Antibiotic-resistant Strains Research Articles

Eradication of Biofilms on Catheters: Potentials of Tamarix ericoides Rottl. Bark Coating in Preventing Catheter-Associated Urinary Tract Infections (CAUTIs)

Catheter-associated urinary tract infections (CAUTIs) cause serious complications among hospitalized patients due to biofilm-forming microorganisms which make treatment ineffective by forming antibiotic-resistant strains. As most CAUTI-causing bacterial pathogens have already developed multidrug resistance, there is an urgent need for alternative antibacterial agents to prevent biofilms on catheter surfaces. As a trial to find out such a potential agent of natural origin, the bark of Tamarix ericoides Rottl., a little-known plant from the Tamaricaceae family, was examined for its antibacterial and antibiofilm activities against one of the major, virulent, CAUTI-causing bacterial pathogens: Enterococcus faecalis. The methanolic T. ericoides bark extract was analyzed for its antibacterial activity using the well diffusion method and microdilution method. Killing kinetics were calculated using time–kill assay, and the ability of biofilm formation and its eradication upon treatment with the T. ericoides bark extract was studied by crystal violet assay. GC-MS analysis was performed to understand the phytochemical presence in the extract. A in vitro bladder model study was performed using extract-coated catheters against E. faecalis, and the effect was visualized using CLSM. The changes in the cell morphology of the bacterium after treatment with the T. ericoides bark extract were observed using SEM. The biocompatibility of the extract towards L929 cells was studied by MTT assay. The anti-E. faecalis activity of the extract-coated catheter tube was quantified by viable cell count method, which exposed 20% of growth after five days of contact with E. faecalis. The anti-adhesive property of the T. ericoides bark extract was studied using CLSM. The extract showed potential antibacterial activity, and the lowest inhibitory concentration needed to inhibit the growth of E. faecalis was found to be 2 mg/mL. The GC-MS analysis of the methanolic fractions of the T. ericoides bark extract revealed the presence of major phytochemicals, such as diethyl phthalate, pentadecanoic acid, methyl 6,11-octadecadienoate, cyclopropaneoctanoic acid, 2-[(2-pentylcyclopropyl) methyl]-, methyl ester, erythro-7,8-bromochlorodisparlure, etc., that could be responsible for the antibacterial activity against E. faecalis. The killing kinetics of the extract against E. faecalis was calculated and the extract showed promising antibiofilm activity on polystyrene surfaces. The T. ericoides bark extract effectively reduced the E. faecalis mature biofilms by 75%, 82%, and 83% after treatment with 1X MIC (2 mg/mL), 2X MIC (4 mg/mL), and 3X MIC (6 mg/mL) concentrations, respectively, which was further confirmed by SEM analysis. The anti-adhesive property of the T. ericoides bark extract studied using CLSM revealed a reduction in the biofilm thickness, and the FDA and PI combination revealed the death of 80% of the cells on the extract-coated catheter tube. In addition, SEM analysis showed extensive damage to the E. faecalis cells after the T. ericoides bark extract treatment, and it was not cytotoxic. Hence, after further studies, T. ericoides bark extract with potential antibacterial, antibiofilm, and anti-adhesive activities can be developed as an alternative agent for treating CAUTIs.

High-Pressure Processing Influences Antibiotic Resistance Gene Transfer in Listeria monocytogenes Isolated from Food and Processing Environments

The study aimed to assess the high-pressure processing (HPP) impact on antibiotic resistance gene transfer in L. monocytogenes from food and food processing environments, both in vitro (in microbiological medium) and in situ (in carrot juice), using the membrane filter method. Survival, recovery, and frequency of antibiotic resistance gene transfer analyses were performed by treating samples with HPP at different pressures (200 MPa and 400 MPa). The results showed that the higher pressure (400 MPa) had a significant effect on increasing the transfer frequency of genes such as fosX, encoding fosfomycin resistance, and tet_A1, tet_A3, tetC, responsible for tetracycline resistance, both in vitro and in situ. In contrast, the Lde gene (the gene encoding ciprofloxacin resistance) was not transferred under any conditions. In the food matrix (carrot juice), greater variability in results was observed, suggesting that food matrices may have a protective effect on bacteria and modify HPP efficacy. In general, an increase in MIC values for antibiotics was noted in transconjugants compared to donors. Genotypic analysis of transconjugants showed differences in genetic structure, especially after exposure to 400 MPa pressure, indicating genotypic changes induced by pressure stress. The study confirms the possibility of antibiotic resistance genes transfer in the food environment, even from strains showing initial susceptibility to antibiotics carrying so-called silent antibiotic resistance genes, highlighting the public health risk of the potential spread of antibiotic-resistant strains through the food chain. The findings suggest that high-pressure processing can increase and decrease the frequency of resistance gene transfer depending on the strain, antibiotic combination, and processing conditions.

