Biofilm Formation Assay Research Articles

In Silico Analysis and Validation of ymcA Gene of Bacillus Subtilis

This study aimed to analyze and validate the ymcA gene of Bacillus subtilis in silico. The bacterial strains used were B. subtilis 2049 (T) and B. subtilis HS, obtained from the National Center for Microbial Resource, Pune. The media used were LB medium and Mineral Salt Medium (MSM). The biofilm formation assay was performed in a microtiter plate, with each well inoculated with 980 µl of MSM and 20 µl of test cultures. The plate was incubated for 120 hrs at 37°C following phosphate buffer assay. The contents of the plate were removed by gently tapping at the bottom of the plate, rinsed with phosphate buffer saline, and de-stained using 70% ethanol for 15 min. The genomic DNA of B. subtilis 2049 (T) was extracted using the Chloroform: Isoamylalcohol method. The supernatant was taken in a sterile tube and stored at -80°C until further use.

Three-Dimensional Melted Electrowriting Drug Coating Fibers for the Prevention of Device-Associated Infections: A Pilot Study.

Medical device-related infections (DRIs), especially prevalent among critically ill patients, impose significant health and economic burdens and are mainly caused by bacteria. Severe infections often necessitate device removal when antibiotic therapy is inefficient, delaying recovery. To tackle this issue, PCL drug-eluting coated meshes were explored, and they were printed via melt electrowriting (MEW). These meshes were coated with gentamicin sulfate (GS) and tetracycline hydrochloride (TCH) and underwent FTIR analysis to confirm drug integration. Antimicrobial activity was assessed via agar diffusion assays and biofilm formation assays against bacterial strains: Pseudomonas aeruginosa ATCC 27853, Escherichia coli ATCC 25922, Staphylococcus aureus ATCC 43300, and Staphylococcus epidermidis ATCC 35984. FTIR analysis evidenced the presence of the drugs in the meshes. TCH displayed broad-spectrum antimicrobial activity against all strains, whereas GS was effective against all except S. aureus. These findings indicate the potential of cost-effective ultra-fine drug coating fibers for medical device applications, offering infection prevention during implantation. This preliminary study demonstrates the feasibility of producing drug-eluting fibers for DRI prevention through a non-toxic, fast, and cost-efficient technique, paving the way for enhanced patient care and reduced healthcare costs.

Genetic Complexity of CC5 Staphylococcus aureus Isolates Associated with Sternal Bursitis in Chickens: Antimicrobial Resistance, Virulence, Plasmids, and Biofilm Formation.

Sternal bursitis, a common inflammatory condition in poultry, poses significant challenges to both animal welfare and public health. This study aimed to investigate the prevalence, antimicrobial resistance, and genetic characteristics of Staphylococcus aureus isolates associated with sternal bursitis in chickens. Ninety-eight samples were collected from affected chickens, and 24 S. aureus isolates were identified. Antimicrobial susceptibility testing revealed resistance to multiple agents, with a notable prevalence of aminoglycoside resistance genes. Whole genome sequencing elucidated the genetic diversity and virulence profiles of the isolates, highlighting the predominance of clonal complex 5 (CC5) strains. Additionally, biofilm formation assays demonstrated moderate biofilm production capacity among the isolates. These findings underscore the importance of vigilant monitoring and targeted interventions to mitigate the impact of sternal bursitis in poultry production systems.

Molecular Characteristics of Salmonella Spp. Responsible for Bloodstream Infections in a Tertiary Hospital in Nanjing, China, 2019-2021.

