# | Rank | Similarity | Title + Abs. | Year | PMID |
|---|---|---|---|---|---|
| 0 | 1 | 2 | 3 | 4 | 5 |
| 9760 | 0 | 0.9980 | Mutations leading to ceftolozane/tazobactam and imipenem/cilastatin/relebactam resistance during in vivo exposure to ceftazidime/avibactam in Pseudomonas aeruginosa. Identifying resistance mechanisms to novel antimicrobials informs treatment strategies during infection and antimicrobial development. Studying resistance that develops during the treatment of an infection can provide the most clinically relevant mutations conferring resistance, but cross-sectional studies frequently identify multiple candidate resistance mutations without resolving the driver mutation. We performed whole-genome sequencing of longitudinal Pseudomonas aeruginosa from a patient whose P. aeruginosa developed imipenem/cilastatin/relebactam and ceftolozane/tazobactam resistance during ceftazidime/avibactam treatment. This analysis determined new mutations that arose in isolates resistant to both imipenem/cilastatin/relebactam and ceftolozane/tazobactam. Mutations in penicillin-binding protein 3 ftsI, the MexAB-OprM repressor nalD, and a virulence regulator pvdS were found in resistant isolates. Importantly, drug efflux was not increased in the resistant isolate compared to the most closely related susceptible isolates. We conclude that mutations in peptidoglycan synthesis genes can alter the efficacy of multiple antimicrobials. IMPORTANCE: Antibiotic resistance is a significant challenge for physicians trying to treat infections. The development of novel antibiotics to treat resistant infections has not been prioritized for decades, limiting treatment options for infections caused by many high-priority pathogens. Cross-resistance, when one mutation provides resistance to multiple antibiotics, is most problematic. Mutations that cause cross-resistance need to be considered when developing new antibiotics to guide developers toward drugs with different targets, and thus a better likelihood of efficacy. This work was undertaken to determine the mutation that caused resistance to three antibiotics for highly resistant Pseudomonas aeruginosa infection treatment while the bacteria were exposed to only one of these agents. The findings provide evidence that drug developers should endeavor to find effective antibiotics with new targets and that medical providers should utilize medications with different mechanisms of action in bacteria that have become resistant to even one of these three agents. | 2025 | 39932323 |
| 9767 | 1 | 0.9979 | Metallo-β-lactamase NDM-1 serves as a universal vaccine candidate for combatting antimicrobial resistance. The rapid emergence and spread of antimicrobial resistance have become critical global health issues, leading to significant morbidity and mortality worldwide. With the increase in resistance to multiple drugs, especially frontline clinical antibiotics, there is an urgent need for novel and effective alternative strategies. Herein, we developed a vaccine targeting the antimicrobial resistance enzyme NDM-1, which was first identified in Klebsiella pneumoniae and has quickly spread to other gram-negative bacteria. Our results demonstrate that NDM-1 primarily triggers a humoral immune response and effectively protects mice from lethal Klebsiella pneumoniae infection, as evidenced by increased survival rates, reduced bacterial loads, and decreased lung inflammation in mice. The specific antibodies generated were able to inhibit the enzymatic activity of NDM-1, bacterial growth, and exhibit opsonophagocytic activity against Klebsiella pneumoniae in vitro. Both active and passive immunization with NDM-1 showed an additive effect when combined with meropenem therapy. Furthermore, NDM-1 immunization induced cross-reactivity with NDM-1 variants, potentially providing broad protection against bacteria carrying different NDM genes. Additionally, heptamerization of NDM-1 improved its immunogenicity and protective efficacy in mice. These results highlight the potential of vaccine development based on antibiotic resistance candidates for broadly combatting antimicrobial resistance. | 2025 | 40505900 |
