Prevalence, antimicrobial resistance, and genomic characterization of Salmonella strains isolated in Hangzhou, China: a two-year study.

This study explored the molecular epidemiology and resistance mechanisms of 271 non-duplicate Salmonella enterica (S. enterica) strains, isolated mainly from adults (209/271) in a tertiary hospital in Hangzhou between 2020 and 2021. Through whole-genome sequencing and bioinformatics, the bacterial strains were classified into 46 serotypes and 54 sequence types (ST), with S. Enteritidis, S. 1,4,[5],12:i:-, and S. Typhimurium being the most prevalent serotypes and ST11, ST34, and ST19 the most common STs. The strains isolated from adults were primarily S. Enteritidis (59/209), while from children were mainly S. 1,4,[5],12:i:- (20/62). Worryingly, 12.55% strains were multi-drug resistant (MDR), with resistance rates to cefepime (FEP), ceftazidime (CAZ), ceftriaxone (CRO) and cefotaxime (CTX) of 7.38%, 9.23%, 15.87% and 16.24%, respectively, and resistance rates to levofloxacin (LEV) and ciprofloxacin (CIP) of 8.49% and 19.19%, respectively. It is worth noting that the resistance rates of CRO and CTX in children reached 30.65%. A total of 34 strains carried extended-spectrum ß-lactamase (ESBL) genes, dominated by blaCTX-M-65 (13/34) and blaCTX-M-55 (12/34); it is notable that one strain of S. Saintpaul carried both blaCTX-M-27 and blaCTX-M-55. The resistance mechanism to cephalosporins was mainly due to ESBL genes (20/43), and other genes included AmpC and ß-lactamase genes. The strains resistant to quinolones mainly carried qnrS1 (27/53), and others included qnrB6, aac(6')-Ib-cr, and mutations in gyrA and parC. One strain did not carry common quinolone resistance genes but had a parC (p.T57S) mutation to cause CIP resistance. This research provides vital insights into the molecular epidemiology and resistance mechanisms of clinical S. enterica, implicating possible infection control strategies.

Risk factors and molecular epidemiology of intestinal colonization by carbapenem-resistant Gram-negative bacteria in patients with hematological diseases: a multicenter case‒control study.

Patients with hematological diseases are considered to be at high risk for intestinal colonization by carbapenem-resistant Gram-negative bacteria (CR-GNB). However, the epidemiological data regarding risk factors and molecular characteristics of intestinal colonized CR-GNB isolates in this population are insufficient in China. A multicenter case‒control study involving 4,641 adult patients with hematological diseases from 92 hospitals across China was conducted. Following culture of collected rectal swabs, mass spectrometry and antimicrobial susceptibility tests were performed to identify GNB species and CR phenotype. Risk factors were assessed through retrospective clinical information. Whole-genome sequencing was used to analyze the molecular characteristics of CR-GNB isolates. This trial is registered with ClinicalTrials.gov as NCT05002582. Our results demonstrated that among 4,641 adult patients, 10.8% had intestinal colonization by CR-GNB. Of these, 8.1% were colonized by carbapenem-resistant Enterobacterales (CRE), 2.6% were colonized by carbapenem-resistant Pseudomonas aeruginosa (CRPA), and 0.3% were colonized by carbapenem-resistant Acinetobacter baumannii (CRAB). The risk factors for CR-GNB colonization include male gender, acute leukemia, hematopoietic stem cell transplantation, ß-lactam antibiotic usage, and the presence of non-perianal infections within 1 week. Compared with CRPA-colonized patients, patients using carbapenems were more likely to be colonized with CRE. NDM was the predominant carbapenemase in colonized CRE. This study revealed a high CR-GNB intestinal colonization rate among adult patients with hematological diseases in China, with CRE being the predominant one. Notably, a significant proportion of CRE exhibited metallo-ß-lactamase production, indicating a concerning trend. These findings emphasize the importance of active screening for CR-GNB colonization in patients with hematological diseases.IMPORTANCECarbapenem-resistant Gram-negative bacteria (CR-GNB) has emerged as a significant threat to public health. Patients with hematological diseases are at high risk of CR-GNB infections due to their immunosuppressed state. CR-GNB colonization is an independent risk factor for subsequent infection. Understanding the risk factors and molecular characteristics of CR-GNB associated with intestinal colonization in patients with hematological diseases is crucial for empirical treatment, particularly in patients with febrile neutropenia. However, the epidemiology data are still insufficient, and our study aims to determine the intestinal colonization rate of CR-GNB, identify colonization risk factors, and analyze the molecular characteristics of colonized CR-GNB isolates.

