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908600.9889Emergence and selection of isoniazid and rifampin resistance in tuberculosis granulomas. Drug resistant tuberculosis is increasing world-wide. Resistance against isoniazid (INH), rifampicin (RIF), or both (multi-drug resistant TB, MDR-TB) is of particular concern, since INH and RIF form part of the standard regimen for TB disease. While it is known that suboptimal treatment can lead to resistance, it remains unclear how host immune responses and antibiotic dynamics within granulomas (sites of infection) affect emergence and selection of drug-resistant bacteria. We take a systems pharmacology approach to explore resistance dynamics within granulomas. We integrate spatio-temporal host immunity, INH and RIF dynamics, and bacterial dynamics (including fitness costs and compensatory mutations) in a computational framework. We simulate resistance emergence in the absence of treatment, as well as resistance selection during INH and/or RIF treatment. There are four main findings. First, in the absence of treatment, the percentage of granulomas containing resistant bacteria mirrors the non-monotonic bacterial dynamics within granulomas. Second, drug-resistant bacteria are less frequently found in non-replicating states in caseum, compared to drug-sensitive bacteria. Third, due to a steeper dose response curve and faster plasma clearance of INH compared to RIF, INH-resistant bacteria have a stronger influence on treatment outcomes than RIF-resistant bacteria. Finally, under combination therapy with INH and RIF, few MDR bacteria are able to significantly affect treatment outcomes. Overall, our approach allows drug-specific prediction of drug resistance emergence and selection in the complex granuloma context. Since our predictions are based on pre-clinical data, our approach can be implemented relatively early in the treatment development process, thereby enabling pro-active rather than reactive responses to emerging drug resistance for new drugs. Furthermore, this quantitative and drug-specific approach can help identify drug-specific properties that influence resistance and use this information to design treatment regimens that minimize resistance selection and expand the useful life-span of new antibiotics.201829746491
249510.9886Transmission of Mobile Colistin Resistance (mcr-1) by Duodenoscope. BACKGROUND: Clinicians increasingly utilize polymyxins for treatment of serious infections caused by multidrug-resistant gram-negative bacteria. Emergence of plasmid-mediated, mobile colistin resistance genes creates potential for rapid spread of polymyxin resistance. We investigated the possible transmission of Klebsiella pneumoniae carrying mcr-1 via duodenoscope and report the first documented healthcare transmission of mcr-1-harboring bacteria in the United States. METHODS: A field investigation, including screening targeted high-risk groups, evaluation of the duodenoscope, and genome sequencing of isolated organisms, was conducted. The study site included a tertiary care academic health center in Boston, Massachusetts, and extended to community locations in New England. RESULTS: Two patients had highly related mcr-1-positive K. pneumoniae isolated from clinical cultures; a duodenoscope was the only identified epidemiological link. Screening tests for mcr-1 in 20 healthcare contacts and 2 household contacts were negative. Klebsiella pneumoniae and Escherichia coli were recovered from the duodenoscope; neither carried mcr-1. Evaluation of the duodenoscope identified intrusion of biomaterial under the sealed distal cap; devices were recalled to repair this defect. CONCLUSIONS: We identified transmission of mcr-1 in a United States acute care hospital that likely occurred via duodenoscope despite no identifiable breaches in reprocessing or infection control practices. Duodenoscope design flaws leading to transmission of multidrug-resistant organsisms persist despite recent initiatives to improve device safety. Reliable detection of colistin resistance is currently challenging for clinical laboratories, particularly given the absence of a US Food and Drug Administration-cleared test; improved clinical laboratory capacity for colistin susceptibility testing is needed to prevent the spread of mcr-carrying bacteria in healthcare settings.201930204838
908820.9885Cocrystallizing and Codelivering Complementary Drugs to Multidrugresistant Tuberculosis Bacteria in Perfecting Multidrug Therapy. Bacteria cells exhibit multidrug resistance in one of two ways: by raising the genetic expression of multidrug efflux pumps or by accumulating several drug-resistant components in many genes. Multidrug-resistive tuberculosis bacteria are treated by multidrug therapy, where a few certain antibacterial drugs are administered together to kill a bacterium jointly. A major drawback of conventional multidrug therapy is that the administration never ensures the reaching of different drug molecules to a particular bacterium cell at the same time, which promotes growing drug resistivity step-wise. As a result, it enhances the treatment time. With additional tabletability and plasticity, the formation of a cocrystal of multidrug can ensure administrating the multidrug chemically together to a target bacterium cell. With properly