Global phylogeography and genomic characterization of blaKPC and blaNDM-positive clinical Klebsiella aerogenes isolates from China, 2016-2022.

Carbapenem-resistant Klebsiella aerogenes (CRKA), being one of the members of carbapenem-resistant Enterobacteriaceae (CRE), has caused great public health concern, but with fewer studies compared to other CRE members. Furthermore, studies on phylogenetic analysis based on whole genome Single-Nucleotide Polymorphism (SNP) of CRKA were limited. Here, 20 CRKA isolates (11 blaKPC-2-bearing and 9 blaNDM-1/5-harboring) were characterized by antimicrobial susceptibility testing, conjugation assay, whole genome sequencing (WGS) and bioinformatics analysis. Additionally, the phylogeographic relationships of K. aerogenes were further investigated from public databases. All isolates were multidrug-resistant (MDR) bacteria, and they demonstrated susceptibility to colistin. Most blaKPC-2 or blaNDM-1/5-carrying plasmids were found to be conjugative. Phylogenetic analysis revealed the clonal dissemination of K. aerogenes primarily occurred within clinical settings. Notably, some strains in this study showed the potential for clonal transmission, sharing few SNPs between K. aerogenes and KPC- and/or NDM-positive K. aerogenes isolated from various countries. The STs of K. aerogenes strains had significant diversity. WGS analysis showed that the IncFIIK plasmid was the most prevalent carrier of blaKPC-2, and, blaNDM-1/5 were detected on the IncX3 plasmids. The Tn6296 and Tn3000 transposons were most common vehicles for facilitating the transmission of blaKPC-2 and blaNDM-1/5, respectively. This study highlights the importance of continuous screening and surveillance by WGS for analysis of drug-resistant strains in hospital settings, and provide clinical information that supports epidemiological and public health research on human pathogens.

Genomic epidemiology and ceftazidime-avibactam high-level resistance mechanisms of Pseudomonas aeruginosa in China from 2010 to 2022.

Ceftazidime-avibactam (CZA) resistance is a huge threat in the clinic; however, the underlying mechanism responsible for high-level CZA resistance in Pseudomonas aeruginosa (PA) isolates remains unknown. In this study, a total of 5,763 P. aeruginosa isolates were collected from 2010 to 2022 to investigate the ceftazidime-avibactam (CZA) high-level resistance mechanisms of Pseudomonas aeruginosa (PA) isolates in China. Fifty-six PER-producing isolates were identified, including 50 isolates carrying blaPER-1 in PA, and 6 isolates carrying blaPER-4. Of these, 82.1% (46/56) were classified as DTR-PA isolates, and 76.79% (43/56) were resistant to CZA. Importantly, blaPER-1 and blaPER-4 overexpression led to 16-fold and >1024-fold increases in the MICs of CZA, respectively. WGS revealed that the blaPER-1 gene was located in two different transferable IncP-2-type plasmids and chromosomes, whereas blaPER-4 was found only on chromosomes and was carried by a class 1 integron embedded in a Tn6485-like transposon. Overexpression of efflux pumps may be associated with high-level CZA resistance in blaPER-1-positive strains. Kinetic parameter analysis revealed that PER-4 exhibited a similar kcat/Km with ceftazidime and a high (∼3359-fold) IC50 value with avibactam compared to PER-1. Our study found that overexpression of PER-1 combined with enhanced efflux pump expression and the low affinity of PER-4 for avibactam contributes to high-level resistance to CZA. Additionally, the Tn6485-like transposon plays a significant role in disseminating blaPER. Urgent active surveillance is required to prevent the further spread of high-level CZA resistance in DTR-PA isolates.

ß-Hemolysin, not agrA mutation, inhibits the hemolysis of α-hemolysin in Staphylococcus aureus laboratory and clinical strains.

