Relevant Pathogens Research Articles

Antimicrobial and Antibiofilm Activity of Chitosan Nanoparticles Against Staphylococcus aureus Strains Isolated from Bovine Mastitis Milk

Background/Objectives: Bovine mastitis (BM), a prevalent and economically burdensome bacterial infection affecting dairy cattle, poses a significant challenge to the dairy industry. The traditional approach to combating BM, relying heavily on antibiotics, faces growing concerns due to the increasing antibiotic resistance exhibited by pathogens. The objective of this study was to evaluate and determine the antimicrobial and anti-biofilm potential of chitosan nanoparticles (NQo) on S. aureus strains isolated from milk samples obtained from dairy areas in southern Chile from cows diagnosed with BM. Methods: NQo were synthesized using the ionotropic gelation method and thoroughly characterized by transmission electron microscopy (TEM) and dynamic light scattering (DLS). Results: The NQo exhibit a robust positive charge (Z-potential of +55.4 ± 2.5 mV) and an exceptionally small size (20.3 ± 3.2 nm). This unique combination of properties makes NQo particularly well-suited for targeting and interacting with bacterial pathogens. To assess the effectiveness of NQo against BM, we conducted a series of experiments using a Staphylococcus aureus strain isolated from milk samples of cows diagnosed with BM in southern Chile. NQo demonstrated a remarkable ability to inhibit bacterial proliferation and effectively modulate biofilm formation in the S. aureus strains. Furthermore, the performance of NQo in comparison to established antibiotics like ampicillin and gentamicin strongly suggests that these nanoparticles hold immense potential as an attractive alternative for the control, prevention, and/or treatment of BM. Conclusions: NQo exhibit both antimicrobial and antibiofilm activity against a clinically relevant BM pathogen. Further investigations are necessary to develop a hydrogel formulation optimized for effective delivery to the target diseased tissue.

Effects of climate change on the occurrence and distribution of Western equine encephalitis virus in South America.

The Western equine encephalitis virus (WEEV) is a globally relevant vector-borne pathogen that causes encephalitis. The role of environmental variables in the epidemiology of WEEV has become greater in the context of climate change. In December 2023, a significant resurgence of WEEV began in South America, with major ongoing outbreaks in Argentina and Uruguay. In this study, we employed a machine learning algorithm to model the distribution of WEEV in South America, considering both present and future scenarios. Ecological retrospective study. We conducted a modelling study to identify areas with the highest prevalence of WEEV in South America, based on confirmed human and equine cases during the 2023/2024 outbreak and climatic variables. Our analysis utilised Maxent software, a machine learning algorithm for species distribution modelling. Our results indicate that environmental variables, particularly thermal seasonality and annual rainfall, can directly influence the occurrence of WEEV, leading to increased virus incidence. Consequently, high-risk areas may shift in the future. Countries, such as Paraguay, Venezuela, Colombia, and various regions in Brazil, particularly the Northeast, Midwest, and the Pantanal biomes, will be significantly impacted, drastically altering the current distribution of WEEV. The ongoing WEEV outbreak in South America is concerning because it coincides with migratory bird stopovers. These birds are natural hosts that can spread the virus to unaffected areas. Our results will help to identify priority areas for developing preventive measures and establishing epidemiological surveillance.

Microbial indicators for water quality in recirculating shower technology.

