrobial resistance. In this review, types of resistance and major mechanisms of antibacterial resistance with examples including target site modifications, decreased influx, increased efflux pumps, and enzymatic inactivation of antibacterials has been discussed. Moreover, biofilm formation, and horizontal gene transfer methods has also been included. Furthermore, measures (interventions) taken to control antimicrobial resistance and next-generation antimicrobials have been discussed in detail. Overall, this review provides valuable insights into the diverse mechanisms employed by bacteria to resist the effects of antibacterial drugs, with the aim of informing future research and guiding antimicrobial stewardship efforts.

Physiochemical characterization of a potential Klebsiella phage MKP-1 and analysis of its application in reducing biofilm formation.

The common intestinal pathogen Klebsiella pneumoniae (K. pneumoniae) is one of the leading causes of fatal superbug infections that can resist the effects of commonly prescribed medicines. The uncontrolled use or misuse of antibiotics has increased the prevalence of drug-resistant K. pneumoniae strains in the environment. In the quest to search for alternative therapeutics for treating these drug-resistant infections, bacteriophages (bacterial viruses) emerged as potential candidates for in phage therapy against Klebsiella. The effective formulation of phage therapy against drug-resistant Klebsiella infections demands thorough characterization and screening of many bacteriophages. To contribute effectively to the formulation of successful phage therapy against superbug infections by K. pneumoniae, this study includes the isolation and characterization of a novel lytic bacteriophage MKP-1 to consider its potential to be used as therapeutics in treating drug-resistant Klebsiella infections. Morphologically, having a capsid attached to a long non-contractile tail, it was found to be a siphovirus that belongs to the class Caudoviricetes and showed infectivity against different strains of the target host bacterium. Comparatively, this double-stranded DNA phage has a large burst size and is quite stable in various physiological conditions. More interestingly, it has the potential to degrade the tough biofilms formed by K. pneumoniae (Klebsiella pneumoniae subsp. pneumoniae (Schroeter) Trevisan [ATCC 15380]) significantly. Thus, the following study would contribute effectively to considering phage MKP-1 as a potential candidate for phage therapy against Klebsiella infection.

Investigation of antibiotic resistance, virulence genes, and biofilm formation of Escherichia coli isolated from sheep feces in Shiraz industrial slaughterhouse, South of Iran.

Background: With the increase in human population, the consumption of livestock products such as sheep meat has also increased. Sheep are the reservoir and shedder of Escherichia coli that can be transmitted to humans. Aims: Characterization of fecal E. coli isolated from sheep in slaughterhouse. Methods: Stool specimens were collected from 30 apparently healthy sheep from different flocks in Shiraz industrial slaughterhouse. The resistance of E. coli isolates against 10 antibiotics was determined by disk diffusion method. The presence of three major extended spectrum beta-lactamase (ESBL) genes and five tetracycline resistance genes as well as seven virulence genes were investigated by polymerase chain reaction (PCR) technique. Using the microtiter plate method, the biofilm formation ability of E. coli isolates was investigated. Results: The highest frequency of resistance was to amoxicillin (100%) followed by tetracycline (25%). All E. coli isolates were susceptible to gentamicin and nitrofurantoin, and only one isolate was resistant to the tested third-generation cephalosporins. Multidrug resistance phenotype was observed in 16.7% of the isolates. bla TEM (25%) was the most prevalent ESBL gene and tetA (62.5%) was the most prevalent tetracycline resistance gene in the isolates. crl, csgA, fimH, and bcsA genes were present in all isolates, and the prevalence of papC and afa genes was 95.8% and 83.3%, respectively. In total, 62.5% of the isolates were biofilm producers. Conclusion: According to the concept of One Health, the presence of virulent antibiotic-resistant biofilm producing strains of E. coli in sheep is a risk to public health.

An insight on the powerful of bacterial quorum sensing inhibition.

