Multidrug-resistant Bacteria Research Articles

Multidrug Resistant Gram-negative Bacteria in Surgical Site Infections: Antimicrobial Resistance and Preventive Measures

Abstract Multidrug resistant (MDR) gram-negative bacteria (GNB) are responsible for high mortality and morbidity in healthcare settings worldwide. They have been declared as priority pathogens by the WHO for their continuously escalating antimicrobial resistance. Nevertheless, data associated with MDR GNB in healthcare-associated infections are insufficient. Surgical site infections (SSIs) are among the most commonly occurring healthcare-associated infections. Such infections are particularly common when bacteria from the patient's normal microflora are transferred to the surgical sites during surgical procedures. SSIs affect approximately 0.5%-3% of patients undergoing surgery, resulting in prolonged hospital stay compared with patients without SSIs. SSIs result in severe problems and lead to a heavy economic burden. Most SSIs can be avoided if suitable preventive measures are employed. Novel findings support the dedicated usage of oral preoperative surgical antimicrobial prophylaxis for specific surgeries based on sites/organs. Immediate interventions are sought to control the transmission of MDR GNB typically found in hospital settings. The present narrative review aims to describe MDR GNB in SSIs in different sites. Antimicrobial resistance epidemiology and preventive measures for SSIs are also discussed. Different intrinsic and extrinsic factors and control measures are elaborated for curbing SSIs.

Phytochemical analysis and biological activities of solvent extracts and silver nanoparticles obtained from Woodwardia unigemmata (Makino) Nakai

Multidrug resistant bacteria are causing health problems and economic burden worldwide; alternative treatment options such as natural products and nanoparticles have attained great attention recently. Therefore, we aimed to determine the phytochemicals, antibacterial potential, and anticancer activity of W. unigemmata. Extracts in different organic and inorganic solvents were prepared, silver nanoparticles were prepared using the green synthesis method. Phytochemicals and antioxidant activity was determined spectrophotometry, anticancer potential was determined against gastric cancer and normal gastric epithelial cells using CCK8 and colony formation assays W. unigemmata was found to have a significant enrichment of various phytochemicals including flavonoids, terpenoids, alkaloids, carotenoids, tannins, saponins, quinines, carbohydrates, phenols, coumarins and phlobatanins. Among them phenolics (5289.89 ± 112.67) had high enrichment followed by reducing sugar (851.53 ± 120.15), flavonoids (408.28 ± 20.26) and ascorbic acid (347.64 ± 16.32), respectively. The extracts prepared in organic solvents showed strong antibacterial activity against P. aeruginosa (chloroform, 13.66±0.88, ethyl acetate, 8.66±4.33, methyl alcohol, 13.33±1.66, N-hexane, 12.33±0.88) and S. aureus (chloroform, 15±0.57, ethyl acetate, 16.33±0.33, methyl alcohol, 17.66±0.33 and N-hexane, 16.33±0.33). Aqueously prepared AgNPs showed remarkable activity against P. aeruginosa follwed by E. coli, 17.66 ± 1.85, S. aureus, 16.00 ± 1.73, K. pneumoniae, 14.33 ± 1.20, respectively. The ethanolic extracts (500 μg, 1000 μg, 2000 μg) of the W. unigemmata were found to have cytotoxicity against both gastric cancer (AGS and SGC7901) and normal cell lines (GES-1); a significant cellular proliferation arrest was observed. These results suggest that W. Unigemmata contains numerous bioactive phytochemicals and can be useful as a drug against MDR bacterial strains. These biomolecules covering AgNPs may enhance their biological activities, which can be employed in the treatment of various microbial infections.

Modular Engineering of Lysostaphin with Significantly Improved Stability and Bioavailability for Treating MRSA Infections.

