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Characterizing the nature of hydrodynamical transport properties in quantum dynamics provides valuable insights into the fundamental understanding of exotic non-equilibrium phases of matter. Experimentally simulating infinite-temperature transport on large-scale complex quantum systems is of considerable interest. Here, using a controllable and coherent superconducting quantum simulator, we experimentally realize the analog quantum circuit, which can efficiently prepare the Haar-random states, and probe spin transport at infinite temperature. We observe diffusive spin transport during the unitary evolution of the ladder-type quantum simulator with ergodic dynamics. Moreover, we explore the transport properties of the systems subjected to strong disorder or a tilted potential, revealing signatures of anomalous subdiffusion in accompany with the breakdown of thermalization. Our work demonstrates a scalable method of probing infinite-temperature spin transport on analog quantum simulators, which paves the way to study other intriguing out-of-equilibrium phenomena from the perspective of transport.
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OBJECTIVES: Carbapenem-resistant Klebsiella pneumoniae (CRKP) is a major nosocomial infectious pathogen with rapidly increasing prevalence. The genomic epidemiological characteristics of CRKP nationwide, especially the evolving trends within the predominant clones, should be evaluated clearly. METHODS: We collected 3415 K. pneumoniae strains from 28 hospitals across China. Antimicrobial susceptibility testing and WGS were performed. Subsequent genomic analyses, including sequence typing, K-locus (KL) identification, antimicrobial resistance gene screening, and virulence score assessment were performed. The phylogenetic relationship of clonal group 11 was determined based on core-genome analysis, and the presence of the pLVPK-like virulence plasmid in ST11 isolates was confirmed using plasmid core-gene analysis. Additionally, the trends of the ST11 lineage with different KL types on a global scale were investigated using Beast2. RESULTS: Of the K. pneumoniae strains, 708 were identified as CRKP isolates (20.7%), of which 97.7% were MDR. ST11 was the predominant clone, and KPC-2 was the prevalent carbapenemase in China, although the prevalence of specific clones and carbapenemases varied by geographic region. Among ST11 isolates, KL47 and KL64 were the predominant KL types, and KL64 gradually replaced KL47, with a higher percentage of KL64 isolates harbouring the pLVPK-like plasmid. Global genome data showed a significant increase in the effective population size of KL64 over the last 5 years. CONCLUSIONS: The prevalence of CRKP was very high in certain regions in China. The increasing convergence of virulence and resistance, particularly in ST11-KL64 isolates, should be given more attention and further investigation.
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Antibacterianos , Enterobacteriaceae Resistentes a los Carbapenémicos , Infecciones por Klebsiella , Klebsiella pneumoniae , Pruebas de Sensibilidad Microbiana , Filogenia , Plásmidos , Secuenciación Completa del Genoma , China/epidemiología , Klebsiella pneumoniae/genética , Klebsiella pneumoniae/efectos de los fármacos , Klebsiella pneumoniae/aislamiento & purificación , Klebsiella pneumoniae/clasificación , Infecciones por Klebsiella/epidemiología , Infecciones por Klebsiella/microbiología , Humanos , Plásmidos/genética , Antibacterianos/farmacología , Enterobacteriaceae Resistentes a los Carbapenémicos/genética , Enterobacteriaceae Resistentes a los Carbapenémicos/efectos de los fármacos , Enterobacteriaceae Resistentes a los Carbapenémicos/aislamiento & purificación , beta-Lactamasas/genética , Genoma Bacteriano , Carbapenémicos/farmacología , Proteínas Bacterianas/genética , Tipificación de Secuencias Multilocus , Virulencia/genética , Infección Hospitalaria/epidemiología , Infección Hospitalaria/microbiología , Epidemiología Molecular , Prevalencia , Farmacorresistencia Bacteriana Múltiple/genéticaRESUMEN
As a widely spread Gram-negative bacteria, Klebsiella pneumoniae (KP) mainly causes acquired infections in hospitals, such as lung infections, urinary tract infections, and bloodstream infections. In recent years, the number of multidrug-resistant KP strains has increased dramatically, posing a great threat to human health. Carbapenem-resistant KP (CRKP) can be colonized in human body, especially in gastrointestinal tract, and some colonized patients can be infected during hospitalization, among which invasive operation, underlying disease, admission to intensive care unit, antibiotic use, severity of the primary disease, advanced age, operation, coma, and renal failure are common risk factors for secondary infection. Active screening and preventive measures can effectively prevent the occurrence of CRKP infection. Based on the epidemiological status, this study aims to discuss the correlation between colonization and secondary infection induced by CRKP and risk factors for their happening and provide some reference for nosocomial infection prevention and control.
