OBJECTIVES:Carbapenem-resistant Acinetobacter baumannii (CRAB) is a major cause of hospital- and ventilator-associated pneumonia (HAP/VAP) with limited treatment options. Eravacycline (ERA) shows potent in vitro activity and favorable pulmonary pharmacokinetics, but clinical evidence for CRAB HAP/VAP remains scarce. We evaluated the real-world effectiveness and safety of ERA. METHODS:We conducted a retrospective multicenter cohort study at 12 hospitals in China (April 2022-March 2024). Adults with microbiologically confirmed CRAB HAP/VAP treated with ERA or best available therapy (BAT) for ≥ 4 days were propensity scores matched. Primary outcomes were clinical success at end of treatment (EOT) and 28-day mortality. RESULTS:After 3349 patients screened, 382 were included (ERA 204; BAT 178). Baseline characteristics were balanced. Clinical success at EOT was higher with ERA than BAT (63.2% vs 55.1%), while 28-day mortality was similar (40.1% vs 42.0%). ERA achieved higher microbiological eradication at EOT (45.1% vs 32.0%) and day 14 (36.8% vs 22.5%). Adverse events occurred less frequently with ERA. In targeted first-line treatment, ERA showed higher clinical success, greater microbiological eradication and faster clinical response without increased mortality. CONCLUSION:Eravacycline improved microbiological clearance, clinical response, and safety compared with BAT for CRAB HAP/VAP, particularly when used as targeted first-line therapy.

BACKGROUND:This study investigate the molecular epidemiology and population characteristics of 184 Acinetobacter baumannii clinical isolates collected in Zhejiang (2015-2020), shedding light on the persistence and success of ST208-KL2 lineage. METHODS:Whole-genome sequencing and bioinformatic analysis characterized the population structure and transmission dynamics of 184 A. baumannii. Plasmid analysis identified the surrounding structures of blaOXA-58 and blaNDM-1 genes. Serum inhibition assays and Galleria mellonella virulence experiments, combined with global epidemiological analysis, explored the persistence and dominance of ST208-KL2. RESULTS:Of the isolates, approximately 78.8% (145/184) exhibited carbapenem resistance, primarily driven by blaOXA-23, blaOXA-72, blaOXA-58, and blaNDM-1. The A. baumannii population was divided into 2 clusters, distinguished by differences in ST types and resistance islands profiles. Cluster2 accounted for 71 department-time transmission events, mainly involving long-term interdepartmental spread, particularly in the rehabilitation medicine department and intensive care unit. Recombination analysis revealed that recombination occurred mainly in capsular locus (KL) regions, prophage regions, and predicted protein regions. Phenotypic experiments found that ST208-KL2 isolates displayed increased virulence and greater resistance to serum inhibition compared to ST208-KL7 isolates. This finding likely explains its persistently higher prevalence throughout the study period, except in 2019. CONCLUSIONS:Cluster2 isolates demonstrated significant advantages in ARG prevalence, resistance rates, and transmission capacity. ST208-KL2, with its superior serum resistance and virulence compared to ST208-KL7, has emerged as a dominant lineage with global implications for infection control and public health.

Ceftazidime-avibactam (CZA) has become an effective therapeutic option against carbapenem-resistant Klebsiella pneumoniae (CRKP). The emergence of Klebsiella pneumoniae carbapenemase (KPC) variants in CRKP is a major cause of CZA resistance. However, high-level CZA resistance conferred by accumulated KPC mutations was seldom reported. In this study, we observed that high-level ceftazidime-avibactam resistance was attributed to stepwise KPC mutational accumulation. A total of 21 KPC-producing K. pneumoniae isolates were collected from a single patient over one year, encompassing 17 harboring blaKPC-2, 2 harboring blaKPC-33, and 2 harboring blaKPC-275. The patient's treatment course indicated that prolonged CZA pressure likely drove the accumulation of mutations, leading to the sequential evolution from blaKPC-2 to blaKPC-33 and ultimately to blaKPC-275. Molecular docking and steady-state kinetics revealed that the newly identified variant KPC-275 confers high-level CZA resistance, mediated by the cumulative effects of D179Y and T243P mutations, which enhance ceftazidime affinity and diminish avibactam inhibitory activity. Antimicrobial susceptibility testing demonstrated that compared to blaKPC-2, expression of blaKPC-33 and blaKPC-275 in E. coli DH5α elevated the MIC of CZA by 128-fold and 1024-fold, respectively. Moreover, unlike the individual D179Y or T243P mutations, the combination of both conferred high-level resistance to CZA but imposed a fitness cost. Whole-genome sequencing results demonstrated that these highly homologous ST11 CRKP strains carried blaKPC within Tn6296 on IncFII/IncR plasmids. Additionally, the plasmid carrying blaKPC-275 integrated virulence-associated fragments via IS5075, forming a hybrid virulence-resistance plasmid. Furthermore, global phylogeographic analysis of 928 KPC variant-producing K. pneumoniae isolates revealed pronounced geographical clustering and clone-driven dissemination, with Asia, particularly China, representing the largest reservoir and ST11 identified as the predominant lineage. In view of the widespread prevalence of KPC-KP strains, clinicians should be aware of the risk of treatment failure due to blaKPC mutation-mediated CZA resistance during therapy.