maintaining the basic philosophy of multidrug therapy here, the synergistic effects of drug molecules can ensure killing the bacteria, even before getting the option to raise the drug resistance against them. This can minimize the treatment span, expenditure and drug resistance. A potential threat of epidemic from tuberculosis has appeared after the Covid-19 outbreak. An unwanted loop of finding molecules with the potential to kill tuberculosis, getting their corresponding drug approvals, and abandoning the drug after facing drug resistance can be suppressed here. This perspective aims to develop the universal drug regimen by postulating the principles of drug molecule selection, cocrystallization, and subsequent harmonisation within a short period to address multidrug-resistant bacteria.202337150990
489930.9884Chemiluminescent Carbapenem-Based Molecular Probe for Detection of Carbapenemase Activity in Live Bacteria. Carbapenemase-producing organisms (CPOs) pose a severe threat to antibacterial treatment due to the acquisition of antibiotic resistance. This resistance can be largely attributed to the antibiotic-hydrolyzing enzymes that the bacteria produce. Current carbapenem "wonder drugs", such as doripenem, ertapenem, meropenem, imipenem, and so on, are resistant to regular β-lactamases, but susceptible to carbapenemases. Even worse, extended exposure of bacteria to these drugs accelerates the spread of resistance genes. In order to preserve the clinical efficacy of antibacterial treatment, carbapenem drugs should be carefully regulated and deployed only in cases of a CPO infection. Early diagnosis is therefore of paramount importance. Herein, we report the design, synthesis, and activity of the first carbapenemase-sensitive chemiluminescent probe, CPCL, which may be used to monitor CPO activity. The design of our probe enables enzymatic cleavage of the carbapenem core, which is followed by a facile 1,8-elimination process and the emission of green light through rapid chemical excitation. We have demonstrated the ability of the probe to detect a number of clinically relevant carbapenemases and the successful identification of CPO present in bacterial cultures, such as those used for clinical diagnosis. We believe that our use of "turn-on" chemiluminescence activation will find significant application in future diagnostic assays and improve antibacterial treatment.202031957167
976040.9884Mutations 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.202539932323
485250.9883Recent trends in antibiotic resistance in European ICUs. PURPOSE OF REVIEW: Antimicrobial resistance is an emerging problem in ICUs worldwide. As numbers of published results from national/international surveillance studies rise rapidly, the amount of new information may be overwhelming. Therefore, we reviewed recent trends in antibiotic resistance in ICUs across Europe in the past 18 months. RECENT FINDINGS: In this period, infections caused by methicillin-resistant Staphylococcus aureus appeared to stabilize (and even decrease) in some countries, and infection rates due to Gram-positive bacteria resistant to vancomycin, linezolid or daptomycin have remained low. In contrast, we are witnessing a continent-wide emergence of infections caused by multiresistant Gram-negative bacteria, especially Escherichia coli and Klebsiella pneumoniae, with easily exchangeable resistance genes located on plasmids, producing enzymes such as extended spectrum β-lactamases and carbapenamases. In the absence of new antibiotics, prevention of infections, reducing unnecessary antibiotic use, optimizing adherence to universal hygienic and infection control measures, and improving implementation of diagnostic tests are our only tools to combat this threat. SUMMARY: As the epidemiology of antibiotic resistance in ICUs is rapidly changing toward more frequently occurring epidemics and endemicity of multi and panresistant Gram-negative pathogens, better infection control and improved diagnostics will become even more important than before.201121986462
908960.9882An adjunctive therapy administered with an antibiotic prevents enrichment of antibiotic-resistant clones of a colonizing opportunistic pathogen. A key challenge in antibiotic stewardship is figuring out how to use antibiotics therapeutically without promoting the evolution of antibiotic resistance. Here, we demonstrate proof of concept for an adjunctive therapy that allows intravenous antibiotic treatment without driving the evolution and onward transmission of resistance. We repurposed the FDA-approved bile acid sequestrant cholestyramine, which we show binds the antibiotic daptomycin, as an 'anti-antibiotic' to disable systemically-administered daptomycin reaching the gut. We hypothesized that adjunctive cholestyramine could enable therapeutic daptomycin treatment in the bloodstream, while preventing transmissible resistance emergence in opportunistic pathogens colonizing the gastrointestinal tract. We tested this idea in a mouse model of Enterococcus faecium gastrointestinal tract colonization. In mice treated with daptomycin, adjunctive cholestyramine therapy reduced the fecal shedding of daptomycin-resistant E. faecium by up to 80-fold. These results provide proof of concept for an approach that could reduce the spread of antibiotic resistance for important hospital pathogens.202033258450