Genome sequencing unveils blaKPC-2-harboring plasmids as drivers of enhanced resistance and virulence in nosocomial Klebsiella pneumoniae.

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.

Clinical and laboratory insights into the threat of hypervirulent Klebsiella pneumoniae.

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

Chromosomal integration and plasmid fusion occurring in ST20 carbapenem-resistant Klebsiella pneumoniae isolates coharboring blaNDM-1 and blaIMP-4 induce resistance transmission and fitness variation.

To investigate the epidemiology of ST20 carbapenem-resistant Klebsiella pneumoniae (CRKP) in China, and further explore the genomic characteristics of blaIMP-4 and blaNDM-1 coharboring isolates and plasmid contributions to resistance and fitness. Seven ST20 CRKP isolates were collected nationwide, and antimicrobial susceptibility testing was performed. Antimicrobial resistance genes, virulence genes, and plasmid replicons were identified via whole-genome sequencing, and clonality assessed via core-genome multilocus sequence typing. Furthermore, we found four dual-metallo-ß-lactamases (MBL)-harbouring isolates, the gene location was detected by Southern blotting, and plasmid location analysis showed that blaIMP-4 was located on a separate plasmid, a self-conjugative fusion plasmid, or the bacterial chromosome. These isolates were subjected to long-read sequencing, the presence of blaIMP-4 in different locations was identified by genomic comparison, and transposon units were detected via inverse PCR. We subsequently found that blaIMP-4 on the fusion plasmid and bacterial chromosome was formed via intact plasmid recombination by the IS26 and ltrA, respectively, and the circular transposon unit was related to cointegration, however, blaIMP-4 in different locations did not affect the gene stability. The blaNDM-1-harbouring plasmid contributed to the increased resistance to ß-lactams and shortened survival lag time which was revealed in plasmid cured isolates. In summary, the K. pneumoniae ST20 clone is a high-risk resistant clone. With the use of ceftazidime/avibactam, MBL-positive isolates, especially dual-MBL-harbouring isolates, should be given additional attention.

High-Performance Self-Powered Photoelectrochemical Ultraviolet Photodetectors Based on an In2O3 Nanocube Film.

Ultraviolet photodetectors (UV PDs) have attracted significant attention due to their wide range of applications, such as underwater communication, biological analysis, and early fire warning systems. Indium oxide (In2O3) is a candidate for developing high-performance photoelectrochemical (PEC)-type UV PDs owing to its high UV absorption and good stability. However, the self-powered photoresponse of the previously reported In2O3-based PEC UV PDs is unsatisfactory. In this work, high-performance self-powered PEC UV PDs were constructed by using an In2O3 nanocube film (NCF) as a photoanode. In2O3 NCF photoanodes were synthesized on FTO by using hydrothermal methods with a calcining process. The influence of the electrolyte concentration, bias potential, and irradiation light on the photoresponse properties was systematically studied. In2O3 NCF PEC UV PDs exhibit outstanding self-powered photoresponses to 365 nm UV light with a high responsivity of 44.43 mA/W and fast response speed (20/30 ms) under zero bias potential, these results are superior to those of previously reported In2O3-based PEC UV PDs. The improved self-powered photoresponse is attributed to the higher photogenerated carrier separation efficiency and faster charge transport of the in-situ grown In2O3 NCF. In addition, these PDs exhibit excellent multicycle stability, maintaining the photocurrent at 98.69% of the initial value after 700 optical switching cycles. Therefore, our results prove the great promise of In2O3 in self-powered PEC UV PDs.

