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905100.9901Chlorogenic acid inhibits virulence and resistance gene transfer in outer membrane vesicles of carbapenem-resistant Klebsiella pneumoniae. INTRODUCTION: Carbapenem-resistant Klebsiella pneumoniae (CRKp) infection poses a significant global public health challenge, with the misuse of antibiotics further contributing to the development of resistance and triggering harmful inflammatory responses. Outer membrane vesicles (OMVs) released by CRKp under sub-lethal concentration of MEM pressure (KOMV-MEM) exhibit enhanced virulence and greater efficiency in transferring resistance genes. METHODS: We investigated the inhibitory effects of chlorogenic acid (CA) on KOMV-MEM characteristics and its protective role in KOMV-MEM infected mice. Based on LC-MS proteomic analysis of vesicles, we screened for potential targets of KOMV-MEM in promoting macrophage (MØ) pyroptosis pathways and inducing resistance gene transfer. Subsequently, computational predictions and experimental validation were performed to determine how CA regulates these mechanisms. RESULTS: This study confirmed that, under MEM pressure, the exacerbated infection levels in CRKp-inoculated mice are attributable to the high virulence of KOMV-MEM. Computational and experimental results demonstrated that CA inhibits pyroptosis by reducing MØ capture of KOMV-MEM through blocking the interaction between GroEL and LOX-1. Furthermore, CA prevents the spread of resistance genes by disrupting the conjugation and transfer processes between KOMV-MEM and recipient bacteria. Finally, in vitro and in vivo assays showed that CA inhibits KOMV-MEM resistance enzymes, thereby preventing the hydrolysis of MEM in the environment and depriving susceptible bacteria of protection. DISCUSSION: These findings provide the first confirmation that CA can inhibit both the virulence and the transmission of drug resistance in KOMV-MEM. This underscores the potential of CA treatment as a promising antimicrobial strategy against CRKp infection.202540230687
976510.9897Daunorubicin resensitizes Gram-negative superbugs to the last-line antibiotics and prevents the transmission of antibiotic resistance. Although meropenem, colistin, and tigecycline are recognized as the last-line antibiotics for multidrug-resistant Gram-negative bacteria (MDR-GN), the emergence of mobile resistance genes such as bla(NDM), mcr, and tet(X) severely compromises their clinical effectiveness. Developing novel antibiotic adjuvants to restore the effectiveness of existing antibiotics provides a feasible approach to address this issue. Herein, we discover that a Food and Drug Administration (FDA)-approved drug daunorubicin (DNR) drastically potentiates the activity of last-resort antibiotics against MDR-GN pathogens and biofilm-producing bacteria. Furthermore, DNR effectively inhibits the evolution and spread of colistin and tigecycline resistance. Mechanistically, DNR and colistin combination exacerbates membrane disruption, induces DNA damage and the massive production of reactive oxygen species (ROS), ultimately leading to bacterial cell death. Importantly, DNR restores the effectiveness of colistin in Galleria mellonella and murine models of infection. Collectively, our findings provide a potential drug combination strategy for treating severe infections elicited by Gram-negative superbugs.202337235051
249320.9896Multidrug-resistant hypervirulent Klebsiella pneumoniae: an evolving superbug. Multidrug-resistant hypervirulent Klebsiella pneumoniae (MDR-hvKP) combines high pathogenicity with multidrug resistance to become a new superbug. MDR-hvKP reports continue to emerge, shattering the perception that hypervirulent K. pneumoniae (hvKP) strains are antibiotic sensitive. Patients infected with MDR-hvKP strains have been reported in Asia, particularly China. Although hvKP can acquire drug resistance genes, MDR-hvKP seems to be more easily transformed from classical K. pneumoniae (cKP), which has a strong gene uptake ability. To better understand the biology of MDR-hvKP, this review discusses the virulence factors, resistance mechanisms, formation pathways, and identification of MDR-hvKP. Given their destructive and transmissible potential, continued surveillance of these organisms and enhanced control measures should be prioritized.202540135944