| 223 | 2 | 0.9979 | Phosphoethanolamine Transferases as Drug Discovery Targets for Therapeutic Treatment of Multi-Drug Resistant Pathogenic Gram-Negative Bacteria. Antibiotic resistance caused by multidrug-resistant (MDR) bacteria is a major challenge to global public health. Polymyxins are increasingly being used as last-in-line antibiotics to treat MDR Gram-negative bacterial infections, but resistance development renders them ineffective for empirical therapy. The main mechanism that bacteria use to defend against polymyxins is to modify the lipid A headgroups of the outer membrane by adding phosphoethanolamine (PEA) moieties. In addition to lipid A modifying PEA transferases, Gram-negative bacteria possess PEA transferases that decorate proteins and glycans. This review provides a comprehensive overview of the function, structure, and mechanism of action of PEA transferases identified in pathogenic Gram-negative bacteria. It also summarizes the current drug development progress targeting this enzyme family, which could reverse antibiotic resistance to polymyxins to restore their utility in empiric therapy. | 2023 | 37760679 |
| 9763 | 3 | 0.9979 | Mechanisms of tigecycline resistance in Gram-negative bacteria: A narrative review. Tigecycline serves as a critical "final-resort" antibiotic for treating bacterial infections caused by multidrug-resistant bacteria for which treatment options are severely limited. The increasing prevalence of tigecycline resistance, particularly among Gram-negative bacteria, is a major concern. Various mechanisms have been identified as contributors to tigecycline resistance, including upregulation of nonspecific Resistance Nodulation Division (RND) efflux pumps due to mutations in transcriptional regulators, enzymatic modification of tigecycline by monooxygenase enzymes, and mutations affecting tigecycline binding sites. This review aims to consolidate our understanding of tigecycline resistance mechanisms in Gram-negative bacteria and offer insights and perspectives for further drug development. | 2024 | 39629109 |
| 9758 | 4 | 0.9979 | Study on collateral sensitivity of tigecycline to colistin-resistant Enterobacter cloacae complex. The past decade has witnessed the emergence and spread of carbapenem-resistant Enterobacter cloacae complex (CRECC), presenting a significant clinical challenge and urgently demanding new treatment strategies against antimicrobial resistance (AMR). This study focused on the impact of tigecycline on the susceptibility of CRECC isolates to colistin and the collateral sensitivity in CRECC. Under tigecycline pressure, the resistance of five clinically isolated CRECC strains to colistin was converted from resistance to sensitivity. These mutants exhibited significantly higher expression of acrA, acrB, and ramA genes, with mutations in the ramR gene. Overexpression of ramA in certain mutants did not alter ramR expression. No mutations were identified in lipid A synthesis genes; however, phoQ was consistently downregulated, and arnA expression varied among CRECC405-resistant mutants. Low-dose colistin and tigecycline combination therapy outperformed monotherapy in antimicrobial efficacy. Overall, collateral susceptibility to tigecycline was observed in CRECC isolates with colistin resistance. The overexpression of acrA, acrB, and ramA, due to ramR mutations, led to tigecycline resistance. Inconsistent expression levels of lipid A synthesis genes affected lipid A modification, which in turn upregulated arnA expression in CRECC405-resistant mutants. Increased sensitivity to colistin was associated with the downregulation of phoQ and arnA expression. IMPORTANCE: Antimicrobial resistance (AMR) is escalating faster than our ability to manage bacterial infections, with antibiotic-resistant bacteria emerging as a significant public health risk. Innovative strategies are urgently needed to curb AMR dissemination. Our research identified collateral sensitivity in Enterobacter cloacae complex following tigecycline (TGC) resistance, resulting in newfound sensitivity to colistin (COL), a drug to which it was once resistant. Synergistic tigecycline and colistin therapy significantly suppress bacterial growth, offering a promising approach to combat infections and curb AMR progression through the strategic pairing of antibiotics with complementary sensitivities. | 2025 | 40407373 |
| 9099 | 5 | 0.9979 | Small molecule downregulation of PmrAB reverses lipid A modification and breaks colistin resistance. Infections caused by multi-drug resistant bacteria, particularly Gram-negative bacteria, are an ever-increasing problem. While the development of new antibiotics remains one option in the fight against bacteria that have become resistant to currently available antibiotics, an attractive alternative is the development of adjuvant therapeutics that restore the efficacy of existing antibiotics. We report a small molecule adjuvant that suppresses colistin resistance in multidrug resistant Acinetobacter baumannii and Klebsiella pneumoniae by interfering with the expression of a two-component system. The compound downregulates the pmrCAB operon and reverses phosphoethanolamine modification of lipid A responsible for colistin resistance. Furthermore, colistin-susceptible and colistin-resistant bacteria do not evolve resistance to combination treatment. This represents the first definitive example of a compound that breaks antibiotic resistance by directly modulating two-component system activity. | 2014 | 24131198 |
