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Journal of Food Protection Jun 2024Bacillus thuringiensis-based commercial products as a biopesticide have been used for more than 60 years in agriculture. However, as one of the species in B. cereus...
Bacillus thuringiensis-based commercial products as a biopesticide have been used for more than 60 years in agriculture. However, as one of the species in B. cereus group, B. thuringiensis has been considered as an emerging hazard with the potential to cause food toxico-infections. The present study aimed to evaluate the biofilm-forming ability of B. thuringiensis biopesticide strains and their attachment on spinach, compared to foodborne B. cereus strains. Biofilm formations of tested strains were found to be strain-specific and affected by the nutrient conditions more than the incubation time. Nutrient starvation conditions generally reduced the biofilm formation of tested B. thuringiensis and B. cereus strains, particularly B. thuringiensis ABTS-1857 strain was found as the non-biofilm former in starvation conditions. It is worth mentioning that B. thuringiensis SA-11 strain showed stronger biofilm-forming ability with more air-liquid interface biofilm than the other two B. thuringiensis biopesticide strains, but no such higher attachment of B. thuringiensis SA-11 to spinach was observed. These results indicate that B. thuringiensis SA-11 strain can enter the food processing lines by the attachment on spinach leaves, and it has the potential to form biofilms throughout the processing lines or the production environment when sufficient nutrients are available. However, more biofilm tests of B. thuringiensis biopesticide strains in the vegetable production chain should be performed. The dry formulation of commercial B. thuringiensis biopesticides enhanced their adhesion on spinach leaves, whereas the strength of adhesion was not improved by the formulation. In addition, 1-2 log reductions of spores after the intensive washing of spinach leaves in the lab were detected. However, the log reduction due to the actual washing done by the food processing companies in large-volume washing baths or by consumers at home would be limited and less than this lab simulation.
PubMed: 38936698
DOI: 10.1016/j.jfp.2024.100321 -
Bioorganic Chemistry Jun 2024Di-branched and tetra-branched versions of a previously reported analogue of the lipopeptide battacin were successfully synthesised using thiol-maleimide click and 1, 2,...
Di-branched and tetra-branched versions of a previously reported analogue of the lipopeptide battacin were successfully synthesised using thiol-maleimide click and 1, 2, 3-triazole click chemistry. Antimicrobial studies against drug resistant clinical isolates of Escherichia coli (ESBL E. coli Ctx-M14), Pseudomonas aeruginosa (P. aeruginosa Q502), and Methicillin resistant Staphylococcus aureus (MRSA ATCC 33593), as well as clinically isolated Acinetobacter baumannii (A. baumannii ATCC 19606), and P. aeruginosa (ATCC 27853), revealed that the dendrimeric peptides have antimicrobial activity in the low micromolar range (0.5 -- 4 μM) which was 10 times more potent than the monomer peptides. Under high salt concentrations (150 mM NaCl, 2 mM MgCl, and 2.5 mM CaCl) the di-branched lipopeptides retained their antimicrobial activity while the monomer peptides were not active (>100 μM). The di-branched triazole click lipopeptide, Peptide 12, was membrane lytic, showed faster killing kinetics, and exhibited antibiofilm activity against A. baumannii and MRSA and eradicated > 85 % preformed biofilms at low micromolar concentrations. The di-branched analogues were > 30-fold potent than the monomers against Candida albicans. Peptide 12 was not haemolytic (HC10 = 932.12 μM) and showed up to 40-fold higher selectivity against bacteria and fungi than the monomer peptide. Peptide 12 exhibited strong proteolytic stability (>80 % not degraded) in rat serum over 24 h whereas > 95 % of the thiol-maleimide analogue (Peptide 10) was degraded. The tetra-branched peptides showed comparable antibacterial potency to the di-branched analogues. These findings indicate that dual branching using triazole click chemistry is a promising strategy to improve the antimicrobial activity and proteolytic stability of battacin based lipopeptides. The information gathered can be used to build effective antimicrobial dendrimeric peptides as new peptide antibiotics.