Engineered FnCas9 mediated mutation profiling for clarithromycin resistance in Helicobacter pylori strains isolated from Indian patients with gastrointestinal disorders

Helicobacter pylori is a highly prevalent gut pathogen with reported implications in a wide range of gastrointestinal disorders. Antibiotic based therapy, especially with clarithromycin is one of most effective treatment strategies against H. pylori. However, rising global prevalence of clarithromycin resistance in certain H. pylori strains, primarily attributed to point mutations in the 23 s ribosomal RNA coding gene, pose a major challenge in the effective eradication of this pathogen. There are a number of established methodologies devised for H. pylori mutation detection, so as to provide a tailored treatment plan to the patients and resist further transmissions of antibiotic resistant strains. However, there is no ‘gold standard’ method available to detect mutation status in clinical isolates of H. pylori from infected patients. CRISPR-Cas9 based technologies have revolutionized the field of mutation detection in biological samples, particularly during the recent COVID-19 pandemic. Although multiple assays have been reported for detection of H. pylori in clinical samples including CRISPR diagnostics (CRISPRDx) platforms, there is no such assay reported till date to detect specific mutations that confer antibiotic resistance to this pathogen. In this study, we have developed an assay using engineered FnCas9 (en31-FnCas9) protein to effectively detect the A2142G and A2143G mutations in the 23 s rDNA of H. pylori strains isolated from gastric biopsy samples. The data from in vitro cleavage assays and strip-based lateral flow tests using en31-FnCas9 and guide RNAs targeting the conserved and mutated loci of H. pylori 23 s rDNA are in perfect congruence with the data from Sanger sequencing and restriction fragment length polymorphism (RFLP) analysis. Our results indicate that en31-FnCas9 based mutation analysis can be deployed as an efficient diagnostic methodology to detect clarithromycin susceptibility in patients with suspected H. pylori infections.

Isolation and Identification of Effective Probiotics on Staphylococcus epidermidis Strains Isolated from Urine Sample

Background: The increasing prevalence of antibiotic-resistant Staphylococcusepidermidis strains underscores the urgent need for alternative therapeutic approaches. Probiotics, known for their ability to competitively exclude pathogens and modulate host immune responses, present promising potential in combating S. epidermidis infections. Objectives: This study aimed to evaluate the effectiveness of probiotics in inhibiting the growth of S.epidermidis. Methods: Staphylococcus epidermidis was isolated from urine samples of hospitalized patients in Isfahan, Iran. Probiotics were isolated from yogurt and milk. The antibacterial activity of these probiotics was assessed using agar well diffusion and broth microdilution methods. Time-kill assays and acid tolerance tests were also conducted. Anti-biofilm effects were evaluated, and the potential inhibitory mechanisms were explored through chemical analysis using high-performance liquid chromatography (HPLC). Cytotoxicity was assessed via 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays. Results: Two probiotic strains, Streptococcus lutetiensis OR496927.1 and Lactiplantibacillus plantarum OR496928, were successfully isolated from dairy products. Both strains exhibited cytotoxic effects on S. epidermidis isolates, with S. lutetiensis demonstrating significant activity at 1/2 minimum inhibitory concentration (MIC) and L. plantarum at 1/4 MIC. L. plantarum thrived at pH 3, while S. lutetiensis exhibited growth at both pH 3 and 4. Both probiotics showed anti-biofilm activity, though L. plantarum demonstrated stronger effects overall. The strains produced lactic, formic, and acetic acids, which were key factors in their inhibitory effects. Toxicity was observed at a concentration of 50% after 24 hours, while cell viability remained unaffected at lower concentrations. Conclusions: The findings highlight the potential of probiotics to address antibiotic-resistant S. epidermidis infections. Further research is necessary to explore their therapeutic applications and optimize treatment strategies.