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OBJECTIVES: Using a random forest algorithm, we previously found that teicoplanin-associated gene A (tcaA) might play a role in resistance of methicillin-resistant Staphylococcus aureus (MRSA) to ß-lactams, which we have investigated further here. METHODS: Representative MRSA strains of prevalent clones were selected to identify the role of tcaA in the MRSA response to ß-lactams. tcaA genes were deleted by homologous recombination in the selected MRSA strains, and antibiotic susceptibility tests were applied to evaluate the effect of tcaA on the minimum inhibitory concentrations (MICs) of glycopeptides and ß-lactams. Scanning electron microscopy, RNA sequencing, and quantitative reverse transcription-polymerase chain reaction were performed to explore the mechanism of tcaA in MRSA resistance to ß-lactams. RESULTS: The MIC of penicillin plus clavulanate decreased from 3 mg/L to 0.064 mg/L and that of oxacillin decreased from 16 to 0.5 mg/L when tcaA was knocked out in the LAC strain. Compared with wild-type MRSA isolates, when tcaA was deleted, all selected strains were more susceptible to ß-lactams. Susceptibility to ceftobiprole was restored in the ceftobiprole-resistant strain when tcaA was deleted. tcaA knockout caused "log-like" abnormal division of MRSA, and tcaA deficiency mediated low expression of mecA, ponA, and murA2. CONCLUSIONS: Machine learning is a reliable tool for identifying drug resistance-related genes. tcaA may be involved in S. aureus cell division and may affect mecA, ponA, and murA2 expression. Furthermore, tcaA is a potential resistance breaker target for ß-lactams, including ceftobiprole, in MRSA.
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Antibacterianos , Cefalosporinas , Staphylococcus aureus Resistente a Meticilina , Pruebas de Sensibilidad Microbiana , Resistencia betalactámica , Staphylococcus aureus Resistente a Meticilina/efectos de los fármacos , Staphylococcus aureus Resistente a Meticilina/genética , Antibacterianos/farmacología , Cefalosporinas/farmacología , Humanos , Resistencia betalactámica/genética , Proteínas Bacterianas/genética , Infecciones Estafilocócicas/microbiología , Infecciones Estafilocócicas/tratamiento farmacológico , beta-Lactamas/farmacología , Técnicas de Inactivación de GenesRESUMEN
OBJECTIVES: Fosfomycin has regained attention for treating infections caused by methicillin-resistant Staphylococcus aureus and multidrug-resistant coagulase-negative staphylococci. In this research, our objective was to investigate the mechanisms underlying fosfomycin resistance in Staphylococcus capitis. METHODS: The minimum inhibitory concentrations (MICs) of fosfomycin were assessed in 109 clinical S. capitis isolates by the agar dilution method. By cloning the fos-like genes into the shuttle vector, pTSSCm-Pcap, and observing the change in fosfomycin MICs, the gene function was verified. Core genome multilocus sequence typing and comparative genomics analysis were conducted to determine the population characteristics of S. capitis isolates and analyse the genetic environment of the fos-like genes. RESULTS: We identified a novel fosfomycin resistance gene, fosSC, on the chromosome in 58 out of 109 (53.2%) S. capitis isolates. The deduced products of the fosSC genes shared 67.15-67.88% amino acid sequence identity with FosB. The RN-pT-fosSC transformants carrying fosSC showed a 512-fold increase in the fosfomycin MICs. The fosSC gene was embedded in a conserved genetic context, but IS431mec was located to the left of the fosSC gene in cluster L due to the insertion of staphylococcal cassette chromosome mec. CONCLUSIONS: The chromosomal fosSC genes in some lineages of S. capitis explained their high-level fosfomycin resistance. Ongoing surveillance is crucial for monitoring the potential threat of horizontal transfer, which could be facilitated by the presence of mobile genetic elements surrounding the fosSC gene.
