UNASSIGNED: The emergence of carbapenem-resistant Klebsiella pneumoniae (CRKP) has garnered international concern due to its significant antibiotic resistance. Notably, children exhibit distinct resistance mechanisms compared to adults, necessitating a differential approach to antibiotic selection. A thorough analysis of CRKP\'s epidemiology and drug resistance mechanisms is essential for establishing a robust foundation for clinical anti-infection strategies and precise prevention and control measures.
UNASSIGNED: This study involved the collection of 31 non-repetitive strains from pediatric and adult patients at a tertiary hospital in China, spanning from July 2016 to July 2022, testing for resistance genes, antimicrobial susceptibility, and homology analysis.
UNASSIGNED: Infants (0-1 year) were the largest pediatric CRKP group, with 61.3% of cases. The neonatal intensive care unit (NICU) and pediatrics were the main departments affected. Adults with CRKP had a mean age of 67 years, with the highest prevalence in neurology and emergency ICU. Antimicrobial susceptibility testing revealed that adult CRKP strains exhibited higher resistance to amikacin, ciprofloxacin, cotrimoxazole, and aztreonam compared to pediatric strains. Conversely, pediatric strains showed a higher rate of resistance to ceftazidime/avibactam. The predominant resistance genes identified were bla NDM-5 in children (58.1%) and bla KPC-2 in adults (87.1%), with over 93% of both groups testing positive for extended-spectrum beta-lactamase (ESBL) genes. Multilocus Sequence Typing (MLST) indicated ST2735 and ST11 as the predominant types in children and adults, respectively. Pulsed-field gel electrophoresis (PFGE) identified clonal transmission patterns of ST11 bla KPC-2 and ST15 bla OXA-232 across both age groups. Notably, this study reports the first instance of ST1114-type CRKP co-producing bla NDM-5 and bla OXA-181 in the NICU.
UNASSIGNED: This study reveals distinct resistance mechanisms and epidemiology in CRKP from children and adults. The identified clonal transmission patterns emphasize the need for improved infection control to prevent the spread of resistant strains.

BACKGROUND: This study aimed to assess the performance of three commercial panels, the ERIC Carbapenem-Resistant Enterobacteriaceae Test (ERIC CRE test), the NG-Test CARBA 5 (NG CARBA 5), and the BD Phoenix CPO Detect Panel (CPO panel), for the detection of main types of carbapenemases among carbapenem-resistant Enterobacterales (CRE).
METHODS: We collected 502 isolates of carbapenem-resistant Enterobacterales (CRE) demonstrating intermediate or resistant profiles to at least one carbapenem antibiotic (ertapenem, imipenem, meropenem, or doripenem). Carbapenemase genes and their specific types were identified through multiplex PCR and sequencing methods. Subsequently, the ERIC CRE test, CPO panel, and NG CARBA 5 assay were conducted on these isolates, and the results were compared with those obtained from multiplex PCR.
RESULTS: The results indicated that the ERIC CRE test exhibited an overall sensitivity and specificity of 98.1% and 93.6%, respectively, which were comparable to 99.1% and 90.6% for the NG CARBA 5. However, the CPO panel demonstrated a sensitivity of only 56.2% in identifying Ambler classes, exhibiting the poorest sensitivity for class A. Moreover, while the ERIC CRE test outperformed the NG CARBA 5 in identifying multi-gene isolates with multiple carbapenemase-encoding genes, the CPO panel failed to accurately classify these isolates.
CONCLUSIONS: Our findings support the utilization of the ERIC CRE test as one of the methods for detecting carbapenemases in clinical laboratories. Nonetheless, further optimization is imperative for the CPO panel to enhance its accuracy in determining carbapenemase classification and address limitations in detecting multi-gene isolates.