| 9759 | 6 | 0.9979 | Rapid emergence of resistance to broad-spectrum direct antimicrobial activity of avibactam. Avibactam (AVI) is a diazabicyclooctane (DBO) β-lactamase inhibitor used clinically in combination with ceftazidime. At concentrations higher than those typically achieved in vivo, it also has broad-spectrum direct antibacterial activity against Enterobacterales strains, including metallo-β-lactamase-producing isolates, mediated by inhibition of penicillin-binding protein 2 (PBP2). This activity has some mechanistic similarities to that of more potent novel DBOs (zidebactam and nacubactam) in late clinical development. We found that resistance to AVI emerged readily, with a mutation frequency of 2 × 10(-6) to 8 × 10(-5). Whole-genome sequencing of resistant isolates revealed a heterogeneous mutational target that permitted bacterial survival and replication despite PBP2 inhibition, in line with prior studies of PBP2-targeting drugs. While such mutations are believed to act by upregulating the bacterial stringent response, we found a similarly high mutation frequency in bacteria deficient in components of the stringent response, although we observed a different set of mutations in these strains. Although avibactam-resistant strains had increased lag time, suggesting a fitness cost that might render them less problematic in clinical infections, there was no statistically significant difference in growth rates between susceptible and resistant strains. The finding of rapid emergence of resistance to avibactam as the result of a large and complex mutational target adds to our understanding of resistance to PBP2-targeting drugs and has potential implications for novel DBOs with potent direct antibacterial activity, which are being developed with the goal of expanding cell wall-active treatment options for multidrug-resistant gram-negative infections.IMPORTANCEAvibactam (AVI) is the first in a class of novel β-lactamase inhibitor antibiotics called diazabicyclooctanes (DBOs). In addition to its ability to inhibit bacterial β-lactamase enzymes that can destroy β-lactam antibiotics, we found that AVI had direct antibacterial activity, at concentrations higher than those used clinically, against even highly multidrug-resistant bacteria. This activity is the result of inhibition of the bacterial enzyme penicillin-binding protein 2 (PBP2). Resistance to other drugs that inhibit PBP2 occurs through mutations that involve upregulation of the bacterial "stringent response" to stress. We found that bacteria developed resistance to AVI at a high rate, as a result of mutations in stringent response genes. We also found that bacteria with impairments in the stringent response could still develop resistance to AVI through different mutations. Our findings indicate the importance of studying how resistance will emerge to newer, more potent DBOs in development and early clinical use. | 2025 | 40503840 |
| 4822 | 7 | 0.9978 | A Molecular Perspective on Colistin and Klebsiella pneumoniae: Mode of Action, Resistance Genetics, and Phenotypic Susceptibility. Klebsiella pneumoniae is a rod-shaped, encapsulated, Gram-negative bacteria associated with multiple nosocomial infections. Multidrug-resistant (MDR) K. pneumoniae strains have been increasing and the therapeutic options are increasingly limited. Colistin is a long-used, polycationic, heptapeptide that has regained attention due to its activity against Gram-negative bacteria, including the MDR K. pneumoniae strains. However, this antibiotic has a complex mode of action that is still under research along with numerous side-effects. The acquisition of colistin resistance is mainly associated with alteration of lipid A net charge through the addition of cationic groups synthesized by the gene products of a multi-genic regulatory network. Besides mutations in these chromosomal genes, colistin resistance can also be achieved through the acquisition of plasmid-encoded genes. Nevertheless, the diversity of molecular markers for colistin resistance along with some adverse colistin properties compromises the reliability of colistin-resistance monitorization methods. The present review is focused on the colistin action and molecular resistance mechanisms, along with specific limitations on drug susceptibility testing for K. pneumoniae. | 2021 | 34202395 |