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Antibacterianos , Farmacorresistencia Bacteriana , Fosfomicina , Pruebas de Sensibilidad Microbiana , Infecciones Estafilocócicas , Staphylococcus capitis , Fosfomicina/farmacología , Antibacterianos/farmacología , Humanos , Infecciones Estafilocócicas/microbiología , Staphylococcus capitis/genética , Staphylococcus capitis/efectos de los fármacos , Farmacorresistencia Bacteriana/genética , Tipificación de Secuencias Multilocus , Genes Bacterianos/genéticaRESUMEN
The threat posed by Klebsiella pneumoniae in healthcare settings has worsened due to the evolutionary advantages conferred by blaKPC-2-harboring plasmids (pKPC-2). However, the specific evolutionary pathway of nosocomial K. pneumoniae carrying pKPC-2 and its transmission between patients and healthcare environments are not yet well understood. Between 1 August and 31 December 2019, 237 ST11 KPC-2-producing-carbapenem-resistant K. pneumoniae (CRKP) (KPC-2-CRKP) were collected from patient or ward environments in an intensive care unit and subjected to Illumina sequencing, of which 32 strains were additionally selected for Nanopore sequencing to obtain complete plasmid sequences. Bioinformatics analysis, conjugation experiments, antimicrobial susceptibility tests, and virulence assays were performed to identify the evolutionary characteristics of pKPC-2. The pKPC-2 plasmids were divided into three subgroups with distinct evolutionary events, including Tn3-mediated plasmid homologous recombination, IS26-mediated horizontal gene transfer, and dynamic duplications of antibiotic resistance genes (ARGs). Surprisingly, the incidence rates of multicopy blaKPC-2, blaSHV-12, and blaCTX-M-65 were quite high (ranging from 27.43% to 67.01%), and strains negative for extended-spectrum ß-lactamase tended to develop multicopy blaKPC-2. Notably, the presence of multicopy blaSHV-12 reduced sensitivity to ceftazidime/avibactam (CZA), and the relative expression level of blaSHV-12 in the CZA-resistant group was 6.12 times higher than that in the sensitive group. Furthermore, a novel hybrid pKPC-2 was identified, presenting enhanced virulence levels and decreased susceptibility to CZA. This study emphasizes the notable prevalence of multicopy ARGs and provides a comprehensive insight into the intricate and diverse evolutionary pathways of resistant plasmids that disseminate among patients and healthcare environments.IMPORTANCEThis study is based on a CRKP screening program between patients and ward environments in an intensive care unit, describing the pKPC-2 (blaKPC-2-harboring plasmids) population structure and evolutionary characteristics in clinical settings. Long-read sequencing was performed in genetically closely related strains, enabling the high-resolution analysis of evolution pathway between or within pKPC-2 subgroups. We revealed the extremely high rates of multicopy antibiotic resistance genes (ARGs) in clinical settings and its effect on resistance profile toward novel ß-lactam/ß-lactamase inhibitor combinations, which belongs to the last line treatment choices toward CRKP infection. A novel hybrid pKPC-2 carrying CRKP with enhanced resistance and virulence level was captured during its clonal spread between patients and ward environment. These evidences highlight the threat of pKPC-2 to CRKP treatment and control. Thus, surveillance and timely disinfection in clinical settings should be practiced to prevent transmission of CRKP carrying threatful pKPC-2. And rational use of antibiotics should be called for to prevent inducing of pKPC-2 evolution, especially the multicopy ARGs.
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Infección Hospitalaria , Infecciones por Klebsiella , Humanos , Klebsiella pneumoniae/genética , Klebsiella/genética , Infecciones por Klebsiella/tratamiento farmacológico , Infección Hospitalaria/epidemiología , Virulencia/genética , beta-Lactamasas/genética , Antibacterianos/farmacología , Plásmidos/genética , Carbapenémicos/farmacologíaRESUMEN
Daptomycin (DAP) is effective against methicillin-resistant Staphylococcus aureus (MRSA). However, reduced susceptibility to DAP in MRSA may lead to treatment failures. We aim to determine the distribution of DAP minimum inhibitory concentrations (MICs) and DAP heteroresistance (hDAP) among MRSA lineages in China. A total of 472 clinical MRSA isolates collected from 2015 to 2017 in China were examined for DAP susceptibility. All isolates (n = 472) were found to be DAP susceptible, but 35.17% (166/472) of them exhibited a high DAP MIC (MIC >0.5 µg/mL). The high DAP MIC group contained a larger proportion of isolates with a higher vancomycin or teicoplanin MIC (>1.5 µg/mL) than the low DAP MIC group (19.3% vs 7.8%, P < 0.001; 22.3% vs 8.2%, P < 0.001). We compared the clonal complex (CC) distributions and clinical characteristics in MRSA isolates stratified by DAP MIC. CC5 isolates were less susceptible to DAP (MIC50 = 1 µg/mL) than CC59 isolates (MIC50 = 0.5 µg/mL, P < 0.001). Population analysis profiling revealed that 5 of 10 ST5 and ST59 DAP-susceptible MRSA isolates investigated exhibited hDAP. The results also showed that CC5 MRSA with an agrA mutation (I238K) had a higher DAP MIC than those with a wild-type agrA (P < 0.001). The agrA-I238K mutation was found to be associated with agr dysfunction as indicated by the loss of δ-hemolysin production. In addition, agr/psmα defectiveness was associated with hDAP in MRSA. Whole-genome sequencing analysis revealed mutations in mprF and walR/walK in DAP-resistant subpopulations, and most DAP-resistant subpopulations (6/8, 75%) were stable. Our study suggests that the increased DAP resistance and hDAP in MRSA may threaten the effectiveness against MRSA infections.