883630.9895Identification of an anti-virulence drug that reverses antibiotic resistance in multidrug resistant bacteria. The persistent incidence of high levels of multidrug-resistant (MDR) bacteria seriously endangers global public health. In response to MDR-associated infections, new antibacterial drugs and strategies are particularly needed. Screening to evaluate a potential compound to reverse antibiotic resistance is a good strategy to alleviate this crisis. In this paper, using high-throughput screening methods, we identified that oxyclozanide potentiated tetracycline antibiotics act against MDR bacterial pathogens by promoting intracellular accumulation of tetracycline in resistant bacteria. Furthermore, mechanistic studies demonstrated that oxyclozanide could directly kill bacteria by disrupting bacterial membrane and inducing the overproduction of bacterial reactive oxygen species. Oxyclozanide effectively reduced the production of virulence proteins in S. aureus and neutralized the produced α-hemolysin, thereby effectively alleviating the inflammatory response caused by bacteria. Finally, oxyclozanide significantly reversed tetracycline resistance in animal infection assays. In summary, these results demonstrated the capacity of oxyclozanide as a novel antibiotic adjuvant, antibacterial and anti-virulence multifunctional compound to circumvent MDR bacteria and improve the therapeutic effect of persistent infections caused by MDR bacteria worldwide.202235797943
883540.9893Resistance Mechanism and Physiological Effects of Microcin Y in Salmonella enterica subsp. enterica Serovar Typhimurium. Salmonella bacteria pose a significant threat to animal husbandry and human health due to their virulence and multidrug resistance. The lasso peptide MccY is a recently discovered antimicrobial peptide that acts against various serotypes of Salmonella. In this study, we further explore the resistance mechanism and activity of MccY. Mutants of Ton system genes, including tonB, exbB, and exbD, in Salmonella enterica subsp. enterica serovar Typhimurium were constructed, and the MICs to MccY exhibited significant increases in these deletion mutants compared to the MIC of the parent strain. Subsequently, MccY resistance was quantitatively analyzed, and these mutants also showed greatly reduced rates of killing, even with a high concentration of MccY. In addition, a minimal medium with low iron environment enhanced the sensitivity of these mutants to MccY. Measurements of a series of physiological indicators, including iron utilization, biofilm formation, and motility, demonstrated that MccY may decrease the virulence of S. Typhimurium. Transcriptomic analysis showed that iron utilization, biofilm formation, flagellar assembly, and virulence-related genes were downregulated to varying degrees when S. Typhimurium was treated with MccY. In conclusion, deletion of Ton system genes resulted in resistance to MccY and the susceptibility of these mutants to MccY was increased and differed under a low-iron condition. This lasso peptide can alter multiple physiological properties of S. Typhimurium. Our study will contribute to improve the knowledge and understanding of the mechanism of MccY resistance in Salmonella strains. IMPORTANCE The resistance of Salmonella to traditional antibiotics remains a serious challenge. Novel anti-Salmonella drugs are urgently needed to address the looming crisis. The newly identified antimicrobial peptide MccY shows broad prospects for development and application because of its obvious antagonistic effect on various serotypes of Salmonella. However, our previous study showed that the peptide could confer resistance to Salmonella by disrupting the receptor gene fhuA. In this study, we further explored the potential resistance mechanism of MccY and demonstrated the importance of the Salmonella Ton complex for MccY transport. Disruption in Ton system genes resulted in S. Typhimurium resistance to this peptide, and MccY could alter multiple bacterial physiological properties. In summary, this study further explored the resistance mechanism and antibacterial effect of MccY in S. Typhimurium and provided a scientific basis for its development and application.202236453909