UNASSIGNED: Carbapenem-Resistant Enterobacteriaceae (CRE) has posed a significant threat to humans.The aim of this study was to investigate the molecular characteristics of blaKPC-producing Escherichia coli in a university-affiliated tertiary hospital.
UNASSIGNED: Polymerase chain reaction (PCR) and BLAST+ software were used to detect the prevalence of blaKPC in E. coli and Klebsiella pneumoniae. Whole-genome sequencing was performed for the blaKPC-harboring clinical E. coli isolates. Antimicrobial resistance genes, MLSTs, KPC-carrying plasmid typing and genetic environment of blaKPC were analyzed. A maximum likelihood core single nucleotide polymorphism (SNP)-based phylogeny tree was constructed to determine the evolutionary relationships within this ST131 collection. Conjugation experiments were performed to determine the mobilization of blaKPC. The minimal inhibitory concentrations of the common antimicrobial agents were determined using the broth microdilution method.
UNASSIGNED: The prevalence of blaKPC in 424 clinical E. coli isolates and 1636 E. coli strains from GenBank database were 2.2% (45/2060) whereas the detection rate of blaKPC in K. pneumoniae from the GenBank database was 29.8% (415/1394). The blaKPC-harboring conjugants exhibited resistance to multiple β-lactams, except for cefepime-zidebactam and ceftazidime-avibactam. All blaKPC-carring E. coli isolates were susceptible to tigecycline and polymyxin B. ST131 was the dominant sequence type of blaKPC-carring E. coli, accounting for 40.0% (18/45). Most of the blaKPC-producing ST131 E. coli (89.5%,17/19) belonged to clade C ST131 lineage. Genetic environment analysis revealed that 57.8% (26/45) of blaKPC gene was linked to Tn4401-associated structure ISKpn6-blaKPC-ISKpn7. IncN was the most common plasmid type in KPC-producing E. coli whereas IncFII was the dominant plasmid type in KPC-producing K. pneumoniae.
UNASSIGNED: The detection rate of blaKPC was lower in E. coli compared with K. pneumoniae. The dominant sequence and plasmid types of blaKPC-harboring isolates differed between E. coli and K. pneumoniae. Further studies about the role of the defense system in acquisition of KPC-plasmids in E. coli will be performed to provide new insights into the low prevalence of blaKPC.

Bacterial multi-drug resistance has become a concern worldwide, especially after the emergence of carbapenemases. Adjuvants with antibacterial potentiation activity can resensitise drug-resistant strains to carbapenems. However, only a few adjuvants with antibacterial potentiation activity are currently available in clinical practice. Here, we first docked the library containing more than 30,000 small molecules to carbapenemases including Klebsiella pneumoniae carbapenemase 2 (KPC-2) and New Delhi metallo-β-lactamase-5 (NDM-5), through in silico virtual screening to obtain lead compounds against carbapenemase-producing Enterobacterales. Meanwhile, the in vitro antibacterial potentiation assays revealed that ibandronate, azacytidine, ribostamycin sulfate and cidofovir exhibited synergistic or additive activity in the presence of meropenem, with good biocompatibility based on red blood cell hemolysis and cell viability tests. Furthermore, the combination of meropenem and azacytidine showed high efficacy in a mouse sepsis model infected with an NDM-5-producing clinical strain, with a 100% survival rate, decreased bacterial burden and alleviated pathological deterioration. These results suggest that the virtual screening is a promising strategy to identify new antibiotic adjuvants targeting carbapenemase-producing Enterobacterales.

Carbapenem-resistant Escherichia coli (CREC) has become a major public health problem worldwide. To date, there is a limited understanding of the global distribution of CREC. In this study, we performed a comprehensive genomic analysis of 7, 731 CRECs of human origin collected from different countries worldwide between 2005 and 2023. Our results showed that these CRECs were distributed in 75 countries, mainly from the United States (17.49%), China (14.88%), and the United Kingdom (14.73%). Eight carbapenemases were identified among the CRECs analyzed, including KPC, IMP, NDM, VIM, OXA, FRI, GES, and IMI. NDM was the most predominant carbapenemase (52.15%), followed by OXA (30.09%) and KPC (14.72%). Notably, all CRECs carried multiple antibiotic resistance genes (ARGs), with 178 isolates carrying mcr-1 and 9 isolates carrying tet(X). The CREC isolates were classified into 465 known sequence types (STs), with ST167 being the most common (11.5%). Correlation analysis demonstrated the significant role of mobile genetic elements in facilitating the transfer of carbapenem resistance genes. Furthermore, some CRECs from different countries showed high genetic similarity, suggesting clonal transmission exists. According to the GWAS results, the genetic difference of blaNDM-positive CRECs from China were mainly enriched in bacterial Type IV secretion system pathways compared with those from the United Kingdom and the United States. Therefore, continuous global surveillance of CRECs is imperative in the future.