To investigate the clinical and molecular characteristics of Salmonella spp. causing bloodstream infections (BSIs) in our hospital. We studied 22 clinical Salmonella isolates from BSIs and 16 from non-BSIs, performing antimicrobial susceptibility testing (AST) and whole genome sequencing (WGS). The analysis included serovars, antibiotic resistance genes (ARGs), virulence factors (VFs), sequence types (STs), plasmid replicons, and genetic relationships. We also assessed pathogenicity of the isolates causing BSIs through growth, biofilm formation, and anti-serum killing assays. WGS analysis identified 13 Salmonella serovars, with four responsible for BSIs. S. Enteritidis was the most prevalent serovar, involved in 19 (50.0%) cases. BSIs were caused by 17S. Enteritidis, two S. Typhimurium, two S. Munster and one S. Diguel. Of the 38 isolates, 27 (71.1%) exhibited high resistance to ampicillin, and 24 (63.2%) to ampicillin/sulbactam. Thirty-six types of ARGs were identified, with blaTEM-1B (n = 25, 65.8%) being the most frequent. Ten plasmid replicons were found; the combination of IncFIB(S)-IncFII(S)-IncX1 was the most common in S. Enteritidis (94.7%). Fifteen STs were identified, among which ST11 was the most prevalent and clonally disseminated, primarily responsible for BSIs. A total of 333 different VFs were detected, 177 of which were common across all strains. No significant differences were observed between the BSI and non-BSI isolates in terms of resistance rates, ARGs, plasmid replicons, and VFs, except for seven VFs. No strong pathogenicity was observed in the BSI-causing isolates. BSIs were predominantly caused by clonally disseminated S. Enteritidis ST11, the majority of which carried multiple ARGs, VFs and plasmid replicons. This study provides the first data on clonally disseminated S. Enteritidis ST11 causing BSIs, highlighting the urgent need for enhanced infection control measures.

Study of Biofilm, Virulence Genes, and Risk Factors in Urinary Catheter-Associated Escherichia coli Infections

Background: Catheter-associated urinary tract infections (CAUTIs) are prevalent among intensive care unit (ICU) patients and pose significant health risks. The causative agent, Escherichia coli, is commonly associated with these infections. Objectives: The primary objective of our study was to evaluate various risk factors associated with CAUTIs. Additionally, we investigated the capacity of E. coli to form biofilms and the presence of virulence genes in these infections. Methods: We conducted a prospective study involving 204 patients admitted to ICUs with indwelling urinary catheters who subsequently developed CAUTIs. The isolated pathogen in all cases was E. coli. We subjected the isolated E. coli strains to microbiological analyses, including biofilm formation assays and polymerase chain reaction (PCR) for detecting virulence genes (pap-C, fim-H, sfa, afa, hylA, and cnf1). Results: Our findings revealed that 111 out of 204 isolated E. coli strains (54.4%) could form biofilms in vitro. Among the detected virulence genes, fim-H was the most frequently observed (32.4%), followed by pap-C (14.2%), sfa (12.3%), and afa1 (11.3%). The least frequently detected genes were cnf1 (3.9%) and hylA (2.5%). Notably, there was a significant association between the presence of fim-H, pap-C, afa1, and hylA genes and the ability of E. coli to form biofilms (P = 0.001, P = 0.001, P = 0.04, P = 0.046, respectively). Regarding the timing of CAUTIs, most cases occurred 7 - 10 days after catheter insertion (48.53%), followed by 3 - 6 days after insertion (45.59%). The least frequent occurrence was after 10 days from catheter insertion (5.86%). Early presence of CAUTIs (within 3 - 6 days) was significantly associated with diabetes mellitus (DM) and post-operative complications (both with P = 0.046). Furthermore, we observed a significant increase in the presence of the cnf1 gene in cases of early CAUTIs (3 - 6 days after catheter insertion, P = 0.001). Conclusions: Our study highlights the importance of understanding the risk factors, virulence genes, and biofilm formation capacity in E. coli-related CAUTIs. These findings may guide preventive strategies and improve patient outcomes.

Biosynthesized silver nanoparticles prevent bacterial infection in chicken egg model and mitigate biofilm formation on medical catheters.