Clinical characteristics and prognosis of bloodstream infections with carbapenem-resistant Gram-negative organisms in patients with hematological malignancies: a multicenter case-control study in China.

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

Emergence of high-level colistin resistance mediated by multiple determinants, including mcr-1.1, mcr-8.2 and crrB mutations, combined with tigecycline resistance in an ST656 Klebsiella pneumoniae.

Colistin and tigecycline are usually regarded as the last resort for multidrug-resistant Klebsiella pneumoniae infection treatment. Emergence of colistin and tigecycline resistance poses a global healthcare challenge and is associated with high mortality due to limited therapeutic options. Here, we report the ST656 extensively drug-resistant K. pneumoniae strain KP15-652, which was isolated from a patient's urine in China. Antimicrobial susceptibility testing showed it to be resistant to tigecycline, amikacin, levofloxacin, ciprofloxacin, and high-level colistin resistance (> 2048 mg/L). Whole-genome sequencing revealed that it harbors one chromosome and seven plasmids, including four plasmids carrying multiple acquired resistance genes. Transformation/conjugation tests and plasmid curing assays confirmed that mcr-1.1, mcr-8.2 and crrB mutations are responsible for the high-level colistin resistance and that a series of efflux pump genes, such as tmexCD1-toprJ1, tet(A) and tet(M), contribute to tigecycline resistance. mcr-1.1 and tet(M) are located on an IncX1 plasmid, which has conjugation transfer potential. mcr-8.2 and tet(A) are located on a multireplicon IncR/IncN plasmid but unable to be transferred via conjugation. Moreover, another conjugable and fusion plasmid carries the tmexCD1-toprJ1 gene cluster, which may have arisen due to IS26-mediated replicative transposition based on 8-bp target-site duplications. Importantly, a complex class 1 integron carrying various resistance genes was detected on this fusion plasmid. In conclusion, it is possible that the high-level of colistin resistance is caused by the accumulated effect of several factors on the chromosome and mcr-carrying plasmids, combined with many other resistances, including tigecycline. Effective surveillance should be performed to prevent further dissemination.

A Novel CMY Variant Confers Transferable High-Level Resistance to Ceftazidime-Avibactam in Multidrug-Resistant Escherichia coli.

Here, our objective was to explore the molecular mechanism underlying ceftazidime-avibactam resistance in a novel CMY-178 variant produced by the clinical Escherichia coli strain AR13438. The antibiotic susceptibility of the clinical isolate, its transconjugants, and its transformants harboring transferable blaCMY were determined by the agar dilution method. S1-PFGE, cloning experiments, and whole-genome sequencing (WGS) were performed to investigate the molecular characteristics of ceftazidime-avibactam resistance genes. Kinetic parameters were compared among the purified CMY variants. Structural modeling and molecular docking were performed to assess the affinity between the CMYs and drugs. The horizontal transferability of the plasmid was evaluated by a conjugation experiment. The fitness cost of the plasmid was analyzed by determining the maximal growth rate, the maximum optical density at 600 nm (OD600), and the duration of the lag phase. AR13438, a sequence type 457 E. coli strain, was resistant to multiple cephalosporins, piperacillin-tazobactam, and ceftazidime-avibactam at high levels and was susceptible to carbapenems. WGS and cloning experiments indicated that a novel CMY gene, blaCMY-178, was responsible for ceftazidime-avibactam resistance. Compared with the closely related CMY-172, CMY-178 had a nonsynonymous amino acid substitution at position 70 (Asn70Thr). CMY-178 increased the MICs of multiple cephalosporins and ceftazidime-avibactam compared with CMY-172. The kinetic constant Ki values of CMY-172 and CMY-178 against tazobactam were 2.12 ± 0.34 and 2.49 ± 0.51 µM, respectively. Structural modeling and molecular docking indicated a narrowing of the CMY-178 ligand-binding pocket and its entrance and a stronger positive charge at the pocket entrance compared with those observed with CMY-172. blaCMY-178 was located in a 96.9-kb IncI1-type plasmid, designated pAR13438_2, which exhibited high transfer frequency without a significant fitness cost. In conclusion, CMY-178 is a novel CMY variant that mediates high-level resistance to ceftazidime-avibactam by enhancing the ability to hydrolyze ceftazidime and reducing the affinity for avibactam. Notably, blaCMY-178 could be transferred horizontally at high frequency without fitness costs. IMPORTANCE Ceftazidime-avibactam is a novel ß-lactam-ß-lactamase inhibitor (BLBLI) combination with powerful activity against Enterobacterales isolates producing AmpC, such as CMY-like cephalosporinase. However, in recent years, CMY variants have been reported to confer ceftazidime-avibactam resistance. We reported a novel CMY variant, CMY-178, that confers high-level ceftazidime-avibactam resistance with potent transferability. Therefore, this resistance gene is a tremendous potential menace to public health and needs attention of clinicians.