979970.9882Microbiology and drug resistance mechanisms of fully resistant pathogens. The acquisition of vancomycin resistance by Gram-positive bacteria and carbapenem resistance by Gram-negative bacteria has rendered some hospital-acquired pathogens impossible to treat. The resistance mechanisms employed are sophisticated and very difficult to overcome. Unless alternative treatment regimes are initiated soon, our inability to treat totally resistant bacteria will halt other developments in medicine. In the community, Gram-positive bacteria responsible for pneumonia could become totally resistant leading to increased mortality from this common infection, which would have a more immediate impact on our current lifestyles.200415451497
978880.9881Global antibacterial resistance: The never-ending story. Bacterial resistance is undoubtedly recognised as a major medical challenge in most healthcare systems. Resistance-determining genes, mostly in combination, and multidrug-resistant (MDR) pathogens are spreading with unprecedented speed. Well known resistance carriers with high clinical impact include the Gram-positive organisms Staphylococcus aureus and Enterococcus spp. In contrast to these organisms that are usually still treatable with newer alternative antibacterial drugs, some Gram-negative bacteria, especially Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and Acinetobacter spp., have developed resistance to most or all available antibiotics. Such strains are already a reality in some Mediterranean and Asian countries. According to their resistance epidemiology (based on major drivers favouring resistance), three regions are pinpointed as high-impact resistance hot spots. Despite the clear medical need for novel antibiotics without cross-resistance issues, antibacterial research and development pipelines are nearly dry, thus failing to provide the flow of novel antibiotics required to match the fast emergence and spread of MDR bacteria. In a globalised world, only concerted global actions can mitigate a future with untreatable infectious diseases.201327873580
981090.9881Drug-resistant bacteria in the critically ill: patterns and mechanisms of resistance and potential remedies. Antimicrobial resistance in the intensive care unit is an ongoing global healthcare concern associated with high mortality and morbidity rates and high healthcare costs. Select groups of bacterial pathogens express different mechanisms of antimicrobial resistance. Clinicians face challenges in managing patients with multidrug-resistant bacteria in the form of a limited pool of available antibiotics, slow and potentially inaccurate conventional diagnostic microbial modalities, mimicry of non-infective conditions with infective syndromes, and the confounding of the clinical picture of organ dysfunction associated with sepsis with postoperative surgical complications such as hemorrhage and fluid shifts. Potential remedies for antimicrobial resistance include specific surveillance, adequate and systematic antibiotic stewardship, use of pharmacokinetic and pharmacodynamic techniques of therapy, and antimicrobial monitoring and adequate employment of infection control policies. Novel techniques of combating antimicrobial resistance include the use of aerosolized antibiotics for lung infections, the restoration of gut microflora using fecal transplantation, and orally administered probiotics. Newer antibiotics are urgently needed as part of the armamentarium against multidrug-resistant bacteria. In this review we discuss mechanisms and patterns of microbial resistance in a select group of drug-resistant bacteria, and preventive and remedial measures for combating antibiotic resistance in the critically ill.202339816646
8173100.9880Advancing Antibacterial Strategies: CRISPR-Phage-Mediated Gene Therapy Targeting Bacterial Resistance Genes. One of the most significant issues facing the world today is antibiotic resistance, which makes it increasingly difficult to treat bacterial infections. Regular antibiotics no longer work against many bacteria, affecting millions of people. A novel approach known as CRISPR-phage therapy may be beneficial. This technique introduces a technology called CRISPR into resistant bacteria using bacteriophages. The genes that cause bacteria to become resistant to antibiotics can be identified and cut using CRISPR. This enables antibiotics to function by inhibiting the bacteria. This approach is highly precise, unlike conventional antibiotics, so it doesn't damage our bodies' beneficial bacteria. Preliminary studies and limited clinical trials suggest that this technique can effectively target drug-resistant bacteria such as Klebsiella pneumoniae and Methicillinresistant Staphylococcus aureus (MRSA). However, challenges in phage engineering, host delivery, and the growing threat of bacterial CRISPR resistance demand urgent and strategic innovation. Our perspective underscores that without proactive resolution of these hurdles, the current hopefulness could disappear. Looking ahead, integrating next-generation Cas effectors, non-DSB editors, and resistance monitoring frameworks could transform CRISPR-phage systems from an experimental novelty into a clinical mainstay. This shift will require not only scientific ingenuity but also coordinated advances in regulatory, translational, and manufacturing efforts.202540990280