Investigating the application of innovative antimicrobial surface coatings on medical devices is an important field of research. Many of these coatings have significant drawbacks, including biocompatibility, coating stability and the inability to effectively combat multiple drug-resistant bacteria. In this research, we developed an antibiofilm surface coating for medical catheters using biosynthesized silver nanoparticles (b-Cs-AgNPs) developed using leaves extract of Calliandra surinamensis. Various characterization techniques were employed to thoroughly characterize the synthesized b-Cs-AgNPs and c-AgNPs. b-Cs-AgNPs were compatible with human normal kidney cells and chicken embryos. It did not trigger any skin inflammatory response in in vivo rat model. b-Cs-AgNPs demonstrated potent zone of inhibition of 19.09mm when subjected to the disc diffusion method in E. coli confirming strong antibacterial property. Different anti-bacterial assays including liquid growth curve, colony counting assay, biofilm formation assay supported the potent antimicrobial efficacy of b-Cs-AgNPs alone and when coated to medical grade catheters. Mechanistic studies reveal the presence of ferulic acid, that was important for the synthesis of b-AgNPs along with enhanced antibacterial effects of b-Cs-AgNPs compared to c-AgNPs, supported by molecular docking analysis. These results together demonstrated the effective role b-Cs-AgNPs in combating infections and mitigating biofilm formations, highlighting their need for further study in the field of biomedical applications.

Inhibition of Candida albicans Biofilm Formation and Attenuation of Its Virulence by Liriope muscari.

(1) Background: Although Candida albicans accounts for the majority of fungal infections, therapeutic options are limited and require alternative antifungal agents with new targets; (2) Methods: A biofilm formation assay with RPMI1640 medium was performed with Liriope muscari extract. A combination antifungal assay, dimorphic transition assay, and adhesion assay were performed under the biofilm formation condition to determine the anti-biofilm formation effect. qRT-PCR analysis was accomplished to confirm changes in gene expression; (3) Results: L. muscari extract significantly reduces biofilm formation by 51.65% at 1.56 μg/mL use and therefore increases susceptibility to miconazole. L. muscari extract also inhibited the dimorphic transition of Candida; nearly 50% of the transition was inhibited when 1.56 μg/mL of the extract was treated. The extract of L. muscari inhibited the expression of genes related to hyphal development and extracellular matrix of 34.4% and 36.0%, respectively, as well as genes within the Ras1-cAMP-PKA, Cph2-Tec1, and MAP kinase signaling pathways of 25.58%, 7.1% and 15.8%, respectively, at 1.56 μg/mL of L. muscari extract treatment; (4) Conclusions: L. muscari extract significantly reduced Candida biofilm formation, which lead to induced antifungal susceptibility to miconazole. It suggests that L. muscari extract is a promising anti-biofilm candidate of Candida albicans since the biofilm formation of Candida albicans is an excellent target for candidiasis regulation.

Exploring the virulence potential of Staphylococcus aureus CC121 and CC152 lineages related to paediatric community-acquired bacteraemia in Manhiça, Mozambique

Staphylococcus aureus is a frequent agent of bacteraemia. This bacterium has a variety of virulence traits that allow the establishment and maintenance of infection. This study explored the virulence profile of S. aureus strains causing paediatric bacteraemia (SAB) in Manhiça district, Mozambique. We analysed 336 S. aureus strains isolated from blood cultures of children younger than 5 years admitted to the Manhiça District Hospital between 2001 and 2019, previously characterized for antibiotic susceptibility and clonality. The strains virulence potential was evaluated by PCR detection of the Panton-Valentine leucocidin (PVL) encoding genes, lukS-PV/lukF-PV, assessment of the capacity for biofilm formation and pathogenicity assays in Galleria mellonella. The overall carriage of PVL-encoding genes was over 40%, although reaching ~ 70 to 100% in the last years (2014 to 2019), potentially linked to the emergence of CC152 lineage. Strong biofilm production was a frequent trait of CC152 strains. Representative CC152 and CC121 strains showed higher virulence potential in the G. mellonella model when compared to reference strains, with variations within and between CCs. Our results highlight the importance of monitoring the emergent CC152-MSSA-PVL+ and other lineages, as they display important virulence traits that may negatively impact the management of SAB paediatric patients in Manhiça district, Mozambique.

Antimicrobial Resistance and Biofilm Formation of Bordetella bronchiseptica in Central China, with Evidence of a Rare Heteroresistance Strain to Gentamicin.