Investigating Possible Interspecies Communication of Plasmids Associated with Transfer of Third-Generation Cephalosporin, Quinolone, and Colistin Resistance Between Simultaneously Isolated Escherichia Coli and Klebsiella Pneumoniae.

The coinfection process producing multiple species of pathogens provides a specific ecological niche for the exchange of genetic materials between pathogens, in which plasmids play a vital role in horizontal gene transfer, especially for drug resistance, but the underlying transfer pathway remains unclear. Interspecies communication of the plasmids associated with the transfer of third-generation cephalosporins, quinolones, and colistin resistance has been observed in simultaneously isolated Escherichia coli and Klebsiella pneumoniae from abdominal drainage following surgery. The MICs of antimicrobial agents were determined by the broth microdilution method. The complete chromosome and plasmid sequences were obtained by combining Illumina paired-end short reads and MinION long reads. S1-PFGE, southern blot analysis and conjugation assay confirmed the transferability of the mcr-1-harboring plasmid. Both the E. coli isolate EC15255 and K. pneumoniae isolate KP15255 from the same specimen presented multidrug resistance. Each of them harbored one chromosome and three plasmids, and two plasmids and their mediated resistance could be transferred to the recipient by conjugation. Comparison of their genome sequences suggested that several genetic communication events occurred between species, especially among their plasmids, such as whole-plasmid transfer, insertion, deletion, amplification, or inversion. Exchange of plasmids or the genetic elements they harbor plays a critical role in antimicrobial resistance gene transmission and poses a substantial threat to nosocomial infection control, necessitating the continued surveillance of multidrug resistant pathogens, especially during coinfection. IMPORTANCE The genome sequence of bacterial pathogens commonly provides a detailed clue of genetic communication among clones or even distinct species. The intestinal microecological environment is a representative ecological niche for genetic communication. However, it is still difficult to describe the details of horizontal gene transfer or other genetic events within them because the evidence in the genome sequence is incomplete and limited. In this study, the simultaneously isolated Escherichia coli and Klebsiella pneumoniae from a coinfection process provided an excellent example for observation of interspecies communication between the two genomes and the plasmids they harbor. A complete genome sequence acquired by combining the Illumina and MinION sequencing platforms facilitated the understanding of genetic communication events, such as whole-plasmid transfer, insertion, deletion, amplification, or inversion, which contribute to antimicrobial resistance gene transmission and are a substantial threat to nosocomial infection control.

Epidemiology and Genetic Characteristics of Carbapenem-Resistant Escherichia coli in Chinese Intensive Care Unit Analyzed by Whole-Genome Sequencing: a Prospective Observational Study.

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.

Characterization of two novel VIM-type metallo-ß-lactamases, VIM-84 and VIM-85, associated with the spread of IncP-2 megaplasmids in Pseudomonas aeruginosa.