Methicillin-resistant Staphylococcus aureus (MRSA) is a refractory pneumonia-causing pathogen due to the antibiotic resistance and the characteristics of persisting inside its host cell. Lysostaphin is a typical bacteriolytic enzyme for degrading bacterial cell walls via hydrolysis of pentaglycine cross-links, showing potential to combat multidrug-resistant bacteria. However, there are still grand challenges for native lysostaphin because of its poor shelf stability and limited bioavailability. To tackle these limitations, a modular assembly strategy is proposed to actively engineer the native lysostaphin, involving nanoassembly preparation via fusing with lysine-rich polypeptide. The engineered lysine component significantly improves the membrane-penetration capability of lysostaphin, greatly increasing its intracellular antibacterial activity by 12-fold compared to wild-type lysostaphin. Notably, the half-life of the nanoassembled lysostaphin is approximately 13 times longer than that of its native counterpart, greatly outperforming other studies. Most importantly, the shelf stability of our engineered lysostaphin is significantly improved, retaining over 99.9% of antibacterial activity after 12 weeks at room temperature. This modular assembly strategy successfully enhances the overall performance of lysostaphin, offering great promise for a platform technique to refine enzymatic material for widespread clinical demands.

Novel Insights into the Nobilamide Family from a Deep-Sea Bacillus: Chemical Diversity, Biosynthesis and Antimicrobial Activity Towards Multidrug-Resistant Bacteria

With rising concerns about antimicrobial resistance, the identification of new lead compounds to target multidrug-resistant bacteria is essential. This study employed a fast miniaturized screening to simultaneously cultivate and evaluate about 300 marine strains for biosurfactant and antibacterial activities, leading to the selection of the deep-sea Bacillus halotolerans BCP32. The integration of tandem mass spectrometry molecular networking and bioassay-guided fractionation unveiled this strain as a prolific factory of surfactins and nobilamides. Particularly, 84 nobilamide congeners were identified in the bacterial exometabolome, 71 of them being novel metabolites. Among these, four major compounds were isolated, including the known TL-119 and nobilamide I, as well as the two new nobilamides T1 and S1. TL-119 and nobilamide S1 exhibited potent antibiotic activity against various multidrug-resistant Staphylococcus strains and other Gram-positive pathogens, including the foodborne pathogen Listeria monocytogenes. Finally, in silico analysis of Bacillus halotolerans BCP32 genome revealed nobilamide biosynthesis to be directed by a previously unknown heptamodular nonribosomal peptide synthetase.

A Bioinspired Virus-Like Mechano-Bactericidal Nanomotor for Ocular Multidrug-Resistant Bacterial Infection Treatment.

Multidrug-resistant (MDR) bacteria and their associated biofilms are major causative factors in eye infections, often resulting in blindness and presenting considerable global health challenges. Presently, mechano-bactericidal systems, which combine distinct topological geometries with mechanical forces to physically induce bacterial apoptosis, show promising potential. However, the physical interaction process between current mechano-bactericidal systems and bacteria is generally based on passive diffusion or Brownian motion and lacks the force required for biofilm penetration; thus, featuring low antibacterial efficacy. Here, a biomimetic mechano-bactericidal nanomotor (VMSNT) is synthesized by functionalizing COOH-PEG-phenylboronic acid (PBA) on virus-like mesoporous silica, with subsequent partial coating of Au caps. Enhanced by self-thermophoresis capabilities and virus-like topological shapes, VMSNT significantly improves mechanical antibacterial effects and biofilm penetration. In addition, scanning electron microscope (SEM) and confocal laser scanning microscope (CLSM)analyses demonstrate that VMSNT can precisely target bacteria within the infection microenvironment, facilitated by PBA's ability to recognize and bind to the peptidoglycan on bacterial surfaces. Remarkably, VMSNT is also effective in eliminating MDR bacteria and reducing inflammation in mice models of methicillin-resistant Staphylococcus aureus (MRSA)-infected keratitis and endophthalmitis, with minimal adverse effects. Overall, such a nanomotor presents a promising approach for addressing the challenges of ocular MDR bacterial infections.