922150.9892Breaking antimicrobial resistance by disrupting extracytoplasmic protein folding. Antimicrobial resistance in Gram-negative bacteria is one of the greatest threats to global health. New antibacterial strategies are urgently needed, and the development of antibiotic adjuvants that either neutralize resistance proteins or compromise the integrity of the cell envelope is of ever-growing interest. Most available adjuvants are only effective against specific resistance proteins. Here, we demonstrate that disruption of cell envelope protein homeostasis simultaneously compromises several classes of resistance determinants. In particular, we find that impairing DsbA-mediated disulfide bond formation incapacitates diverse β-lactamases and destabilizes mobile colistin resistance enzymes. Furthermore, we show that chemical inhibition of DsbA sensitizes multidrug-resistant clinical isolates to existing antibiotics and that the absence of DsbA, in combination with antibiotic treatment, substantially increases the survival of Galleria mellonella larvae infected with multidrug-resistant Pseudomonas aeruginosa. This work lays the foundation for the development of novel antibiotic adjuvants that function as broad-acting resistance breakers.202235025730
482160.9891Enterobacter hormaechei replaces virulence with carbapenem resistance via porin loss. Pathogenic Enterobacter species are of increasing clinical concern due to the multidrug-resistant nature of these bacteria, including resistance to carbapenem antibiotics. Our understanding of Enterobacter virulence is limited, hindering the development of new prophylactics and therapeutics targeting infections caused by Enterobacter species. In this study, we assessed the virulence of contemporary clinical Enterobacter hormaechei isolates in a mouse model of intraperitoneal infection and used comparative genomics to identify genes promoting virulence. Through mutagenesis and complementation studies, we found two porin-encoding genes, ompC and ompD, to be required for E. hormaechei virulence. These porins imported clinically relevant carbapenems into the bacteria, and thus loss of OmpC and OmpD desensitized E. hormaechei to the antibiotics. Our genomic analyses suggest porin-related genes are frequently mutated in E. hormaechei, perhaps due to the selective pressure of antibiotic therapy during infection. Despite the importance of OmpC and OmpD during infection of immunocompetent hosts, we found the two porins to be dispensable for virulence in a neutropenic mouse model. Moreover, porin loss provided a fitness advantage during carbapenem treatment in an ex vivo human whole blood model of bacteremia. Our data provide experimental evidence of pathogenic Enterobacter species gaining antibiotic resistance via loss of porins and argue antibiotic therapy during infection of immunocompromised patients is a conducive environment for the selection of porin mutations enhancing the multidrug-resistant profile of these pathogens.202539977318
980770.9890Multi-label classification for multi-drug resistance prediction of Escherichia coli. Antimicrobial resistance (AMR) is a global health and development threat. In particular, multi-drug resistance (MDR) is increasingly common in pathogenic bacteria. It has become a serious problem to public health, as MDR can lead to the failure of treatment of patients. MDR is typically the result of mutations and the accumulation of multiple resistance genes within a single cell. Machine learning methods have a wide range of applications for AMR prediction. However, these approaches typically focus on single drug resistance prediction and do not incorporate information on accumulating antimicrobial resistance traits over time. Thus, identifying multi-drug resistance simultaneously and rapidly remains an open challenge. In our study, we could demonstrate that multi-label classification (MLC) methods can be used to model multi-drug resistance in pathogens. Importantly, we found the ensemble of classifier chains (ECC) model achieves accurate MDR prediction and outperforms other MLC methods. Thus, our study extends the available tools for MDR prediction and paves the way for improving diagnostics of infections in patients. Furthermore, the MLC methods we introduced here would contribute to reducing the threat of antimicrobial resistance and related deaths in the future by improving the speed and accuracy of the identification of pathogens and resistance.202235317240
975880.9890Study 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.202540407373
976790.9890Metallo-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.202540505900