PubMed: 38936047
DOI: 10.1016/j.bioorg.2024.107567 -
Emerging Microbes & Infections Jun 2024, a group of multi-drug resistant, Gram-positive, aerobic and partially acid-fast bacteria, are emerging causes of bacterial conjunctivitis and keratitis. However, the...
, a group of multi-drug resistant, Gram-positive, aerobic and partially acid-fast bacteria, are emerging causes of bacterial conjunctivitis and keratitis. However, the pathogenesis of keratitis is largely unknown. To address this, we used New Zealand White rabbits to develop the first eye infection model and conducted tests to study the pathogenesis mechanisms of . There is increasing evidence that biofilms play a significant role in ocular infections, leading us to hypothesize that biofilm formation is crucial for effective infection. In order to look for potential candidate genes which are important in biofilm formation and keratitis. We performed genome sequencing of two ocular isolates, -PW1004 and -PW899, to identify potential virulence factors. Through and studies, we characterized their biological roles in mediating keratitis. Our findings confirmed that is an ocular pathogen by fulfilling the Koch's postulates, and using genome sequence data, we identified encoding a mycolyltransferase, as a crucial gene in biofilm formation and causing keratitis in the rabbit model. This is the first report demonstrating the novel role of mycolyltransferase in causing ocular infections. Overall, our findings contribute to a better understanding of pathogenesis and provide a potential target for treatment. Specific inhibitors targeting TmytC could serve as an effective treatment option for infections.
PubMed: 38934251
DOI: 10.1080/22221751.2024.2373317 -
Heliyon Jun 2024Current biofilm modelling of the opportunistic pathogen, (PA) in people with cystic fibrosis (PwCF) is limited in its ability to mimic the complexities of the cystic...
Current biofilm modelling of the opportunistic pathogen, (PA) in people with cystic fibrosis (PwCF) is limited in its ability to mimic the complexities of the cystic fibrosis (CF) lung environment. Recent adaptations of the Microbial Identification after Passive CLARITY Technique (MiPACT) in CF research have allowed for the direct imaging of PA biofilm spatial organization and structure in expectorated sputum. Here, we performed a comparative analysis of and within patient () measures of PA biofilms using sputa from new onset infected children with CF. MiPACT-fluorescent hybridization (FISH) and fluorescent anti-Psl monoclonal antibody (mAb) staining was performed to directly visualize PA and Psl (exopolysaccharide in PA biofilm matrix) in 11 CF sputum specimens. Corresponding PA isolates, recovered from the same sputum samples, were grown as biofilms in a glass slide chamber model, then visualized by fluorescent live-cell and anti-Psl mAb staining. We observed that PA biovolume, aggregation and Psl antibody binding (normalized per PA biovolume) in CF sputum did not correlate with the model, although a trend towards significance in the biovolume relationship was observed with the addition of sputum supernatant to the model.
PubMed: 38933957
DOI: 10.1016/j.heliyon.2024.e32424 -
Infection and Drug Resistance 2024Persistent infections caused by (), which are resistant to antibiotic treatment, pose a growing global public health concern. Biofilm formation is known to be...
BACKGROUND
Persistent infections caused by (), which are resistant to antibiotic treatment, pose a growing global public health concern. Biofilm formation is known to be associated with persistent infections due to its role in enhancing antimicrobial resistance and the tolerance of many pathogenic bacteria.
OBJECTIVE
This study aims to evaluate the biofilm formation of clinical isolates of and its impact on antibiotic eradication.
METHODS
The thickness, morphology, and structure of biofilms derived from nine strains were examined using confocal laser scanning microscopy, scanning electron microscopy, and transmission electron microscopy. Subsequently, the susceptibility of both planktonic and biofilm bacteria was assessed through the determination of minimum inhibitory concentration and minimum biofilm eradication concentration for amoxicillin, clarithromycin, levofloxacin, and tetracycline.
RESULTS
The results revealed varying biofilm thicknesses and densities among the strains, characterised by the presence of numerous filaments intertwining and connecting bacterial cells. Additionally, several cases exhibited susceptibility based on MIC measurements but resistance according to MBEC measurements, with MBEC indicating a higher resistance rate. Pearson Correlation analysis demonstrated a positive correlation between biofilm thickness and MBEC results (0 < < 1), notably significant for amoxicillin ( = 0.801, = 0.009) and tetracycline ( = 0.696, = 0.037).