Staphylococcus aureus produces various hemolysins regulated by the Agr-QS system, except ß-hemolysin encoded by the gene hlb. A classical laboratory S. aureus strain RN4220 displays only the ß-hemolysin phenotype. It was suspected that the 8A mutation at the end of its agrA gene delayed the expressions of hla and RNAIII, then failed to express α- and δ-hemolysins. However, hla gene expression was detected at the later culture time without α-hemolysin phenotype, the reason for such a phenotype has not been clearly understood. We created hlb knockout and complementary mutants via homologous recombination in RN4220 and NRS049, two strains that normally produce ß-hemolysin and carry agrA mutation. We found interestingly that the presence or absence of α-hemolysin phenotype in such strains depended on the expression of ß-hemolysin instead of agrA mutations, which only inhibited δ-hemolysin expression. The hemolysis phenotype was verified by the Christie-Atkinson-Munch-Peterson (CAMP) test. Quantitative reverse transcription PCR was carried out to evaluate the relative gene expressions of hlb, hla, and RNAIII. The construction of mutants did not affect the agrA mutation status. We demonstrate that the absence of α-hemolysin in S. aureus RN4220 and NRS049 strains is attributed to their production of ß-hemolysin instead of agrA mutation. Our findings broaden the understanding of the molecular mechanisms that control hemolysin expression in S. aureus that is crucial for the development of new therapeutic strategies to combat S. aureus infections. IMPORTANCE: α-Hemolysin is a critical virulence factor in Staphylococcus aureus and its expression is largely controlled by the Agr-QS system. Nonetheless, the hemolysis phenotype and the regulation of the Agr-QS system in S. aureus still hold many mysteries. Our study finds that it is the expression of ß- hemolysin rather than the agrA mutation that inhibits the function of the α-hemolysin in an important S. aureus strain RN4220 and a clinical strain presents a similar phenotype, which clarifies the misunderstood hemolytic phenotype and mechanism of S. aureus. Our findings highlight the interactions among different toxins and their biological roles, combined with QS system regulation, which is ultimately the true underlying cause of its virulence. This emphasizes the importance of considering the collaborative action of various factors in the infection process caused by this significant human pathogen.

Emergence and plasmid cointegration-based evolution of NDM-1-producing ST107 Citrobacter freundii high-risk resistant clone in China.

Carbapenem-resistant Citrobacter freundii (CRCF) poses an enormous challenge in the health care setting. However, the epidemiology and plasmid dynamic evolution of this species have not been well studied, especially for the novel high-risk resistant clones in the intensive care units (ICUs). Here, we characterised the cointegration-based plasmid dynamic evolution of the emerging ST107 CRCF clone in China. Twenty CRCF strains were identified, including ST22 (30%), ST107 (25%), ST396 (10%) and ST116 (10%). Interestingly, the tigecycline (TGC) resistance gene cluster tmexCD2-toprJ2 and blaNDM-1 and blaKPC-2 were simultaneously found in one ST107 strain. Epidemiological analysis showed that ST107 clone contained human- and environment-derived strains from five countries. Notably, 93.75% (15/16) of the isolates harboured blaNDM-1 or blaKPC-2. Plasmid fusion among various ST107 strains of two patients occurred in the same ICU, mediated by Tn5403 and IS26-based insertion and deletion events. pCF1807-2 carried blaNDM-1 while pCF1807-3 carried both tmexCD2-toprJ2 and blaKPC-2 in the CF1807 strain. Importantly, the cointegrate plasmid pCF1807-2 exhibited higher transfer efficiency and could remain stable after serial passage. Notably, no fitness cost was observed for the host. In conclusion, ST107 CRCF is a high-risk resistant clone due to its ability to integrate resistant plasmids. Our findings elucidated the potential threat and global transmission of the ST107 lineage, and reasonable monitoring should be performed to prevent its further spread in hospitals.

Integrated genomic analysis of antibiotic resistance and virulence determinants in invasive strains of Streptococcus pneumoniae.