9772100.9890Naringenin Microsphere as a Novel Adjuvant Reverses Colistin Resistance via Various Strategies against Multidrug-Resistant Klebsiella pneumoniae Infection. The efficacy of colistin, the last option against multidrug-resistant (MDR) Gram-negative bacteria, is severely threatened by the prevalence of plasmid- or chromosome-mediated colistin resistance genes. Herein, naringenin has dramatically restored colistin sensitivity against colistin-resistant Klebsiella pneumoniae infection without affecting bacterial viability, inducing resistance and causing obvious cell toxicity. Mechanism analysis reveals that naringenin potentiates colistin activity by multiple strategies including inhibition of mobilized colistin resistance gene activity, repression of two-component system regulation, and acceleration of reactive oxygen species-mediated oxidative damage. A lung-targeted delivery system of naringenin microspheres has been designed to facilitate naringenin bioavailability, accompanied by an effective potentiation of colistin for Klebsiella pneumoniae infection. Consequently, a new recognition of naringenin microspheres has been elucidated to restore colistin efficacy against colistin-resistant Gram-negative pathogens, which may be an effective strategy of developing potential candidates for MDR Gram-negative bacteria infection.202236530172
8403110.9889Uncovering virulence factors in Cronobacter sakazakii: insights from genetic screening and proteomic profiling. The increasing problem of antibiotic resistance has driven the search for virulence factors in pathogenic bacteria, which can serve as targets for the development of new antibiotics. Although whole-genome Tn5 transposon mutagenesis combined with phenotypic assays has been a widely used approach, its efficiency remains low due to labor-intensive processes. In this study, we aimed to identify specific genes and proteins associated with the virulence of Cronobacter sakazakii, a pathogenic bacterium known for causing severe infections, particularly in infants and immunocompromised individuals. By employing a combination of genetic screening, comparative proteomics, and in vivo validation using zebrafish and rat models, we rapidly screened highly virulent strains and identified two genes, rcsA and treR, as potential regulators of C. sakazakii toxicity toward zebrafish and rats. Proteomic profiling revealed upregulated proteins upon knockout of rcsA and treR, including FabH, GshA, GppA, GcvH, IhfB, RfaC, MsyB, and three unknown proteins. Knockout of their genes significantly weakened bacterial virulence, confirming their role as potential virulence factors. Our findings contribute to understanding the pathogenicity of C. sakazakii and provide insights into the development of targeted interventions and therapies against this bacterium.IMPORTANCEThe emergence of antibiotic resistance in pathogenic bacteria has become a critical global health concern, necessitating the identification of virulence factors as potential targets for the development of new antibiotics. This study addresses the limitations of conventional approaches by employing a combination of genetic screening, comparative proteomics, and in vivo validation to rapidly identify specific genes and proteins associated with the virulence of Cronobacter sakazakii, a highly pathogenic bacterium responsible for severe infections in vulnerable populations. The identification of two genes, rcsA and treR, as potential regulators of C. sakazakii toxicity toward zebrafish and rats and the proteomic profiling upon knockout of rcsA and treR provides novel insights into the mechanisms underlying bacterial virulence. The findings contribute to our understanding of C. sakazakii's pathogenicity, shed light on the regulatory pathways involved in bacterial virulence, and offer potential targets for the development of novel interventions against this highly virulent bacterium.202337750707
8381120.9889The Klebsiella pneumoniae tellurium resistance gene terC contributes to both tellurite and zinc resistance. Klebsiella pneumoniae is widely recognized as a pathogen responsible for hospital-acquired infections and community-acquired invasive infections. It has rapidly become a significant global public health threat due to the emergence of hypervirulent and multidrug-resistant strains, which have increased the challenges associated with treating life-threatening infections. Tellurium resistance genes are widespread on virulence plasmids in K. pneumoniae isolates. However, the core function of the ter operon (terZABCDEF) in K. pneumoniae remains unclear. In this study, the multidrug-resistant K. pneumoniae P1927 strain was isolated from the sputum of a hospitalized pneumonia patient. The ter operon, along with antimicrobial resistance and