CONCLUSION
Different strains of exhibit variations in their capacity to release outer membrane vesicles (OMVs) and form biofilms. Biofilm formation can influence the effectiveness of amoxicillin and tetracycline in eradicating susceptible bacterial strains.
PubMed: 38933776
DOI: 10.2147/IDR.S468126 -
Frontiers in Veterinary Science 2024An increase in chronic, non-responsive bovine respiratory disease (BRD) infections in North American feedlot cattle is observed each fall, a time when cattle are... (Review)
Review
An increase in chronic, non-responsive bovine respiratory disease (BRD) infections in North American feedlot cattle is observed each fall, a time when cattle are administered multiple antimicrobial treatments for BRD. A number of factors are responsible for BRD antimicrobial treatment failure, with formation of biofilms possibly being one. It is widely accepted that biofilms play a role in chronic infections in humans and it has been hypothesized that they are the default lifestyle of most bacteria. However, research on bacterial biofilms associated with livestock is scarce and significant knowledge gaps exist in our understanding of their role in AMR of the bacterial BRD complex. The four main bacterial species of the BRD complex, , , , and are able to form biofilms and there is evidence that at least retains this ability . However, there is a need to elucidate whether their biofilm-forming ability contributes to pathogenicity and antimicrobial treatment failure of BRD. Overall, a better understanding of the possible role of BRD bacterial biofilms in clinical disease and AMR could assist in the prevention and management of respiratory infections in feedlot cattle. We review and discuss the current knowledge of BRD bacteria biofilm biology, study methodologies, and their possible relationship to AMR.
PubMed: 38933702
DOI: 10.3389/fvets.2024.1353551 -
Viruses Jun 2024Pentasilver hexaoxoiodate (AgIO) has broad-spectrum antimicrobial efficacy, including the long-term prevention of microbial adherence, the rapid killing of planktonic...
Pentasilver hexaoxoiodate (AgIO) has broad-spectrum antimicrobial efficacy, including the long-term prevention of microbial adherence, the rapid killing of planktonic microorganisms, and the elimination of mature biofilms. This study's goal was to determine whether it may also have antiviral activity against structurally distinct viruses. AgIO was tested following ASTM E1052-20, Standard Practice to Assess the Activity of Microbicides Against Viruses in Suspension, against adenovirus type 5, murine norovirus, poliovirus type 1, SARS-CoV-2 (original), and SARS-CoV-2 (omicron) (host cells: H1HeLa, RAW 264.7, LLC-MK2, Vero E6, and Vero E6, respectively). A 0.1 g/mL AgIO suspension was prepared and the viruses were exposed for 30 min, 4 h, or 24 h. Exposure to AgIO resulted in complete kill of SARS-CoV-2 (omicron) within 30 min, as well as complete kill of both SARS-CoV-2 (original) and the murine norovirus within 4 h. AgIO showed increasing activity over time against the adenovirus, but did not achieve a 3-log reduction within 24 h, and showed no antiviral activity against the poliovirus. These results demonstrate that AgIO has antiviral activity against medically important viruses, in addition to its well-characterized antimicrobial activity, suggesting that it may be valuable in situations where the prevention or simultaneous treatment of microbes and viruses are necessary.
Topics: Antiviral Agents; Animals; Mice; Chlorocebus aethiops; Humans; SARS-CoV-2; Vero Cells; Silver Compounds; Cell Line; Poliovirus; Norovirus; RAW 264.7 Cells
PubMed: 38932251
DOI: 10.3390/v16060959 -
Viruses May 2024Bacteriophages (phages) are viruses that infect the bacteria within which their reproduction cycle takes place, a process that ends in the lysis and death of the...