Revolutionizing healthcare: The role of silver nanoparticles in modern medicine

Silver nanoparticles (AgNPs) are emerging as powerful tools in healthcare due to their unique properties, including antimicrobial activity, high surface area, and biocompatibility. They are widely used in medical applications such as wound healing, drug delivery, cancer therapy, and diagnostics, particularly for combating multidrug-resistant bacteria. AgNPs enhance the effectiveness of traditional antibiotics and show potential in synergistic therapies with other nanomaterials. However, challenges remain regarding their toxicity to human cells and the environment. The lack of standardized synthesis and application protocols complicates their regulatory approval and widespread use. To address these concerns, we should focus on engineering AgNPs to reduce toxicity, enhance specificity, and develop biodegradable systems to minimize environmental impact. However, AgNPs hold significant promise for advancing medical treatments, and current research is essential to ensure their safe and effective use in healthcare.

Clinical and molecular analysis of ESBL, carbapenemase, and colistin-resistant bacteria in UTI patients.

Uropathogens, particularly bacteria, can infect any part of the urinary tract and cause bacteriuria. Our study aimed to examine the antibiotic-resistant profile, associated risk factors, and phenotypic and genotypic features of ESBL, carbapenemase, and mcr resistance genes in multidrug-resistant bacteria. Samples were inoculated on culture media, identified using standard biochemical tests, and species confirmation was performed via 16S rRNA gene amplification. Furthermore, antibiotic susceptibilities were evaluated using the Kirby-Bauer disc diffusion method. The phenotypically confirmed resistant strains were further inspected for ESBL, carbapenemases, and mcr variants using PCR. Merely 57.24% (83/145) of the samples exhibited growth. Of these, 39.70% (33/83) were identified as Klebsiella pneumoniae, 27.70% (23/83) as Escherichia coli, 10.80% (9/83) as Pseudomonas aeruginosa, 9.60% (8/83) as Staphylococcus aureus, 7.20% (6/83) as Proteus mirabilis, and 4.80% (4/83) as Staphylococcus saprophyticus. Overall, 22.54% (16/71) of the gram-negative strains were confirmed molecularly to have resistant genes. The ESBL - producers accounted for 21.74% (5/23) of E. coli, 21.21% (7/33) of K. pneumoniae, and 22.22% (2/9) of P. aeruginosa. Likewise, carbapenemase-harboring strains included 6.06% (2/33) of K. pneumoniae, 4.35% (1/23) of E. coli, and 11.11% (1/9) of P. aeruginosa. Notably, 3.03% (1/33) of K. pneumoniae, 8.70% (2/23) of E. coli, and 11.11% (1/9) of P. aeruginosa strains tested positive for the mcr-1 gene. None of the Proteus strains showed any resistant genes. The most common variants were blaSHV-11 (non-ESBL) and blaCTX-M-15 (ESBL) accounted for 28.57% (4/14) each, blaTEM-116 accounted for 14.29% (2/14), blaSHV-1, blaSHV-75, blaTEM-1 and blaOXA-1 accounted for 7.14% (1/14) each of the ESBL. Similarly, the carbapenemase variants included blaOXA-48, blaNDM-1, blaVIM-1, and blaKPC-2, each accounting for 25.0% (1/4), while 37.50% (6/16) of the strains exhibited co-existence of different gene variants. Based on our findings, it can be concluded that females, especially those in middle age, were more infected. These pathogens exhibited a wide range of ESBL, carbapenemase, and mcr-1 variants. Imipenem was suggested as the preferred medication.

AIE-Active Antibacterial Photosensitizer Disrupting Bacterial Structure: Multicenter Validation against Drug-Resistant Pathogens.

Antimicrobial resistance (AMR) has emerged as a global challenge in treating bacterial infections, creating an urgent need for broad-spectrum antimicrobial agents that can effectively combat multidrug-resistant (MDR) bacteria. Despite advancements in novel antimicrobial agents, many fail to comprehensively cover common resistant bacterial strains or undergo rigorous multi-center validation. Herein, a cationic AIE-active photosensitizers are developed, ITPM, derived from a triphenylamine-pyridine backbone to address the MDR challenge. Rigorous validation demonstrates that ITPM possesses superior fluorescence imaging capabilities and exceptional antibacterial efficacy. And its broad-spectrum activity is verified through a multi-center study involving six clinically relevant MDR strains. Additionally, resistance development studies and comparisons with advanced clinical antibiotics reveal that ITPM exhibits potent, broad-spectrum antimicrobial activity with minimal resistance development. This efficacy is attributed to its unique antibacterial mechanism involving disrupting bacterial internal structures. These findings establish ITPM as a promising candidate for broad-spectrum antimicrobial therapy, offering a potential solution to the growing crisis of AMR in clinical settings.