Bordetella bronchiseptica is a significant contributor to respiratory disease in pigs, leading to substantial economic losses in the swine industry worldwide. We isolated 52 B. bronchiseptica strains from 542 samples collected from pigs with atrophic rhinitis and bronchopneumonia in central China. Multi-locus sequence typing identified two prevalent sequence types: ST6 (69.23%) and ST7 (30.77%). PCR-based detection of seven virulence genes (fhaB, prn, cyaA, dnt, bteA, fla, and bfrZ) revealed that six of these genes were present in over 90% of the isolates, with bfrZ being the exception at 59.62%. Antimicrobial susceptibility testing, performed using the K-B method, demonstrated high sensitivity to enrofloxacin, polymyxin, and doxycycline but a notable resistance to tylosin, trimethoprim, tobramycin, ciprofloxacin, and amikacin. Remarkably, 86.54% of the isolates exhibited a multidrug-resistant phenotype. Notably, we successfully screened a strain of B. bronchiseptica with a heteroresistance phenotype to gentamicin using population analysis profiling, which is a rare case. Biofilm-formation assays indicated that 96.15% of the isolates possessed biofilm-forming capabilities. These findings provide crucial insights into the prevalence of B. bronchiseptica in central China, facilitating the development of effective preventive measures to safeguard both animal and human health.

A challenging case of carbapenem resistant Klebsiella pneumoniae-related pyogenic liver abscess with capsular polysaccharide hyperproduction: a case report

BackgroundCarbapenem-resistant Klebsiella pneumoniae (CRKP) infections are a major public health problem, necessitating the administration of polymyxin E (colistin) as a last-line antibiotic. Meanwhile, the mortality rate associated with colistin-resistant K. pneumoniae infections is seriously increasing. On the other hand, importance of administration of carbapenems in promoting colistin resistance in K. pneumoniae is unknown.Case presentationWe report a case of K. pneumoniae-related pyogenic liver abscess in which susceptible K. pneumoniae transformed into carbapenem- and colistin-resistant K. pneumoniae during treatment with imipenem. The case of pyogenic liver abscess was a 50-year-old man with diabetes and liver transplant who was admitted to Abu Ali Sina Hospital in Shiraz. The K. pneumoniae isolate responsible for community-acquired pyogenic liver abscess was isolated and identified. The K. pneumoniae isolate was sensitive to all tested antibiotics except ampicillin in the antimicrobial susceptibility test and was identified as a non-K1/K2 classical K. pneumoniae (cKp) strain. Multilocus sequence typing (MLST) identified the isolate as sequence type 54 (ST54). Based on the patient’s request, he was discharged to continue treatment at another center. After two months, he was readmitted due to fever and progressive constitutional symptoms. During treatment with imipenem, the strain acquired blaOXA−48 and showed resistance to carbapenems and was identified as a multidrug resistant (MDR) strain. The minimum inhibitory concentration (MIC) test for colistin was performed by broth microdilution method and the strain was sensitive to colistin (MIC < 2 µg/mL). Meanwhile, on blood agar, the colonies had a sticky consistency and adhered to the culture medium (sticky mucoviscous colonies). Quantitative real-time PCR and biofilm formation assay revealed that the CRKP strain increased capsule wzi gene expression and produced slime in response to imipenem. Finally, K. pneumoniae-related pyogenic liver abscess with resistance to a wide range of antibiotics, including the last-line antibiotics colistin and tigecycline, led to sepsis and death.ConclusionsBased on this information, can we have a theoretical hypothesis that imipenem is a promoter of resistance to carbapenems and colistin in K. pneumoniae? This needs more attention.

Exploration of agr types, virulence-associated genes, and biofilm formation ability in Staphylococcus aureus isolates from hemodialysis patients with vascular access infections.