Recirculating showers save up to 70-80% of the water and energy use of conventional showers, but water quality in these systems are not studied very well due to the technology's early stages. The aim of this study was to provide an overview of information available on which microorganisms were investigated and at which densities. Based on this platform we further aimed at identifying key microbial indicators and pathogens for monitoring water quality in these systems by integrating data from the top five waterborne outbreaks with findings from studies on (1) microbial investigations in reuse projects involving shower effluents or combined bathroom streams, (2) shower water effluents, and (3) biofilms in conventional showers. Outbreak data were extracted from the National Outbreak Reporting System (NORS) and a systematic literature review, supplemented with additional references found within the papers. Escherichia coli, Total Coliforms, enterococci as faecal indicator bacteria and the heterotrophic plate count were reported in shower effluents at variable, but generally high concentrations, indicating these organisms to be relevant as indication of faecal bacterial contamination and as general microbial densities in recirculating showers. Pseudomonas aeruginosa was abundant in conventional shower biofilms, detectable in shower effluents at concentrations in the range of 2-4 logs CFU/100mL and ranked among the top five etiological agents of waterborne outbreaks. Consequently, P. aeruginosa is considered as a significant reference pathogen for assessing water quality in recirculating shower systems. A diverse range of Legionella species, particularly Legionella pneumophila, are the primary cause of waterborne outbreaks, and persist in conventional shower biofilms. Therefore, we consider it to be significant as an indicator species in monitoring water quality. Staphylococcus aureus, Mycobacterium spp., and fungi such as Candida albicans could serve as supplementary microbial parameters. Trace organisms such as protozoa (Cryptosporidium spp. and Giardia spp.) and model viruses are also recommended for assessing treatment efficacy. In conclusion, while further research is required to validate these findings, this review critically evaluates relevant pathogens, creating the basis for future microbial water quality assessments in recirculating showers.

PathoGD: an integrative genomics approach to primer and guide RNA design for CRISPR-based diagnostics

Critical to the success of CRISPR-based diagnostic assays is the selection of a diagnostic target highly specific to the organism of interest, a process often requiring iterative cycles of manual selection, optimisation, and redesign. Here we present PathoGD, a bioinformatic pipeline for rapid and high-throughput design of RPA primers and gRNAs for CRISPR-Cas12a-based pathogen detection. PathoGD is fully automated, leverages publicly available sequences and is scalable to large datasets, allowing rapid continuous monitoring and validation of primer/gRNA sets to ensure ongoing assay relevance. We designed primers and gRNAs for five clinically relevant bacterial pathogens, and experimentally validated a subset of the designs for detecting Streptococcus pyogenes and/or Neisseria gonorrhoeae in assays with and without pre-amplification. We demonstrated high specificity of primers and gRNAs designed, with minimal off-target signal observed for all combinations. We anticipate PathoGD will be an important resource for assay design for current and emerging pathogens. PathoGD is available on GitHub at https://github.com/sjlow23/pathogd.

Methyl jasmonate spray for the protection of broad-leaf trees against oomycete and fungal pathogens

Methyl jasmonate spray for the protection of broad-leaf trees against oomycete and fungal pathogens

P-1849. Investigating the Impact of SARS-CoV-2 on the Immune Response to Other Pathogens Using VirScan Epitope Profiling