Carbapenem-resistant Acinetobacter baumannii (CRAB) is a persistent nosocomial pathogen, posing a major global health threat owing to limited treatment options. Although tigecycline is still effective against CRAB, resistance emergence has become a critical concern. This study aimed to elucidate the in vivo evolutionary mechanisms underlying tigecycline resistance in CRAB. A total of 11 STpas2-SToxf540 CRAB strains were recovered from rectal swabs, sputum samples, and the surrounding environmental specimens of an intensive care unit (ICU) hospitalized patient who had received tigecycline treatment. CgSNP analysis confirmed environment-to-patient transmission among these CRAB isolates. Comparative genomic analysis indicated that mutations in adeS, pgaA, and gbsA may be associated with tigecycline resistance. In situ mutagenesis and antimicrobial susceptibility testing verified that the adeS N125S mutation mediates tigecycline resistance and collateral sensitivity to cefoperazone/sulbactam. Growth curve assays demonstrated that the adeS N125S mutation imposes a fitness cost on CRAB. Transcriptional analysis showed that the adeS N125S mutation drives the development of tigecycline resistance by upregulating the expression of the AdeABC efflux pump. By examining 45,377 publicly available global A. baumannii genome sequences, we characterized the molecular epidemiology of the STpas2-SToxf540 lineage and the distribution of adeS mutations. Our findings underscore the need to strengthen surveillance and rational antimicrobial use to prevent CRAB dissemination and antimicrobial resistance evolution, particularly in ICUs.

IntroductionCarbapenem-resistant Acinetobacter baumannii (CRAB) poses a global health threat due to limited therapeutic options. Cefiderocol, a novel siderophore-conjugated cephalosporin, demonstrates potent in vitro activity against a variety of Gram-negative bacteria, including CRAB. However, cefiderocol's recent introduction into clinical practice means that while several resistance mechanisms have been identified, their full characterization remains incomplete, and novel mechanisms are likely to emerge as clinical use expands.MethodsIn this study, in vitro evolution experiments were performed under cefiderocol pressure using a clinical CRAB isolate as the parental strain to investigate cefiderocol resistance mechanisms.ResultsGenomic comparison and mutant reconstruction revealed that mutations in pbp1b (G271R) and the intergenic region upstream of piuA (-6_-8del) conferred a 4-fold increase in cefiderocol MIC. In silico predictions and EMSA confirmed that the intergenic mutation occurred within the piuA promoter region. qRT-PCR analysis indicated that the piuA promoter mutation significantly reduced piuA expression. This downregulation of piuA expression impaired cefiderocol transport, leading to reduced susceptibility to cefiderocol. A search across publicly deposited genome sequences identified ten piuA promoter mutations in A. baumannii. Among these, the−-6_-8del was the most commonly observed variant, which was primarily associated with ST2Pas/ST457Oxf, ST2Pas/ST208Oxf, and ST499Pas. Functional characterization of the−-6_-8del variant and three additional promoter mutations (-18del, A-17T&-18del, A-17T&-14del) confirmed suppression of piuA expression and reduction of cefiderocol susceptibility.DiscussionCombining in vitro evolution with publicly available A. baumannii genome sequences, this study demonstrates promoter-mediated piuA downregulation as a cefiderocol resistance mechanism in A. baumannii, providing a genomic target for predicting cefiderocol resistance.