223110.9880Phosphoethanolamine 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.202337760679
9790120.9880Emerging antibiotic resistance: carbapenemase-producing enterobacteria. Bad new bugs, still no new drugs. Antimicrobial resistance (AMR) is a global health security threat requiring actions across government sectors and society. Many factors are involved in this phenomenon, being overuse of antibiotics, incorrect antibiotic prophylaxis, and use of antibiotics for zootechnic reasons the main causes of the increasing rate of multi-drug resistant (MDR) bacteria. The impact of resistance to antimicrobials is an important threat due also to the emergence of MDR Gram-negative bacteria resistant to carbapenems, and the lack of the research for new active molecules. The production of extended spectrum beta-lactamase enzymes has been the first threatening mechanism for Gram-negative resistance to antibiotics, which prompted the development of new classes of antibiotics such as carbapenems. Unfortunately, resistance to carbapenems developed because of multiple mechanisms including efflux pumps, porin mutations and enzyme production, being the latter particularly relevant in terms of diffusion due to the genes located within plasmids that drive their horizontal diffusion. In this scenario, antimicrobial stewardship programs (ASP) are a mandatory resource in fighting the resistance spread. The reduction of total amount of antibiotics administration in the hospital setting and guiding prescribers in the correct administration of antibiotics for the smallest period possible, at the correct dosage, can be defined as the first goals of an ASP. Anyway, in an efficacious ASP, apart from antibiotic administration, efforts must been made in ensuring the lowest probability of spreading of MDR by efficacious measures of isolation of carriers, and by offering tools for a rapid diagnosis of viral infections avoiding the administration of unnecessary antibiotics. A continuous audit of the ASP programs and a correct assessment of the allergy to drugs such as penicillin have to complete the program. Currently, only a few options are available for patients with an infection sustained by Gram-negative MDR bacteria. All the options actually available are based on the administration of colystin, an old drug whose real efficacy is reduced due to its relevant toxicity, or on the administration of recently proposed drugs such as ceftolozane-tazobactam, ceftazidime-avibactam and meropenem-vaborbactam. All these new drugs do not have a novel mechanism of action and have limited spectrum in term of activity against MDR bacteria. In conclusion, antimicrobial resistance is a global emergence and AMP is the most powerful tool actually available. Few limited options are available to treat infections due to Carbapenem Resistant Enterobacteria. Antimicrobial molecules with true novel mechanism of action are needed to win the fight against antimicrobial resistance.201931846984
9812130.9879Drug Resistance Mechanisms in Bacteria Causing Sexually Transmitted Diseases and Associated with Vaginosis. Here, we review sexually transmitted diseases (STDs) caused by pathogenic bacteria and vaginal infections which result from an overgrowth of opportunistic bacterial microflora. First, we describe the STDs, the corresponding pathogens and the antimicrobials used for their treatment. In addition to the well-known diseases caused by single pathogens (i.e., syphilis, gonococcal infections, and chlamydiosis), we consider polymicrobial reproductive tract infections (especially those that are difficult to effectively clinically manage). Then, we summarize the biochemical mechanisms that lead to antimicrobial resistance and the most recent data on the emergence of drug resistance in STD pathogens and bacteria associated with vaginosis. A large amount of research performed in the last 10-15 years has shed light on the enormous diversity of mechanisms of resistance developed by bacteria. A detailed understanding of the mechanisms of antimicrobials action and the emergence of resistance is necessary to modify existing drugs and to develop new ones directed against new targets.201627242760
3745140.9879Antimicrobial resistance in methicillin-resistant staphylococcus aureus. In the medical community, antibiotics are revered as a miracle because they stop diseases brought on by pathogenic bacteria. Antibiotics have become the cornerstone of contemporary medical advancements ever since penicillin was discovered. Antibiotic resistance developed among germs quickly, placing a strain in the medical field. Methicillin-resistant Staphylococcus aureus (MRSA), Since 1961, has emerged as the major general antimicrobial resistant bacteria (AMR) worldwide. MRSA can easily transmit across the hospital system and has mostly gained resistance to medications called beta-lactamases. This enzyme destroys the cell wall of beta-lactam antibiotics resulting in resistance against that respective antibiotic. Daptomycin, linezolid and vancomycin were previously used to treat MRSA infections. However, due to mutations and Single nucleotide polymorphisms (SNPs) in Open reading frames (ORFs) and SCCmec machinery of respective antibody, MRSA developed resistance against those antibiotics. The MRSA strains (USA300, CC398, CC130 etc.), when their pan-genomes were analyzed were found the genes involved in invoking resistance against the antibiotics as well as the epidemiology of that respective strain. PENC (penicillin plus potassium clavulanate) is the new antibiotic showing potential in treatment of MRSA though it is itself resistant against penicillin alone. In this review, our main focus is on mechanism of development of AMR in MRSA, how different ORFs are involved in evoking resistance in MRSA and what is the core-genome of different antimicrobial resistant MRSA.202336936699