Abstract Background The emergence and rapid spread of SARS-CoV-2 since 2019 caused substantial global morbidity and mortality and continues to burden healthcare systems worldwide. Public health measures implemented to reduce SARS-CoV-2 spread also reduced circulation of other seasonal respiratory viruses, likely causing gaps in population-level immunity. Whether SARS-CoV-2 infection may dampen immune responses against other pathogens is highly debated and not well understood.Figure 1.VirScan analyses of serum samples pre- and post- clinically confirmed SARS-CoV-2 infection. (A) VirScan total epitope hits and geometric mean (gMean) of epitope binding (EB) scores for SARS-CoV-2 pre- and post- clinically confirmed SARS-CoV-2 infection. (B) gMean of EB scores for select pathogens pre- and post- clinically confirmed SARS-CoV-2 infection. Timepoints included in the VirScan analyses were between 15-174 days prior to and 31-155 days after clinically confirmed SARS-CoV-2 infection. Gray lines denote paired samples for individual subjects. Statistically significant adjusted p values of < 0.05 were determined using paired t test with Holm correction. Methods In 2022, we conducted a longitudinal study of immunocompetent adults ( > 18 years) with recent SARS-CoV-2 infection or vaccination history and increased risk of social or occupational exposure to respiratory viruses. Subjects were followed for 6 months and weekly symptom surveys, blood samples at enrollment, 3 and 6 months post-enrollment, and nasal swabs at report of symptoms were collected. Swabs were tested by RT-PCR (OpenArray) for 27 respiratory pathogens, including SARS-CoV-2. Serum antibodies were assessed by VirScan PhIP-seq for specificity to a broad library of antigen epitopes for clinically relevant pathogens, measuring total epitope hits and epitope binding (EB) scores, a measure similar to antibody titer. Results Of 43 subjects with paired serum samples > 1 week prior to and > 28 days after clinically confirmed SARS-CoV-2 infection, 32 subjects with viral load < Ct 22.2 were assessed by VirScan. SARS-CoV-2 epitope hits and EB scores were significantly increased post-infection compared to pre-infection (Fig 1A). SARS-CoV-2 infection was associated with reduced EB scores for adenovirus D and S. aureus (Fig 1B). However, SARS-CoV-2 infection was not associated with a statistically significant decline of epitope hits or EB scores for most other clinically relevant pathogens. Conclusion We assessed broad changes in the antibody repertoires of subjects prior to and after SARS-CoV-2 infection for clinically relevant pathogens at the epitope level by VirScan. Together these data suggest that SARS-CoV-2 infection is not associated with differential patterns of antibody repertoire kinetics for most non-coronavirus respiratory pathogens in immunocompetent adults. Further analyses in larger cohorts with longer follow-up are needed to confirm these findings. Disclosures Michael J. Boeckh, MD PhD, Allovir: Advisor/Consultant|Allovir: Grant/Research Support|AstraZeneca: Advisor/Consultant|AstraZeneca: Grant/Research Support|Merck: Advisor/Consultant|Merck: Grant/Research Support|Moderna: Advisor/Consultant|Moderna: Grant/Research Support|Symbio: Advisor/Consultant Alpana waghmare, MD, Allovir: Grant/Research Support|Ansun Biopharma: Grant/Research Support|GlaxoKlineSmith: Advisor/Consultant|GlaxoKlineSmith: Grant/Research Support|Pfizer: Grant/Research Support|Vir: Advisor/Consultant

P-1164. Prevalence of invasive Candidiasis and antifungal resistance in neonates: a multicenter three-year retrospective analysis from two large Mexican NICUs

Abstract Background Candida infections are increasingly recognized as clinically relevant pathogens in NICUs, particularly among preterm and low birth-weight infants (LBWI). Due to the emergence of Fluconazole-resistant Candida spp, current treatment guidelines of neonatal invasive Candidiasis (IC) suggest Amphotericin B as first line therapy, leaving Fluconazole as an alternative agent. Microbiological surveillance focused on fungal etiologies in Mexican NICUs is scarce, which may lead to inappropriate antifungal use. Methods Retrospective multicenter study conducted in the NICUs of the two pediatric reference hospitals in NL, Mexico. Clinical and microbiological data of all newborns ≤28 days diagnosed with blood culture-proven invasive Candidiasis from 2021-2023 were collected. LBWIs were defined as newborns < 2500 g at birth, and very LBWI (VLBWI) as < 1500 g. Descriptive statistical analyses were performed to determine the frequency of Candida spp and frequency of antifungal resistance. Results During the studied period, 928 positive blood cultures were included. Only 38 blood cultures (4%) were positive for Candida spp. No outbreaks occurred during the studied period. Twenty one patients (75%) were preterm. Mean gestational age was 29 weeks. Most patients (55%) were VLBWI (Table 1). All episodes were classified as late-onset sepsis. The most common isolated species were C. albicans (45%), followed by C. glabrata (29%), and C. parapsilosis (16%). No Fluconazole resistance was observed (Table 2). Caspofungin resistance was found in 5 C. glabrata isolates and 1 C. albicans. No cases of endophthalmitis or endocarditis were documented. Conclusion We report a low prevalence of blood culture-proven neonatal IC (4%) in two large Mexican NICUs during the studied period. Most patients were LBWI. This is consistent with international data. C. albicans was the most common isolated species. Based on the local epidemiology in two large NICUs of NL Mx, Fluconazole may be considered as a first line antifungal agent instead of Amphotericin B. Local microbial epidemiology and antifungal susceptibility patterns should be considered for the empirical treatment. Disclosures All Authors: No reported disclosures