Bacteria have their own language through which they communicate with one another like all higher organisms. So, many researchers are working hard to identify and comprehend the components of this bacterial communication, known as quorum sensing (QS). In quorum sensing, bacteria use signaling molecules called autoinducers (AIs) to exchange information. Many natural compounds and extraction techniques have been intensively studied to disrupt bacterial signaling and examine their effectiveness for bacterial pathogenesis control. Quorum sensing inhibitors can interfere with QS and block the action of AI signaling molecules. Recent research indicates that quorum sensing inhibitors (QSIs) and quorum quenching enzymes (QQEs) show great promise in reducing the pathogenicity of bacteria and inhibiting biofilm synthesis. In addition, the effectiveness of QQEs and QSIs in experimental animal models was demonstrated. These are taken into account in the development of innovative medical devices, such as dressings and catheters, to prevent bacterial infections. The present review highlights this aspect with a prospective vision for its development and application.

Genomic and induction evidence for bacteriophage contributions to sargassum-bacteria symbioses.

BACKGROUND: Symbioses between primary producers and bacteria are crucial for nutrient exchange that fosters host growth and niche adaptation. Yet, how viruses that infect bacteria (phages) influence these bacteria-eukaryote interactions is still largely unknown. Here, we investigate the role of viruses on the genomic diversity and functional adaptations of bacteria associated with pelagic sargassum. This brown alga has dramatically increased its distribution range in the Atlantic in the past decade and is predicted to continue expanding, imposing severe impacts on coastal ecosystems, economies, and human health. RESULTS: We reconstructed 73 bacterial and 3963 viral metagenome-assembled genomes (bMAGs and vMAGs, respectively) from coastal Sargassum natans VIII and surrounding seawater. S. natans VIII bMAGs were enriched in prophages compared to seawater (28% and 0.02%, respectively). Rhodobacterales and Synechococcus bMAGs, abundant members of the S. natans VIII microbiome, were shared between the algae and seawater but were associated with distinct phages in each environment. Genes related to biofilm formation and quorum sensing were enriched in S. natans VIII phages, indicating their potential to influence algal association in their bacterial hosts. In-vitro assays with a bacterial community harvested from sargassum surface biofilms and depleted of free viruses demonstrated that these bacteria are protected from lytic infection by seawater viruses but contain intact and inducible prophages. These bacteria form thicker biofilms when growing on sargassum-supplemented seawater compared to seawater controls, and phage induction using mitomycin C was associated with a significant decrease in biofilm formation. The induced metagenomes were enriched in genomic sequences classified as temperate viruses compared to uninduced controls. CONCLUSIONS: Our data shows that prophages contribute to the flexible genomes of S. natans VIII-associated bacteria. These prophages encode genes with symbiotic functions, and their induction decreases biofilm formation, an essential capacity for flexible symbioses between bacteria and the alga. These results indicate that prophage acquisition and induction contribute to genomic and functional diversification during sargassum-bacteria symbioses, with potential implications for algae growth. Video Abstract.

Novel extracellular lipase gene Lip1728 influences nutrient-dependent performance bacterial quorum sensing of Burkholderia pyrrocinia WZ10-3.

Quorum sensing (QS) is a cellular communication mechanism in which bacteria secrete and recognize signaling molecules to regulate group behavior. Lipases provide energy for bacterial cell growth but it is unknown whether they influence nutrient-dependent QS by hydrolyzing substrate. A high-yield lipase-producing strain, Burkholderia pyrrocinia WZ10-3, was previously identified in our laboratory, but the composition of its crude enzymes was not elucidated. Here, we identified a key extracellular lipase, Lip1728, in WZ10-3, which accounts for 99 % of the extracellular lipase activity. Lip1728 prefers to hydrolyze triglycerides at sn-1,3 positions, with pNP-C16 being its optimal substrate. Lip1728 exhibited activity at pH 5.0-10.0 and regardless of the presence of metal ions. It had strong resistance to sodium dodecyl sulfate and short-chain alcohols and was activated by phenylmethanesulfonylfluoride (PMSF). Lip1728 knockout significantly affected lipid metabolism and biofilm formation in the presence of olive oil. Finally, oleic acid, a hydrolysate of Lip1728, influenced the production of the signal molecule N-acyl homoserine lactone (AHL) and biofilm formation by downregulating the AHL synthetase gene pyrI. In conclusion, Lip1728, as a key extracellular lipase in B. pyrrocinia WZ10-3, exhibits superior properties that make it suitable for biodiesel production and plays a crucial role in QS.

Multidrug-Resistance of Vibrio Species in Bivalve Mollusks from Southern Thailand: Isolation, Identification, Pathogenicity, and Their Sensitivity toward Chitooligosaccharide-Epigallocatechin-3-Gallate Conjugate.