Staphylococcus aureus, is a pathogen commonly encountered in both community and hospital settings. Patients receiving hemodialysis treatment face an elevated risk of vascular access infections (VAIs) particularly Staphylococcus aureus, infection. This heightened risk is attributed to the characteristics of Staphylococcus aureus, , enabling it to adhere to suitable surfaces and form biofilms, thereby rendering it resistant to external interventions and complicating treatment efforts. Therefore this study utilized PCR and microtiter dish biofilm formation assay to determine the difference in the virulence genes and biofilm formation among in our study collected of 103 Staphylococcus aureus, isolates from hemodialysis patients utilizing arteriovenous grafts (AVGs), tunneled cuffed catheters (TCCs), and arteriovenous fistulas (AVFs) during November 2013 to December 2021. Our findings revealed that both MRSA and MSSA isolates exhibited strong biofilm production capabilities. Additionally, we confirmed the presence of agr types and virulence genes through PCR analysis. The majority of the collected isolates were identified as agr type I. However, agr type II isolates displayed a higher average number of virulence genes, with MRSA isolates exhibiting a variety of virulence genes. Notably, combinations of biofilm-associated genes, such as eno-clfA-clfB-fib-icaA-icaD and eno-clfA-clfB-fib-fnbB-icaA-icaD, were prevalent among Staphylococcus aureus, isolates obtained from vascular access infections. These insights contribute to a better understanding of the molecular characteristics associated with Staphylococcus aureus, infections in hemodialysis patients and provided more targeted and effective treatment approaches.

The Functional Study of Response Regulator ArlR Mutants in Staphylococcus Aureus.

Staphylococcus aureus is a major cause of hospital-associated infections worldwide. The organism's ability to form biofilms has led to resistance against current treatment options such as beta-lactams, glycopeptides, and daptomycin. The ArlRS two-component system is a crucial regulatory system necessary for S. aureus autolysis, biofilm formation, capsule synthesis, and virulence. This study aims to investigate the role of the arlR deletion mutant in the detection and activation of S. aureus. We created an arlR deleted mutant and complementary strains and characterized their impact on the strains using partial growth measurement. The quantitative real-time PCR was performed to determine the expression of icaA, and the microscopic images of adherent cells were captured at the optical density of 600 to determine the primary bacterial adhesion. The biofilm formation assay was utilized to investigate the number of adherent cells using crystal violet staining. Eventually, the Triton X-100 autolysis assay was used to determine the influence of arlR on the cell autolytic activities. Our findings indicate that the deletion of arlR reduced the transcriptional expression of icaA but not icaR in the ica operon, leading to decrease in polysaccharide intercellular adhesin (PIA) synthesis. Compared to the wild-type and the complementary mutants, the arlR mutant exhibited decreased in biofilm production but increased autolysis. It concluded that the S. aureus response regulatory ArlR influences biofilm formation, agglutination, and autolysis. This work has significantly expanded our knowledge of the ArlRS two-component regulatory system and could aid in the development of novel antimicrobial strategies against S. aureus.

German coasts harbor non-O1/non-O139 Vibrio cholerae with clinical virulence gene profiles

Non-O1/non-O139 Vibrio cholerae (NOVC) are ubiquitous in aquatic ecosystems. In rare cases, they can cause intestinal and extra-intestinal infections in human. This ability is associated with various virulence factors. The presence of NOVC in German North Sea and Baltic Sea was observed in previous studies. However, data on virulence characteristics are still scarce. Therefore, this work aimed to investigating the virulence potential of NOVC isolated in these two regions. In total, 31 NOVC strains were collected and subjected to whole genome sequencing. In silico analysis of the pathogenic potential was performed based on the detection of genes involved in colonization and virulence. Phenotypic assays, including biofilm formation, mobility and human serum resistance assays were applied for validation. Associated toxin genes (hlyA, rtxA, chxA and stn), pathogenicity islands (Vibrio pathogenicity island 2 (VPI-II) and Vibrio seventh pathogenicity island 2 (VSP-II)) and secretion systems (Type II, III and VI secretion system) were observed. A maximum likelihood analysis from shared core genes revealed a close relationship between clinical NOVCs published in NCBI and environmental strains from this study. NOVC strains are more mobile at 37 °C than at 25 °C, and 68% of the NOVC strains could form strong biofilms at both temperatures. All tested strains were able to lyse erythrocytes from both human and sheep blood. Additionally, one strain could survive up to 60% and seven strains up to 40% human serum at 37 °C. Overall, the genetic virulence profile as well as the phenotypic virulence characteristics of the investigated NOVC from the German North Sea and Baltic Sea suggest potential human pathogenicity.