P-1513. In Vitro Activity of Ceftaroline against Bacterial Pathogens from Pediatric Patients Collected During the ATLAS Global Surveillance Program in 2018-2022

Abstract Background The parenteral cephem ceftaroline fosamil is approved for treatment of adults and children with complicated skin and soft tissue infections (SSTI) and community-acquired bacterial pneumonia (CABP) caused by susceptible isolates of Staphylococcus aureus (methicillin-resistant [MRSA; SSTI] and methicillin-susceptible [MSSA; SSTI and CABP]), β-hemolytic streptococci (Streptococcus pyogenes and Streptococcus agalactiae [SSTI]); Streptococcus pneumoniae (CABP, including concurrent bacteremia), Haemophilus influenzae (CABP), and isolates of Escherichia coli, Klebsiella pneumoniae and Klebsiella oxytoca (SSTI and CABP). Several pathogens causing CABP are also frequently associated with bloodstream infections (BSI). This study examined the in vitro susceptibility to ceftaroline and comparator agents among pathogens isolated from pediatric patients with SSTI, respiratory tract infections (RTI), and BSI as part of the Antimicrobial Testing Leadership and Surveillance (ATLAS) surveillance program in 2018-2022. Methods 16,533 non-duplicate, clinically relevant isolates of S. aureus, β-hemolytic streptococci, S. pneumoniae, H. influenzae, M. catarrhalis and Enterobacterales were collected from patients aged 0-17 years old with BSI, RTI and SSTI by 285 medical centres in 60 countries. In vitro susceptibility to ceftaroline was determined by CLSI broth microdilution and results were interpreted using CLSI 2024 breakpoints where available. Extended spectrum β-lactamase (ESBL) screening was performed using the CLSI M100 method. Results The in vitro activity of ceftaroline is summarized in the table. 100% of MSSA and β-hemolytic streptococci isolates, >99% of S. pneumoniae, >99% of H. influenzae, and >92% of ESBL screen-negative E. coli, K. pneumoniae, K. oxytoca and P. mirabilis collected from all pediatric patients combined tested as susceptible to ceftaroline, as did >97% of MRSA. M. catarrhalis ceftaroline MIC values ranged from ≤0.06 - 8 µg/mL, with an MIC90 of 0.25 mg/L. Susceptibility was consistant across each of the age groups. Conclusion Ceftaroline demonstrated potent in vitro activity against a global collection of clinically relevant pathogens collected from pediatric patients. Disclosures Daniel F. Sahm, PhD, Pfizer, Inc.: Advisor/Consultant

P-382. Evaluation of Antibiotic Prophylaxis for Patients Undergoing Whipple Procedure

Abstract Background Pancreatoduodenectomy (PD) or the Whipple is a complex surgical intervention with high complication rates. The purpose of this study is to evaluate the efficacy of standard of care (SOC) perioperative antibiotics, cefazolin plus metronidazole, as prophylaxis for surgical site infection (SSI) in patients undergoing PD at The Johns Hopkins Hospital (JHH). Methods A retrospective study was performed of adult patients undergoing PD at JHH between January 1, 2022 and October 31, 2023. The following information was collected on all patients: peri-operative antibiotics administered, placement of operative drains, pre-operative biliary stent, prior endoscopic retrograde cholangiopancreatography, SSI, pancreatic fistula, and microbiological data. Criteria for SSIs were adapted from the CDC’s National Healthcare Safety Network definitions. SOC prophylaxis included cefazolin plus metronidazole. The primary outcome was the proportion of patients who developed an SSI within 30 days of PD. Secondary outcomes included identification of the causative pathogens of SSI in patients after PD and the proportion of organisms susceptible to SOC antibiotics. Descriptive statistics was used to summarize demographic data and the primary and secondary outcomes. Results A total of 333 patients met inclusion criteria and were documented as having PD during our study period. Of these patients, 106 (31.2%) had post-operative complications including infection or fistula. Overall, 81 patients (24.3%) had a SSI after PD. Seventy-one SSIs occurred in 295 patients (24.1%) receiving SOC antibiotic prophylaxis compared to 10 SSIs in 38 patients (26.3%) receiving non-SOC antibiotics (p=0.761). Of the 81 patients with a SSI, pathogens were identified through post-operative culture data in 33 patients. Thirty-two of the 55 (58%) clinically relevant pathogens were susceptible to SOC antibiotics. Conclusion The incidence of surgical complications associated with PD at our institution is comparable to rates reported in the available literature. While the incidence of clinically relevant organisms not covered by SOC prophylaxis is low, a targeted approach for prophylaxis may be required for select patients. Disclosures All Authors: No reported disclosures