Introduction: Streptococcus pneumoniae is an important human pathogen that may cause severe invasive pneumococcal diseases (IPDs) in young children and the elderly. A comprehensive comparative whole-genome analysis of invasive and non-invasive serotype strains offers great insights that are applicable to vaccine development and disease control. Methods: In this study, 58 invasive (strains isolated from sterile sites) and 71 non-invasive (serotypes that have not been identified as invasive in our study) pneumococcal isolates were identified among the 756 pneumococcal isolates obtained from seven hospitals in Zhejiang, China (2010-2022). Serotyping, antimicrobial resistance tests, and genomic analyses were conducted to characterize these strains. Results and discussion: The three most invasive serotypes were 23F, 14, and 6B. The invasive pneumococcal isolates' respective resistance rates against penicillin, ceftriaxone, tetracycline, and erythromycin were 34.5%, 15.5%, 98.3%, and 94.7%. Whole-genome sequencing indicated that the predominant invasive clonal complexes were CC271, CC876, and CC81. The high rate of penicillin non-susceptible Streptococcus pneumoniae (PNSP) is related to the clonal distribution of resistance-conferring penicillin-binding proteins (PBP). Interestingly, we found a negative correlation between invasiveness and resistance in the invasive pneumococcal serotype strains, which might be due to the proclivity of certain serotypes to retain their ß-lactam resistance. Moreover, the mutually exclusive nature of zmpC and rrgC+srtBCD suggests their intricate and potentially redundant roles in promoting the development of IPD. These findings reveal significant implications for pneumococcal vaccine development in China, potentially informing treatment strategies and measures to mitigate disease transmission.

Limited protection of pneumococcal vaccines against emergent Streptococcus pneumoniae serotype 14/ST876 strains.

PURPOSE: Streptococcus pneumoniae (Spn) is a major cause of child death. We investigated the epidemiology of S. pneumoniae in a pediatric fever clinic and explored the genomics basis of the limited vaccine response of serotype 14 strains worldwide. METHODS: Febrile disease and pneumonia were diagnosed following criteria from the WHO at the end of 2019 at a tertiary children's hospital. Spn was isolated by culture from nasopharyngeal (NP) swabs. The density was determined by lytA-base qPCR. Isolates were serotyped by Quellung and underwent antimicrobial susceptibility testing. Whole-genome sequencing was employed for molecular serotyping, MLST, antibiotic gene determination, SNP calling, recombination prediction, and phylogenetic analysis. RESULTS: The presence of pneumococcus in the nasopharynx (87.5%, 7/8, p = 0.0227) and a high carriage (100%, 7/7, p = 0.0123) were significantly associated with pneumonia development. Living with siblings (73.7%, 14/19, p = 0.0125) and non-vaccination (56.0%, 28/50, p = 0.0377) contributed significantly to the Spn carriage. Serotype 14 was the most prevalent strain (16.67%, 5/30). The genome analysis of 1497 serotype 14 strains indicated S14/ST876 strains were only prevalent in China, presented limited vaccine responses with higher recombination activities within its cps locus, and unique variation patterns in the genes wzg and lrp. CONCLUSION: With the lifting of the one-child policy, it will be crucial for families with multiple children to get PCV vaccinations in China. Due to the highly variant cps locus and distinctive variation patterns in capsule shedding and binding proteins genes, the prevalent S14/ST876 strains have shown poor response to current vaccines. It is necessary to continue monitoring the molecular epidemiology of this vaccine escape clone.

Characterization of a novel Tn6485h transposon carrying both blaIMP-45 and blaAFM-1 integrated into the IncP-2 plasmid in a carbapenem-resistant Pseudomonas aeruginosa.

OBJECTIVES: To characterize a carbapenem-resistant Pseudomonas aeruginosa (CRPA) with an IncP-2 plasmid containing a novel transposon, Tn6485h, which carries both blaIMP-45 and blaAFM-1. METHODS: Antimicrobial susceptibility testing and filter mating experiment were performed on PA942. The stability of the plasmid carrying both blaIMP-45 and blaAFM-1 was carried out. We determined the growth rate of the transconjugant to investigate fitness cost. Additionally, whole-genome sequencing and genomic analysis were performed on PA942. RESULTS: PA942 strain was resistant to most antibiotics except for ciprofloxacin and colistin. Bioinformatics analysis confirmed that PA942 contains an IncP-2 plasmid with a novel transposon Tn6485h carrying both blaIMP-45 and blaAFM-1. The plasmid pPA942-IMP45 can be transferred into recipient bacteria PAO1Rif with an efficiency of 2.2 × 10-7 and the transconjugant PAO1Rif/ pPA942-IMP45 can be stably inherited for 10 generations in the absence of antibiotics. CONCLUSION: We report a carbapenem-resistant P. aeruginosa strain with an IncP-2 plasmid containing a novel transposon, Tn6485h, which carries both blaIMP-45 and blaAFM-1. The IncP-2 plasmid and transposon Tn6485h may contribute to the spread of MBL genes. Therefore, effective measures to prevent the spread of these plasmids should be taken.