Bacteriophages (phages) are viruses that infect the bacteria within which their reproduction cycle takes place, a process that ends in the lysis and death of the bacterial cell. Some phages are also able to destroy bacterial biofilms. Due to increased antibiotics resistance, , another biofilm-forming pathogen, is a problem in many parts of the world. Zinc oxide (ZnO) and other metal nanoparticles (NPs) are biologically active and also possess anti-biofilm properties. ZnO-NPs were prepared by the green synthesis method using orange peels. The vibrational peaks of the ZnO-NPs were analyzed using FTIR analysis, and their size and morphological properties were determined using scanning electron microscopy (SEM). The ability of the ZnO-NPs to reduce or eliminate biofilm alone or in combination with phages PB10 and PA19 was investigated. The cells were effectively killed in the preformed 48 h biofilms during a 24 h incubation with the ZnO-NP-phage combination, in comparison with the control or ZnO-NPs alone. The treatments on growing biofilms were most efficient in the final stages of biofilm development. All five treatment groups showed a significant biofilm reduction compared to the control group ( < 0.0001) at 48 h of incubation. The influence of the ZnO-NPs and phages on the quorum sensing system of was monitored by quantitative real-time PCR (qRT-PCR) of the autoinducer biosynthesis gene . While the ZnO-NPs repressed the gene transcription, the phages slightly activated it at 24 and 48 h of incubation. Also, the effect of the ZnO-NPs and phage PA19 on the viability of HFF2 cells was investigated and the results showed that the combination of NPs with PA19 reduced the toxic effect of ZnO-NPs and also stimulated the growth in normal cells.
Topics: Zinc Oxide; Pseudomonas aeruginosa; Biofilms; Metal Nanoparticles; Green Chemistry Technology; Bacteriophages; Anti-Bacterial Agents; Nanoparticles
PubMed: 38932188
DOI: 10.3390/v16060897 -
Viruses May 2024Filamentous bacteriophages belonging to the order , family , significantly affect the properties of Gram-negative bacteria, but filamentous phages of many important...
Filamentous bacteriophages belonging to the order , family , significantly affect the properties of Gram-negative bacteria, but filamentous phages of many important pathogens have not been described so far. The aim of this study was to examine filamentous phages for the first time and to determine their effect on bacterial virulence. The filamentous phages were detected in 15.3% of strains as individual prophages in the genome or as tandem repeats, and a slightly higher percentage was detected in the culture collection (23.8%). The phylogenetic analyses revealed 12 new genera within the family. Bacteriophages that were selected and isolated showed structural and genomic characteristics of the family and were unable to form plaques. Upon host infection, these phages did not significantly affect bacterial twitching motility and capsule production but significantly affected growth kinetics, reduced biofilm formation, and increased antibiotic sensitivity. One of the possible mechanisms of reduced resistance to antibiotics is the observed decreased expression of efflux pumps after infection with filamentous phages.
Topics: Acinetobacter baumannii; Phylogeny; Genome, Viral; Biofilms; Inovirus; Host Specificity; Anti-Bacterial Agents; Virulence; Bacteriophages; Prophages
PubMed: 38932150
DOI: 10.3390/v16060857 -
Polymers Jun 2024Nowadays, bacteria resistance to many antibiotics is a huge problem, especially in clinics and other parts of the healthcare system. This critical health issue requires...
Phloroglucinol-Based Carbon Quantum Dots/Polyurethane Composite Films: How Structure of Carbon Quantum Dots Affects Antibacterial and Antibiofouling Efficiency of Composite Films.
Nowadays, bacteria resistance to many antibiotics is a huge problem, especially in clinics and other parts of the healthcare system. This critical health issue requires a dynamic approach to produce new types of antibacterial coatings to combat various pathogen microbes. In this research, we prepared a new type of carbon quantum dots based on phloroglucinol using the bottom-up method. Polyurethane composite films were produced using the swell-encapsulation-shrink method. Detailed electrostatic force and viscoelastic microscopy of carbon quantum dots revealed inhomogeneous structure characterized by electron-rich/soft and electron-poor/hard regions. The uncommon photoluminescence spectrum of carbon quantum dots core had a multipeak structure. Several tests confirmed that carbon quantum dots and composite films produced singlet oxygen. Antibacterial and antibiofouling efficiency of composite films was tested on eight bacteria strains and three bacteria biofilms.
PubMed: 38931997
DOI: 10.3390/polym16121646