Screening a 681-membered yeast collection for the secretion of proteins with antifungal activity.

Fungal pathogens pose a threat to human health and food security. Few antifungals are available and resistance to all has been reported. Novel strategies to control plant and human pathogens as well as food spoilers are urgently required. Environmental yeasts provide a functionally diverse, yet underexploited potential for fungal control based on their natural competition via the secretion of proteins and other small molecules such as iron chelators, volatile organic compounds or biosurfactants. However, there is a lack of standardized workflows to systematically access application-relevant yeast-based compounds and understand their molecular functioning. Towards this goal, we developed a workflow to identify and characterize yeast isolates that are active against spoilage yeasts and relevant human and plant pathogens, herein focusing on discovering yeasts that secrete antifungal proteins. The workflow includes the classification of the secreted molecules and cross-comparison of their antifungal capacity using an independent synthetic calibrant. Our workflow delivered a collection of 681 yeasts of which 212 isolates (31%) displayed antagonism against at least one target strain. While 57.5% of the active yeasts showed iron-depended antagonism, likely due to pulcherrimin-like iron chelators, 31.7% secreted antifungal proteins. Those yeast candidates clustered within twelve OTUs, showed narrow and broad target spectra, and several showed a broad pH and temperature activity profile. Given the tools for yeast biotechnology and protein engineering available, our collection can serve as a rich starting point for genetic and molecular characterization of the various antifungal phenotypes, their mode of action and their future exploitation.

Combined application of metagenomics and FEAST to trace sources of microbial eukaryotic contamination in the Pasig-Marikina-San Juan (PAMARISAN) river system in Metro Manila, Philippines.

Microbial eukaryotes are vital to global microbial diversity, but there is limited information about their composition and sources in contaminated surface waters. This study examined the pathogens and potential sources of microbial eukaryotic communities in polluted sink environments using the 18S rDNA amplicon sequencing combined with the fast expectation-maximization for microbial source tracking (FEAST) program. Six sampling sites were selected along the Pasig-Marikina-San Juan (PAMARISAN) River System, representing different locations within the waterway and classified as sinks (n = 12), whereas animal fecal samples collected from various farms were classified as sources (n = 29). Taxonomic composition revealed Stramenopila, Alveolata, Rhizaria (SAR), Archaeplastida, and Excavata in the rivers, accounting for 85.1%, 13.2%, and 0.36% mean abundance of microbial sink communities, respectively. Clinically relevant human pathogens were also observed in sink environments. The correlation test demonstrated that dissolved oxygen, total suspended solids, pH, temperature, fecal coliform count, and phosphates were important environmental factors driving community variations. Moreover, FEAST results indicated that sewage (19.6%) was the primary source of microbial eukaryotes, followed by duck (0.644%) and cow (0.566%) feces. Spatio-seasonal variations showed higher contributions at downstream stations and during the wet season, highlighting the role of rainfall in enhancing microbial dispersal. Results from community-based microbial source tracking can be used to explore factors shaping microbial eukaryotes in freshwater environments, assess potential pathogen-related hazards, and inform river conservation and management strategies. Furthermore, this also serves as preliminary data for microbial eukaryotic source tracking in the Philippines, laying groundwork for future research.

Elucidating assembly and function of VirB8 cell wall subunits refines the DNA translocation model in Gram-positive T4SSs.