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Daptomicina , Staphylococcus aureus Resistente a Meticilina , Infecciones Estafilocócicas , Humanos , Daptomicina/farmacología , Daptomicina/uso terapéutico , Staphylococcus aureus Resistente a Meticilina/genética , Antibacterianos/farmacología , Antibacterianos/uso terapéutico , Infecciones Estafilocócicas/tratamiento farmacológico , Infecciones Estafilocócicas/epidemiología , Vancomicina/farmacología , Pruebas de Sensibilidad MicrobianaRESUMEN
BACKGROUND: The overuse of antibiotics in livestock is contributing to the burden of antimicrobial resistance in humans, representing a One Health challenge. Livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) has recently become a growing concern, and ST9 is the major LA-MRSA lineage in China and has emerged in clinical settings. METHODS: Antimicrobial susceptibility testing was used to evaluate the tetracycline resistance of ST9 MRSA collections, and gene cloning experiments were performed to explore the resistance mechanisms. Whole-genome sequencing and comparative genomics were used to analyse the genetic features of clinical ST9 isolates. A phylogenetic tree was constructed to investigate the relationship of human- and livestock-derived ST9 isolates. RESULTS: Clinical ST9 isolates were found to possess several types of resistance genes and resistance-related mutations and were multidrug-resistant. Notably, all clinical ST9 isolates were resistant to third-generation tetracyclines. Cloning experiments showed that both the acquisition of the tetracycline resistance gene tet(L)/tet(63) and a mutation in the rpsJ gene contributed to third-generation tetracycline resistance. Phylogenetic analysis showed that the ST9 isolates collected in healthcare systems were probably transmitted from livestock. The ST9 lineage underwent multiple interspecies recombination events and gained many resistance elements. Furthermore, the resistance to third-generation tetracyclines may have evolved under tetracycline pressure in livestock. CONCLUSIONS: The evolution of ST9 MRSA in livestock and transmission of this clone between humans and livestock highlight the importance of establishing control strategies with the One Health approach to reduce the burden of antibiotic resistance.
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Staphylococcus aureus Resistente a Meticilina , Infecciones Estafilocócicas , Animales , Humanos , Ganado , Resistencia a la Tetraciclina/genética , Filogenia , Infecciones Estafilocócicas/epidemiología , Infecciones Estafilocócicas/veterinaria , Antibacterianos/farmacología , Tetraciclina , China/epidemiologíaRESUMEN
In this study, the as-cast microstructure and the evolution of the homogenized microstructure of large-scale industrialized Al-Cu-Mg-Ag heat-resistant aluminum alloy ingots were investigated by means of optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive analysis (EDS), and differential scanning calorimetry (DSC). The results indicate that the dendritic segregation is evident in the ingot along the radial direction, and the grain boundaries are decorated with lots of net-shaped continuous eutectic structures. With the homogenization time extension and the homogenization temperature increase, the eutectic phases (i.e., the primary Al2Cu phase, the Al2CuMg phase, and the AlCuMgAg quaternary phase) at the grain boundaries gradually dissolve back into the matrix. Meanwhile, most of the dendritic grain boundaries gradually become sparse and thinner. Finally, it is found that the optimal homogenization regime of the Al-Cu-Mg-Ag alloy is 420 °C/5 h+480 °C/8 h+515 °C/24 h.
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OBJECTIVES: This study aims to investigate the effect of morinda officinalis polysaccharides (MOP) in inflammatory microenvironment on the expression of silent information regulator sirtuin 1 (SIRT1) and NOD-like receptor thermal protein domain associated protein 3 (NLRP3) in periodontal ligament cells. METHODS: Thirty rats were randomly divided into control group (n=6) and model group (n=24). The model group used orthodontic wire ligation to establish periodontitis, and six rats from each group were killed after 3 weeks. The successful modeling was confirmed by Micro-CT. The remaining rats in the model group were randomly divided into natural recovery group, normal saline (NS) group, and MOP group. In the MOP group, MOP [200 mg/(kg·3d), 50 µL for 4 weeks] was injected into the palatal side of the left maxillary first molar of the rats, while the NS group was injected with equal volume of NS. The natural recovery group did not undergo any treatment. The left maxilla tissues of the rats were collected, and pathological changes in perio-dontal ligament cells were observed by hematoxylin-eosin (HE) staining. The expression of SIRT1 and NLRP3 was detected by immunohistochemistry. Cultivate periodontal ligament fibroblasts in vitro and detect the effect of MOP on cell activity using CCK-8. The 4th generation cells were divided into control group, inflammation group (10 µg/mL lipopolysaccharide), and experimental group (5 µmol/L MOP, 5 µmol/L MOP+10 µg/mL lipopolysaccharide). The expression of SIRT1 and NLRP3 was detected by quantitative realtime polymerase chain reaction (qRT-PCR) and Western blot analyses. The acetylation of NLRP3 and the contents of interleukin (IL)-1ß and IL-18 were detected by immunoprecipitation and enzyme-linked immunosorbent assay, respectively. Statistical analysis of data was conducted using Prism 9.0 software. RESULTS: In the vivo experiments, the expression of NLRP3 and SIRT1 in the MOP group decreased significantly compared with that in the natural recovery group and NS group, while the expression of SIRT1 increased (P<0.05) and inflammatory cell infiltration decreased. In the in vitro experiments, the expression of NLRP3 mRNA and protein in the inflammation group increased (P<0.05), while the expression of SIRT1 significantly decreased (P<0.01); MOP upregulated the expression of SIRT1 in inflammatory cells (P<0.05), reduced the expression of NLRP3 and its acetylation level significantly (P<0.05), suppressed the content of IL-1ß and IL-18 in the supernatant (P<0.01). CONCLUSIONS: The SIRT1 expression decreased, and that of NLRP3 expression increased in inflammatory periodontal ligament cells. MOP intervention promoted SIRT1 expression, resulting in the inhibition of NLRP3. Meanwhile, the acetylation level of NLRP3 reduced through deacetylation, leading to the decreased activity of NLRP3. Thus, MOP acted as inflammatory suppressor.