Impact of Multidrug-Resistant Bacteria in a Cohort of COVID-19 Critically Ill Patients: Data from a Prospective Observational Study Conducted in a High-Antimicrobial-Resistance-Prevalence Center

Impact of Multidrug-Resistant Bacteria in a Cohort of COVID-19 Critically Ill Patients: Data from a Prospective Observational Study Conducted in a High-Antimicrobial-Resistance-Prevalence Center

Novel Leech Antimicrobial Peptides, Hirunipins: Real-Time 3D Monitoring of Antimicrobial and Antibiofilm Mechanisms Using Optical Diffraction Tomography.

Antimicrobial peptides (AMPs) are promising agents for treating antibiotic-resistant bacterial infections. Although discovering novel AMPs is crucial for combating multidrug-resistant bacteria and biofilm-related infections, their clinical potential relies on precise, real-time evaluation of efficacy, toxicity, and mechanisms. Optical diffraction tomography (ODT), a label-free imaging technology, enables real-time visualization of bacterial morphological changes, membrane damage, and biofilm formation over time. Here, a computational analysis of the leech transcriptome using an advanced AI-based peptide screening strategy with ODT to identify potential AMPs is employed. Among the 19 potential AMPs identified, hirunipin 2 demonstrates potent antibacterial activity, low mammalian cytotoxicity, and minimal hemolytic effects. It demonstrates efficacy comparable to melittin, resistance to physiological salts and human serum, and a low likelihood of inducing bacterial resistance. Microscopy and 3D-ODT confirm its disruption of bacterial membranes and intracellular aggregation, leading to cell death. Notably, hirunipin 2 effectively inhibits biofilm formation, eradicates preformed biofilms, and synergizes with antibiotics against multidrug-resistant Acinetobacter baumannii (MDRAB) by enhancing membrane permeability. Additionally, hirunipin 2 significantly suppresses pro-inflammatory cytokine expression in LPS-stimulated macrophages, highlighting its anti-inflammatory properties. These findings highlight hirunipin 2 as a strong candidate for developing novel antibacterial, anti-inflammatory, and antibiofilm therapies, particularly against multidrug-resistant bacterial infections.

Antibacterial activity of Nigella sativa against multi-drug resistant bacteria

Background: Multidrug Resistant (MDR) bacteria are considered as the one of the most dangerous pathogens causing a high mortality rate globally. Medicines from the natural source might be the best therapeutic option in current emerging trends of resistance. Methods: We determined the antibacterial activity of Nigella sativa seeds extracts against the clinical isolates of MDR Staphylococcus aureus and Escherichia coli. The collection of different isolates was done from the different hospitals’ settings in Faisalabad. Identifications of these isolates were done phenotypically and through the conventional PCR via genus and species-specific primers. The isolates were then tested for antimicrobial susceptibility using agar well diffusion technique. The activity of N. sativa seed oil was also evaluated in DMSO at concentrations (25%, 50% and 75%). Results: Against S. aureus, 50% oil concentration in DMSO exhibited highest inhibitory zone of 15 mm followed by 90% ethanol extract showed clear zone of 13 mm and 12 mm zone of inhibition showed by the methanol-based extract. Against E. coli 50% oil concentration in Dimethyl sulfoxide (DMSO) and 90% ethanol extract both showed clear zone of 12 mm and 11 mm zone of inhibition showed by the methanol-based extract. However, Minimum inhibitory concentration (MIC) of 50% oil concentration is 0.4 μl followed by 90% ethanol extract showed 0.4 mg and 0.8 mg showed by the methanol-based extract 90% on S. aureus. The oil concentration MIC value of 50% is 0.4 μl then followed by the ethanol extract at 90% and revealed 0.4mg and methanol was followed by 90% extract showed 0.4 mg to the E. coli. Conclusion: We concluded that N. sativa can be used as a pharmaceutical and new therapy for action against MDR bacteria.