BACKGROUND:KPC and NDM co-producing carbapenem-resistant Klebsiella pneumoniae (KN-CRKP) is an escalating global health threat with limited treatment options. METHODS:Here, we conducted a multicentre retrospective case-control study on KN-CRKP in China (2020-2025), collecting 3012 non-duplicated CRKP isolates, of which 71 (2.4%) were KN-CRKP. For clinical analysis, 39 patients with KN-CRKP infections were identified from 71 isolates and matched in a 1:2 ratio with 78 patients infected by KPC-2-producing CRKP. For global analysis, we retrieved 100,141 genomes from GenBank, of which 662 non-redundant KN-CRKP sequences were combined with our 71 KN-CRKP isolates. Antimicrobial susceptibility testing, whole-genome sequencing (WGS), plasmid transfer and stability, fitness cost, transcriptomics and Bayesian phylogeography were used to investigate evolution mechanisms and molecular epidemiology of KN-CRKP strains. FINDINGS:Among the infected patients, hospital-acquired or ventilator-associated pneumonia was the most common (41.0%, 16/39). Patients with KN-CRKP infections had a non-significantly higher 28-day mortality (38.5%, 15/39) than the KPC-CRKP control group (24.4%, 19/78; p = 0.133), but a significantly higher in-hospital mortality (46.2%, 18/39 vs. 25.6%, 20/78; p = 0.036). Independent risk factors included diabetes, a history of CRO (carbapenem-resistant gram-negative organism) infection treated with ceftazidime-avibactam (CZA) treatment, and recent use of β-lactam/β-lactamase inhibitor combinations. All KN-CRKP isolates were resistant to carbapenems and CZA, but exhibited highly susceptible to colistin (98.6%), cefiderocol (94.4%), and aztreonam-avibactam (100%). The predominant KN-CRKP clones were ST11 (73.2%) and ST307 (15.5%). Global surveillance of 733 global KN-CRKP identified ST11 as a pandemic lineage diverging into China/Brazil subclusters, with emerging clones ST147/ST307 showing post-pandemic increases. Plasmid profiling revealed blaNDM mainly on IncX3/IncN plasmids and blaKPC on IncR/IncFII plasmids, with novel hybrid plasmids carrying both carbapenemases identified. blaNDM-carrying plasmids had higher transferability/stability than blaKPC-carrying ones. In vitro experiments confirmed blaNDM transfer from Citrobacter freundii to blaKPC-carrying K. pneumoniae, forming KN-CRKP. INTERPRETATION:The high mortality and global prevalence of KN-CRKP emphasise the need for enhanced surveillance and infection control globally. FUNDING:National Natural Science Foundation of China (82472323 and 82172306), Zhejiang Province Natural Science Foundation of China (LQN26H200003, LR25H200001, LQN25H200002, MS25H190009), the "Pioneer" and "Leading Goose" R&D Program of Zhejiang Province (2025C02187), the Zhejiang Provincial Medical and Health Technology Project (2025HY0224) and Zhejiang Provincial Disease Prevention and Control Science and Technology Program (2025JK063). We appreciate the statistical support provided by Hui Liu (Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China).

Industrial insect farming generates large quantities of manure, yet the fate and transmission risk of antibiotic resistance genes (ARGs) during insect-manure composting are largely unknown. Here, we compared ARG risks during the composting of silkworm excrement from traditional (TSE) and industrialized (ISE) sericulture. Specifically, in TSE, enriched ARGs were closely linked to pathogens, whereas in ISE, antibiotic-use practices drove ARG enrichment. Through metagenomic binning analysis, we identified 119 ARG-hosting taxa (TSE: 71, ISE: 48). In the TSE group, Pseudomonadota was the primary high-risk MAG, carrying an average of 20 ARGs per genome, while Bacillota dominated in the ISE group, with only five ARGs per genome. Furthermore, 52.1% of high-risk MAGs in the TSE group were considered potential pathogens, whereas the proportion was 33.3% in the ISE group. We then quantified ARG transmission risk using the ARGs-Mobile Genetic Elements (MGEs) distance index and further validated it through a compost-soil microcosm experiment, which indicated a higher risk of ARG transmission in the TSE group. Furthermore, the ARG transmission risk increased in the TSE group but decreased in the ISE group during composting. Notably, over 50% of ARGs formed stable combinations with specific MGEs, highlighting potential targets for reduction strategies. Finally, structural equation modeling revealed that biotic factors (MGEs and bacterial composition) had direct effects on ARGs, while abiotic factors (temperature and compost properties) influenced them indirectly. Overall, this study provides the first ecotechnological insights into ARG risks in insect manure compost, paving the way for sustainable insect bioresource production.