Overexpression of blaGES-1 due to a strong promoter in the class 1 integron contributes to decreased ceftazidime-avibactam susceptibility in carbapenem-resistant Pseudomonas aeruginosa ST235.

Sequence type 235 (ST235) Pseudomonas aeruginosa, harboring so-called international, high-risk, or widespread clones, is associated with relatively high morbidity and mortality, partly due to multiantibiotic and high-level antibiotic resistance. Treatment of infections caused by such strains with ceftazidime-avibactam (CZA) is often successful. However, CZA resistance in carbapenem-resistant P. aeruginosa (CRPA) strains has been consistently reported with the increasing use of this drug. Likewise, we identified thirty-seven CZA-resistant ST235 P. aeruginosa strains from among 872 CRPA isolates. A total of 10.8% of the ST235 CRPA strains were resistant to CZA. Site-directed mutagenesis, cloning, expression, and whole-genome sequencing analysis revealed that overexpression of blaGES-1, which was carried in a class 1 integron of the complex transposon Tn6584, occurred due to a strong promoter, contributing to CZA resistance. Moreover, such overexpression of blaGES-1 combined with an efflux pump resulted in high-level resistance to CZA, considerably reducing the therapeutic options available for treating infections caused by ST235 CRPA. Considering the widespread presence of ST235 P. aeruginosa strains, clinicians should be aware of the risk of CZA resistance development in high-risk ST235 P. aeruginosa. Surveillance initiatives for preventing further dissemination of high-risk ST235 CRPA isolates with CZA resistance are essential.

Clonal outbreak of NDM-1-producing Enterobacter hormaechei belonging to high-risk international clone ST78 with the coexistence of tmexCD2-toprJ2 and mcr-9 in China.

OBJECTIVES: The emergence of carbapenem-resistant Enterobacter cloacae complex (CR-ECC) has posed significant global challenges to the clinical treatment of healthcare-associated infections. This study reports the clonal outbreak of NDM-1-producing Enterobacter hormaechei (E. hormaechei) with the coexistence of tmexCD2-toprJ2 and mcr-9 in China. METHODS: During the outbreak (January 2018 - December 2021), 15 non-repetitive multidrug-resistant E. hormaechei strains were obtained from 13 patients in a tertiary hospital. Antimicrobial susceptibility testing, plasmid stability, plasmid conjugation, plasmid fitness evaluation, colistin induction, whole-genome sequencing, and bioinformatics analysis were performed. A phylogenetic tree was constructed based on single nucleotide polymorphisms of core genomes to illustrate the evolutionary dynamics of mcr-9-carrying E. hormaechei strains worldwide. RESULTS: The 15 E. hormaechei strains belonged to the high-risk international clone ST78 and co-harboured tmexCD2-toprJ2 and blaNDM-1, of which 12 E. hormaechei strains carried the mcr-9 gene. Whole-genome sequencing analysis revealed that tmexCD2-toprJ2 and blaNDM-1 coexisted on the IncFIB/IncFII-type plasmid, which could be transferred to Escherichia coli J53 by conjugation and had a significant effect on host fitness. The mcr-9 gene was located between two insertion sequences, IS903B and IS1R, but lacked the two-component system regulatory gene qseBC, which might be the reason for all mcr-9-positive E. hormaechei strains remaining susceptible to colistin. The expression of mcr-9 was not inducible in strains confirmed by colistin induction assays. Phylogenetic analysis illustrated the silent spread and rapid evolution of mcr-9-carrying E. hormaechei worldwide. CONCLUSION: This study enriched the epidemiological and genomic characterisation of the coexistence of tmexCD2-toprJ2 and mcr-9 in ST78 CR-ECC isolates and demonstrated that they could prolong clonal dissemination in a tertiary hospital in China. Continuous epidemiological surveillance and molecular characterisation of CR-ECC should be conducted to monitor the evolution of CR-ECC around the world.

Parthenolide Attenuates Sepsis-Induced Acute Kidney Injury in Rats by Reducing Inflammation.

