The co-production of KPC and NDM carbapenemases in carbapenem-resistant Klebsiella pneumoniae (CRKP) complicates clinical treatment and increases mortality rates. The emergence of KPC-NDM CRKP is believed to result from the acquisition of an NDM plasmid by KPC CRKP, especially under the selective pressure of ceftazidime-avibactam (CZA). In this study, a CRKP-producing KPC-2 (JNP990) was isolated from a patient at a tertiary hospital in Shandong Province, China. Following sulfamethoxazole-trimethoprim (SXT) treatment, the isolate evolved into a strain that co-produces KPC and NDM (JNP989), accompanied by resistance to SXT (minimum inhibitory concentration > 2/38 mu g/mL) and CZA (dd <= 14 mm). Whole-genome sequencing and S1 nuclease pulsed-field gel electrophoresis revealed that JNP989 acquired an IncC plasmid (NDM plasmid) spanning 197 kb carrying sul1 and bla(NDM-1) genes. The NDM plasmid could be transferred successfully into Escherichia coli J53 at a conjugation frequency of (8.70 +/- 2.47) x 10(-4) . The IncF II /IncR plasmid carrying the bla(KPC-2) gene in JNP990 could only be transferred in the presence of the NDM plasmid at a conjugation frequency of (1.93 +/- 0.41) x 10(-5) . Five CRKP strains with the same resistance pattern as JNP989, belonging to the same clone as JNP989, with sequence type 11 were isolated from other patients in the same hospital. Two strains lost resistance to CZA due to the loss of the bla(NDM-1) -carrying fragment mediated by insertion sequence 26. Plasmid stability testing indicated that the IncC plasmid was more stable than the bla(NDM-1) genes in the hosts. This study describes the evolution of KPC-NDM CRKP and its spread in hospitalized patients following antibiotic treatment, highlighting the severity of the spread of resistance. (c) 2024 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY -NC -ND license ( http://creativecommons.org/licenses/by-nc-nd/4.0/ )

ObjectiveNontyphoidal Salmonella is a significant public health concern due to its ability to cause foodborne illnesses worldwide. This study aims to characterize the nontyphoidal Salmonella strains isolated from patients in China.MethodsA total of 19 nontyphoidal Salmonella strains were characterized through serovar identification, antimicrobial susceptibility testing (AST), biofilm formation assessment. Genetic relatedness was determined using pulsed-field gel electrophoresis (PFGE). WGS was employed to decipher the resistance mechanism and to contextualize the S. serovar Mbandaka strains among previously sequenced isolates in China. The biofilm associated mrkA gene was examined by PCR.ResultsThe predominant serovar identified was S. Enteritidis, followed by S. Mbandaka, S. Thompson, S. Livingston, S. Alachua, and S. Infantis. PFGE analysis indicated a notable genetic similarity among the S. Mbandaka isolates. Phylogenetic analysis suggested that these strains were likely derived from a single source that had persisted in China for over five years. One multidrug resistance (MDR) S. Enteritidis isolate carried a highly transferable IncB/O/K/Z plasmid with blaCTX-M-15. One S. Thompson strain, harboring the mrkABCDF operon in an IncX1 plasmid, isolated from cutaneous lesions, demonstrated robust biofilm formation. However, no mrkABCDF loci were detected in other strains.ConclusionOur study emphasizes the importance of persisted surveillance and prompt response to Salmonella infections to protect public health. The dissemination of blaCTX-M-15-harboring IncB/O/K/Z plasmid and the spread of virulent mrkABCDF operon among Salmonella in China and other global regions warrant close monitoring.

The widespread of different NDM variants in clinical Enterobacterales isolates poses a serious public health concern, which requires continuous monitoring. In this study, three E. coli strains carrying two novel blaNDM variants of blaNDM-36, -37 were identified from a patient with refractory urinary tract infection (UTI) in China. We conducted antimicrobial susceptibility testing (AST), enzyme kinetics analysis, conjugation experiment, whole-genome sequencing (WGS), and bioinformatics analysis to characterize the blaNDM-36, -37 enzymes and their carrying strains. The blaNDM-36, -37 harboring E. coli isolates belonged to ST227, O9:H10 serotype and exhibited intermediate or resistance to all β-lactams tested except aztreonam and aztreonam/avibactam. The genes of blaNDM-36, -37 were located on a conjugative IncHI2-type plasmid. NDM-37 differed from NDM-5 by a single amino acid substitution (His261Tyr). NDM-36 differed from NDM-37 by an additional missense mutation (Ala233Val). NDM-36 had increased hydrolytic activity toward ampicillin and cefotaxime relative to NDM-37 and NDM-5, while NDM-37 and NDM-36 had lower catalytic activity toward imipenem but higher activity against meropenem in comparison to NDM-5. This is the first report of co-occurrence of two novel blaNDM variants in E. coli isolated from the same patient. The work provides insights into the enzymatic function and demonstrates the ongoing evolution of NDM enzymes.