Bacterial type IV secretion systems (T4SSs) are widespread nanomachines specialized in the transport across the cell envelope of various types of molecules including mobile genetic elements during conjugation. Despite their prevalence in Gram-positive bacteria, including relevant pathogens, their assembly and functioning remain unknown. This study addresses these gaps by investigating VirB8 proteins, known to be central components of conjugative T4SSs in Gram-positive bacteria. However, the functional packing and precise role of VirB8 in T4SSs biology remain undefined. Our findings elucidate the nature of VirB8 proteins as cell wall components, where they multimerize and exhibit a conserved assembly pattern, distinct from VirB8 in Gram-negative bacteria. We also demonstrate that VirB8 proteins interact with other T4SS subunits and DNA, indicating their pivotal role in the building of the DNA translocation channel across the cell wall. We lastly propose a distinct architecture for conjugative T4SSs in Gram-positive bacteria compared to their Gram-negative counterparts, possibly attributed to the differences in the cell wall structure.

Heterologous Expression and Characterization of Estercin A, a Class II Lanthipeptide Derived from Clostridium estertheticum CF016, with Antimicrobial Activity against Clinically Relevant Pathogens.

Recent genome mining work revealed that unexplored habitats exhibit great potential for discovering new nonribosomal peptides (NRPs) and ribosomally synthesized and post-translationally modified peptides (RiPPs). Lanthipeptides are a group of RiPPs exhibiting a variety of biological functions. They are characterized by the presence of the thioether-containing bis-amino acids lanthionine and/or methyllanthionine. In this study, we heterologously expressed and structurally characterized estercin A, an unprecedented class II lanthipeptide derived from Clostridium estertheticum CF016 in Escherichia coli. Comprising 27 amino acids, estercin A features three overlapping (methyl-)lanthionine rings, with a shorter C-terminal part compared to most reported class II lanthipeptides. Estercin A exhibited selective antimicrobial properties against methicillin-resistant Staphylococcus aureus, bowel infection-associated Clostridium perfringens and Clostridium tetani. The mode of action of estercin A was determined as binding to lipid II on the cell membrane. Estercin A exhibited stability across a range of pH values and temperatures and showed resistance to degradation by trypsin. Our findings highlight estercin A as a novel and stable antimicrobial peptide with significant potential in combating clinically relevant pathogens.

The Janus Effect: The Biochemical Logic of Antibiotic Resistance.

Antibiotics are essential medicines threatened by the emergence of resistance in all relevant bacterial pathogens. The engagement of the molecular targets of antibiotics offers multiple opportunities for resistance to emerge. Successful target engagement often requires passage of the antibiotic from outside into the cell interior through one or two distinct membrane barriers. Resistance can occur by preventing the accumulation of antibiotics in sufficient quantities outside the cell, decreasing the rates of entry into the cell, and modifying the antibiotic or the target once inside the cell. These competing equilibria and rates are the lens through which the balance of antibiotic efficacy or failure can be viewed. The two faces of antibiotics, cell growth inhibition or resistance, are reminiscent of Janus, the Roman god of doorways and beginnings and endings, and offer a framework through which antibiotic discovery, use, and the emergence of resistance can be rationally viewed.

Clonal shift and impact of azithromycin use on antimicrobial resistance of Staphylococcus aureus isolated from bloodstream infection during the COVID-19 pandemic

Staphylococcus aureus is a relevant pathogen in bloodstream infections (BSI), and the emergency of the COVID-19 pandemic increased its antimicrobial resistance. S. aureus isolates from BSI (September/2019 - March/2021) were analyzed phenotypically and molecularly, in addition to the clinical features of the patients. Of 88 S. aureus isolates recovered from 85 patients, 25 were isolated before the pandemic and 63 during it, and 16 were from patients with COVID-19. A rate of 45.5% of methicillin-resistant isolates (MRSA) were found, and 5% of them were ceftaroline susceptible dose-dependent. Daptomycin non-susceptibility was observed in 9.1% of isolates. The USA800/ST5/SCCmecIV lineage was prevalent among MRSA isolates (41.8%). Besides, 30.2% of the isolates were associated with community-associated MRSA (CA-MRSA) genotypes. There was a significant impact on the resistance rates for cefoxitin, clindamycin and erythromycin among S. aureus isolates from BSI in COVID-19 patients and association with the previous use of azithromycin by them (p < 0.05). A clonal alternation and an increase in the emergence of CA-MRSA lineages were also found, highlighting the importance of constant microbiological surveillance.