virulence genes, was identified on a large hybrid plasmid in K. pneumoniae P1927. We generated a terC deletion mutant and demonstrated that this mutant exhibited reduced virulence in a Galleria mellonella larva infection model. Further physiological functional analysis revealed that terC is not only important for Te(IV) resistance but also for resistance to Zn(II), Mn(II), and phage infection. All genes of the ter operon were highly inducible by Zn(II), which is a stronger inducer than Te(IV), and the terBCDE genes were also induced by Mn(II). Collectively, our study demonstrates novel physiological functions of TerC in Zn(II) resistance and virulence in K. pneumoniae.IMPORTANCEKlebsiella pneumoniae has rapidly become a global threat to public health. Although the ter operon is widely identified in clinical isolates, its physiological function remains unclear. It has been proposed that proteins encoded by the ter operon form a multi-site metal-binding complex, but its exact function is still unknown. TerC, a central component of the tellurium resistance determinant, was previously shown to interact with outer membrane proteins OmpA and KpsD in Escherichia coli, suggesting potential changes in outer membrane structure and properties. Here, we report that TerC confers resistance to Zn(II), Mn(II), and phage infection, and Zn(II) was shown to be a strong inducer of the ter operon. Furthermore, TerC was identified as a novel virulence factor. Taken together, our results expand our understanding of the physiological functions encoded by the ter operon and its role in the virulence of K. pneumoniae, providing deeper insights into the link between heavy metal(loid) resistance determinants and virulence in pathogenic bacteria.202540202338
8837130.9888Phage resistance formation and fitness costs of hypervirulent Klebsiella pneumoniae mediated by K2 capsule-specific phage and the corresponding mechanisms. INTRODUCTION: Phage is promising for the treatment of hypervirulent Klebsiella pneumoniae (hvKP) infections. Although phage resistance seems inevitable, we found that there still was optimization space in phage therapy for hvKP infection. METHODS: The clinical isolate K. pneumoniae FK1979 was used to recover the lysis phage ΦFK1979 from hospital sewage. Phage-resistant bacteria were obtained on LB agar and used to isolate phages from sewage. The plaque assay, transmission electron microscopy (TEM), multiplicity of infection test, one-step growth curve assay, and genome analysis were performed to characterize the phages. Colony morphology, precipitation test and scanning electron microscope were used to characterize the bacteria. The absorption test, spot test and efficiency of plating (EOP) assay were used to identify the sensitivity of bacteria to phages. Whole genome sequencing (WGS) was used to identify gene mutations of phage-resistant bacteria. The gene expression levels were detected by RT-qPCR. Genes knockout and complementation of the mutant genes were performed. The change of capsules was detected by capsule quantification and TEM. The growth kinetics, serum resistance, biofilm formation, adhesion and invasion to A549 and RAW 264.7 cells, as well as G. mellonella and mice infection models, were used to evaluate the fitness and virulence of bacteria. RESULTS AND DISCUSSION: Here, we demonstrated that K2 capsule type sequence type 86 hvKP FK1979, one of the main pandemic lineages of hvKP with thick capsule, rapidly developed resistance to a K2-specific lysis phage ΦFK1979 which was well-studied in this work to possess polysaccharide depolymerase. The phage-resistant mutants showed a marked decrease in capsule expression. WGS revealed single nucleotide polymorphism (SNP) in genes encoding RfaH, galU, sugar glycosyltransferase, and polysaccharide deacetylase family protein in the mutants. RfaH and galU were further identified as being required for capsule production and phage sensitivity. Expressions of genes involved in the biosynthesis or regulation of capsule and/or lipopolysaccharide significantly decreased in the mutants. Despite the rapid and frequent development of phage resistance being a disadvantage, the attenuation of virulence and fitness in vitro and in vivo indicated that phage-resistant mutants of hvKP were more susceptible to the immunity system. Interestingly, the newly isolated phages targeting mutants changed significantly in their plaque and virus particle morphology. Their genomes were much larger than and significantly different from that of ΦFK1979. They possessed much more functional proteins and strikingly broader host spectrums than ΦFK1979. Our study suggests that K2-specific phage has the potential to function as an antivirulence agent, or a part of phage cocktails combined with phages targeting phage-resistant bacteria, against hvKP-relevant infections.202337538841