Nano(micro)plastics (NMPs) and agrochemicals are ubiquitous pollutants. The small size and physicochemical properties of NMPs make them potential carriers for pollutants, affecting their bioavailability and impact on living organisms. However, little is known about their interactions in terrestrial ecosystems. This study investigates the adsorption of Fenpropathrin (FPP) onto two different sizes of polystyrene NMPs and examines their impacts on an insect model, silkworm Bombyx mori. We analyzed the systemic effects of acute exposure to NMPs and FPP, individually and combined, at organismal, tissue, cellular, and gut microbiome levels. Our results showed that NMPs can adsorb FPP, with smaller particles having higher adsorption capacity, leading to size-dependent increases in the bioaccumulation and toxicity of FPP. These effects led to higher mortality, reduced body weight, delayed development, and decreased cocoon production in silkworms. Additionally, the pollutants caused physical and oxidative damage to the midgut and altered gene expression related to juvenile hormone (JH) and silk protein synthesis. The gut microbiome analysis revealed significant changes and reduced abundance of potentially beneficial bacteria. Thus, the aggravated toxicity induced by NMPs was size-dependent, with smaller particles (NPs) having a greater impact. This study demonstrates the role of NMPs as carriers for contaminants, increasing their bioavailability and toxicity in terrestrial ecosystems. These findings have significant implications for ecosystem health and biodiversity.

In this 4-month-long prospective observational study, we explored the colonization rate of extended-spectrum β-lactamase-producing Escherichia coli (ESBL-EC) in the patient and ward environment of an intensive care unit (ICU). Additionally, we evaluated the risk factors for colonization and analyzed genomic characteristics and modes of transmission of isolates. Clinical samples were collected from patients and the environment to isolate and screen E. coli strains. ESBL-EC from the E. coli strains was identified using ESBL confirmation and antibiotic susceptibility tests and subsequently characterized using whole-genome sequencing. Clinical data were collected and further analyzed. Among the 214 E. coli isolates, 82 were ESBL-EC, with CTX-M-14 being the dominant enzyme, followed by CTX-M-55 and CTX-M-15. The predominant sequence types (STs) among the 82 ESBL-EC strains were ST10, followed by ST131 and ST1193. Using multiple logistic regression, exposure to third-generation cephalosporins and a special class of anti-positive-bacterial drugs, as well as albumin and enteral nutrition, were high-risk factors for ESBL-EC colonization. The clonal transmissions of ESBL-EC in the ICU were predominantly attributed to the movement of healthcare workers. More effective interventions and active screening are needed to prevent and control ESBL-EC colonization.IMPORTANCEThe increasing prevalence of extended-spectrum β-lactamase-producing Escherichia coli (ESBL-EC) has made drug-resistant bacterial infections rise, endangering people's health and causing socioeconomic burdens. We conducted an ESBL-EC screening program for patients and ward environments in an intensive care unit (ICU). The aim was to describe the molecular characteristics of ESBL-EC and the risk factors for ESBL-EC colonization. In our hospital, the colonization rate of ESBL-EC remained high. The dominant sequence type was ST10, which might be considered a strain of notable concern, possibly causing future outbreaks. However, ST131 and ST1193 should also be considered because they were associated with the majority of the ESBL-EC isolates found. Notably, CTX-M-14 gene screening should be considered in medication guidance because it is the main ESBL enzyme. Owing to the high transmission rate of ESBL-EC, effective interventions and active screening are critical for preventing and controlling its spread, guiding clinicians in rational antibiotic use.

Carbapenem-resistant Providencia spp. (CRPs) isolates are increasing, posing severe therapeutic challenges. Here, we analyzed 46 CRP isolates carrying bla NDM-1 and/or bla KPC-2 from patients (n = 40) with 60% demonstrating clinical infections and clinical environment samples (n = 6). 33 Providencia huaxiensis strains were identified, with ST346 (93.9%, 31/33) being the predominant sequence type. Transmission dynamics analysis identified that Cluster I (n = 12, SNPs≤36) linking to non-transferable pCTX-M-NDM-repM plasmids, replaced Cluster III (n = 13, SNPs<25), which harbored both IncT_NDM-repM (conjugation frequency: 5.04E-2; a fitness cost of 17.31%-19.41% with p < 0.0001) and pCTX-M plasmids. Notably, we identified 9 (29.0%, 9/31) ST346 isolates co-producing KPC-2 and NDM-1 and tracked the evolution of this phenomenon. Bayesian Skyline analysis indicated a 120% expansion of the ST346 clone during 2020-2022, in contrast to the decline in the cross-host ST4 clone (80% reduction). Our study tracks and alerts to the emergence of a hospital-acquired ST346 CR-P. huaxiensis clone with multidrug resistance, hypervirulent phenotype, and elevated transmission risk.