Stimulus responsive wireless sensor integrated smart urine bag for early detection of catheter-associated infections

Urinary catheterization is a routine intervention in intensive care unit (ICU) patients with prolonged immobility. However, extended use of urinary catheters significantly increases the risk of urinary tract infections (UTIs), posing serious healthcare concerns. Early detection of UTIs can effectively prevent disease progression and mitigate additional health complications. Most conventional diagnostic methods rely on periodic urine sample collection and laboratory analysis, which are time-consuming and lack the capacity for continuous, real-time assessment. To address these limitations, we developed a Smart Urinary Bag (SUB) system with an integrated sensor platform designed for real-time monitoring of UTI-associated biomarkers in urine directly within the urinary bag. The sensor platform incorporates two interdigitated electrode (IDE) patterns coated with stimuli-responsive polymers to selectively detect elevations in pH and xanthine oxidase (XOD) levels—two critical biomarkers for urinary infections. These IDEs connect to spiral planar coils, forming sensor tags that enable battery-free, wireless monitoring of urine conditions through near-field inductive coupling with an external reader. The sensor tags, measuring 10 cm × 6 cm, and the coating thickness were optimized using High-Frequency Structure Simulator (HFSS) software to ensure effective wireless readability and sensitivity for practical miniaturization and integration into standard urinary bags. Systematic characterization of the functional coatings confirmed effective compositions that allowed reliable wireless detection of elevated pH (>8) and XOD (>500 U/L) levels in urine, with a response time of less than 3 hours. The sensors maintained stable performance over 14 days under physiologically relevant conditions with high specificity, as verified through tests with both artificial and real urine. As proof of concept, the fully integrated SUB system was tested under simulated patient conditions with varying pH and XOD levels. The platform successfully identified high-risk UTI conditions, enabling timely alerts to healthcare providers for immediate intervention. This platform aims to enhance patient monitoring in ICUs by reducing healthcare provider burden, facilitating early identification of UTI risks, and promoting timely interventions, ultimately reducing antibiotic overuse and addressing the challenge of rising antibiotic-resistant bacterial strains.

Optimizing third party funding to alleviate global drug resistance: A game-theoretic modeling approach

Increasing evidence suggests that human movement, including international travel and mass forced population displacement, acts as a catalyst for global antimicrobial resistance (AMR) transmission. Immigration increases the likelihood of antibiotic-resistant bacterial strains being imported into developed countries, particularly from several developing countries with high antimicrobial resistance. On the other hand, self-medication, easy access to over-the-counter drugs, promiscuous use, and lax oversight all contribute to an increase in antibiotic use in most lower-middle- and middle-income countries. It leads to antimicrobial resistance and an increased health burden, particularly in high-income countries. Third-party funding agencies are working to reduce the global antimicrobial resistance burden. Understanding the complex system of antibiotic overuse, third-party funding, and cross-border transmission of antimicrobial-resistant strains is a critical task for public health policymakers. In this study, a modeling framework is developed using a combination of epidemiological and game theory methods. This framework aims to describe the phenomenon of migration between countries, specifically focusing on the movement between developing and developed nations. Additionally, the framework incorporates the analysis of self-medication behavior within the developing population. Simulations of the model are conducted, followed by a sensitivity analysis, in order to investigate the influence of various parameters on the optimal funding amount. Our findings indicate that the total cost due to treatment of infection and funding is a convex function of the amount of third-party assistance. This means that there is an optimal level of funding in place to keep the total cost of antimicrobial resistance as low as possible. The sensitivity analyses in relation to various epidemiological and behavioral parameters indicate that the optimal fund is highly dependent on the other parameters of the system. Third-party assistance may be required, as predicted, to reduce the amount of self-medication, but it is only beneficial up to a certain point. These findings result in useful policy recommendations as well as intriguing new research directions.