Isoegomaketone exhibits potential as a new Mycobacterium abscessus inhibitor.

Although the incidence of Mycobacterium abscessus infection has recently increased significantly, treatment is difficult because this bacterium is resistant to most anti-tuberculosis drugs. In particular, M. abscessus is often resistant to available macrolide antibiotics, so therapeutic options are extremely limited. Hence, there is a pressing demand to create effective drugs or therapeutic regimens for M. abscessus infections. The aim of the investigation was to assess the capability of isoegomaketone (iEMK) as a therapeutic option for treating M. abscessus infections. We determined the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of iEMK for both reference and clinically isolated M. abscessus strains. In addition to time-kill and biofilm formation assays, we evaluated iEMK's capability to inhibit M. abscessus growth in macrophages using an intracellular colony counting assay. iEMK inhibited the growth of reference and clinically isolated M. abscessus strains in macrophages and demonstrated effectiveness at lower concentrations against macrophage-infected M. abscessus than when used to treat the bacteria directly. Importantly, iEMK also exhibited anti-biofilm properties and the potential to mitigate macrolide-inducible resistance, underscoring its promise as a standalone or adjunctive therapeutic agent. Overall, our results suggest that further development of iEMK as a clinical drug candidate is promising for inhibiting M. abscessus growth, especially considering its dual action against both planktonic bacteria and biofilms.

Microbiological safety and antimicrobial resistance profiles of ready-to-eat seafood in Bayelsa, Nigeria

Abstract The global significance of processed seafood necessitates vigilant monitoring for health risks, particularly in the ready-to-eat (RTE) sector. This study assessed the microbiological safety and antimicrobial resistance (AMR) profiles of 520 RTE seafood samples collected from Bayelsa, Nigeria. Escherichia coli identification was conducted using culture-based and polymerase chain reaction (PCR) methods. The isolates were further characterized using standard bacteriological techniques. PCR screening was employed to detect virulence and resistance genes. Of the processed RTE seafood samples assessed, 12.1% tested positive for E. coli. Extended-spectrum beta-lactamase (ESBL)-producing E. coli accounted for 2.3% of the samples. Various diarrheagenic determinants were identified, with aggregative adherence regulator-activated island (aaiC) and attaching and effacing (eae) being the most prevalent. Higher AMR levels were observed in ESBL-producing strains. Additionally, extracellular virulence factors, biofilm formation, and hydrophobicity assays revealed diverse pathogenic potentials among the isolates. The detection of beta-lactamase AMR genes, such as blaTEM (15.9%), blaCTX−M−15 (3.2%), and blaCTX−M−1 (1.6%), underscores the genetic mechanisms responsible for resistance in E. coli strains recovered from RTE seafood. These findings underscore the need for thorough monitoring and strict control procedures to ensure the safety of RTE seafood and mitigate the risks associated with AMR in food consumption.

Aromatherapeutic Antibacterials: Comparative Study of 40 Essential Oils and Their Biofilm Inhibition in Pseudomonas aeruginosa ATCC9027