Ceftazidime-avibactam (CZA) is currently one of the last resorts used to treat infections caused by carbapenem-resistant Enterobacteriaceae and Pseudomonas aeruginosa. However, KPC variants have become the main mechanism mediating CZA resistance in KPC-producing gram-negative bacteria after increasing the application of CZA. Our previous study revealed that CZA-resistant KPC-33 had emerged in carbapenem-resistant P. aeruginosa (CRPA) and had resulted in death due to hypervirulence and extensive drug resistance; however, the evolutionary path of KPC-33-producing CRPA has not been investigated. Here, we observed the emergence of blaKPC-33 in CRPA under drug pressure, leading to resistance to CZA. We further elucidated the pathway of resistance development due to blaKPC mutations in P. aeruginosa. Three KPC-producing P. aeruginosa (KPC-PA) strains (including one blaKPC-33-positive strain and two blaKPC-2-positive strains) were successively isolated from a hospitalized patient. The blaKPC-33-positive CZA-resistant strain SRPA0656 (CZA MIC >128 μg/mL, imipenem MIC = 32 μg/mL) was isolated after the blaKPC-2-positive P. aeruginosa SRP2863 (CZA MIC = 1 μg/mL, imipenem MIC >128 μg/mL) was treated with CZA. The subsequent use of carbapenems to treat the infection led to the re-emergence of the KPC-2-producing strain SRPA3703. Additionally, we collected four other KPC-33-producing P. aeruginosa strains. Antimicrobial susceptibility testing revealed that all the KPC-33-bearing P. aeruginosa strains in this study were multidrug-resistant but susceptible to colistin and amikacin. Whole-genome sequencing indicated that blaKPC-33 was located on two Tn4401-like transposons contained in the plasmids and that most of these plasmids could be transferred into P. aeruginosa PAO1Rif isolates. Growth rate determination demonstrated that the relative growth rate of P. aeruginosa harboring blaKPC-33 was faster than that of P. aeruginosa harboring blaKPC-2 in the logarithmic phase. Global phylogenetic analysis revealed that most KPC-PA strains were isolated from China and the USA. MLST revealed that the most common ST in KPC-PA was ST463, which was detected only in China, and that all the strains carried blaKPC-2 or its derivatives. These results indicated that the use of CZA for the treatment of KPC-2-producing P. aeruginosa may have contributed to the evolution of KPC-33. The widespread dissemination of KPC-PA (especially the ST463) and Tn4401 transposons may increase the spread of CRPA isolates carrying blaKPC-33. Close attention to the development of resistance to CZA during clinical treatment of CRPA infection and monitoring CZA-resistant strains is necessary to prevent further spread.

Ecosystems are interconnected networks of diverse habitat types, rather than isolated patches. However, the role of the multi-habitat landscape in influencing microbial diversity remains poorly understood. This study investigates bacterial and fungal communities within a 2500-year agricultural heritage system, the Mulberry-dyke and Fish-pond (MF), which integrates various terrestrial and aquatic habitats. Using amplicon sequencing, metagenomics, metatranscriptomics, and genomic analyses, these findings reveal a significant proportion of unclassified microbial taxa, underscoring the importance of MF systems as an untapped reservoir of microbial genetic resources. Moreover, single-nucleotide-level analyses demonstrate that a multi-habitat landscape enhances microbial diversity through ecosystem-wide assembly, facilitated by cross-habitat microbial dispersal. Taxa found across multiple habitats exhibit convergence in microdiversity and adaptive genetic traits, indicating both ecological and functional mechanisms underlying their adaptability. A global analysis of public microbiome datasets furthermore confirms that regions with higher habitat heterogeneity support significantly higher taxonomic and functional diversity of microbiomes. Overall, this study sheds new light on the overlooked microbial diversity in traditional agricultural heritages and emphasizes the value of ancestral ecological wisdom underlying multi-habitat integration for ecosystem management. These insights offer valuable guidance for developing sustainable agricultural strategies, enhancing microbial diversity, and reinforcing ecosystem resilience in the face of global change.