BIOACTIVE COMPOUNDS POTENTIATION AND ANTIBACTERIAL ACTIVITIES OF A PETALONIA FASCIA EXTRACT ON METHICILLIN-RESISTANT STAPHYLOCOCCUS AUREUS STRAINS

The bioactive algal components that contribute to their antimicrobial properties have garnered significant attention, particularly in light of the rising incidence of antibiotic resistance. The current study aimed to evaluate the antibacterial activity of a Petalonia fascia methanolic extract and to explore the potentiation action of extract–antibiotic combinations with the available antibiotics, as well as the effects of their mixture on multidrug-resistant (MDR) bacteria, namely, five methicillin-resistant Staphylococcus aureus (MRSA) strains. The algal crude extract displayed antibacterial activity against all assayed isolates, with an inhibition zone ranging from 16 to 21 mm and the best spectrum of bactericidal effect with a ratio of MBC/MIC < 4 obtained on the five tested bacterial strains. Amoxicillin–extract mixtures decreased the bacterial growth rate dramatically on all five S. aureus isolates in a time-dependent manner. These results indicate the ability of the extract to modulate antibiotic activity. However, the possibility of its use to solve the issue of antibiotic-resistant bacterial strains and their application as therapeutic agents against infectious diseases warrants further investigation.

Comparison of Different Concentrations of Antibiotics with Nanoparticles Synthesized by Biological Method on Pseudomonas aeruginosa Isolated from The Surface

Background: The widespread and indiscriminate use of antibiotics, disinfectants, and antiseptics in medical centers has led to the emergence of resistance in Pseudomonas aeruginosa, a major cause of hospital infections. Objectives: This study aims to compare the effects of antibiotics—cotrimoxazole, cephalexin, cefotaxime, cefazolin, gentamicin, imipenem, ampicillin, and ceftazidime—with silver nanoparticles synthesized in medicinal plant extract against Pseudomonas aeruginosa bacteria. Methods: Ten antibiotic-resistant strains of Pseudomonas aeruginosa were isolated from surfaces at the maternity hospital of Amir al-Mominin Hospital in Zabul city. In this study, nanoparticles were synthesized using an aqueous extract of the medicinal plant Capparis. The minimum inhibitory concentration (MIC) and minimum lethal concentration (MLC) of the synthesized nanoparticles and antibiotics were determined by the microdilution method. Results: The minimum inhibitory concentrations for the antibiotics ceftriaxone, cephalexin, cotrimoxazole, gentamicin, cefotaxime, imipenem, ceftazidime, ampicillin, and cefazolin were 128, 64, 32, 16, 4, 64, 64, 8, and 64 µg/mL, respectively. The minimum inhibitory concentration for the synthesized silver nanoparticles was 1024 μg/mL, with inhibition observed in four strains at this concentration. Conclusions: This study demonstrated good antimicrobial effects of synthesized silver nanoparticles on Pseudomonas aeruginosa. Therefore, silver nanoparticles may be recommended as a potent antimicrobial agent for disinfecting hospital surfaces.

A Critical Review of Postbiotics as Promising Novel Therapeutic Agents for Clostridial Infections.

Clostridial infections, known for their severity and rapid progression, present significant challenges in both clinical and veterinary fields. These bacteria, which can survive without oxygen and produce protective spores, cause many diseases, ranging from simple gastrointestinal disorders to severe and potentially fatal infections including botulism, tetanus, and gas gangrene. The rising occurrence of antibiotic-resistant strains and the repetitive character of some Clostridial illnesses, including Clostridioides difficile infections (CDI), highlight the immediate need for alternate treatment approaches. Postbiotics, which are metabolites derived from probiotics, are showing great potential as effective agents against these diseases. The current study offers a comprehensive investigation of the potential of postbiotics as therapeutic agents for treating Clostridial infections, including C. difficile, Clostridium perfringens, Clostridium botulinum, and Clostridium tetani. It also examines the processes by which postbiotics exert their effects. Preliminary investigations have shown that postbiotics have promising antibacterial and antibiofilm properties, indicating their potential as adjunct agents in methods for controlling microbial growth. Nevertheless, more study is required to thoroughly demonstrate their medicinal uses.