This study aimed to characterize two novel VIM-type metallo-ß-lactamases, VIM-84 and VIM-85, and reveal the important role of the IncP-2 type megaplasmids in the spread of antimicrobial resistance (AMR) genes. VIM-84 and VIM-85 were encoded by two novel genes bla VIM-84 and bla VIM-85 which showed similarity to bla VIM-24. Both bla VIM-84 and bla VIM-85 are harbored into class 1 integrons embedded into the Tn1403 transposon. The bla VIM-85 gene was identified in a megaplasmid, which was related to 17 megaplasmid sequences with sizes larger than 430 kb, deposited previously in Genbank. A comparative analysis of complete plasmid sequences showed highly similar backbone regions and various AMR genes. A phylogenetic tree revealed that these megaplasmids, which were widely distributed globally, were vehicles for the spread of AMR genes. The bla VIM-24, bla VIM-84, and bla VIM-85 genes were cloned into pGK1900, and the recombinant vectors were further transformed into Escherichia coli DH5α and Pseudomonas aeruginosa PAO1. The antimicrobial susceptibility test of the cloning strains showed high levels of resistance to ß-lactams while they remained susceptible to aztreonam. Enzymatic tests revealed that both, VIM-84 and VIM-85, exhibited higher activity in hydrolyzing ß-lactams compared to VIM-24. A D117N mutation found in VIM-24 affected binding to the antibiotics. IMPORTANCE The metallo-ß-lactamases-producing Pseudomonas aeruginosa strains play an important role in hospital outbreaks and the VIM-type enzyme is the most prevalent in European countries. Two novel VIM-type enzymes in our study, VIM-84 and VIM-85, have higher levels of resistance to ß-lactams and greater hydrolytic activities for most ß-lactams compared with VIM-24. Both bla VIM-84 and bla VIM-85 are harbored into class 1 integrons embedded into the Tn1403 transposon. Notably, the genes bla VIM-85 are carried by three different IncP-2-type megaplasmids which are distributed locally and appear responsible for the spread of antimicrobial resistance genes in hospital settings.

Epidemiological Characteristics of OXA-232-Producing Carbapenem-Resistant Klebsiella pneumoniae Strains Isolated during Nosocomial Clonal Spread Associated with Environmental Colonization.

Here, a program was designed to surveil the colonization and associated infection of OXA-232-producing carbapenem-resistant Klebsiella pneumoniae (CRKP) (OXA-232-CRKP) in an intensive care unit (ICU) and to describe the epidemiological characteristics during surveillance. Samples were sourced from patient and environment colonization sites in the ICU from August to December 2019. During the surveillance, 106 OXA-232-CRKP strains were isolated from 8,656 samples of colonization sites, with an average positive rate of 1.22%. The rate from patient colonization sites was 3.59% (60/1,672 samples), over 5 times higher than that of the environment (0.66% [46/6,984 samples]). Rectal swabs and ventilator-related sites had the highest positive rates among patient and environment colonization sites, respectively. Six of the 15 patients who had OXA-232-CRKP at colonization sites suffered from OXA-232-CRKP-related infections. Patients could obtain OXA-232-CRKP from the environment, while long-term patient colonization was mostly accompanied by environmental colonization with subsequent infection. Antimicrobial susceptibility testing presented similar resistance profiles, in which all isolates were resistant to ertapenem but showed different levels of resistance to meropenem and imipenem. Whole-genome sequencing and single-nucleotide polymorphism (SNP) analysis suggested that all OXA-232-CRKP isolates belonged to the sequence type 15 (ST15) clone and were divided into two clades with 0 to 45 SNPs, sharing similar resistance genes, virulence genes, and plasmid types, indicating that the wide dissemination of OXA-232-CRKP between the environment and patients was due to clonal spread. The strains all contained ß-lactam resistance genes, including blaOXA-232, blaCTX-M-15, and blaSHV-106, and 75.21% additionally carried blaTEM-1. In brief, wide ST15 clonal spread and long-term colonization of OXA-232-CRKP between patients and the environment were observed, with microevolution and subsequent infection. IMPORTANCE OXA-232 is a variant of OXA-48 carbapenemase, which has been increasingly reported in nosocomial outbreaks in ICUs. However, the OXA-232-CRKP transmission relationship between the environment and patients in ICUs was still not clear. Our study demonstrated the long-term colonization of OXA-232-CRKP in the ICU environment, declared that the colonization was a potential risk to ICU patients, and revealed the possible threat that this OXA-232-CRKP clone would bring to public health. The wide dissemination of OXA-232-CRKP between the environment and patients was due to ST15 clonal spread, which presented a multidrug-resistant profile and carried disinfectant resistance genes and virulence clusters, posing a challenge to infection control. The study provided a basis for environmental disinfection, including revealing common environmental colonization sites of OXA-232-CRKP and suggesting appropriate usage of disinfectants to prevent the development of disinfectant resistance.