Acinetobacter species have emerged as a significant public health concern due to their remarkable capacity to acquire antimicrobial resistance. Environmental reservoirs play a crucial role in spreading antimicrobial resistance genes and potentially pathogenic bacteria to clinical settings. However, most studies on nonhuman isolates have focused on a limited sample size. Comprehensive population sampling on One Health principles is essential to monitor the antibiotic resistome and virulome in Acinetobacter spp. Here, we identified three carbapenems-resistant Acinetobacter spp. isolates harboring blaNDM-1 and discovered two novel Acinetobacter species in pharmaceutical production environments. A total of 94 Acinetobacter spp. strains were isolated from pharmaceutical production environments across 17 cities in China, forming 17 distinct Acinetobacter clusters comprising two novel species and 15 previously known species. Phylogenetic analysis indicated that Acinetobacter spp. isolated from pharmaceutical settings are predominantly confined to these settings. Genomic analysis revealed 10 specific families of blaCHDL genes in 51 isolates and blaNDM-1 in three isolates. The overall rates of phenotypic resistance to antimicrobials were low among Acinetobacter spp. isolates, with less than 10 % resistance observed for all tested drugs, and only three isolates carrying blaNDM-1 were resistant to carbapenems. The blaNDM-1 gene was located in approximately 49 kb PTU-Pse8 conjugative plasmids with conserved backbones, although plasmid pXH1688-NDM displayed enhanced growth and stability. Two novel Acinetobacter species, A. yuyunsongii sp. nov. and A. chenhuanii sp. nov., were characterized using phenotypic and genomic analyses. Particularly, A. yuyunsongii sp. nov. XH1639 harbors a blaOXA-58-carrying conjugative plasmid and exhibits multidrug-resistant phenotype. Our study advances Acinetobacter taxonomy and underscores the urgency of monitoring the dynamics of Acinetobacter species in environmental sources to implement effective measures to mitigate transmission risks to healthcare facilities.

ABSTRACT Carbapenem-resistant Acinetobacter spp. pose a significant challenge in clinical settings due to limited treatment options for nosocomial infections. Carbapenem-hydrolyzing class D beta-lactamases are the primary cause for carbapenem resistance, while metallo-beta-lactamases (MBLs) New Delhi metallo beta-lactamase (NDM) and imipenemase (IMP) also contribute. This study investigated five MBL-producing Acinetobacter spp. strains isolated from a clinic in China in 2010. The blaIMP-8-carrying A1014 was the first identified CRAB among all known STPas150 isolates worldwide. Through whole-genome sequencing and the southern blot analysis, we determined that blaIMP-8 was located on a pR4WN-type plasmid and blaNDM-1 was located on four distinct pSU1904NDM-type plasmids. The blaIMP-8 gene was identified within a class 1 integron organized as a 5’-conserved segment (intI), variable region (blaIMP-8-aac(6')-Ib), and 3’-conserved segment (qacEΔ1/sul1). All available sequences of blaIMP variants in A. baumannii from the NCBI were investigated and classified into five types of class 1 integrons. All blaNDM-1 plasmids were transferable, and the blaNDM-1 genes were in a conservative region. Additionally, multiple resistance genes, including those conferring resistance to aminoglycosides, tetracyclines, and macrolides, were detected on plasmids from these strains. All strains were resistant to meropenem and imipenem, while they were all susceptible to tigecycline and intermediate to polymyxin. A207 and A1014 were susceptible to cefiderocol, and only blaIMP-8-carrying A1014 had low MIC value (4/2 µg/mL) toward cefoperazone/sulbactam. In conclusion, we characterized the phenotypic and genotypic features of one IMP-8-producing and four NDM-1-producing plasmids recovered from Acinetobacter spp. strains isolated in 2010, contributing to the understanding of the dissemination and evolution of these enzymes.IMPORTANCEGiven the low prevalence of IMP among A. baumannii and the limited sequencing technology in earlier years, research on blaIMP in A. baumannii is scarce, and genetic information on blaNDM-1-producing Acinetobacter spp. strains isolated in earlier years is limited. This study revisited five MBL-carrying Acinetobacter spp. strains isolated in 2010, characterizing their phenotypic and genotypic features. This retrospective analysis serves as a form of “bacterial archaeology,” providing evidence of the evolutionary changes in genetic elements conferring antibiotic resistance.