Growing evidence suggests that biofilm formation in Pseudomonas aeruginosa (PA) results from quorum sensing, reducing bacterial sensitivity to antibiotics and fostering the development of antibiotic-resistant strains. Addressing the need for a compound that can inhibit quorum sensing signals to mitigate biofilm formation in PA, this study screened 40 essential oils for their potential as quorum sensing inhibitors against PA ATCC9027. Utilizing the agar well diffusion assay, the antibacterial activity of these essential oils was compared with levofloxacin, revealing that 25 out of 40 essential oils exhibited antibacterial activity against PA ATCC9027. The highest antibacterial activity was exhibited by essential oils from Cinnamomum burmannii (Cinnamon Bark Oil), Cananga odorata (Ylang-ylang Oil), and Eucalyptus globulus (Eucalyptus Oil), confirmed by respective MIC values of 0.09765% (v/v), 0.390625% (v/v), and 1.5625% (v/v), and MBC values of 0.09765% (v/v), &gt; 1.5625% (v/v), and &gt; 1.5625% (v/v). Growth curve inhibition assay followed by crystal violet biofilm formation assay revealed that only Ylang-ylang Oil exhibited biofilm formation inhibition at 1/4 MIC concentration. Docking analysis of compounds from these essential oils against quorum sensing enzymes (LasR, PqsR, and QscR) revealed that Ylang-ylang Oil compounds exhibited the highest binding affinity. In conclusion, among the 40 essential oils tested, 25 show potential as antibacterials against PA ATCC9027, with Ylang-ylang Oil standing out as a promising candidate for quorum sensing inhibitor development. The use and development of quorum sensing inhibitors from Ylang-ylang Oil compounds are expected to reduce the burden of antibiotic resistance, especially in Pseudomonas aeruginosa.

Stenotrophomonas maltophilia complex: insights into evolutionary relationships, global distribution and pathogenicity.

Stenotrophomonas maltophilia complex (Smc) comprises opportunistic Gram-negative bacilli responsible for various nosocomial infections. Limited data exists concerning its evolutionary lineage, global prevalence and pathogenicity. We conducted an extensive genomic analysis on 734 Smc genomes, of which 90 were newly sequenced and isolated from different patients. The species composition and evolutionary relationships of Smc were examined using core protein sequence analysis. Pathogenicity evaluation was used by assays for swimming motility, biofilm formation and identification of virulence factors. The broth microdilution method was used to evaluate the drug resistance spectrum of clinical isolates. Phylogenetic analyses delineated 24 species-level clades, dominated by S. maltophilia (42.8%), S. sepilia (13.6%) and S. geniculata (9.9%). Geographically, strains were primarily distributed in Europe (34.2%), Asia (33.7%) and North America (24.0%), with intricate global distribution patterns. Meanwhile, 154 virulence-associated genes and 46 antimicrobial resistance genes within Smc were identified. These genes encoded span various functions, including motility, adherence, toxin, RND antibiotic efflux pumps, beta-lactamases and aminoglycoside-modifying enzymes. Moreover, significant variations were indicated in swimming motility and biofilm-forming capability across the different species, with S. sepilia exhibiting superior levels of both traits. Additionally, no statistically significant discrepancy was detected among Smc species to other antibiotics, despite the fact that all S. geniculata isolates were resistant to Ceftazidime and much higher than other species. Our findings indicate the need to pay increased attention to other mainstream species of Smc besides S. maltophilia in order to better manage Smc-related infections and tailor effective treatment strategies.

Chemical composition, antimicrobial and antiproliferative activity of the essential oil from Ambrosia artemisiifolia L

ABSTRACT The aim of our study was to characterize the composition and certain bioactivities of the essential oil of Ambrosia artemisiifolia. Eighty organic compounds were identified in the essential oils obtained by hydrodistillation and microwave-assisted isolation. Germacrene D was the main component in both oils. The essential oil obtained by hydrodistillation exerted antibacterial activity against two S. aureus strains, with MIC values of 0.015% for the methicillin-susceptible strain and 0.25% for the methicillin-resistant strain. In the biofilm formation assay, a dose-dependent inhibition was observed in case of the K. pneumoniae ATCC 600,703. In the ethidium bromide accumulation assay, a dose-dependent inhibition activity was observed against the bacterial efflux pump of the Gram-negative bacteria E. coli ATCC 25,922. The essential oil displayed strong in vitro cytotoxicity against the multidrug-resistant (MDR) Colo 320 cancer cell line with an IC50 value of 0.0103%. The essential oil showed strong inhibition on the proliferation of the doxorubicin-sensitive Colo 205 cells (IC50 values of 0.054%) and in the case of MDR Colo 320 colonic adenocarcinoma cells (IC50 values of 0.008%). This is the first report of the cytotoxic and antiproliferative activities of the essential oil from these species.