Background: Sepsis is a common complication of severe trauma, burns, infection, or major surgery. This disease-related end-organ dysfunction results from systemic inflammatory response syndrome (SIRS). Acute kidney damage (AKI), also known as acute renal failure, is one of the most frequent and serious sequelae of sepsis. Nuclear transcription factor-κB (NF-κB) regulates the transcription of inflammation-related genes and operates as a mediator in the immune system. While parthenolide (PTL) has been reported to prevent harmful inflammatory reactions, its effects on sepsis-associated AKI are unknown. The current study investigates the effects of PTL in sepsis-associated AKI using cell and cecal ligation and puncture (CLP) models. Methods: Lipopolysaccharide (LPS)-stimulated rat glomerular mesangial cells were treated with 10 µM PTL. Inflammatory mediators, including TNF-α, IL-6, and IL-1ß, in the culture supernatants were measured by ELISA, and NF-κB levels were assessed by qPCR. After the generation of the septic CLP model, rats were intraperitoneally injected with 500 g/kg PTL and were euthanized after 72 h. Serum and kidney samples were analyzed. Results: TNF-α, IL-1ß, and IL-6 levels were elevated after LPS treatment of rat glomerular mesangial cells (p=0.004, p=0.002, and p=0.004, respectively) but were significantly reduced in the PTL treatment group (p ≤ 0.001, p=0.01, and p ≤ 0.001). NF-κB p65 levels were also increased after LPS treatment in this group and were reduced in the PTL treatment group. PTL treatment also reduced kidney damage after CLP induction, as shown by histological analysis and reductions in the levels of BUN, Cre, KIM-1, and NAGL. CLP-induced kidney inflammation together with increased levels of proinflammatory cytokines and inflammatory-related proteins. The elevated levels of renal TNF-α, IL-6, and IL-1ß were downregulated after PTL treatment. The PTL treatment also reduced the CLP-induced activation of NF-κB p65 in the damaged kidneys. Conclusion: PTL reduced inflammation induced by CLP-induced AKI in rat models and LPS-induced damage to glomerular mesangial cells by suppressing NF-κB signaling.

An XDR Pseudomonas aeruginosa ST463 Strain with an IncP-2 Plasmid Containing a Novel Transposon Tn6485f Encoding blaIMP-45 and blaAFM-1 and a Second Plasmid with Two Copies of blaKPC-2.

The increased carbapenem resistance among Pseudomonas aeruginosa has become a serious health issue worldwide. We reported an extensively drug-resistant (XDR) P. aeruginosa PA30 isolate which belonged to sequence type ST463 and contained an IncP-2 plasmid (pPA30_1) carrying two genes, namely, blaIMP-45 and blaAFM-1, which encoded the metallo-ß-lactamases AFM-1 and IMP-45, respectively. Additionally, the strain had a plasmid (pPA30_2) with two copies of the blaKPC-2 genes embedded. The plasmid pPA30_1 was highly similar to the previously reported plasmid pHS17-127, which has the same genetic architecture. This plasmid contained blaIMP-45, located in a second gene cassette of the integron In786, carried by a Tn1403-derivative transposon acquiring an ISCR27n3-blaAFM-1 structure. Interestingly, the transposon in pPA30_1 acquired an extra ISCR1-qnrVC6 module and formed a novel transposon, which was subsequently annotated as Tn6485f. The blaKPC-2 genes in pPA30_2 underwent duplication due to the inversion of the IS26-blaKPC-2-IS26 element, which resulted in two copies of blaKPC-2. IMPORTANCE The ST463 clone is an emerging high-risk sequence type that is spreading with blaKPC-2-containing plasmids. The core blaKPC-2 genetic platform is ISKpn27-blaKPC-2-ISKpn6 in almost all samples, and the adjacent region beyond the core platform varies by IS26-mediated inversion or duplication events, amplifying the blaKPC-2 gene copies. The ST463 P. aeruginosa strain PA30 in our study contains another two metallo-ß-lactamase genes, namely, blaIMP-45 and blaAFM-1, in a novel transposon Tn6485f that is harbored by the IncP-2 megaplasmid. The pPA30_1 carrying blaIMP-45 and blaAFM-1 is highly related to pHS17-127 from the ST369 P. aeruginosa strain, indicating the putative dissemination of the megaplasmid between different clones.

Homogeneous ensemble models for predicting infection levels and mortality of COVID-19 patients: Evidence from China.