Prevalence and antibiogram pattern of multidrug-resistant Staphylococcus aureus infections in individuals with sickle cell disease. A retrospective study, hematological and genetic analysis

The prevalence of Staphylococcus aureus in the circulation (bacteremia) of individuals with sickle cell disease (SCD) may provide a substantial risk for illness and death. Strains of S. aureus exhibit a wide variety of virulence traits, including the ability to generate various toxins and develop treatment resistance. MRSA is characterized by its resistance to a range of beta-lactam antibiotics. This study’s objectives included assessing the frequency of S. aureus infection in SCA patients, analyzing laboratory markers of the CBC test, examining the antibiotic susceptibility pattern, and investigating the mecA gene and heteroresistance, which could potentially link to a higher occurrence of S. aureus infection in SCA patients. The retrospective study was done to gather clinical data on individuals with sickle cell anemia (SCA) who had bloodstream infections. From 2017 to 2021, blood samples and data were gathered by King Saud University Medical City (KSUMC) in Riyadh, Saudi Arabia. The S. aureus strains were re-cultivation, Vitek system and PCR techniques were employed to ascertain the antibiotic resistance patterns. It was confirmed that 2406 patients with SCD had contracted an infection. A total of 138 (5.73 %) patients with SCD were diagnosed with bacteremia. “Of the 138 strains isolated, the MRSA strain revealed as the most prevailing, including 30 isolates (21.7 %), whereas non-MRSA strains constituted 17 isolates (12.3 %).” Males had a higher rate of infection compared to females. The results indicated that all the S. aureus isolates exhibited resistance to ampicillin, while the resistance to penicillin was 98 %. Furthermore, the results indicated that over 65 % of the isolates exhibited resistance to amoxicillin, amoxicillin, cefazolin, imipenem, and oxacillin. The mecA gene was identified in all S. aureus strains obtained from patients with SCD. The current study recognizes the PCR assay as a more dependable technique for assessing antibiotic resistances, in contrast to the Vitek method. A study found strong links between S. aureus infections in individuals with SCD and three different factors: hemoglobin (Hb) level, mean corpuscular volume (RDW), and white blood cell (WBC) count (p < 0.004, 0.005, and 0.02, respectively). The study revealed that 34 % of the S. aureus strains that were examined exhibited heteroresistance to the mecA gene as well as resistance to oxacillin. The results clearly demonstrated that Ampicillin, Penicillin, amoxicillin, cefazolin, imipenem, and oxacillin are unsuitable choices for the treatment of blood infections in individuals with SCD. “The findings of this study confirmed that all S. aureus isolates were sensitive to gentamicin, and more than 80 % of the isolates were sensitive to ciprofloxacin, moxifloxacin, levofloxacin, clindamycin, and vancomycin.” Further investigation is necessary to explore potential factors that increase the susceptibility of individuals with SCD to bacteremia caused by antibiotic-resistant strains of S. aureus.

Tackling antibiotic resistance—insights from eHealthResp’s educational interventions

Antibiotic resistance (AR) poses a significant challenging issue in public health worldwide. This phenomenon led to the emergence of antibiotic-resistant bacterial strains, making the treatment of respiratory infections increasingly difficult. Educational interventions targeting healthcare professionals are important to improve prescription practices and promote responsible antibiotic use. Digital tools, including clinical decision support systems and mobile applications, have proven to effectively enhance educational interventions and clinical decision-making. The eHealthResp project is one such initiative that includes an online course and a mobile app designed to improve antibiotic use for upper respiratory tract infections (URTIs). The online course provides clinical information and case studies, whereas the mobile app acts as a clinical decision support system for URTIs diagnosis. The purpose of this study is to analyse the utilization patterns of eHealthResp digital tools among primary care physicians and community pharmacists. Results showed that both physicians and pharmacists (n = 35) had favorable progress and high grades when completing the online course assessment. The mobile app data indicated a diverse range of searched cases with different respiratory symptoms, with the most common being acute nasal discharge and pain when swallowing. Most observations presented mild symptoms for less than seven days, suggesting the occurrence of acute self-limited infections. Despite limitations, digital tools show promise in enhancing patient care outcomes for managing URTIs. Future efforts should focus on expanding participation among health professionals and enhancing educational interventions to promote responsible antibiotic use.

Doxifluridine effectively kills antibiotic-resistant Staphylococcus aureus in chronic obstructive pulmonary disease.