Vibrio spp. is a Gram-negative bacteria known for its ability to cause foodborne infection in association with eating raw or undercooked seafood. The majority of these foodborne illnesses are caused by mollusks, especially bivalves. Thus, the prevalence of Vibrio spp. in blood clams (Tegillarca granosa), baby clams (Paphia undulata), and Asian green mussels (Perna viridis) from South Thailand was determined. A total of 649 Vibrio spp. isolates were subjected to pathogenicity analysis on blood agar plates, among which 21 isolates from blood clams (15 isolates), baby clams (2 isolates), and green mussels (4 isolates) showed positive ß-hemolysis. Based on the biofilm formation index (BFI) of ß-hemolysis-positive Vibrio strains, nine isolates exhibited a strong biofilm formation capacity, with a BFI in the range of 1.37 to 10.13. Among the 21 isolates, 6 isolates (BL18, BL82, BL84, BL85, BL90, and BL92) were tlh-positive, while trh and tdh genes were not detected in all strains. Out of 21 strains, 5 strains showed multidrug resistance (MDR) against amoxicillin/clavulanic acid, ampicillin/sulbactam, cefotaxime, cefuroxime, meropenem, and trimethoprim/sulfamethoxazole. A phylogenetic analysis of MDR Vibrio was performed based on 16s rDNA sequences using the neighbor-joining method. The five MDR isolates were identified to be Vibrio neocaledonicus (one isolate), Vibrio fluvialis (one isolate) and, Vibrio cidicii (three isolates). In addition, the antimicrobial activity of chitooligosaccharide-epigallocatechin gallate (COS-EGCG) conjugate against MDR Vibrio strains was determined. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of COS-EGCG conjugate were in the range of 64-128 µg/mL. The antimicrobial activity of the conjugate was advocated by the cell lysis of MDR Vibrio strains, as elucidated by scanning electron microscopic images. Vibrio spp. isolated from blood clams, baby clams, and Asian green mussels were highly pathogenic, exhibiting the ability to produce biofilm and being resistant to antibiotics. However, the COS-EGCG conjugate could be used as a potential antimicrobial agent for controlling Vibrio in mollusks.

Potential Role of SdiA in Biofilm Formation and Drug Resistance in Avian Pathogenic Escherichia coli.

Avian pathogenic Escherichia coli (APEC) constitutes a significant cause of colibacillosis, a localized or systemic inflammatory disorder in avian species, resulting in considerable economic losses within the global poultry industry. SdiA (suppressor of division inhibitor) is a transcription factor recognized as a LuxR homolog in Escherichia coli, regulating various behaviors, including biofilm formation, multidrug resistance, and the secretion of virulence factors. However, the function of SdiA in APEC strains and its correlation with virulence and multidrug resistance remains unknown. This study probed into the function of SdiA by analyzing the effect of sdiA deletion on the transcription profile of an APEC strain. The microarray data revealed that SdiA upregulates 160 genes and downregulates 59 genes, exerting a particularly remarkable influence on the transcription of multiple virulence genes. A series of antibiotic sensitivity tests, biofilm formation assays, motility assays, and transcriptome analyses were performed, while a Normality test and t-test were conducted on the datasets. This research confirmed that SdiA inhibits biofilm formation by 1.9-fold (p-value < 0.01) and motility by 1.5-fold (p-value < 0.01). RT-qPCR revealed that SdiA positively regulates multidrug resistance by upregulating the expression of yafP, cbrA, and eamB. Collectively, the results of this study indicate the role of SdiA in the pathogenesis of APEC by controlling biofilm formation, motility, and multidrug resistance.

Carbon Source and Substrate Surface Affect Biofilm Formation by the Plant-Associated Bacterium Pseudomonas donghuensis P482.