Fecal Shedding, Antimicrobial Resistance and In Vitro Biofilm formation on Simulated Gallstones by Salmonella Typhi Isolated from Typhoid Cases and Asymptomatic Carriers in Nairobi, Kenya.

Typhoid fever, caused by the human restricted pathogen Salmonella Typhi, remains a major global public health concern. Even after successful treatment, approximately 3-5% of patients with typhoid fail to clear the bacteria within one year and become chronic carriers. Most typhoid carriers have gallstones in their gallbladder, and biofilm formation on gallstones is highly correlated with chronic carriage. This study's goal was to identify asymptomatic typhoid carriers in an endemic setting in Kenya, and to compare acute versus chronic isolates. A cohort of typhoid fever patients identified through blood and/or stool culture, and their household contacts, were followed up after treatment to detect longitudinal S. Typhi stool shedding. An abdominal ultrasound scan was used to identify individuals with gallstones. A total of 32 index patients and 32 household contacts were successfully followed-up. Gallstones were detected in 4 cases and 1 household contact. The duration of S. Typhi shedding was significantly longer in individuals with gallstones compared to those without, P<0.001. Eighty-three (83) S. Typhi strains were tested for susceptibility to commonly used antimicrobials and examined by in vitro biofilm formation assays. Out of 37 infected individuals, 32.4% had infections caused by multidrug resistant (MDR) S. Typhi strains and only 18.9% were infected by susceptible strains. Non-MDR strains formed significantly better biofilms in vitro than the MDR strains (P<0.001). This study provides data on S. Typhi chronic carriage that will influence public health approaches aimed at reducing typhoid transmission and the burden of infection.

Evaluation of Lakadong turmeric derived curcumin nanogel against resistant biofilms: In-silico, antibacterial and antibiofilm analysis

The emergence of drug resistance can lead to increased mortality and morbidity as treatment efficacy declines, and there is an urgent need to explore novel antibacterial compounds with enhanced effectiveness against drug-resistant bacteria, particularly resistant biofilms. Curcumin, with its antimicrobial activity, can be a potential safe agent; however, studies on its efficacy against resistant biofilm are limited. This study, therefore, aims to explore the potential of curcumin and/or its novel derivatives against a spectrum of resistant biofilm-related pathogens, including bacteria, fungi, and human pathogens. Another study objective is to investigate the effectiveness of the high-yielding Lakadong turmeric (LKD)-derived curcumin for its antibacterial effects and the ability to inhibit biofilm formation in Gram-positive and Gram-negative bacteria using in-vitro assays. A molecular docking study was used to select the most potential binding interaction between the selected protein structure and ligand molecule for the potential efficacy of curcumin against resistant biofilms. Lakadong-derived curcumin-loaded nano gels (LKD-Cur Nanogel) were prepared and tested for antibacterial (zone-inhibition) and biofilm formation (scanning confocal microscope) activity against Staphylococcus aureus and Pseudomonas aeruginosa. Furthermore, Curcumin derivatives were studied in-silico for potential effectiveness against a spectrum of resistant biofilms. The in-silico results showed that curcumin and/or its novel derivatives exhibited high selectivity toward a range of targeted proteins compared to curcumin. Moreover, LKD-Cur Nanogel exhibited significant anti-bacterial activity with an increased mean zone of inhibition compared to positive control. The biofilm formation assay illustrated that LKD-Cur Nanogel effectively disrupted established bacterial biofilms (both for P. aeruginosa and S. aureus) grown on microtiter plates at a concentration of 1,000 μg/ml compared to the control. Therefore, it can be concluded that curcumin and/or its newly modified derivatives could hold promising antibacterial activity targeting diverse biofilm-associated pathogens based on the in-silico and in-vitro study. Moreover, it can be concluded that LKD-derived curcumin nanogels have good antibacterial and antibiofilm efficacy.