| 9752 | 8 | 0.9978 | Engineered Phages and Engineered and Recombinant Endolysins Against Carbapenem-Resistant Gram-Negative Bacteria: A Focused Review on Novel Antibacterial Strategies. Antibiotic resistance has escalated globally, affecting not only commonly used antibiotics but also last-resort agents such as carbapenems and colistin. The rise of antibiotic-resistant bacteria has prompted microbiologists to devise new strategies, with bacteriophages emerging as one of the most promising options. Nevertheless, certain mechanisms have been identified in bacteria that confer resistance to phages. While phage resistance is currently less widespread than antibiotic resistance, challenges such as biofilm formation, newly emerging resistance mechanisms against phages, and the natural limitations of unmodified phages have driven the advancement of engineered phages. This study aims to examine the efficacy of engineered phages and both engineered and recombinant endolysins against carbapenem-resistant Gram-negative bacteria (CR-GNB). We performed a literature review through PubMed, Scopus, Web of Science, and Google Scholar, concentrating on studies that utilized these agents against carbapenem-resistant Gram-negative bacteria (CR-GNB). Reviewed studies indicate potential antibacterial activity of these agents against CR-GNB. By engineering and modifying phages, these agents exhibit improved antimicrobial efficacy, temperature stability, and membrane permeability. Furthermore, they demonstrate the ability to eliminate bacteria with multidrug-resistant (MDR) and extensively drug-resistant (XDR) profiles. These findings suggest the promising potential of engineered phages and endolysins for future clinical applications against CR-GNB. | 2025 | 40696543 |
| 9773 | 9 | 0.9978 | Cross resistance emergence to polymyxins in Acinetobacter baumannii exposed in vitro to an antimicrobial peptide. Multidrug-resistant bacteria are a growing public health concern. Antimicrobial peptides (AMPs) are proposed alternatives to classical antibiotics towards infections caused by resistant bacteria. TAT-RasGAP(317-326) is an AMP able to target Gram-negative bacteria and is especially efficient towards Acinetobacter baumannii. In this study, we performed in vitro resistance selection on several A. baumannii strains, in order to determine to which extent these bacteria can develop resistance to TAT-RasGAP(317-326). A. baumannii rapidly developed resistance to TAT-RasGAP(317-326) and subsequently, in approximately half of the cases, cross-resistance to last-resort polypeptidic antibiotics polymyxins. Cross-resistant isolates predominantly bore mutations in the pmrAB operon, involved in modulation of lipopolysaccharides' charge at the bacterial surface, similarly to polymyxin-resistant clinical isolates. We thus show here that contact of A. baumannii with an AMP structurally different from polymyxins can induce unexpected cross-resistance towards them. This indicates that precautions must be taken for the clinical application of AMPs. | 2025 | 40442488 |
| 9777 | 10 | 0.9978 | Colistin resistance in Acinetobacter baumannii is mediated by complete loss of lipopolysaccharide production. Infections caused by multidrug-resistant (MDR) Gram-negative bacteria represent a major global health problem. Polymyxin antibiotics such as colistin have resurfaced as effective last-resort antimicrobials for use against MDR Gram-negative pathogens, including Acinetobacter baumannii. Here we show that A. baumannii can rapidly develop resistance to polymyxin antibiotics by complete loss of the initial binding target, the lipid A component of lipopolysaccharide (LPS), which has long been considered to be essential for the viability of Gram-negative bacteria. We characterized 13 independent colistin-resistant derivatives of A. baumannii type strain ATCC 19606 and showed that all contained mutations within one of the first three genes of the lipid A biosynthesis pathway: lpxA, lpxC, and lpxD. All of these mutations resulted in the complete loss of LPS production. Furthermore, we showed that loss of LPS occurs in a colistin-resistant clinical isolate of A. baumannii. This is the first report of a spontaneously occurring, lipopolysaccharide-deficient, Gram-negative bacterium. | 2010 | 20855724 |