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Morinda , Proteína con Dominio Pirina 3 de la Familia NLR , Ratas , Animales , Proteína con Dominio Pirina 3 de la Familia NLR/metabolismo , Sirtuina 1/genética , Sirtuina 1/metabolismo , Interleucina-18/metabolismo , Morinda/metabolismo , Proteínas NLR , Lipopolisacáridos , Ligamento Periodontal/metabolismo , Dominios Proteicos , InflamaciónRESUMEN
Cryptococcus spp. is a complex species that often causes cryptococcosis, which is one of the most common opportunistic infections in adults living with HIV and has very high morbidity and mortality rates. This study aimed to investigate the antifungal susceptibility profiles and epidemiological characteristics of the Cryptococcus neoformans species complex (CNSC) and the Cryptococcus gattii species complex (CGSC) in Zhejiang Province, China. A total of 177 CNSC and 3 CGSC isolates were collected, and antifungal susceptibility was tested by FUNGUS 3 and verified with an E-test. Moreover, multiple classification methods and genomic analyses were performed. The majority of the isolates (96.11%) were C. neoformans (formerly C. neoformans var. grubii) (ST5-VNI-A-α). Our study highlights that most of the patients with cryptococcosis were non-HIV patients in China, and nearly half of them did not have underlying diseases that led to immune insufficiency. Most of the Cryptococcus spp. isolates in this study were sensitive to common antifungal drugs. Two 5-flucytosine (5-FC)-resistant strains were identified, and FUR1 mutation was detected in the 5-FC-resistant isolates. Typing based on whole-genome sequencing (WGS) showed better discrimination than that achieved with multilocus sequence typing (MLST) and indicated a clear population structure. A phylogenetic analysis based on WGS included more genomic information than traditional classification methods.
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Carbapenem-resistant Klebsiella pneumoniae (CRKP) is a common nosocomial pathogen causing severe infectious diseases, and ST307 CRKP is an emerging clone. In this study, we collected five ST307 CRKP isolates, evaluated their antimicrobial susceptibility using microbroth dilution, and their clonality and population structure by PFGE, cgMLST, and SNP-based phylogenetic analysis. Then, the genome characteristics, such as antimicrobial resistance genes and plasmid profiles, were studied by subsequent genomic analysis. The plasmid transfer ability was evaluated by conjugation, and the carbapenem resistance mechanism was elucidated by gene cloning. The results showed that all five ST307 CRKP isolates harboured blaCMY-6, blaOXA-48, and blaNDM-1; however, the end of the blaNDM-1 signal peptide was interrupted and truncated by an IS10 element, resulting in the deactivation of carbapenemase. The ST307 isolates were closely related, and belonged to the globally disseminated clade. blaOXA-48 and blaNDM-1 were located on the different mobilisable IncL/M- and IncA/C2-type plasmids, respectively, and either the pOXA-48 or pNDM-1 transconjugants were ertapenem resistant. Gene cloning showed that blaCMY-6 could elevate the MICs of carbapenems up to 64-fold and was located on the same plasmid as blaNDM-1. In summary, ST307 is a high-risk clone type, and its prevalence should be given additional attention.
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Staphylococcus capitis, which causes bloodstream infections in neonatal intensive care units, is a common cause of healthcare-associated infections. Thus, a standardized high-resolution typing method to document the transmission and dissemination of multidrug-resistant S. capitis isolates is required. We aimed to establish a core genome multilocus sequence typing (cgMLST) scheme to surveil S. capitis. The cgMLST scheme was defined based on primary and validation genome sets and tested with outbreaks of linezolid-resistant isolates and a validation set. Phylogenetic analysis was performed to investigate the population structure and compare it with the result of cgMLST analysis. The S. capitis population consists of 1 dominant, NRCS-A, and 4 less common clones. In this work, a multidrug-resistant clone (L clone) with linezolid resistance is identified. With the features of type III SCCmec and multiple copies of mutations of G2576T and C2104T in the 23S rRNA, the L clone has been spreading silently across China.