Chronic obstructive pulmonary disease (COPD) is a leading cause of morbidity and mortality globally, often exacerbated by infections such as methicillin-resistant Staphylococcus aureus (MRSA). The rise in antibiotic-resistant strains complicates treatment and underscores the need for novel therapeutic drugs. In this paper, we further investigated the antimicrobial potential of a fluoropyrimidine anticancer drug doxifluridine against multidrug-resistant S. aureus. Determination of minimum inhibitory concentration (MIC) or minimum bactericidal concentration (MBC), monitoring of growth curve, time-kill assays, biofilm bactericidal assays, and chequerboard studies were conducted to evaluate the antibacterial efficacy of doxifluridine. Safety was assessed via hemolysis and cytotoxicity assays, and an in vivo Galleria mellonella larvae model was employed to test protective effects. Doxifluridine demonstrated significant antibacterial activity against clinical multidrug resistance (MDR) S. aureus isolates, with MIC and MBC values ranging from 0.5 to 2 µg/mL and 1 to 4 µg/mL, respectively. The results revealed doxifluridine's potent bactericidal effects within 8 hours. Moreover, doxifluridine-treated bacteria showed a substantial reduction in biofilm mass and viability. Furthermore, chequerboard assays indicated synergistic interactions between doxifluridine and other antibiotics, reducing MIC values by two- to eightfold. More importantly, safety evaluations confirmed that doxifluridine did not exhibit hemolytic toxicity or cytotoxicity. Finally, doxifluridine significantly increased the survival rate of MRSA-infected G. mellonella larvae in vivo. In brief, doxifluridine exhibited promising in vitro and in vivo antibacterial activity against MRSA, suggesting its potential as a repurposed drug for treating resistant bacterial infections in COPD patients.IMPORTANCEThe study provides robust evidence for the antibacterial efficacy of doxifluridine against Methicillin-resistant Staphylococcus aureus in chronic obstructive pulmonary disease (COPD) patients. Its rapid action, ability to disrupt biofilms, and synergistic effects with other antibiotics, combined with a favorable safety profile, highlight its potential as a repurposed therapeutic agent. Future clinical trials will be essential to confirm these findings and pave the way for its integration into clinical practice. This work not only provides candidate for tackling the management of bacterial infections in COPD but also exemplifies the potential of drug repurposing in combating antibiotic-resistant infections.

Structural and Functional Insight Into YefM-YoeB Complex of Toxin-Antitoxin System From Streptococcus pneumoniae.

Streptococcus pneumonia is a Gram-positive and facultative anaerobic bacterium that causes a number of diseases, including otitis media, community-acquired pneumonia, sepsis, and meningitis. With the emergence of antibiotic-resistant strains, there is an urgent need to develop antibiotics with a novel mechanism. The toxin-antitoxin (TA) system, which is primarily found in prokaryotes, consists of a toxin and its equivalent antitoxin genes. The YefM-YoeB module is a Type II TA system, where the YoeB toxin functions as a putative mRNA interferase upon activation, while the YefM antitoxin acts as a transcription repressor by binding to its promoter region along with YoeB. In this study, we determined the crystal structure of the YefM-YoeB complex from S. pneumoniae TIGR4 to comprehend the binding mechanism of the TA system. Furthermore, an in vitro ribonuclease activity assay was conducted to identify the ribonuclease activity of the YoeB toxin. Additionally, furthermore, the oligomeric state of the YefM-YoeB complex in solution was investigated, and a DNA-binding mode was proposed. These structural and functional insights into the YefM-YoeB complex could provide valuable information for the development of novel antibiotics targeting S. pneumonia-associated diseases.

Antibiotic susceptibility testing using minimum inhibitory concentration (MIC) assays

Antimicrobial resistance is due to genetic changes that allow bacteria to evade antibiotic treatment. Antimicrobial susceptibility testing is critical for the detection of antibiotic-resistant strains, the selection of effective therapeutic strategies against bacterial infections, and the evaluation of the efficacy of novel antimicrobials. Among the variety of clinical microbiology methods used for antibiotic susceptibility testing, minimum inhibitory concentration (MIC) assays have become the gold standard in clinical practice. MIC assays determine the lowest concentration of an antimicrobial agent that is required to inhibit visible bacterial growth in vitro. Here, we outline MIC assay protocols, in strict accordance with European Committee on Antimicrobial Susceptibility Testing (EUCAST) guidelines that aim to assess the susceptibility of non-fastidious organisms to antimicrobial agents. The protocols described in this methods paper are intended to aid the performance of reliable and informative MIC assays for research purposes that are in line with clinical microbiology practices.