| 4881 | 11 | 0.9978 | Investigating colistin drug resistance: The role of high-throughput sequencing and bioinformatics. Bacterial infections involving antibiotic-resistant gram-negative bacteria continue to increase and represent a major global public health concern. Resistance to antibiotics in these bacteria is mediated by chromosomal and/or acquired resistance mechanisms, these give rise to multi-drug resistant (MDR), extensive-drug resistant (XDR) or pan-drug resistant (PDR) bacterial strains. Most recently, plasmid-mediated resistance to colistin, an antibiotic that had been set apart as the last resort antibiotic in the treatment of infections involving MDR, XDR and PDR gram-negative bacteria has been reported. Plasmid-mediated colistin resistant gram-negative bacteria have been described to be PDR, implying a state devoid of alternative antibiotic therapeutic options. This review concisely describes the evolution of antibiotic resistance to plasmid-mediated colistin resistance and discusses the potential role of high-throughput sequencing technologies, genomics, and bioinformatics towards improving antibiotic resistance surveillance, the search for novel drug targets and precision antibiotic therapy focused at combating colistin resistance, and antibiotic resistance as a whole. | 2019 | 31354944 |
| 9100 | 12 | 0.9978 | Unlocking the bacterial membrane as a therapeutic target for next-generation antimicrobial amphiphiles. Gram-positive bacteria like Enterococcus faecium and Staphylococcus aureus, and Gram-negative bacteria like Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter Spp. are responsible for most of fatal bacterial infections. Bacteria present a handful of targets like ribosome, RNA polymerase, cell wall biosynthesis, and dihydrofolate reductase. Antibiotics targeting the protein synthesis like aminoglycosides and tetracyclines, inhibitors of RNA/DNA synthesis like fluoroquinolones, inhibitors of cell wall biosynthesis like glycopeptides and β-lactams, and membrane-targeting polymyxins and lipopeptides have shown very good success in combating the bacterial infections. Ability of the bacteria to develop drug resistance is a serious public health challenge as bacteria can develop antimicrobial resistance against newly introduced antibiotics that enhances the challenge for antibiotic drug discovery. Therefore, bacterial membranes present a suitable therapeutic target for development of antimicrobials as bacteria can find it difficult to develop resistance against membrane-targeting antimicrobials. In this review, we present the recent advances in engineering of membrane-targeting antimicrobial amphiphiles that can be effective alternatives to existing antibiotics in combating bacterial infections. | 2021 | 34325929 |
| 4866 | 13 | 0.9978 | Resistance to polymyxins in Gram-negative organisms. Polymyxins have recently been re-introduced into the therapeutic arsenal to combat infections caused by multidrug-resistant Gram-negative bacteria. However, the emergence of strains resistant to these last-resort drugs is becoming a critical issue in a growing number of countries. Both intrinsic and transferable mechanisms of polymyxin resistance have been characterised. These mechanisms as well as the epidemiological data regarding four relevant bacterial pathogens (Escherichia coli, Klebsiella pneumoniae, Acinetobacter baumannii and Pseudomonas aeruginosa) are considered in this review. A special focus is made on plasmid-mediated resistance and the spread of mcr genes. | 2017 | 28163137 |
| 9746 | 14 | 0.9978 | Fluoroamphiphilic polymers exterminate multidrug-resistant Gram-negative ESKAPE pathogens while attenuating drug resistance. ESKAPE pathogens are a panel of most recalcitrant bacteria that could "escape" the treatment of antibiotics and exhibit high incidence of drug resistance. The emergence of multidrug-resistant (MDR) ESKAPE pathogens (particularly Gram-negative bacteria) accounts for high risk of mortality and increased resource utilization in health care. Worse still, there has been no new class of antibiotics approved for exterminating the Gram-negative bacteria for more than 50 years. Therefore, it is urgent to develop novel antibacterial agents with low resistance and potent killing efficacy against Gram-negative ESKAPE pathogens. Herein, we present a class of fluoropolymers by mimicking the amphiphilicity of cationic antimicrobial peptides. Our optimal fluoroamphiphilic polymer (PD(45)HF(5)) displayed selective antimicrobial ability for all MDR Gram-negative ESAKPE pathogens, low resistance, high in vitro cell selectivity, and in vivo curative efficacy. These findings implied great potential of fluoroamphiphilic cationic polymers as promising antibacterial agents against MDR Gram-negative ESKAPE bacteria and alleviating antibiotic resistance. | 2024 | 39196947 |