LTX-315 is a novel broad-spectrum antimicrobial peptide against clinical multidrug-resistant bacteria.

Infections stemming from multidrug-resistant bacteria present a substantial threat to public health today. Discovering or synthesizing novel compounds is crucial to alleviate this pressing situation. The main purpose of this study is to verify the antibacterial activity of LTX-315 and explore its primary action mode. Through antibacterial phenotype assay screening, we obtained a potent compound named LTX-315 from diverse drug libraries, 10,926 compounds in total. Then, the bactericidal effect and its action mode were explored through biochemical and chemistry methods such as atime-killing curve, scanning electronic microscopy, isothermal titration calorimetry analysis, and nuclear magnetic resonance. Finally, the efficacy in vivo of LTX-315 against drug-resistant bacteria was proved through amice infection model. In this study, LTX-315, an oncolytic peptide, was discovered to effectively eliminate gram-positive and gram-negative pathogens, even for those multidrug-resistant strains. Through strong electrostatic interactions, LTX-315 can bind to the membrane component phosphatidylglycerol (PG) with extremely high affinity (nanomolar level). Strikingly, in contrast to the typical electrostatic interactions of antibacterial peptides, the indole group of LTX-315, situated near the alkyl chain, exhibits significantly enhanced recognition and interaction with PG due to the hydrophobic effect of the alkyl chain. Furthermore, it exerts various impacts on cell membranes, including damaging integrity, increasing permeability, and decreasing membrane fluidity. Additionally, microscopy revealed significant cell disintegration. The influence, in turn, disrupts several physiological activities inside cells, such as increasing the reactive oxygen species level, ultimately leading to cell death. Finally, the efficacy of LTX-315 in vivo against multidrug-resistant and hypervirulent Klebsiella pneumoniae was demonstrated. The unique mechanism of LTX-315 involves high-affinity binding to PG and subsequent membrane disruption, providing a novel approach against multidrug-resistant bacteria compared to conventional antibiotics. As a potential candidate, it shows promise in effectively treating bacterial infections, particularly those caused by drug-resistant bacteria, thereby addressing the escalating challenge of antibiotic resistance worldwide.

Pioneering study of Egyptian Neem and Jojoba extracts with molecular docking combat hospital multidrug resistant bacteria.