5034150.9879Resensitizing carbapenem- and colistin-resistant bacteria to antibiotics using auranofin. Global emergence of Gram-negative bacteria carrying the plasmid-borne resistance genes, bla(MBL) and mcr, raises a significant challenge to the treatment of life-threatening infections by the antibiotics, carbapenem and colistin (COL). Here, we identify an antirheumatic drug, auranofin (AUR) as a dual inhibitor of metallo-β-lactamases (MBLs) and mobilized colistin resistance (MCRs), two resistance enzymes that have distinct structures and substrates. We demonstrate that AUR irreversibly abrogates both enzyme activity via the displacement of Zn(II) cofactors from their active sites. We further show that AUR synergizes with antibiotics on killing a broad spectrum of carbapenem and/or COL resistant bacterial strains, and slows down the development of β-lactam and COL resistance. Combination of AUR and COL rescues all mice infected by Escherichia coli co-expressing MCR-1 and New Delhi metallo-β-lactamase 5 (NDM-5). Our findings provide potential therapeutic strategy to combine AUR with antibiotics for combating superbugs co-producing MBLs and MCRs.202033067430
8185160.9879RNA-cleaving DNAzymes as a diagnostic and therapeutic agent against antimicrobial resistant bacteria. The development of nucleic-acid-based antimicrobials such as RNA-cleaving DNAzyme (RCD), a short catalytically active nucleic acid, is a promising alternative to the current antibiotics. The current rapid spread of antimicrobial resistance (AMR) in bacteria renders some antibiotics useless against bacterial infection, thus creating the need for alternative antimicrobials such as DNAzymes. This review summarizes recent advances in the use of RCD as a diagnostic and therapeutic agent against AMR. Firstly, the recent diagnostic application of RCD for the detection of bacterial cells and the associated resistant gene(s) is discussed. The next section summarises the therapeutic application of RCD in AMR bacterial infections which includes direct targeting of the resistant genes and indirect targeting of AMR-associated genes. Finally, this review extends the discussion to challenges of utilizing RCD in real-life applications, and the potential of combining both diagnostic and therapeutic applications of RCD into a single agent as a theranostic agent.202234505182
9766170.9879Facile accelerated specific therapeutic (FAST) platform develops antisense therapies to counter multidrug-resistant bacteria. Multidrug-resistant (MDR) bacteria pose a grave concern to global health, which is perpetuated by a lack of new treatments and countermeasure platforms to combat outbreaks or antibiotic resistance. To address this, we have developed a Facile Accelerated Specific Therapeutic (FAST) platform that can develop effective peptide nucleic acid (PNA) therapies against MDR bacteria within a week. Our FAST platform uses a bioinformatics toolbox to design sequence-specific PNAs targeting non-traditional pathways/genes of bacteria, then performs in-situ synthesis, validation, and efficacy testing of selected PNAs. As a proof of concept, these PNAs were tested against five MDR clinical isolates: carbapenem-resistant Escherichia coli, extended-spectrum beta-lactamase Klebsiella pneumoniae, New Delhi Metallo-beta-lactamase-1 carrying Klebsiella pneumoniae, and MDR Salmonella enterica. PNAs showed significant growth inhibition for 82% of treatments, with nearly 18% of treatments leading to greater than 97% decrease. Further, these PNAs are capable of potentiating antibiotic activity in the clinical isolates despite presence of cognate resistance genes. Finally, the FAST platform offers a novel delivery approach to overcome limited transport of PNAs into mammalian cells by repurposing the bacterial Type III secretion system in conjunction with a kill switch that is effective at eliminating 99.6% of an intracellular Salmonella infection in human epithelial cells.202133712689
9758180.9879Study 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
2510190.9878Diagnosis of Multidrug-Resistant Pathogens of Pneumonia. Hospital-acquired pneumonia and ventilator-associated pneumonia that are caused by multidrug resistant (MDR) pathogens represent a common and severe problem with increased mortality. Accurate diagnosis is essential to initiate appropriate antimicrobial therapy promptly while simultaneously avoiding antibiotic overuse and subsequent antibiotic resistance. Here, we discuss the main conventional phenotypic diagnostic tests and the advanced molecular tests that are currently available to diagnose the primary MDR pathogens and the resistance genes causing pneumonia.202134943524