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Staphylococcus aureus Resistente a Meticilina , Infecciones Estafilocócicas , Staphylococcus capitis , Antibacterianos/farmacología , Antibacterianos/uso terapéutico , Humanos , Recién Nacido , Linezolid/farmacología , Linezolid/uso terapéutico , Staphylococcus aureus Resistente a Meticilina/genética , Tipificación de Secuencias Multilocus/métodos , Filogenia , Infecciones Estafilocócicas/tratamiento farmacológico , Infecciones Estafilocócicas/epidemiología , Staphylococcus capitis/genéticaRESUMEN
OBJECTIVES: In this study, we evaluated the ceftobiprole (BPR) susceptibilities of 472 methicillin-resistant Staphylococcus aureus (MRSA) isolates, and investigated the mechanisms underlying BPR resistance. METHODS: For all MRSA isolates, BPR MIC was determined by agar dilution. We sequenced the BPR-resistant isolates through Illumina short- and MinION long-read sequencing. We also selected MRSA isolates of ST5, ST59, and ST239, and exposed them to increasing BRP concentrations. The isolated mutants developing BPR resistance were sequenced. RESULTS: A total of 471 MRSA isolates were susceptible to BPR, with MICs ranging from 0.25 to 2 mg/L. Compared with HA-MRSA isolates (MIC50 = 2 mg/L; MIC90 = 2 mg/L), CA-MRSA isolates (MIC50 = 0.5; MIC90 = 2 mg/L) were more susceptible to BPR (p < 0.001). Compared with isolates with staphylococcal cassette chromosome mec (SCCmec) type II or III (MIC50 = 2 mg/L; MIC90 = 2 mg/L), isolates with SCCmec type IV (MIC50 = 1 mg/L; MIC90 = 1 mg/L) or V (MIC50 = 0.5 mg/L; MIC90 = 1 mg/L) were more susceptible to BPR (p < 0.001). Nanopore sequencing revealed two copies of SCCmec repeats in the BPR-resistant MRSA isolate. In addition, SCCmec amplification could be induced by BPR exposure in ST239 MRSA isolates; however, no amplification was observed in the other lineages. The induced BPR-resistant MRSA isolates also acquired mutations in mecA and other genes, such as guaA, guaB, relA, rpoA, and oatA, which were speculated as factors contributing to BPR-resistance development. DISCUSSION: BPR showed significant antibacterial activity against MRSA isolates in China; however, the emergence of a BPR-resistant isolate before its launch was a cause for concern. Multiple genes and pathways are potentially involved in the development of BPR resistance in MRSA, and our data demonstrated the role of nanopore-sequencing in revealing the tandem repeat-mediated resistance mechanism in MRSA.
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Staphylococcus aureus Resistente a Meticilina , Infecciones Estafilocócicas , Antibacterianos/farmacología , Cefalosporinas/farmacología , Cromosomas , Humanos , Pruebas de Sensibilidad Microbiana , Infecciones Estafilocócicas/microbiologíaRESUMEN
Fosfomycin has gained attention as a combination therapy for methicillin-resistant Staphylococcus aureus infections. Hence, the detection of novel fosfomycin-resistance mechanisms in S. aureus is important. Here, the minimal inhibitory concentrations (MICs) of fosfomycin in CC1 methicillin-resistant S. aureus were determined. The pangenome analysis and comparative genomics were used to analyse CC1 MRSA. The gene function was confirmed by cloning the gene into pTXΔ. A phylogenetic tree was constructed to determine the clustering of the CC1 strains of S. aureus. We identified a novel gene, designated fosY, that confers fosfomycin resistance in S. aureus. The FosY protein is a putative bacillithiol transferase enzyme sharing 65.9-77.5% amino acid identity with FosB and FosD, respectively. The function of fosY in decreasing fosfomycin susceptibility was confirmed by cloning it into pTXΔ. The pTX-fosY transformant exhibited a 16-fold increase in fosfomycin MIC. The bioinformatic analysis showed that fosY is in a novel genomic island designated RIfosY (for "resistance island carrying fosY") that originated from other species. The global phylogenetic tree of ST1 MRSA displayed this fosY-positive ST1 clone, originating from different regions, in the same clade. The novel resistance gene in the fos family, fosY, and a genomic island, RIfosY, can promote cross-species gene transfer and confer resistance to CC1 MRSA causing the failure of clinical treatment. This emphasises the importance of genetic surveillance of resistance genes among MRSA isolates.