Bioactivity and metabolic profiling of crude extracts from endophytic bacteria linked to Solanum mauritianum Scope: Discovery of Antibacterial and Anticancer Properties

Bacterial endophytes associated with Solanum mauritianum Scop. represent a promising source of novel bioactive compounds with potential antibacterial and anticancer properties. This study aimed to investigate the diversity, distribution, and bioactivity of crude extracts derived from endophytic bacteria, focusing on their effects against bacterial pathogens of public health relevance and two cancer cell lines. Fresh, healthy plant samples were collected, and endophytes were isolated using standard cultural techniques. Identification of the endophytes was carried out through conventional and molecular methods. The comprehensive profiling and characterization of crude secondary metabolites were conducted using Liquid Chromatography-Quadrupole Time-of-Flight Mass Spectrometry (LC-QTOF-MS/MS) and Gas Chromatography-High Resolution Time-of-Flight Mass Spectrometry (GC-HRTOF-MS). The antibacterial activity and minimum inhibitory concentration were evaluated for the secondary metabolites using the Resazurin Microtitre assay. The anticancer activity of the metabolites was evaluated against A549 Lung carcinoma cells and U87MG Glioblastoma cells (ATCC culture cell lines). The result revealed a diversity of bacterial endophytes, including Pantoea species, Luteibacter sp. Bacillus safensis, Arthrobacter sp., and Bacillus licheniformis. These endophytes displayed distinct-tissue-specific distribution patterns within S. mauritianum. Metabolic profiling of three endophytes (P. ananatis, B. licheniformis, and Arthrobacter sp.) revealed 14 common and numerous unique metabolites. The crude secondary metabolites exhibited broad-spectrum antibacterial activity against reference strains of Bacillus cereus, Pseudomonas aeruginosa, and Staphylococcus epidermidis, where MICs as low as 0.125mg/ml were recorded across several secondary metabolites of Pantoea ananatis, Bacillus licheniformis, and Arthrobacter sp. The cytotoxicity assays on UMG87 glioblastoma and A549 lung carcinoma cells revealed that the secondary metabolites did not induce cell death but instead promoted cell proliferation with different viability rates. While this proliferative effect limits their direct application as anticancer agents, it raises intriguing possibilities for their role in tissue regeneration or repair. This study provides critical insights into the microbial diversity of S. mauritianum and underscores the potential of its endophytic bacteria as sources of bioactive compounds with diverse biotechnological applications.

Affinity-based covalent sialyltransferase probes enabled by ligand-directed chemistry.

Sialyltransferases (ST) are key enzymes found in, among others, mammals and bacteria that are responsible for producing sialylated glycans, which play critical roles in human health and disease. However, chemical tools to study sialyltransferases have been limited to non-covalent inhibitors and probes that do not allow isolation and profiling of these important enzymes. Here we report a new class of covalent affinity-based probes (AfBP) for ST by using ligand-directed chemistry (LDchem). Our affinity-based probes are armed with a simple to synthesise but robust O-nitrobenzoxadiazole (O-NBD) warhead, which is a lysine-specific SNAr electrophilic warhead with an advantageous turn-on fluorescence property. We chemoenzymatically synthesised a series of CMP-Neu5Ac based probes and demonstrated their high specificity in labelling a range of recombinant STs with submicromolar sensitivity. Importantly, with our LDchem ST probe, we successfully labelled the endogenous lipooligosaccharide ST (Lst) in live Neisseria gonorrhoeae, a clinically relevant human pathogen. Our results demonstrated that this new class of covalent ST probes offer a robust platform for ST profiling and future studies of STs in their native environments.

Distribution and influencing factors of antibiotic resistance genes in two mussel species along the coasts of the East China Sea and the Yellow Sea.