Background: Persistence of long-term COVID-19 pandemic is putting high pressure on healthcare services worldwide for several years. This article aims to establish models to predict infection levels and mortality of COVID-19 patients in China. Methods: Machine learning models and deep learning models have been built based on the clinical features of COVID-19 patients. The best models are selected by area under the receiver operating characteristic curve (AUC) scores to construct two homogeneous ensemble models for predicting infection levels and mortality, respectively. The first-hand clinical data of 760 patients are collected from Zhongnan Hospital of Wuhan University between 3 January and 8 March 2020. We preprocess data with cleaning, imputation, and normalization. Results: Our models obtain AUC = 0.7059 and Recall (Weighted avg) = 0.7248 in predicting infection level, while AUC=0.8436 and Recall (Weighted avg) = 0.8486 in predicting mortality ratio. This study also identifies two sets of essential clinical features. One is C-reactive protein (CRP) or high sensitivity C-reactive protein (hs-CRP) and the other is chest tightness, age, and pleural effusion. Conclusions: Two homogeneous ensemble models are proposed to predict infection levels and mortality of COVID-19 patients in China. New findings of clinical features for benefiting the machine learning models are reported. The evaluation of an actual dataset collected from January 3 to March 8, 2020 demonstrates the effectiveness of the models by comparing them with state-of-the-art models in prediction.

Emergence of Plasmids Co-Harboring Carbapenem Resistance Genes and tmexCD2-toprJ2 in Sequence Type 11 Carbapenem Resistant Klebsiella pneumoniae Strains.

Objectives: To characterize two plasmids co-harboring carbapenem resistance genes and tmexCD2-toprJ2 in carbapenem-resistant Klebsiella pneumoniae (CRKP) strains. Methods: Two clinical CRKP strains were isolated and characterized by antimicrobial susceptibility testing, conjugation assays, whole-genome sequencing, and bioinformatics analysis. Results: The two CRKP strains NB4 and NB5 were both resistant to imipenem, meropenem and tigecycline. Whole-genome sequencing revealed that two CRKP strains belonged to the ST11 type and carried multiple resistance genes. The tmexCD2-toprJ2 clusters in both strains were located on the IncFIB(Mar)-like/HI1B-like group of hybrid plasmids, which co-harbored the metallo-ß-lactamase gene blaNDM-1. In addition, the co-existence of blaNDM-1 and blaKPC-2 and the presence of tmexCD2-toprJ2 in CRKP strain NB5 was observed. Conclusions: In this study, tmexCD2-toprJ2 gene clusters were identified in two NDM-1-producing CRKP ST11 strains. These gene clusters will likely spread into clinical high-risk CRKP clones and exacerbate the antimicrobial resistance crisis. In addition, we detected the co-occurrence of blaNDM-1, blaKPC-2 and tmexCD2-toprJ2 in a single strain, which will undoubtedly accelerate the formation of a "superdrug resistant" bacteria. Hence, effective control measures should be implemented to prevent the further dissemination of such organisms in clinical settings.

Panax notoginseng Alleviates Sepsis-Induced Acute Kidney Injury by Reducing Inflammation in Rats.

Background: Sepsis is defined as a host inflammatory response to infection that can result in end-organ dysfunction. One of the most common consequences of sepsis is acute kidney injury (AKI). Panax notoginseng powder (PNP) has been previously reported to protect against overactive inflammation process. However, the potential effect of PNP on septic AKI is poorly described. The current study was conducted to investigate the protective effects of PNP in septic AKI rats. Methods: A model of septic AKI was established on male SD rats by using the cecal ligation and puncture procedure. PNP was administrated by gavage after the cecal ligation and puncture (CLP) procedure, and the mice were sacrificed at 6, 12, and 72 h after induction of sepsis. The serum and kidney samples were collected and assayed for biochemical tests, histopathological staining, inflammation, and apoptosis-related gene/protein expression. In addition, 15 rats in each group were used to calculate the 7-day survival rate. Results: CLP-induced kidney injury was observed by the histopathological score, which markedly was attenuated by PNP treatment. Consistently, PNP intervention significantly alleviated the elevated levels of serum creatinine and blood urea nitrogen in CLP-induced sepsis rats. The CLP procedure also triggered proinflammatory cytokine production and increased the expression of various inflammation-related proteins in the kidneys. However, PNP inhibited the renal expression of IL-18, IL-1ß, TNF-α, and IL-6 to substantially improve inflammatory response. Mechanistically, CLP induced the increase of the NF-κB p65 level in the injured kidneys, while PNP notably inhibited the corresponding protein expression. Conclusion: PNP attenuated kidney inflammation to protect against CLP-induced septic AKI in rats via inhibiting the NF-κB signaling pathway.