Hospital surfacesare often contaminatedwith multidrug-resistant pathogenic bacteria that cause healthcare-associated infections and lead to increased mortality and morbidity. Thereis a need for new alternative antibacterial agents to overcome antibiotic resistance. Azadirachta indica and Simmondsia chinensis have been found to possess antibacterial activity and medicinal value. The antibacterial activity of these plant extracts against clinical isolates was investigated using the agar disc diffusion method. These clinical isolates included E. coli, Pseudomonas aeruginosa, Acinetobacter spp., Klebsiella pneumoniae, Stenotrophomonas maltophilia, and methicillin-resistant Staphylococcus aureus (MRSA), which were identified by the vitek-2 system, and resistance genes of selected bacterial strains were identified by using the bioFire FilmArray test. The most potent extract of these plants was the ethanolic extract, where the inhibition percentage of ethanolic Jojoba and Neem extracts was 90.9% and 74.5%, respectively against all the tested pathogens. On the other hand, the methanolic extracts of Neem and Jojoba have different degrees of antibacterial activity against the tested pathogens. The phytochemical components of the most potent extracts (ethanolic extracts) were investigated by gas chromatography‒mass spectrometry (GC\MS), which revealed that the ethanolic extracts were enriched in phenolics, flavonoids, and sugars. FTIR analyses of the plant extracts confirmed the presence of alcoholic, carboxylic, and aldehydic moieties. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) activity of the ethanolic extracts of Neem and Jojoba increased in a dose-dependent manner, with average IC50 values of 98.17 ± 0.85, 4.95 ± 0.06, and 4.17 ± 0.04 mg/mL, respectively, for the ethanolic Neem extract, the ethanolic Jojoba extract, and ascorbic acid (standard). Furthermore, increased cytotoxicity was demonstrated in the HFB4 cell line in a dose-dependent manner. The average IC50s of the ethanolic Neem extract and the ethanolic Jojoba extract were 18.18 ± 0.15 and 76.16 ± 1.49 mg/mL, respectively. Moreover, the results for the antibiofilm activity of the ethanolic Neem extract showed that 99.5% of the biofilms formed at 25 mg/ml. Inaddition, 50 mg/ml of the ethanolic extract of Jojoba had a suppressive effect of 98.2%. The significant components Nonanoic acid (21.9405%) and Palmitic Acid (16.0869%) from Neem and pinitol from Jojoba (82.85%) were selected throughout the molecular docking investigation, by which the chosen constituents inhibited the crystal structure of penicillin-binding protein 4 (PBP4) from Staphylococcus aureus (PDB ID: 1TVF) and the crystal structure of the OXA-48 beta-lactamase (PDB ID: 7AUX) from K. pneumoniae. Overall, our study reveals the effectiveness of antimicrobial plant extracts as therapeutic solutions for antibiotic resistance in Egypt and worldwide with some modifications to decrease their cytotoxicity.

Genomic Characterization of Carbapenemase-Producing Enterobacteriaceae from Clinical and Epidemiological Human Samples

Background/Objectives: Infections caused by multidrug-resistant (MDR)bacteria pose a significant public health threat by worsening patient outcomes, contributing to hospital outbreaks, and increasing health and economic burdens. Advanced genomic tools enhance the detection of resistance genes, virulence factors, and high-risk clones, thus improving the management of MDR infections. In the Autonomous Community of Aragon, the diversity and incidence of carbapenemase-producing Enterobacteriaceae (CPE) have increased during the last years. This study analyses CPE trends at a tertiary hospital in Spain from 2021 to 2023, aiming to optimize personalized medicine. Methods: CPE isolates were the first isolate per patient, year, species, and carbapenemase from January 2021 to December 2023. Additional metadata were collected from the laboratory’s information system. Antibiotic susceptibility testing was performed by broth microdilution. Whole-genome sequencing (WGS) was performed using Illumina short reads. De novo assembly was used to generate draft genomes in order to determine their complete taxonomic classification, resistome, plasmidome, sequence type (ST), core–genome multilocus sequence typing (cgMLST), and phylogenetic relationships using a suite of bioinformatics tools and in-house scripts. Results: Between 2021 and 2023, 0.4% out of 38,145 Enterobacteriaceae isolates were CPE. The CPE rate tripled in 2022 and doubled again in 2023. The most common species was Klebsiella pneumoniae (51.8%) and the most common carbapenemase was blaOXA-48. WGS revealed concordant species identification and the carbapenemase distribution in detail. Resistance rates to critical antibiotics, such as carbapenems, were variable, but in most cases were above 70%. Genetic diversity was observed in WGS and phylogenetic analyses, with plasmids often mediating carbapenemase dissemination. Conclusions: The increasing rate of CPE in healthcare settings highlights a critical public health challenge, with limited treatment options. Genomic characterization is essential to understanding resistance mechanisms, aiding therapy, limiting outbreaks, and improving precision medicine.

Exploiting the fitness cost of metallo-β-lactamase expression can overcome antibiotic resistance in bacterial pathogens.