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Fosfomicina , Staphylococcus aureus Resistente a Meticilina , Infecciones Estafilocócicas , Antibacterianos/farmacología , Antibacterianos/uso terapéutico , Fosfomicina/farmacología , Islas Genómicas , Humanos , Pruebas de Sensibilidad Microbiana , Filogenia , Infecciones Estafilocócicas/epidemiología , Staphylococcus aureusRESUMEN
Objective: To determine the genetic structure of ermB-positive Tn1546-like mobile elements in methicillin-resistant Staphylococcus aureus (MRSA) from mainland China. Methods: A total of 271 erythromycin-resistant MRSA isolates were isolated from Sir Run Run Shaw Hospital (SRRSH) from 2013 to 2015. Whole-genome sequencing was performed for the ermB-positive strains, and the genetic environment of the ermB genes was analyzed. Southern hybridization analysis and transformation tests were performed to confirm the location of the ermB gene. Results: A total of 64 isolates (64/271, 23.6%) were ermB-positive strains, with 62 strains (62/64, 96.9%) belonging to the CC59 clone. The other two strains, SR130 and SR231, belonging to CC5-ST965, both harbored 14,567 bp ermB-positive Tn1546-like elements and displayed multidrug-resistant profiles. PFGE followed by Southern blot demonstrated that the ermB genes were located on the plasmids of both SR130 and SR231, while two copies of ermB were located on the chromosome of SR231. Further sequencing demonstrated that SR231 carried one Tn1546-ermB elements in the plasmid and two identical copies integrated on the chromosome, which had 99.99% identity to the element in the plasmid of SR130. The Tn1546-ermB elements were highly similar (100% coverage, >99.9% identity) to the element Tn6636 reported in a previous study from Taiwan. The plasmids (pSR130 and pSR231) harboring ermB-positive Tn1546-like elements were also identical to the mosaic plasmid pNTUH_5066148. However, conjugation of ermB-carrying plasmids of SR130 and SR231 were failed after triple repeats. Conclusion: Multiple copies of ermB-positive Tn1546-like mobile elements were found in CC5-ST965 MRSA from mainland China, showing the wide dissemination of these Enterococcus faecium-originated ermB-positive Tn1546-like elements. Molecular epidemiological study of Tn1546-like elements is essential to avoid the spreading of resistant determinants.
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Background: Surgical sites infections (SSIs) caused by Methicillin-resistant Staphylococcus aureus (MRSA) constitute a major clinical problem. Understanding the transmission mode of MRSA is important for its prevention and control. Aim: We investigated the transmission mode of a MRSA outbreak in a trauma and orthopedic hospital ward. Methods: Clinical data were collected from patients (n = 9) with MRSA infection in a trauma and orthopedic ward from January 1, 2015 to December 31, 2019. The wards (n = 18), patients (n = 48), medical staff (n = 23), and their households (n = 5) were screened for MRSA. The transmission mode of MRSA isolates was investigated using next-generation sequencing and phylogenetic analyses. The resistance genes, plasmids, and single-nucleotide variants of the isolates were analyzed to evaluate microevolution of MRSA isolates causing SSIs. The MRSA colonization-positive doctor was asked to suspend his medical activities to stop MRSA spread. Findings: Nine MRSA infected patients were investigated, of which three patients were diagnosed with SSI and had prolonged hospitalization due to the persistent MRSA infection. After screening, MRSA isolates were not detected in environmental samples. The surgeon in charge of the patients with SSI caused by MRSA and his son were positive for MRSA colonization. The MRSA from the son was closely related to the isolates detected in MRSA-induced SSIs patients with 8-9 single-nucleotide variants, while ST88-MRSA isolates with three different spa types were detected in the surgeon's nasal cavity. Comparative genomic analysis showed that ST88-MRSA isolates acquired mutations in genes related to cell wall synthesis, colonization, metabolism, and virulence during their transmission. Suspending the medical activity of this surgeon interrupted the spread of MRSA infection in this ward. Conclusion: Community-associated MRSA clones can invade hospitals and cause severe postoperative nosocomial infections. Further MRSA surveillance in the households of health workers may prevent the transition of MRSA from colonization to infection.
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Staphylococcus aureus Resistente a Meticilina , Infecciones Estafilocócicas , Humanos , Staphylococcus aureus Resistente a Meticilina/genética , Infecciones Estafilocócicas/epidemiología , Filogenia , Hospitales , Personal de Salud , NucleótidosRESUMEN
OBJECTIVES: The aim of this study was to investigate the genomic epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) in China to identify predominant lineages and their associations with clinical data and antimicrobial resistance profiles. METHODS: We performed a national prevalence study of patients with S. aureus infections in 22 tertiary hospitals in China from 2015 to 2017. Clinical data from patients and the antimicrobial phenotypes were collected for each isolate. Genome sequencing was performed on a proportion of isolates and a phylogenetic analysis was undertaken. Genotypic and phenotypic ß-lactam susceptibilities were compared. RESULTS: A total of 1900 patients with S. aureus infections were included, of which 40% involved MRSA. Community-associated MRSA (CA-MRSA) infections were 24% of the total isolates. Genomic data showed that more than three-quarters of the MRSA were from three dominant lineages CC239 (25%, 116/471), CC5 (21%, 96/471) and CC59 (33%, 154/471) with CC59 accounting for more than half of the CA-MRSA isolates. Penicillin susceptibility genomic features were observed in 53% (251/470) of MRSA, including almost all of the CC59 (152/154) lineage, and 96% (242/251) of these isolates demonstrated in vitro susceptibility to penicillin or amoxicillin combined with clavulanic acid. Phylogenetic analysis indicated that the CC59 lineage can be divided into six lineages with all Asian CC59 isolates likely arising from an ancestral Mainland China lineage. CONCLUSIONS: This study showed a high prevalence of CA-MRSA in China, largely due to the widespread presence of CC59. As almost all isolates in this lineage possess genetic variants leading to increased ß-lactam susceptibility, we suggest that to improve antibiotic stewardship combinations of penicillins and ß-lactamase inhibitors should be included in the antibiotic susceptibility testing panels used to inform treatment decisions and research undertaken on this combination therapy.