Antibiotic resistance genes (ARGs) are emerging environmental contaminants that pose increasing risks to ecosystems and human health. However, the distribution and drivers of ARGs associated with woody plants remain underexplored. In this study, we leverage large-scale sampling and metagenomics to provide a comprehensive survey of ARGs in both mulberry (Morus) field soil and rhizosphere across China. Our findings revealed significant regional differences in ARG diversity and composition, exhibiting a distance-decay pattern. The most abundant ARG types identified were multidrug, novobiocin, and macrolide-lincosamide-streptogramin, with the dominant resistance mechanisms being efflux pumps, antibiotic target alteration, and enzymatic inactivation. Structural equation modelling further showed that ARG profiles were primarily influenced by mobile genetic elements (MGEs) and annual mean temperature, with high-risk ARGs increasing significantly. We also observed notable regional and compartmental differences in MGEs, with both richness and abundance being higher in the rhizosphere compared to bulk soil. Moreover, co-occurrence network analysis revealed that ARG-MGE associations in the rhizosphere were stronger and more complex, likely promoting ARG dissemination. Our results not only provide the first overview of ARG profiles in widely planted mulberry but also characterize the factors shaping the antibiotic resistome, paving the way for managing ARG risks in woody plants.

Hypervirulent Klebsiella pneumoniae (hvKP) typically causes severe invasive infections affecting multiple sites in healthy individuals. In the past, hvKP was characterized by a hypermucoviscosity phenotype, susceptibility to antimicrobial agents, and its tendency to cause invasive infections in healthy individuals within the community. However, there has been an alarming increase in reports of multidrug-resistant hvKP, particularly carbapenem-resistant strains, causing nosocomial infections in critically ill or immunocompromised patients. This presents a significant challenge for clinical treatment. Early identification of hvKP is crucial for timely infection control. Notably, identifying hvKP has become confusing due to its prevalence in nosocomial settings and the limited predictive specificity of the hypermucoviscosity phenotype. Novel virulence predictors for hvKP have been discovered through animal models or machine learning algorithms, while standardization of identification criteria is still necessary. Timely source control and antibiotic therapy have been widely employed for the treatment of hvKP infections. Additionally, phage therapy is a promising alternative approach due to escalating antibiotic resistance. In summary, this narrative review highlights the latest research progress in the development, virulence factors, identification, epidemiology of hvKP, and treatment options available for hvKP infection.

OBJECTIVE:To investigate clinical characteristics of hematological malignancy (HM) patients with carbapenem-resistant gram-negative organism (CRO) bloodstream infections (BSI) in China, and to elucidate the prognostic risk factors of CRO BSI. METHODS:We conducted a multicenter case-control study of 201 HM patients with CRO BSI between 2018-2020. Antimicrobial susceptibility testing and whole genome sequencing were performed for CRO isolates. Independent risk factors for 28-day crude mortality were analyzed using Cox proportional hazards regression models. The subgroups of major species were also evaluated. RESULTS:The pathogens responsible for CRO BSI in HM patients dominated by ST11 CRKP, ST167 CREC and ST463 CRPA. Most isolates produced carbapenemases with KPC and NDM being the main. CRO isolates had resistance rates to conventional antimicrobials ranging from 55%-100% and poor susceptibility to novel antimicrobials related to carbapenemases and species. The 28-day crude mortality was 24.2%. Non-Hodgkin lymphoma, heart disease, blaKPC-2 positive, empirical antibiotic therapy with linezolid, Pitt bacteremia score >3.5 were risk factors for 28-day mortality and appropriate definitive antibiotic therapy, tigecycline-containing therapy and aminoglycoside-containing therapy were protective factors. blaKPC-2 positive in CRKP and ST463 in CRPA were associated with Pitt bacteremia score >3.5. Solid tumor and other site infections before BSI were risk factors for ST463 CRPA BSI and pulmonary infection before BSI was risk factor for KPC-KP BSI. CONCLUSIONS:The antimicrobial resistance of CRO isolates for BSI in HM patients is critical. HM patients with CRO BSI should be treated with appropriate definitive antibiotic therapy based on early clarification of pathology and their antimicrobial susceptibility.