The ability of bacteria to colonize diverse environmental niches is often linked to their competence in biofilm formation. It depends on the individual characteristics of a strain, the nature of the colonized surface (abiotic or biotic), or the availability of certain nutrients. Pseudomonas donghuensis P482 efficiently colonizes the rhizosphere of various plant hosts, but a connection between plant tissue colonization and the biofilm formation ability of this strain has not yet been established. We demonstrate here that the potential of P482 to form biofilms on abiotic surfaces and the structural characteristics of the biofilm are influenced by the carbon source available to the bacterium, with glycerol promoting the process. Also, the type of substratum, polystyrene or glass, impacts the ability of P482 to attach to the surface. Moreover, P482 mutants in genes associated with motility or chemotaxis, the synthesis of polysaccharides, and encoding proteases or regulatory factors, which affect biofilm formation on glass, were fully capable of colonizing the root tissue of both tomato and maize hosts. Investigating the role of cellular factors in biofilm formation using these plant-associated bacteria shows that the ability of bacteria to form biofilm on abiotic surfaces does not necessarily mirror its ability to colonize plant tissues. Our research provides a broader perspective on the adaptation of these bacteria to various environments.

Artificial Intelligence-Driven Analysis of Antimicrobial-Resistant and Biofilm-Forming Pathogens on Biotic and Abiotic Surfaces.

The growing threat of antimicrobial-resistant (AMR) pathogens to human health worldwide emphasizes the need for more effective infection control strategies. Bacterial and fungal biofilms pose a major challenge in treating AMR pathogen infections. Biofilms are formed by pathogenic microbes encased in extracellular polymeric substances to confer protection from antimicrobials and the host immune system. Biofilms also promote the growth of antibiotic-resistant mutants and latent persister cells and thus complicate therapeutic approaches. Biofilms are ubiquitous and cause serious health risks due to their ability to colonize various surfaces, including human tissues, medical devices, and food-processing equipment. Detection and characterization of biofilms are crucial for prompt intervention and infection control. To this end, traditional approaches are often effective, yet they fail to identify the microbial species inside biofilms. Recent advances in artificial intelligence (AI) have provided new avenues to improve biofilm identification. Machine-learning algorithms and image-processing techniques have shown promise for the accurate and efficient detection of biofilm-forming microorganisms on biotic and abiotic surfaces. These advancements have the potential to transform biofilm research and clinical practice by allowing faster diagnosis and more tailored therapy. This comprehensive review focuses on the application of AI techniques for the identification of biofilm-forming pathogens in various industries, including healthcare, food safety, and agriculture. The review discusses the existing approaches, challenges, and potential applications of AI in biofilm research, with a particular focus on the role of AI in improving diagnostic capacities and guiding preventative actions. The synthesis of the current knowledge and future directions, as described in this review, will guide future research and development efforts in combating biofilm-associated infections.

Enhancing biofilm formation with powder carriers for efficient nitrogen and phosphorus removal.

This study assesses the improvement in nitrogen and phosphorus removal from wastewater achieved through the integration of zeolite and attapulgite carrier materials into the activated sludge (AS) process. It was found that the addition of these materials significantly enhanced the processing performance of the reactor. Specifically, the use of zeolite and attapulgite powders increased sludge particle sizes to averages of 231.56 µm and 219.62 µm, respectively. This facilitated micro-granule formation, substantially improving the settling characteristics of the sludge and boosting the activity and proliferation of essential microbes. Illumina MiSeq sequencing demonstrated significant accumulations of DGAOs (Candidatus_Competibacter) and DPAOs (Candidatus_Accumulibacter). Furthermore, these carriers augmented the protein content in extracellular polymers, enhancing the hydrophobicity of the sludge and promoting aggregation. Comparative analysis based on the extended Derjaguin, Landau, Verwey, and Overbeek (DLVO) theory indicated a preferential adhesion affinity of sludge for zeolite compared to attapulgite, attributed primarily to Lewis acid-base and electric double-layer interactions. These findings underscore zeolite's enhanced efficacy in biomass fixation and suggest significant potential for the technological advancement of wastewater treatment plants.

Biofilm formation on MgFe-LDH@quartz sand as novel wetland substrate under varied C/N ratios for BDE-47 removal.