Carbapenems are last-resort antibiotics for treating bacterial infections. The widespread acquisition of metallo-β-lactamases, such as VIM-2, contributes to the emergence of carbapenem-resistant pathogens, and currently, no metallo-β-lactamase inhibitors are available in the clinic. Here we show that bacteria expressing VIM-2 have impaired growth in zinc-deprived environments, including human serum and murine infection models. Using transcriptomic, genomic and chemical probes, we identified molecular pathways critical for VIM-2 expression under zinc limitation. In particular, disruption of envelope stress response pathways reduced the growth of VIM-2-expressing bacteria in vitro and in vivo. Furthermore, we showed that VIM-2 expression disrupts the integrity of the outer membrane, rendering VIM-2-expressing bacteria more susceptible to azithromycin. Using a systemic murine infection model, we showed azithromycin's therapeutic potential against VIM-2-expressing pathogens. In all, our findings provide a framework to exploit the fitness trade-offs of resistance, potentially accelerating the discovery of additional treatments for infections caused by multidrug-resistant bacteria.

Synergistic Antibacterial Effect of ZnO Nanoparticles and Antibiotics against Multidrug-resistant Biofilm Bacteria.

The misuse of antibiotics leads to a global increase in antibiotic resistance. Therefore, it is imperative to search for alternative compounds to conventional antibiotics. ZnO nanoparticles (Zn NP) are one of these alternatives because they are an effective option to overcome biofilm bacterial cells and a novel way to overcome multidrug resistance in bacteria. The current research study aims to characterize the efficacy of ZnO nanoparticles alone and in combination with other antibacterial drugs against bacterial biofilms. ZnO NPs were prepared by co-precipitation method, and their anti-biofilm and antibacterial activities alone or combined with four types of broad-spectrum antibacterial (Norfloxacin, Colistin, Doxycycline, and Ampicillin) were evaluated against E. coli and S. aureus bacterial strains. Finally, the cytotoxicity and the hemolytic activity were evaluated. ZnO NPs were prepared, and results showed that their size was around 10 nm with a spherical shape and a zeta potential of -21.9. In addition, ZnO NPs were found to have a strong antibacterial effect against Gram-positive and Gram-negative microorganisms, with a minimum inhibitory concentration (MIC) of 62.5 and 125 μg/mL, respectively. Additionally, they could eradicate biofilmforming microorganisms at a concentration of 125 μg/m. ZnO NPs were found to be non-toxic to erythrocyte cells. Still, some toxicity was observed for Vero cells at effective concentration ranges needed to inhibit bacterial growth and eradicate biofilm-forming organisms. When combined with different antibacterial, ZnO NP demonstrated synergistic and additive effects with colistin, and the MIC and MBEC of the combination decreased significantly to 0.976 μg/mL against planktonic and biofilm strains of MDR Gram-positive bacteria, resulting in significantly reduced toxicity. The findings of this study encourage the development of alternative therapies with high efficacy and low toxicity. ZnO nanoparticles have demonstrated promising results in overcoming multi-drug resistant bacteria and biofilms, and their combination with colistin has shown a significant reduction in toxicity. Further studies are needed to investigate the potential of ZnO nanoparticles as a viable alternative to conventional antibiotics.

Synergistic Effect of the Bee Venom with Traditional Antibiotics on Multi-Drug Resistant Bacteria

Synergistic Effect of the Bee Venom with Traditional Antibiotics on Multi-Drug Resistant Bacteria

Epidemiology and Mechanism of Drug Resistance of Multidrug-Resistant Klebsiella Pneumoniae Isolated from Patients with Urinary Tract Infection in Beijing Teaching Hospital, China.