5183140.9888Development of phage resistance in multidrug-resistant Klebsiella pneumoniae is associated with reduced virulence: a case report of a personalised phage therapy. OBJECTIVES: Phage-resistant bacteria often emerge rapidly when performing phage therapy. However, the relationship between the emergence of phage-resistant bacteria and improvements in clinical symptoms is still poorly understood. METHODS: An inpatient developed a pulmonary infection caused by multidrug-resistant Klebsiella pneumoniae. He received a first course of treatment with a single nebulized phage (ΦKp_GWPB35) targeted at his bacterial isolate of Kp7450. After 14 days, he received a second course of treatment with a phage cocktail (ΦKp_GWPB35+ΦKp_GWPA139). Antibiotic treatment was continued throughout the course of phage therapy. Whole-genome analysis was used to identify mutations in phage-resistant strains. Mutated genes associated with resistance were further analysed by generating knockouts of Kp7450 and by measuring phage adsorption rates of bacteria treated with proteinase K and periodate. Bacterial virulence was evaluated in mouse and zebrafish infection models. RESULTS: Phage-resistant Klebsiella pneumoniae strains emerged after the second phage treatment. Comparative genomic analyses revealed that fabF was deleted in phage-resistant strains. The fabF knockout strain (Kp7450ΔfabF) resulted in an altered structure of lipopolysaccharide (LPS), which was identified as the host receptor for the therapeutic phages. Virulence evaluations in mice and zebrafish models showed that LPS was the main determinant of virulence in Kp7450 and alteration of LPS structure in Kp7450ΔfabF, and the bacteriophage-resistant strains reduced their virulence at cost. DISCUSSION: This study may shed light on the mechanism by which some patients experience clinical improvement in their symptoms post phage therapy, despite the incomplete elimination of pathogenic bacteria.202337652124
8857150.9888Colistin-phage combinations decrease antibiotic resistance in Acinetobacter baumannii via changes in envelope architecture. Multidrug-resistant bacterial infections are becoming increasingly common, with only few last-resort antibiotics such as colistin available for clinical therapy. An alternative therapeutic strategy gaining momentum is phage therapy, which has the advantage of not being affected by bacterial resistance to antibiotics. However, a major challenge in phage therapy is the rapid emergence of phage-resistant bacteria. In this work, our main aim was to understand the mechanisms of phage-resistance used by the top priority pathogen Acinetobacter baumannii. We isolated the novel phage Phab24, capable of infecting colistin-sensitive and -resistant strains of A. baumannii. After co-incubating Phab24 with its hosts, we obtained phage-resistant mutants which were characterized on both genotypic and phenotypic levels. Using whole genome sequencing, we identified phage-resistant strains that displayed mutations in genes that alter the architecture of the bacterial envelope at two levels: the capsule and the outer membrane. Using an adsorption assay, we confirmed that phage Phab24 uses the bacterial capsule as its primary receptor, with the outer membrane possibly serving as the secondary receptor. Interestingly, the phage-resistant isolates were less virulent compared to the parental strains in a Galleria mellonella infection model. Most importantly, we observed that phage-resistant bacteria that evolved in the absence of antibiotics exhibited an increased sensitivity to colistin, even though the antibiotic resistance mechanism per se remained unaltered. This increase in antibiotic sensitivity is a direct consequence of the phage-resistance mechanism, and could potentially be exploited in the clinical setting.202134736365
9099160.9888Small 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.201424131198