Layered double hydroxide (LDH)-coated substrates could enhance the removal of various wastewater-born pollutants. However, research on biofilms attached to LDH-coatings and their synergistic purification effects on strongly hydrophobic persistent organic pollutants (POPs) remains limited. This study aims to investigate biofilm formation on MgFe-LDH@quartz sand and its effectiveness in removing tetrabromodiphenyl ether (BDE-47), an emerging halogenated POP in municipal wastewater. Under different C/N ratios (3, 5, and 10), BDE-47 removal rates ranged from 28.0% to 41.6% after 72 h. The optimal performance was achieved with LDH coating at C/N = 5, when substrate biofilm reached its highest extracelluar polymer substances (EPS) content, dehydrogenase activity and relative hydrophobicity. Moreover, distinct distribution patterns of EPS components' fluorescence peaks were observed in the LDH-coating treatment using three dimensional excitation-emission matrix (3D-EEM). While substrate adsorption was the primary mechanism for BDE-47 removal, accounting for 59.6%-83.4% of the total, biofilm adsorption and degradation contributed a relatively lower amount, ranging from 11.5% to 21.4%, and were more dependent on the C/N ratio. Notably, the maximum carrying capacity of protein predicted by the logistic growth model exhibited a strong positive correlation with the total BDE-47 removal rate (R2 = 0.82, p < 0.05), highlighting the importance of biofilm extracelluar proteins.

Exploring staphylococcus in urinary tract infections: A systematic review and meta-analysis on the epidemiology, antibiotic resistance and biofilm formation.

This study aimed to determine the epidemiology, biofilm formation and antibiotic resistance of staphylococci collected worldwide in the context of UTIs. This systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Forty studies from 23 countries were selected for quantitative review. Electronic databases (PubMed, Scopus, Google Scholar, and Web of Sciences) were searched for articles published between 2010 and 2024 on the epidemiology, biofilm formation, and antibiotic resistance of uropathogenic staphylococci. Strict inclusion and exclusion standards were applied during the review of the articles. Forty articles were included in this systematic review. The prevalence of uropathogenic staphylococci varies from country to country, with the pooled prevalence of S. aureus and coagulase-negative staphylococci (CoNS) being 8.71 % (95 %CI: 6.145-11.69) and 13.17 % (95 %CI: 8.08-19.27) respectively. Among CoNS isolates, S. epidermidis was the most common with 19.3 % (95 %CI: 5.88-38.05). The prevalence of methicillin-resistant S. aureus isolates increased significantly from 23 % in 2010-2015 to 47 % in 2021-2024 (p = 0.03). S. haemolyticus is the most antibiotic-resistant species in CoNS, with 45 % of isolates resistant to methicillin, 33 % to gentamicin, and 29 % to tetracycline. Eighty-eight S. aureus strains were biofilm producers, including 35 % moderate biofilm producers and 48 % strong biofilm producers. The combined frequencies of icaA, clfA and fnbpA were 100, 99, and 89 %, respectively. The development of antibiotic resistance and biofilm formation by staphylococci involved in UTIs explains the need for periodic regional surveillance of these infections, which poses a serious public health problem.

The Impact of Cyclodextrins on the Physiology of Candida boidinii: Exploring New Opportunities in the Cyclodextrin Application.

Cyclodextrins, commonly used as excipients in antifungal formulations to improve the physicochemical properties and availability of the host molecules, have not been systematically studied for their effects and bioactivity without a complex active substance. This paper evaluates the effects of various cyclodextrins on the physiology of the test organism Candida boidinii. The research examines their impact on yeast growth, viability, biofilm formation and morphological changes. Native ACD, BCD, randomly methylated α- and ß-CD and quaternary ammonium α-CD and ß-CD were investigated in the 0.5-12.5 mM concentration range in both static and dynamic systems. The study revealed that certain cyclodextrins exhibited notable antifungal effects (up to ~69%) in dynamic systems; however, the biofilm formation was enhanced in static systems. The magnitude of these effects was influenced by several variables, including the size of the internal cavity, the concentration and structure of the cyclodextrins, and the contact time. Furthermore, the study found that CDs exhibited distinct effects in both static and dynamic systems, potentially related to their tendency to form aggregates. The findings suggest that cyclodextrins may have the potential to act as antifungal agents or growth promoters, depending on their structure and surrounding environments.

BolA-like protein (IbaG) promotes biofilm formation and pathogenicity of Vibrio parahaemolyticus.