An injectable and biodegradable hydrogel incorporated with photoregulated NO generators to heal MRSA-infected wounds.

The development of degradable hydrogel fillers with high antibacterial activity and wound-healing property is urgently needed for the treatment of infected wounds. Herein, an injectable, degradable, photoactivated antibacterial hydrogel (MPDA-BNN6@Gel) was developed by incorporating BNN6-loaded mesoporous polydopamine nanoparticles (MPDA-BNN6 NPs) into a fibrin-based hydrogel. After administration, MPDA-BNN6@Gel created local hyperthermia and released large quantities of NO gas to treat methicillin-resistant Staphylococcus aureus infection under the stimulation of an 808 nm laser. Experiments confirmed that the bacteria were eradicated through irreversible damage to the cell membrane, genetic metabolism, and material energy. Furthermore, in the absence of laser irradition, the fibrin and small amount of NO that originated from MPDA-BNN6@Gel promoted wound healing in vivo. This work indicates that MPDA-BNN6@Gel is a promising alternative for the treatment of infected wounds and provides a facile tactic to design a photoregulated bactericidal hydrogel for accelerating infected wound healing. STATEMENT OF SIGNIFICANCE: The development of a degradable hydrogel with high antibacterial activity and wound-healing property is an urgent need for the treatment of infected wounds. Herein, an injectable, degradable, and photo-activated antibacterial hydrogel (MPDA-BNN6@Gel) has been developed by incorporating BNN6-loaded mesoporous polydopamine nanoparticles (MPDA-BNN6 NPs) into a fibrin-based hydrogel. After administration of MPDA-BNN6@Gel, the MPDA-BNN6@Gel could generate local hyperthermia and release large quantities of NO gas to treat the methicillin-resistant Staphylococcus aureus infection under the irradiation of 808 nm laser. Furthermore, in the absence of a laser, the fibrin and a small amount of NO originating from MPDA-BNN6@Gel could promote wound healing in vivo.

Emergence of a KPC-90 Variant that Confers Resistance to Ceftazidime-Avibactam in an ST463 Carbapenem-Resistant Pseudomonas aeruginosa Strain.

Carbapenem-resistant Pseudomonas aeruginosa (CRPA) has become a serious challenge in the clinic. Recently, the prevalence of CRPA isolates carrying the blaKPC-2 gene has been increasing in China. Ceftazidime-avibactam (CZA) has shown good efficacy against large portions of KPC-2-producing CRPA strains. However, with the increasing usage of this drug, CZA resistance in CRPA strains has been reported. Here, we reported for the first time that resistance of the ST463 CRPA strain to CZA was caused by a novel variant in the KPC gene that arose after CZA exposure. The CRPA strain PA2207 is a carbapenem- and CZA-resistant strain that harbors a mutated blaKPC gene, named blaKPC-90. Cloning and expression of blaKPC-90 in Escherichia coli DH5α revealed that KPC-90 led to a 64-fold increase in the MIC value of CZA. Conjugation experiments further confirmed that blaKPC-90 was located on a conjugative plasmid. Whole-genome sequencing analysis showed that this plasmid had high sequence similarity to a previously reported novel blaKPC-2-harboring plasmid in a clinical P. aeruginosa strain isolated in China. In addition, overexpression of an efflux pump (MexXY-OprM) might be associated with the CZA resistance phenotype, as determined by reverse transcription-quantitative PCR and efflux pump inhibition experiments. For the first time, we reported a KPC variant, KPC-90, in a clinical ST463 CRPA strain with CZA resistance that was mediated by a 2 amino acid insertion outside the KPC omega-loop region. Our study further highlights that diverse KPC variants that mediate CZA resistance have emerged in the CRPA strain. Furthermore, KPC-90 mutation combined with efflux pump overexpression resulted in a high level of resistance to CZA in the PA2207 isolate. Effective surveillance should be conducted to prevent CZA resistance from spreading in the CRPA strain. IMPORTANCE For the first time, we reported a KPC variant, KPC-90, in a clinical ST463 CRPA strain with CZA resistance. CZA resistance was mediated by a 2 amino acid insertion outside the KPC omega-loop region in CRPA. Our study further emphasized that CZA resistance caused by blaKPC gene mutation could be selected in CRPA after CZA therapy. Considering the widespread presence of the ST463 CRPA strain in China, clinicians should pay attention to the risk of the development of CZA resistance in CRPA strains under treatment pressure.