Rapid and sensitive whole cell E. coli detection using deep eutectic solvents/graphene oxide/gold nanoparticles field-effect transistor

Every year, millions of people suffer from gastrointestinal inflammation caused by E. coli. The increase of antibiotic-resistant strains and similar inflammatory and infectious syndromes symptoms have made rapid and sensitive diagnosis of this pathogen challenging. This study developed a Field-Effect Transistor based on deep eutectic solvents, graphene oxide, and gold nanoparticles (DES/GO/AuNPs-FET) to detect E. coli. Comparing the output current showed DES, which was a mixture of ethylene glycol and choline chloride, with ionic behavior, in addition to improving the electrical properties of GO, also led to the formation of AuNPs by self-assembly, which significantly increased the sensor's sensing performance. E. coli lipopolysaccharide aptamer immobilized on DES/GO/AuNPs-FET; capturing E. coli and changing the conformation caused changes in the charge carrier flow in the FET. This nanobiosensor detected E. coli in a completely selective manner in complex matrices like human blood serum. The excellent sensing performance of this nanobiosensor compared to other biosensors with a low detection limit (LOD = 3 CFU/ml), label-free, fast, and real-time detection showed that DES/GO/AuNPs-FET could be a reliable alternative to existing detection methods.

From Burst to Sustained Release: The Effect of Antibiotic Structure Incorporated into Chitosan-Based Films.

Background/Objectives: Medical devices are susceptible to bacterial colonization and biofilm formation, which can result in severe infections, leading to prolonged hospital stays and increased burden on society. Antibacterial films have the potential to assist in preventing biofilm formation, thereby reducing administration of antibiotics and the emergence of antibiotic-resistant strains. In a previous study, a chitosan-based matrix crosslinked with tannic acid and loaded with gentamicin was reported. In this study, five different antibiotics (moxifloxacin, ciprofloxacin, trimethoprim, sulfamethoxazole or linezolid) were loaded into these chitosan-based films, and their impact on the release behavior carefully assessed. Methods: The samples were characterized according to their thickness, swelling, and mass loss in phosphate-buffered saline (PBS), as well as by morphology using scanning electron microscopy (SEM) and optical phase contrast microscopy. Antibiotic release over time was quantified in PBS by high-performance liquid chromatography (HPLC). Antibacterial activity was investigated by disk diffusion test and antibiotic release over time. Finally, the cytotoxicity of the samples was assessed with human dermal fibroblasts. Results: The obtained results differed significantly, especially regarding the antibiotic release time and antibacterial activity, which varied from one day to six months, enabling classification of the films from burst/transient to prolonged release. The films also showed antibacterial features against bacteria mostly present in medical devices and displayed to be non-cytotoxic. Conclusions: In conclusion, it was demonstrated that the antibiotics structure significantly alters the release kinetics, and that by carefully selecting the antibiotic, the consequent release can be tuned. This approach yielded films that could be used for potentially-scalable release in antimicrobial coatings specific to medical devices, aiming to reduce biomaterial associated infections (BAIs).

Surface-enhanced Raman spectroscopy for the rapid identification of fosfomycin resistant and sensitive strains of E. Coli

Development of rapid detection and discrimination technique for the antibiotic resistant and sensitive bacterial strains is required for this purpose, Surface-enhanced Raman spectroscopy (SERS) technique is considered to have great potential. To develop a fast and sensitive detection and discrimination methodology based on SERS technique along with chemometric tools for the differentiation among fosfomycin sensitive and resistant Escherichia coli (E. coli.) strains. In this research work, three E. Coli strains resistant to fosfomycin with three fosfomycin sensitive E. coli strains were characterized in which silver nanoparticles were employed as SERS substrate. Moreover, MATLAB 7.8 (2009a) was used for the preprocessing, baseline correction and normalization of SERS spectra. Using principal component analysis (PCA) and partial least squares discriminant analysis (PLSDA), several E. Coli strains were identified on the basis of their distinctive SERS spectral properties. The differentiating SERS spectral features which can be associated with the resistance and sensitivity against fosfomycin antibiotic, are obtained by comparing mean SERS spectrum of strains of resistant E. coli with sensitive E. coli strains. Chemometric techniques, such as principal components analysis, have been proven effective for qualitative analysis. Additionally, PLSDA was employed to classify the SERS spectra acquired from the pellets of several bacterial strains. SERS is a useful analytical method for quickly differentiating between E. Coli strains that are sensitive to fosfomycin and those that are resistant to it.