Vibrio parahaemolyticus is a gram-negative halophilic bacterium widespread in temperate and tropical coastal waters; it is considered to be the most frequent cause of Vibrio-associated gastroenteritis in many countries. BolA-like proteins, which reportedly affect various growth and metabolic processes including flagellar synthesis in bacteria, are widely conserved from prokaryotes to eukaryotes. However, the effects exerted by BolA-like proteins on V. parahaemolyticus remain unclear, and thus require further investigation. In this study, our purpose was to investigate the role played by BolA-like protein (IbaG) in the pathogenicity of V. parahaemolyticus. We used homologous recombination to obtain the deletion strain ΔibaG and investigated the biological role of BolA family protein IbaG in V. parahaemolyticus. Our results showed that IbaG is a bacterial transcription factor that negatively modulates swimming capacity. Furthermore, overexpressing IbaG enhanced the capabilities of V. parahaemolyticus for swarming and biofilm formation. In addition, inactivation of ibaG in V. parahaemolyticus SH112 impaired its capacity for colonizing the heart, liver, spleen, and kidneys, and reduced visceral tissue damage, thereby leading to diminished virulence, compared with the wild-type strain. Finally, RNA-sequencing revealed 53 upregulated and 71 downregulated genes in the deletion strain ΔibaG. KEGG enrichment analysis showed that the two-component system, quorum sensing, bacterial secretion system, and numerous amino acid metabolism pathways had been altered due to the inactivation of ibaG. The results of this study indicated that IbaG exerts a considerable effect on gene regulation, motility, biofilm formation, and pathogenicity of V. parahaemolyticus. To the best of our knowledge, this is the first systematic study on the role played by IbaG in V. parahaemolyticus infections. Thus, our findings may lead to a better understanding of the metabolic processes involved in bacterial infections and provide a basis for the prevention and control of such infections.

d-Methionine-induced DNases disperse established Burkholderia pseudomallei biofilms and promotes ceftazidime susceptibility.

Burkholderia pseudomallei biofilm is correlated with pathogenesis, antibiotic resistance, and relapsing cases of melioidosis, leading to challenges in clinical management. There is increasing interest in employing biofilm dispersal agents as adjunctive treatments for biofilm-associated infections. Methionine (Met) has shown promise as an anti-biofilm agent by inducing bacterial DNase production, resulting in the degradation of extracellular DNA (eDNA) and dispersion of bacterial biofilm. In this study, we investigated the impact of 0.05-50 µM D-Met and L-Met on the 24-h established biofilm of a clinical isolate, B. pseudomallei H777. Our findings revealed the ability of D-Met and L-Met to disperse the established biofilm in a non-dose-dependent manner accompanied by eDNA depletion. Real-time PCR analysis further identified an up-regulation of bacterial nuclease genes, including recJ, eddB, nth, xth, and recD, in the presence of 0.05 µM D-Met. Similarly, recJ and eddB in B. pseudomallei were up-regulated in response to the presence of 0.05 µM L-Met. Notably, D-Met enhanced the susceptibility of B. pseudomallei H777 biofilm cells to ceftazidime. Our findings indicate a correlation between methionine supplementation and the up-regulation of nuclease genes, leading to eDNA depletion and the dispersal of preformed B. pseudomallei H777 biofilm. This enhances the susceptibility of biofilm cells to ceftazidime, showing promise in combating biofilm-associated B. pseudomallei infections.

Comparative genomic and morphological analyses of capsular and capsular-deficient pneumococcal strains simultaneously isolated from a patient with invasive pneumococcal disease.

INTRODUCTION: To understand the in-vivo dynamics in pneumococci, investigation into the carriage in patients with invasive pneumococcal disease (IPD) is extremely important. METHODS: To clarify genomic and morphological differences between pneumococcal strains simultaneously isolated from different sites in a patient with IPD, we conducted comparative analyses of two strains. A capsular strain isolated from the blood and a non-capsular strain isolated from the sputum of a patient with IPD were used. RESULTS: The strain isolated from blood was serotype 24B with capsule. The strain isolated from sputum with capsular type 24 genes was non-encapsulated, and genomic analysis revealed an insertion region in the wcxK gene. Its biofilm-forming capacity was higher than that of the capsular strain, as was that of the pspK-positive true non-encapsulated strain. Furthermore, observing the microbe using transmission electron microscopy revealed that the strain isolated from sputum lacked a capsule, like the pspK-positive true non-encapsulated strain. CONCLUSIONS: Our analysis of the two strains isolated from the blood and sputum of a patient with IPD showed one possible in-vivo morphological change in Streptococcus pneumoniae.