| 9776 | 15 | 0.9978 | Mechanisms of polymyxin resistance: acquired and intrinsic resistance in bacteria. Polymyxins are polycationic antimicrobial peptides that are currently the last-resort antibiotics for the treatment of multidrug-resistant, Gram-negative bacterial infections. The reintroduction of polymyxins for antimicrobial therapy has been followed by an increase in reports of resistance among Gram-negative bacteria. Some bacteria, such as Klebsiella pneumoniae, Pseudomonas aeruginosa, and Acinetobacter baumannii, develop resistance to polymyxins in a process referred to as acquired resistance, whereas other bacteria, such as Proteus spp., Serratia spp., and Burkholderia spp., are naturally resistant to these drugs. Reports of polymyxin resistance in clinical isolates have recently increased, including acquired and intrinsically resistant pathogens. This increase is considered a serious issue, prompting concern due to the low number of currently available effective antibiotics. This review summarizes current knowledge concerning the different strategies bacteria employ to resist the activities of polymyxins. Gram-negative bacteria employ several strategies to protect themselves from polymyxin antibiotics (polymyxin B and colistin), including a variety of lipopolysaccharide (LPS) modifications, such as modifications of lipid A with phosphoethanolamine and 4-amino-4-deoxy-L-arabinose, in addition to the use of efflux pumps, the formation of capsules and overexpression of the outer membrane protein OprH, which are all effectively regulated at the molecular level. The increased understanding of these mechanisms is extremely vital and timely to facilitate studies of antimicrobial peptides and find new potential drugs targeting clinically relevant Gram-negative bacteria. | 2014 | 25505462 |
| 9756 | 16 | 0.9977 | Genomewide identification of genetic determinants of antimicrobial drug resistance in Pseudomonas aeruginosa. The emergence of antimicrobial drug resistance is of enormous public concern due to the increased risk of delayed treatment of infections, the increased length of hospital stays, the substantial increase in the cost of care, and the high risk of fatal outcomes. A prerequisite for the development of effective therapy alternatives is a detailed understanding of the diversity of bacterial mechanisms that underlie drug resistance, especially for problematic gram-negative bacteria such as Pseudomonas aeruginosa. This pathogen has impressive chromosomally encoded mechanisms of intrinsic resistance, as well as the potential to mutate, gaining resistance to current antibiotics. In this study we have screened the comprehensive nonredundant Harvard PA14 library for P. aeruginosa mutants that exhibited either increased or decreased resistance against 19 antibiotics commonly used in the clinic. This approach identified several genes whose inactivation sensitized the bacteria to a broad spectrum of different antimicrobials and uncovered novel genetic determinants of resistance to various classes of antibiotics. Knowledge of the enhancement of bacterial susceptibility to existing antibiotics and of novel resistance markers or modifiers of resistance expression may lay the foundation for effective therapy alternatives and will be the basis for the development of new strategies in the control of problematic multiresistant gram-negative bacteria. | 2009 | 19332674 |
| 4823 | 17 | 0.9977 | A Review of Resistance to Polymyxins and Evolving Mobile Colistin Resistance Gene (mcr) among Pathogens of Clinical Significance. The global rise in antibiotic resistance in bacteria poses a major challenge in treating infectious diseases. Polymyxins (e.g., polymyxin B and colistin) are last-resort antibiotics against resistant Gram-negative bacteria, but the effectiveness of polymyxins is decreasing due to widespread resistance among clinical isolates. The aim of this literature review was to decipher the evolving mechanisms of resistance to polymyxins among pathogens of clinical significance. We deciphered the molecular determinants of polymyxin resistance, including distinct intrinsic molecular pathways of resistance as well as evolutionary characteristics of mobile colistin resistance. Among clinical isolates, Acinetobacter stains represent a diversified evolution of resistance, with distinct molecular mechanisms of intrinsic resistance including naxD, lpxACD, and stkR gene deletion. On the other hand, Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa are usually resistant via the PhoP-PhoQ and PmrA-PmrB pathways. Molecular evolutionary analysis of mcr genes was undertaken to show relative relatedness across the ten main lineages. Understanding the molecular determinants of resistance to polymyxins may help develop suitable and effective methods for detecting polymyxin resistance determinants and the development of novel antimicrobial molecules. | 2023 | 37998799 |