Carbapenem resistant Klebsiella pneumoniae is associated with nosocomial infections and can cause high mortality, which poses great threat to human health. This study was aimed at investigating the molecular epidemiology and antimicrobial resistance profiles of carbapenem resistant Klebsiella pneumoniae isolates and providing clues for management and control of carbapenem resistant Klebsiella pneumoniae infections.
A total of 2324 Klebsiella pneumoniae strains were isolated from the First Affiliated Hospital of Guangxi Medical University from June 2018 to October 2020, and 103 carbapenem resistant Klebsiella pneumoniae strains from inpatients were collected, and the specimens mainly came from the sputum, urine, secretions, and blood. The antimicrobial susceptibility tests were performed using the VITEK 2 Compact system or the Kirby-Bauer disk-diffusion method. The resistance genes were detected by polymerase chain reaction and sequencing. The homology analysis of carbapenem resistant Klebsiella pneumoniae strains was performed by multilocus sequence typing.
Antimicrobial susceptibility results showed that the 103 carbapenem resistant Klebsiella pneumoniae strains were resistant to most common antibiotics. Resistance genes detection showed that the carbapenem resistant Klebsiella pneumoniae isolates mainly carried metallo-beta-lactamase, and the predominant gene was NDM-1. The homology analysis found that the major ST type were ST11, follow by ST15 and ST17.
The carbapenem resistant Klebsiella pneumoniae isolates in our study shown resistance to most common antibiotics. Of the 103 carbapenem resistant Klebsiella pneumoniae strains, 91 strains (88.35%) carried carbapenemases genes, and NDM was the predominant carbapenemase gene detected. ST11 was the major ST typing of carbapenem resistant Klebsiella pneumoniae in our hospital. Our finding may play a role in control and management of the carbapenem resistant Klebsiella pneumoniae infections and guiding clinical antibiotic therapy. In addition, metallo-beta-lactamase should be served as a key target to be monitored in carbapenem resistant Klebsiella pneumoniae infection.

Carbapenem-resistant Enterobacterales (CRE) constitute an urgent threat to worldwide public health. The spread of CRE is facilitated by transmission via the environment. Wastewater treatment plants (WWTPs) are considered to be important sources of antibiotic resistance and hot spots of antibiotic-resistant bacteria (ARB) which can facilitate dissemination of antibiotic resistance genes. In this study, water samples were collected over one year from a WWTP in Jinan, Shandong province, China, from different functional sites in the wastewater treatment process. Carbapenem-resistant Escherichia coli (CREC) were isolated by selective cultivation and whole-genome sequenced to investigate the occurrence and characteristics of CREC in the WWTP. A total of 77 CREC isolates were included in the study and the detection rate of CREC in the WWTP water inlet was found to be 85%. An additional 10 CREC were isolated from a nearby teaching hospital during the sampling period and included for comparison to the environmental isolates. Susceptibility testing showed that all CREC were multidrug-resistant. 6 different carbapenem resistance genes (CRGs) were detected, including blaNDM-5 (n = 75), blaNDM-1 (n = 6), blaNDM-4 (n = 3), blaNDM-6 (n = 1), blaNDM-9 (n = 1), and blaKPC-2 (n = 4). 42 CREC isolates were whole-genome sequenced with Illumina short-read sequencing. 11 of these were also sequenced with Nanopore long-read sequencing. Plasmids carrying CRGs were found to belong to IncX3 (n = 35), IncFII (n = 12), IncFIA (n = 5), IncFIB (n = 2), IncC (n = 1), and IncP6 (n = 1). Clonal dissemination of CREC belonging to ST167, ST448, and ST746 was observed between different parts of the WWTP. Furthermore, isolates from the WWTP, including an isolate belonging to the high-risk ST167 strain, were found to be clonally related to CREC isolated at the hospital. The spread of CRGs is of considerable concern and strategies to prevent environmental dissemination of this contaminant urgently needs to be implemented.

Carbapenem-resistant Klebsiella pneumoniae (CRKP), which harbors the bla NDM plasmid, has been reported extensively and is considered a global threat clinically. However, characterization and comparisons of bla NDM-1-carrying and bla NDM-5-harboring IncX3-type plasmids in CRKP are lacking. Here, we systematically compared the differences in the characteristics, genetic backgrounds, transferability, and fitness costs between bla NDM-1-carrying and bla NDM-5-carrying plasmids in K. pneumoniae isolates. Fifteen NDM-producing CRKP isolates were recovered from 1376 CRKP isolates between 2019 and 2021, of which 4 were positive for bla NDM-1 and 11 were positive for bla NDM-5. All strains were highly resistant to carbapenem but remained susceptible to tigecycline and colistin. Core-genome-based phylogenetic analyses revealed that these strains were not clonally related. Whole-genome sequencing showed that bla NDM-1 and bla NDM-5 were located on ~54 kb and ~46 kb IncX3-type plasmids, respectively. The backbone, genetic context, and fitness cost of the bla NDM-1-bearing plasmid were highly similar to those of the bla NDM-5-carrying plasmid, but the transferability of the bla NDM-1-positive plasmid was greater than that of the bla NDM-5-positive plasmid. In conclusion, the transmission of bla NDM-1 or bla NDM-5 is mainly disseminated by plasmids rather than clonal spread. The high transfer frequency of the IncX3 plasmid facilitates the prevalence and dissemination of NDM-KP among Enterobacteriaceae. IMPORTANCE The emergence of NDM-producing Klebsiella pneumoniae is a severe challenge to public health. The widespread presence of bla NDM-1 and bla NDM-5 in Enterobacteriaceae has aroused broad concern. In this study, we performed molecular characterization of bla NDM-1-carrying and bla NDM-5-harboring IncX3-type plasmids in carbapenem-resistant Klebsiella pneumoniae (CRKP) and compared their phenotypes between strains with different bla NDM subtype. Our findings highlight the importance of IncX3-type plasmids in the transfer of the bla NDM-1 and bla NDM-5 genes and demonstrate that the bla NDM-1 plasmid possesses higher transfer ability. These data will provide important insights into carbapenem resistance gene transfer via plasmids and their further spread in clinical settings.