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Staphylococcus aureus Resistente a Meticilina , Infecciones Estafilocócicas , Antibacterianos/uso terapéutico , China/epidemiología , Evolución Molecular , Humanos , Staphylococcus aureus Resistente a Meticilina/genética , Pruebas de Sensibilidad Microbiana , Penicilinas , Filogenia , Infecciones Estafilocócicas/tratamiento farmacológico , Infecciones Estafilocócicas/epidemiología , Staphylococcus aureusRESUMEN
Treatment failure of methicillin-resistant Staphylococcus aureus (MRSA) infections remains problematic in clinical practice because therapeutic options are limited. Penicillin plus potassium clavulanate combination (PENC) was shown to have potential for treating some MRSA infections. We investigated the susceptibility of MRSA isolates and constructed a drug susceptibility prediction model for the phenotype of the PENC. We determined the minimum inhibitory concentration of PENC for MRSA (n=284) in a teaching hospital (SRRSH-MRSA). PENC susceptibility genotypes were analysed using a published genotyping scheme based on the mecA sequence. mecA expression in MRSA isolates was analysed by qPCR. We established a random forest model for predicting PENC-susceptible phenotypes using core genome allelic profiles from cgMLST analysis. We identified S2-R isolates with susceptible mecA genotypes but PENC-resistant phenotypes; these isolates expressed mecA at higher levels than did S2 MRSA (2.61 vs 0.98, P<0.05), indicating the limitation of using a single factor for predicting drug susceptibility. Using the data of selected UK-sourced MRSA (n=74) and MRSA collected in a previous national survey (NA-MRSA, n=471) as a training set, we built a model with accuracies of 0.94 and 0.93 for SRRSH-MRSA and UK-sourced MRSA (n=287, NAM-MRSA) validation sets. The AUROC of this model for SRRSH-MRSA and NAM-MRSA was 0.96 and 0.97. Although the source of the training set data affects the scope of application of the prediction model, our data demonstrated the power of the machine learning approach in predicting susceptibility from cgMLST results.
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Ácido Clavulánico/farmacología , Staphylococcus aureus Resistente a Meticilina/efectos de los fármacos , Staphylococcus aureus Resistente a Meticilina/genética , Penicilinas/farmacología , Algoritmos , Antibacterianos/farmacología , Proteínas Bacterianas/genética , ADN Bacteriano/genética , Genotipo , Aprendizaje Automático , Staphylococcus aureus Resistente a Meticilina/aislamiento & purificación , Pruebas de Sensibilidad Microbiana , Proteínas de Unión a las Penicilinas/genética , Staphylococcus aureus/genéticaRESUMEN
Currently, the mechanism of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) transmission mechanism is unclear; however, it must be considered in conjunction with asymptomatic S. aureus strains colonization dynamics. This epidemiological study aimed to determine the role of the household in CA-MRSA transmission in China. Five patients with culture-confirmed CA-MRSA infection and five control patients were recruited from the Sir Run Run Shaw Hospital in Zhejiang, China, between December 2019 and January 2020. The household members of the patients, their pets, and environmental surfaces were sampled and screened for MRSA colonization. Mass spectrometry identification and antimicrobial susceptibility testing were performed on the MRSA isolates. Whole-genome sequencing and core genome multilocus sequence typing (cgMLST) were performed to determine the origin and transmission of the MRSA isolates in the households. Overall, 14 S. aureus-positive specimens (14.1%, 14/99) were obtained from the five households of patients with CA-MRSA infections, of which 12 (85.7%) were MRSA. The overall positivity of MRSA was 12.1% (12/99) among the samples from the CA-MRSA households, while no MRSA isolates were detected in the five control households. Most MRSA isolates belonged to epidemic CA-MRSA clones, such as ST59 (15/35, 42.9%) and ST508 (15/35, 42.9%). The cgMLST results confirmed that MRSA was transmitted among patients, contacts, and pets in the households and was present on environmental surfaces in the CA-MRSA patients' households. In conclusion, the study revealed that the home environment was an important MRSA reservoir. Therefore, focusing on MRSA decolonization in patients alone is not sufficient for infection control of CA-MRSA.