Abstract Background Salmonella enterica is a significant public health concern due to its ability to cause foodborne illnesses worldwide. To gain insights into the epidemiology and characteristics of Salmonella strains in China, a total of 20 Salmonella isolates were subjected to phenotypic and molecular analyses. Methods The 20 Salmonella strains were characterized through serotype identification, antimicrobial susceptibility testing (AST), biofilm formation assessment and plasmid transmission studies. Molecular characteristics and relatedness were determined using pulsed-field gel electrophoresis (PFGE) and whole genome sequencing (WGS). Additionally, SNP-based phylogenetic analysis and core genome multilocus sequence typing (cgMLST) were employed to contextualize the strains among previously sequenced S. enterica isolates in China and worldwide. Results The predominant serovar identified was Salmonella enterica serovar Enteritidis ( S. Enteritidis), followed by S. Mbandaka, Thompson, Livingston, Alachua, and Infantis. The SNP-based phylogenetic analysis revealed substantial diversity among S. Enteritidis isolates, with a minimum of 32 SNPs between strains. Conversely, S. Mbandaka isolates were suspected to have originated from a single clonal expansion, displaying a difference within 6 SNPs. SNP-based phylogenetic analysis suggested S. Mbandaka clone in this study was likely to have been derived from a single source that persisted over 5 years in China. S. Mbandaka, Infantis, Livingston, and Alachua exhibited susceptibility to the tested antibiotics, while strains of S. Thompson and Enteritidis demonstrated resistance to ampicillin, quinolone, and sulfamethoxazole/trimethoprim (SMZ/TMP). Particularly concerning was the identification of one S. Enteritidis isolate carrying the highly transferable IncB/O/K/Z plasmid with bla CTX−M15 , conferring cephalosporin resistance. Another isolate, harboring the mrkABCDF operon in an IncX1 plasmid, isolated from cutaneous lesions, demonstrated robust biofilm formation. Conclusions Our study emphasizes the importance of SNP-based surveillance and prompt response to Salmonella infections to protect public health. The dissemination of bla CTX−M15 -harboring IncB/O/K/Z plasmid and the spread of virulent mrkABCDF operon among S. enterica in China and other global regions warrant close monitoring.

Abstract Background Salmonella enterica is a significant public health concern due to its ability to cause foodborne illnesses worldwide. To gain insights into the epidemiology and characteristics of Salmonella strains in China, a total of 20 Salmonella isolates were subjected to phenotypic and molecular analyses. Methods The 20 Salmonella strains were characterized through serotype identification, antimicrobial susceptibility testing (AST), biofilm formation assessment and plasmid transmission studies. Molecular characteristics and relatedness were determined using pulsed-field gel electrophoresis (PFGE) and whole genome sequencing (WGS). Additionally, SNP-based phylogenetic analysis and core genome multilocus sequence typing (cgMLST) were employed to contextualize the strains among previously sequenced S. enterica isolates in China and worldwide. Results The predominant serovar identified was Salmonella enterica serovar Enteritidis (S. Enteritidis), followed by S. Mbandaka, Thompson, Livingston, Alachua, and Infantis. The SNP-based phylogenetic analysis revealed substantial diversity among S. Enteritidis isolates, with a minimum of 32 SNPs between strains. Conversely, S. Mbandaka isolates were suspected to have originated from a single clonal expansion, displaying a difference within 6 SNPs. SNP-based phylogenetic analysis suggested S. Mbandaka clone in this study was likely to have been derived from a single source that persisted over 5 years in China. S. Mbandaka, Infantis, Livingston, and Alachua exhibited susceptibility to the tested antibiotics, while strains of S. Thompson and Enteritidis demonstrated resistance to ampicillin, quinolone, and sulfamethoxazole/trimethoprim (SMZ/TMP). Particularly concerning was the identification of one S. Enteritidis isolate carrying the highly transferable IncB/O/K/Z plasmid with blaCTX−M15, conferring cephalosporin resistance. Another isolate, harboring the mrkABCDF operon in an IncX1 plasmid, isolated from cutaneous lesions, demonstrated robust biofilm formation. Conclusions Our study emphasizes the importance of SNP-based surveillance and prompt response to Salmonella infections to protect public health. The dissemination of blaCTX−M15-harboring IncB/O/K/Z plasmid and the spread of virulent mrkABCDF operon among S. enterica in China and other global regions warrant close monitoring.

高毒力肺炎克雷伯菌(hvKp)能够引起健康个体的社区获得性感染,比经典的肺炎克雷伯菌更具毒性.hvKp在亚洲首次被发现,是化脓性肝脓肿的主要原因.除肝脓肿外,hvKp与肺炎克雷伯菌的不同之处在于其具有很强的转移能力,包括肺、眼和中枢神经系统.由于导致高毒力的遗传决定因素通常在毒力质粒及染色体移动遗传元件上,该文对其与毒力相关的微生物学特征与毒力因子的研究进展进行综述,以期为高毒力肺炎克雷伯菌的早期识别、感染控制和新型治疗药物的研发提供线索.

目的:对引起中枢神经系统感染的一株罕见粘液型溶血葡萄球菌(S.haemolyticus)表型及基因组特征进行分析.方法:收集一株导致中枢神经系统感染粘液型溶血葡萄球菌,通过生物膜形成实验、药敏实验分析生物膜形成和耐药表型,全基因组测序分析其耐药等基因特征.结果:本例溶血葡萄球菌呈粘液型,可见拉丝现象,属于苯唑西林耐药凝固酶阴性葡萄球菌(MRCoNS),同时对红霉素、克林霉素、左氧氟沙星耐药,对万古霉素、利奈唑胺敏感,比普通非粘液型溶血葡萄球菌更易形成生物膜,MLST显示该菌为ST1型,携带mecA、aph(3')-Ⅲa、aac(6')-Ie、aph(2")-Ia等8种耐药基因,mecA基因由类似Tn6191的转座子所携带.结论:呈粘液型菌落特征的溶血葡萄球菌在临床上极为罕见,该变异体比通常的非粘液型菌落更易形成生物膜且呈现出多重耐药现象.临床上应关注此类葡萄球菌的粘液变异体,这有助于其早期识别和感染防控.