8867170.9888Hfq plays important roles in virulence and stress adaptation in Cronobacter sakazakii ATCC 29544. Cronobacter spp. are opportunistic pathogens that cause neonatal meningitis and sepsis with high mortality in neonates. Despite the peril associated with Cronobacter infection, the mechanisms of pathogenesis are still being unraveled. Hfq, which is known as an RNA chaperone, participates in the interaction with bacterial small RNAs (sRNAs) to regulate posttranscriptionally the expression of various genes. Recent studies have demonstrated that Hfq contributes to the pathogenesis of numerous species of bacteria, and its roles are varied between bacterial species. Here, we tried to elucidate the role of Hfq in C. sakazakii virulence. In the absence of hfq, C. sakazakii was highly attenuated in dissemination in vivo, showed defects in invasion (3-fold) into animal cells and survival (10(3)-fold) within host cells, and exhibited low resistance to hydrogen peroxide (10(2)-fold). Remarkably, the loss of hfq led to hypermotility on soft agar, which is contrary to what has been observed in other pathogenic bacteria. The hyperflagellated bacteria were likely to be attributable to the increased transcription of genes associated with flagellar biosynthesis in a strain lacking hfq. Together, these data strongly suggest that hfq plays important roles in the virulence of C. sakazakii by participating in the regulation of multiple genes.201525754196
8838180.9887Dual RNA-seq analysis reveals the interaction between multidrug-resistant Klebsiella pneumoniae and host in a mouse model of pneumonia. BACKGROUND: Multidrug-resistant Klebsiella pneumoniae (MDR-KP) poses a significant global health threat, associated with high morbidity and mortality rates among hospitalized patients. The interaction between MDR-KP and its host is highly complex, and few studies have investigated these interactions from both the pathogen and host perspectives. Here, we explored these interactions in a mouse model of pneumonia using dual RNA-seq analysis. METHODS: PCR identification and antimicrobial susceptibility test were employed to screen for MDR-KP strains. A mouse model of pneumonia was established through aerosolized intratracheal inoculation with high-dose or low-dose bacteria. Bacterial loads, pathological changes, inflammatory cytokine expression, and immune cell infiltration were assessed post-challenge. Dual RNA-seq analysis was conducted on lung tissues following infection. RESULTS: NY13307 was identified as an MDR-KP strain with minimal virulence factor genes and broad-spectrum drug resistance. High-dose bacteria induced more severe pulmonary pathological changes, a significant increase in bacterial load, and notably elevated secretion of inflammatory cytokines compared to low-dose bacteria. Alveolar macrophages and resident interstitial macrophages were identified as the primary sources of these cytokines. Further RNA-seq analysis revealed that, compared to the low-dose group, the high-dose group significantly upregulated hypoxia and pro-inflammatory cytokine-related genes in the host, and siderophore-related genes in the bacteria. Correlation analysis demonstrated a significant association between siderophore-related genes and clusters of genes related to pro-inflammatory cytokines and hypoxia. CONCLUSIONS: In this mouse model of bacterial pneumonia, excessive siderophore expression may trigger the activation of hypoxia signaling pathways and the release of pro-inflammatory cytokines, ultimately reducing survival rates.202540702458
9220190.9886Pathogen virulence genes: Advances, challenges and future directions in infectious disease research (Review). Pathogens, including bacteria, viruses and fungi, employ virulence genes to invade their hosts, circumvent immunity and induce diseases. The present review examines the categorization and regulatory mechanisms of virulence genes and their co‑evolution with antimicrobial resistance. The present review focused on the fimbrial adhesion H adhesion gene of Escherichia coli, the spike protein gene of severe acute respiratory syndrome coronavirus 2 and the enhanced filamentous growth protein 1 (EFG1) morphological transition gene of Candida albicans, as well as their roles in host adhesion, immune evasion and tissue damage. Application of technologies, including multi‑omics integration, artificial intelligence and CRISPR‑based genome editing, is discussed in the context of precision diagnostics, targeted therapy and vaccine development. By elucidating pathogen adaptation dynamics and host‑pathogen interactions, the present review offers a basis for reducing the global burden of drug‑resistant infections through improved surveillance and personalized interventions.202540849821