Klebsiella pneumoniae is an important pathogenic bacterium in causing urinary tract infection. With the overuse of antibiotics, bacteria resistant to quinolones combined with carbapenems are increasing. In this study, we investigated the epidemiology, molecular characteristics, drug resistance of multidrug-resistant Klebsiella pneumoniae (MDR-KPN) isolated from urine samples. It provides theoretical basis for the treatment of urinary tract infection by clinicians. Fifty-one strains of Klebsiella pneumonia were obtained from urine samples collected between 2012 and 2017 in total. All the strains are multi-drug resistant bacteria. This paper used multilocus sequence typing (MLST) to determine molecular epidemiological typing. We performed antimicrobial susceptibility testing and investigated quinolones and carbapenems resistance genes. The strains which we collected were resistant to ciprofloxacin and Levofloxacin. In an epidemiological analysis using MLST, 86.27% (44/51) of isolates were confirmed to be ST11. The main carbapenem resistance gene was KPC-19, 78.43(40/51). Among the quinolone resistance genes, the major resistance genes were aac(6')-Ib-cr, oqxA and oqxB. The main molecular epidemiological types we detected was ST11. The main resistance gene of carbapenems was KPC-19. The quinolone resistance genes are mainly aac(6')-Ib-cr, oqxA and oqxB. The experimental results can help control the use of quinolones and carbapenems, and we could provide rational drug use basis for clinicians to treat urinary tract infection. For MDR-KPN, a combination of multiple antibiotics is necessary.

Eliminating the Tigecycline Reistance RND Efflux Pump Gene Cluster tmexCD-toprJ in Bacteria Using CRISPR/Cas9

Tigecycline, a last-resort antibiotic in the tetracycline class, has been effective in treating infections caused by multidrug-resistant bacteria. However, the emergence of the tigecycline resistance gene cluster tmexCD-toprJ, which encodes a resistance-nodulation-division efflux pump, has significantly limited its therapeutic effectiveness. In this study, we developed two CRISPR/Cas9-based plasmids, pCas9Kill and pCas9KillTS, to target and cleave tmexCD-toprJ gene cluster from bacterial plasmids and chromosomal integrative conjugative elements (ICEs), respectively. The pCas9Kill plasmid designed to eliminate tmexCD-toprJ from plasmids through electroporation, resulting in the resensitization of the bacteria to tigecycline. Nanopore long-read sequencing revealed that the plasmids were repaired by insertion sequences after tmexCD-toprJ removal. In contrast, the pCas9KillTS plasmid introduced via conjugation to target tmexCD-toprJ gene cluster on ICEs within the chromosome. This approach led to chromosomal cleavage and subsequent bacterial cell death. Our results demonstrate that both plasmids effectively inactivated tmexCD-toprJ, with pCas9Kill restoring tigecycline susceptibility in plasmid-bearing strains and pCas9KillTS causing targeted cell death in chromosomal ICE-harboring bacteria. This study highlights the potential of CRISPR/Cas9 systems in addressing antibiotic resistance, providing a promising strategy to combat tigecycline-resistant pathogens.

Real-world multicentre study of cefiderocol treatment of immunocompromised patients with infections caused by multidrug-resistant Gram-negative bacteria: CEFI-ID.

The increase in the population of immunocompromised patients due to advances in management of end-stage diseases and transplants poses challenges in treating infections caused by multi-drug resistant (MDR) pathogens. Cefiderocol (FDC), a siderophore cephalosporin, has shown efficacy against carbapenem-resistant Gram-negative bacteria. This retrospective multicentre study investigated the real-world use of FDC in 114 immunocompromised adults treated for MDR infections in 12 French hospitals (June 2020-November 2023). Clinical and microbiological outcomes, including infection cure, relapse, as well as mortality, and resistance acquisition, were assessed at days 28 and 90. Antibiotic prescription compliance with current guidelines was investigated. At day 28, clinical success was achieved in 53.3% of cases, and overall mortality was 37.7%, consistent with other studies (33-37%). Infection-related mortality accounted for 25.4%. Relapse occurred in 17.5% of patients by day 28, rising by an additional 9.8% among survivors by day 90. Resistance acquisition was observed in two cases at day 28 (Pseudomonas aeruginosa and Stenotrophomonas maltophilia) and in three additional cases by day 90. FDC was used as monotherapy in 49.1% of cases, with a median treatment duration of 10 days. Nearly 25% of strains collected in FDC-treated patients were susceptible to best-practice alternatives. These findings highlight FDC's utility in difficult-to-treat infections, particularly S. maltophilia, but the high relapse rate and resistance acquisition underscore the need for careful monitoring, adherence to guidelines, and reconsideration of empirical use to prevent resistance and improve outcomes in fragile populations.