Antibiotic resistance genes (ARGs) raise a global public health concern. The ARGs profile in marine aquaculture environments was well reported, yet it is poorly revealed in marine bivalves. This study investigated the microbiota, resistome, and environmental factors within the digestive glands of two mussel species (Mytilus coruscus and Mytilus galloprovincialis) cultivated in the East China Sea and Yellow Sea. The microbial communities in the digestive glands of mussels exhibit significant variations across different sampling sites and between the two seas. The three bacterial phyla that predominated in all samples were Firmicutes, Bacteroidota, and Proteobacteria. A total of 88 ARGs were detected, with aminoglycoside resistance genes and multidrug resistance genes being the dominant categories. Analysis revealed that the quinolone resistance gene qnrB, associated with clinically relevant human pathogens, was ubiquitous in all samples. Members of the Enterobacteriaceae family may serve as a reservoir for qnrB within the investigated environment. The distribution of ARGs shows potential associations with the composition of microbial communities in the digestive glands, environmental factors, and mobile genetic elements (MGEs). These findings enhance the elucidation of microbial ecology and antibiotic resistance in marine aquaculture.

Identification of beta-lactamase genes and molecular genotyping of multidrug-resistant clinical isolates of Klebsiella pneumoniae

BackgroundKlebsiella pneumoniae is a clinically relevant pathogen that has raised considerable public health concerns. This study aims to determine the presence of beta-lactamase genes and perform molecular genotyping of multidrug-resistant (MDR) K. pneumoniae clinical isolates.MethodsClinical isolates of MDR K. pneumoniae were collected from educational hospitals affiliated with Babol University of Medical Sciences. The isolates of K. pneumoniae were identified through standard microbial and biochemical tests. Antibiotic resistance was assessed using disk diffusion, modified Hodge test (MHT), combined disk, and polymerase chain reaction (PCR) methods. Enterobacterial Repetitive Intergenic Consensus (ERIC)-PCR was performed for molecular typing.ResultsA total of 42 MDR K. pneumoniae isolates were obtained from various clinical specimens. The highest antibiotic resistance was observed for ampicillin (100%), while the lowest resistance was noted for amikacin (19.04%). The MHT indicated that 38.09% of K. pneumoniae isolates produced carbapenemase enzymes. Metallo-beta-lactamase (MBL) production was found in 54.76% of isolates. Molecular detection of beta-lactamase genes revealed the presence of blaNDM (21.42%), blaKPC (42.85%), blaTEM (76.19%), blaSHV (47.16%), and blaCTX−M (80.95%) genes. ERIC-PCR molecular typing identified seven distinct genetic patterns among the isolates.ConclusionsThis investigation demonstrates the high resistance levels of K. pneumoniae strains. The beta-lactamase genes with the highest and lowest frequencies correspond to blaCTX−M and blaNDM genes, respectively. ERIC-PCR dendrograms suggest a common origin for K. pneumoniae clinical isolates and the propagation of similar clones within hospital wards. These findings indicate that K. pneumoniae isolates are highly virulent, necessitating the development of more effective resistance-fighting techniques and gene transfer research.Clinical trial numberNot applicable.

Chemical and Biotechnological Processes Employed as Emerging Technologies for the Production and Stability of Bacteriocins

Bacteriocins are antimicrobial peptides produced by bacteria with promising potential for controlling pathogens in various fields. This study highlights recent advances in the research on bacteriocins, providing a comprehensive overview of emerging technologies applied to the production and stability of these compounds, as the use of alternative substrates and encapsulation techniques. In recent decades, significant efforts have focused on discovering novel molecules with broad-spectrum activity capable of combating both Gram-positive and Gram-negative microorganisms, including clinically and industrially relevant pathogens. Recent studies explore strategies to optimize bacteriocin production, such as modifications in cultivation parameters aimed at reducing costs and increasing yield. Additionally, microencapsulation techniques have been widely discussed, emphasizing their role in enhancing the stability and efficacy of bacteriocins under adverse conditions. Finally, this article examines the potential applications of bacteriocins, highlighting their use as natural food preservatives, therapeutic alternatives for infection control, and bioactive agents in sustainable agriculture. These advancements establish bacteriocins as versatile agents with significant technological and economic impacts.