The effectiveness of the HB&amp;L system in bacteriuria determining

Urinary tract infections (UTIs) are characterized by high prevalence in various populations, recurrent course, complications and accumulation of antibiotic resistant strains. Researchers continue to search for objective criteria for the laboratory diagnosis of associated diseases, including methods for determining bacteriuria The implementation of anautomatic bacteriological analyzer into the laboratory practice would make possible to organize screening studies of UTIs with high sensitivity and specificity, in parallel with studies of the resistant phenotypes’prevalence. This will help to create the basis for the development of highly effective and reasonable antibiotic therapy, and, in general, to improve the epidemiological situation associated with these infections.

Evaluation and Characterization of Lytic Phages and their Recombinant Endolysins for Control of Staphylococcus aureus aiming to mitigate bovine mastitis

As a natural alternative to conventional antimicrobials, bacteriophages are emerging as highly effective biocontrol agents against Staphylococcus aureus and other pathogenic bacteria. Due to the wide diversity of S. aureus types and the emergence of antibiotic-resistant strains, the search for highly lytic and prevalent bacteriophages against S. aureus is justified. In this study, we sought to characterized the lytic Phage 2 and Phage 4 biologically and morphologically and their recombinant endolysins EndF2 and EndF4. Transmission electron microscopy analysis revealed that these phages exhibited a structure with a polyhedral head and non-contractile tail, typical characteristics of the Siphoviridae family. Host spectrum identification showed that Phage 2 lysed 62.2% (N=90) of S. aureus strains and Phage 4 lysed 51.1% (N=90). In vitro tests with extracorporeal cow teats indicated that Phage 2 reduced the S. aureus load by up to 78.7%. Furthermore, recombinant endolysins EndF2 and EndF4 have catalytic and recognition/binding domains in their structures related to lytic activity, and both endolysins do not present critical aspects of allergenicity. Furthermore, EndF2 lysed 71.4% (N=42) and EndF4 lysed 76.2% (N=42) of the S. aureus strains tested. These findings indicate that Phages 2 and 4 and their recombinant endolysins EndF2 and EndF4 could potentially be used as tools for the prevention and control of S. aureus, suggesting they are potentially valuable biocontrol agents to mitigate the spread of S. aureus in the dairy industries and production chain.

Evaluation of the Antimicrobial Effects of Olive Mill Wastewater Extract Against Food Spoiling/Poisoning, Fish-Pathogenic and Non-Pathogenic Microorganisms.

Although antibiotics are the main therapy for bacterial infections, the reports showed that the overuse (or misuse) of antibiotics will results in several problems such as the development of antibiotic-resistant strains, persistence of drug residues, and numerous environmental concerns. Therefore, finding antibiotic alternatives is considered of vital importance. Investigation of the antimicrobial properties of several plant substances and extracts is of great value to replace antibiotics. With this objective, this study aimed to evaluate the antimicrobial activities of an ethanolic extract prepared from olive mill wastewater (OMWW), which is a by-product of olive oil production with considerable environmental burden, against 38 bacterial strains, including fish-associated pathogens, non-pathogenic isolates, collection strains, and one yeast strain, Candida albicans. Disk diffusion, minimum inhibitory concentration (MIC), and minimum bactericidal/fungicidal concentration (MBC/MFC) tests were used to determine the antimicrobial activity of the OMWWE. According to the results, OMWWE provoked strong inhibitory effects against Shewanella baltica strain SY-S145. It also showed a moderate inhibitory effect on Plesiomonas shigelloides strain SY-PS16 and Vibrio anguillarum strain SY-L24. The MIC and MBC of OMWWE on Shewanella baltica SY-S145, Vibrio gigantis strain C24, and V. anguillarum strain SY-L24 were 500 µg/mL. The MIC and MBC on V. parahaemolyticus ATCC 17802 were 1000 µg/mL, whereas the values for Aeromonas salmonicida ATCC 33658 were 500 µg/mL and 1000 µg/mL, respectively. To put it briefly, the OMWW extract showed high antimicrobial activity and can act as an environmentally friendly additive for the control and prevention of diseases caused by A. veronii, A. hydrophila, P. shigelloides, S. baltica, V. anguillarum, and V. parahaemolyticus. Its active agents also prevented infections of both fish-associated pathogens and food spoiling bacteria, which means it can not only help in the disease control mechanism but also in improving the safety of food by reduction of the microbial contamination.