Molecular Mechanisms Driving the In Vivo Development of KPC-71-Mediated Resistance to Ceftazidime-Avibactam during Treatment of Carbapenem-Resistant Klebsiella pneumoniae Infections.

Here, we characterized the mechanisms resulting in the development of KPC-71-mediated resistance to ceftazidime-avibactam (CZA) during treatment of carbapenem-resistant Klebsiella pneumoniae (CRKP) infections. CZA-susceptible and CZA-resistant K. pneumoniae strains, namely, KP357 and KP697, were isolated from the same patient. Whole-genome sequencing revealed that KP357 and KP697 belonged to the ST11 type and KP697 strain possessed a mutation in the plasmid-borne blaKPC-2 gene. Compared to KPC-2, this blaKPC gene (blaKPC-71) showed a mutated nucleotide and an insertion of 3 nucleotides at positions 542 to 545, which resulted in a variant with the subsequent insertion of a serine between the Ambler positions 182 and 183. This plasmid, carrying blaKPC-71, successfully transformed its CZA-resistant phenotype to Escherichia coli DH5α. Cloning and expression of blaKPC-71 in E. coli DH5α demonstrated that KPC-71 resulted in a 16-fold increase in the MIC value for CZA. Kinetic parameters showed that KPC-71, compared to wild-type KPC-2, exhibited a lower (∼13-fold) Km with ceftazidime and a higher (∼14-fold) 50% inhibitory concentration with avibactam. In addition, both blaKPC-2 and blaKPC-71 gene expression have a negative impact on fitness. In conclusion, we detected a novel KPC variant, KPC-71, in a clinical ST11 CRKP strain resulting in CZA resistance development during treatment. The KPC-71 enzyme was associated with a higher affinity toward ceftazidime and a reduced sensitivity to avibactam, conferring resistance to CZA. Considering the wide application of CZA, clinicians should pay attention to the risk of the development of CZA resistance in CRKP strains under treatment pressure. IMPORTANCE In this study, we report an ST11-type clinical CRKP isolate that produces KPC-71, a novel plasmid backbone KPC variant that confers the development of CZA resistance during treatment. Furthermore, we reveal that resistance to CZA is mediated by the 182S insertion mutation in the KPC enzyme, which increases ceftazidime affinity and decreases avibactam inhibition. In addition, KPC-71 has reduced hydrolysis activity, which leads to susceptibility to carbapenems. To the best of our knowledge, this is a novel KPC-2 variant conferring resistance to CZA and the first report of its emergence. Considering the widespread presence of the ST11 CRKP strain in China, clinicians should pay attention to the risk of the development of CZA resistance in CRKP strains under treatment pressure.

Role of Bioactive Constituents of Panax notoginseng in the Modulation of Tumorigenesis: A Potential Review for the Treatment of Cancer.

Cancer is a leading cause of death, affecting people in both developed and developing countries. It is a challenging disease due to its complicated pathophysiological mechanism. Many anti-cancer drugs are used to treat cancer and reduce mortality rates, but their toxicity limits their administration. Drugs made from natural products, which act as multi-targeted therapy, have the ability to target critical signaling proteins in different pathways. Natural compounds possess pharmacological activities such as anti-cancer activity, low toxicity, and minimum side effects. Panax notoginseng is a medicinal plant whose extracts and phytochemicals are used to treat cancer, cardiovascular disorders, blood stasis, easing inflammation, edema, and pain. P. notoginseng's secondary metabolites target cancer's dysregulated pathways, causing cancer cell death. In this review, we focused on several ginsenosides extracted from P. notoginseng that have been evaluated against various cancer cell lines, with the aim of cancer treatment. Furthermore, an in vivo investigation of these ginsenosides should be conducted to gain insight into the dysregulation of several pathways, followed by clinical trials for the potential and effective treatment of cancer.