Extensively drug-resistant (XDR) bacteria are the main caues for causing clinical infectious diseases. Our aim was to distinguish the present molecular epidemiological situation of XDR Klebsiella pneumoniae, Acinetobacter baumannii, and Escherichia coli isolates recovered from local hospitals in Changzhou. Antibiotic susceptibility and phenotypic analysis, multilocus sequence typing and Pulsed Field Gel Electrophoresis were performed to trace these isolates. Resistant phenotype and gene analysis from 29 XDR strains demonstrated that they mainly included TEM, CTX-M-1/2, OXA-48, and KPC products. A. baumannii strains belonged to sequence type (ST) ST224, and carrying the blaCTX-M-2/TEM gene. The quinolone genes aac(6\')-ib-cr and qnrB were carrying only in A. baumannii and E.coli. Three (2.3%) of these strains were found to contain the blaNDM-1 or blaNDM-5 gene. A new genotype of K. pneumoniae was found as ST2639. Epidemic characteristics of the XDR clones showed that antibiotic resistance genes distributed unevenly in different wards in Changzhou\'s local hospitals. With the sequencing of blaNDM carrying isolates, the plasmids often carrying a highly conservative Tn3-relavent mobile genetic element. The especially coupled insert sequence ISKox3 may be a distinctive resistance gene transfer loci. The genotypic diversity variation of XDRs suggested that tracking and isolating the sources of antibiotic resistance especially MBL-encoding genes such as blaNDM-will help manage the risk of infection by these XDRs.

This 4-month-long prospective observational study investigated the epidemiological characteristics, genetic composition, transmission pattern, and infection control of carbapenem-resistant Escherichia coli (CREC) colonization in patients at an intensive care unit (ICU) in China. Phenotypic confirmation testing was performed on nonduplicated isolates from patients and their environments. Whole-genome sequencing was performed for all E. coli isolates, followed by multilocus sequence typing (MLST), and antimicrobial resistance genes and single nucleotide polymorphisms (SNPs) were screened. The colonization rates of CREC were 7.29% from the patient specimens and 0.39% from the environmental specimens. Among the 214 E. coli isolates tested, 16 were carbapenem resistant, with the blaNDM-5 gene identified as the dominant carbapenemase-encoding gene. Among the low-homology sporadic strains isolated in this study, the main sequence type (ST) of carbapenem-sensitive Escherichia coli (CSEC) was ST1193, whereas the majority of CREC isolates belonged to ST1656, followed by ST131. CREC isolates were more sensitive to disinfectants than were the carbapenem-resistant Klebsiella pneumoniae (CRKP) isolates obtained in the same period, which may explain the lower separation rate. Therefore, effective interventions and active screening are beneficial to the prevention and control of CREC. IMPORTANCE CREC represents a public health threat worldwide, and its colonization precedes or occurs simultaneously with infection; once the colonization rate increases, the infection rate rises sharply. In our hospital, the colonization rate of CREC remained low, and almost all of the CREC isolates detected were ICU acquired. Contamination of the surrounding environment by CREC carrier patients shows a very limited spatiotemporal distribution. As the dominant ST of the CSEC isolates found, ST1193 CREC might be considered a strain of notable concern with potential to cause a future outbreak. ST1656 and ST131 also deserve attention, as they comprised the majority of the CREC isolates found, while blaNDM-5 gene screening should play an important role in medication guidance as the main carbapenem resistance gene identified. The disinfectant chlorhexidine, which is used commonly in the hospital, is effective for CREC rather than CRKP, possibly explaining the lower positivity rate for CREC than for CRKP.