| 9940 | 18 | 0.9977 | Resensitizing tigecycline- and colistin-resistant Escherichia coli using an engineered conjugative CRISPR/Cas9 system. Tigecycline and colistin were referred to as the "last resort" antibiotics in defending against carbapenem-resistant, Gram-negative bacterial infections, and are currently widely used in clinical treatment. However, the emergence and prevalence of plasmid-mediated tet(X4) and mcr-1 genes pose a serious threat to the therapeutic application of tigecycline and colistin, respectively. In this research, a tigecycline- and colistin-resistant bacteria resensitization system was developed based on efficient and specific DNA damage caused by Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)-Associated Protein 9 (Cas9) nucleases. A conjugation method was used to deliver the resensitization system, which harbors two single-guide RNAs targeting tet(X4) and mcr-1 genes and constitutively expressed Cas9. The conjugation efficiency was nearly 100% after conjugation condition optimization in vitro, and the resensitivity efficiency for clinical isolates was over 90%. In addition, when performing resensitization in vivo, the resistance marker was replaced with a glutamate-based, chromosomal, plasmid-balanced lethal system to prevent the introduction of additional resistance genes in clinical settings, making this strategy a therapeutic approach to combat the in vivo spread of antibiotic resistance genes (ARGs) among bacterial pathogens. As a proof of concept, this resensitive system can significantly decrease the counts of tigecycline- and colistin-resistant bacteria to 1% in vivo. Our study demonstrates the efficacy and adaptability of CRISPR-Cas systems as powerful and programmable antimicrobials in resensitizing tet(X4)- and mcr-1-mediated, tigecycline- and colistin-resistant strains, and opens up new pathways for the development of CRISPR-based tools for selective bacterial pathogen elimination and precise microbiome composition change. IMPORTANCE: The emergence of plasmid-encoded tet(X4) and mcr-1 isolated from human and animal sources has affected the treatment of tigecycline and colistin, and has posed a significant threat to public health. Tigecycline and colistin are considered as the "last line of defense" for the treatment of multidrug-resistant (MDR) Gram-negative bacterial infections, so there is an urgent need to find a method that can resensitize tet(X4)-mediated tigecycline-resistant and mcr-1-mediated colistin-resistant bacteria. In this study, we developed a glutamate-based, chromosomal, plasmid-balanced lethal conjugative CRISPR/Cas9 system, which can simultaneously resensitize tet(X4)-mediated tigecycline-resistant and mcr-1-mediated colistin-resistant Escherichia coli. The counts of tigecycline- and colistin-resistant bacteria decreased to 1% in vivo after the resensitization system was administered. This study opens up new pathways for the development of CRISPR-based tools for selective bacterial pathogen elimination and precise microbiome composition change. | 2024 | 38385691 |
| 9927 | 19 | 0.9977 | Induction of beta-lactamase enzymes: clinical applications for the obstetric-gynecologic patient. The emergence of bacteria resistant to antibiotics has resulted in intensive research for new and improved beta-lactam antibiotics. Many improvements in antimicrobial agents are based on a knowledge of the mechanism responsible for resistance. This has led to the development of new extended-spectrum antibiotic compounds. However, several features have been noted since the development of extended-spectrum antibiotics, such as the rapid development of bacterial resistance, the induction of beta-lactamase enzyme activity by these stable antibiotics, failure to detect induced enzyme activity and resistance in the laboratory, and beta-lactam antagonism. The resistance of bacteria to antimicrobial agents has obvious impact on the selection of appropriate therapy against infections caused by these pathogens. Gram-negative anaerobic bacteria, such as Bacteroides fragilis and Bacteroides bivius, are organisms frequently recovered from women whose initial therapy for pelvic infection failed. The transfer of antimicrobial resistance in bacteria indicates that these organisms have a system for the spread of such resistance. Therefore determination of antimicrobial susceptibilities and prompt eradication of isolates from infected patients are necessary to delay the emergence of resistant organisms. | 1987 | 3548378 |