Leaf Structural Traits Vary With Plant Size in Even-Aged Stands of Sapindus mukorossi.

Sapindus mukorossi Gaertn., an important oleaginous woody plant, has garnered increasing research attention owing to its potential as a source of renewable energy (biodiesel). Leaf structural traits are closely related to plant size, and they affect the fruit yield and oil quality. However, plant size factors that predominantly contribute to leaf structural traits remain unknown. Therefore, the purpose of this study was to understand the associations between leaf structural traits and plant size factors in even-aged stands of S. mukorossi. Results showed that leaf length (LL) and leaf area (LA) markedly increased with the increasing diameter at breast height (DBH) and tree height (TH), although other leaf structural traits did not show noticeable changes. Difference in slopes also indicated that the degree of effect of plant size factors on leaf structural traits was in the order of TH > DBH. Leaf structural traits showed no systematic variation with crown width (CW). LA was significantly positively correlated with LL, leaf width (LW), LL/LW, and leaf thickness (LT) and was significantly but negatively correlated with leaf tissue density (LTD) and leaf dry mass content (LDMC). Specific leaf area showed a significantly negative correlation with LT, LDMC, and LTD. LTD showed a significantly positive correlation with LDMC, but a negative correlation with LT. The results were critical to understand the variability of leaf structural traits with plant size, can provide a theoretical foundation for further study in the relationship between leaf structural traits and fruit yield, and regulate leaf traits through artificial management measures to promote plant growth and fruit yield.

Neurodevelopmental outcomes of extremely preterm infants in southern China: A multicenter study.

OBJECTIVE: To assess treatment outcomes and associated factors of extremely preterm infants (EPIs) in GuangXi, China. METHODS: This was a retrospective study consisting of 131 eligible cases with gestational age (GA) between 22 and 28 weeks, and infants were followed until 18-24 months. Data including clinical characteristics, perinatal factors and after-birth conditions were collected from the neonatal intensive care unit in 10 hospitals in Guangxi from January 1st 2010 until May 31st 2016. RESULTS: During that period, 307 EPIs were born in the hospitals. 137 infants died in hospital after their parents decided to withdraw clinical treatment, and 11 infants died despite full resuscitation was provided. Of the 159 surviving infants, 28 infants were lost to follow-up. In total, 131 infants who survived and were presented to follow-up at 18-24 months of age were enrolled into this study. Of the 131 infants evaluated at 18-24 months follow-up, 47 (35.9%) were diagnosed with neurodevelopmental disability (ND), and 84 (64%) demonstrated on tract motor and language skills. The incidence of chorioamnionitis, early onset sepsis (EOS), bronchopulmonary dysplasia (BPD) were all higher in the group of infants who were diagnosed with ND compared to those with normal motor language development (NML), the duration of mechanical ventilation (MV) was longer in ND group, and the higher incidence of ND was seen in the smaller GA babies (p < 0.05). Adjusted the BPD severity, GA was a protective factor of neurodevelopmental outcome (combined OR = 0.338, 95% CI: 0.145-0.791). In EPIs with moderate BPD and severe BPD, chorioamnionitis was a risk factor of ND (OR = 10.313 and 5.778，respectively, 95% CI: 1.389-6.486 and 1.444-23.119, respectively). The Logistic regression analysis showed that GA (OR = 0.207, 95%CI = 0.047-0.917) was a protective factor for ND, and chorioamnionitis (OR = 6.010, 95%CI: 1.331-27.138), moderate-to-severe BPD (OR = 4.285, 95%CI: 1.495-12.287), the duration of MV (OR = 3.508, 95%CI: 2.077-5.926) were independent risk factors for ND in EPIs. CONCLUSIONS: Chorioamnionitis, moderate-to-severe BPD, and the duration of MV were associated with neurodevelopmental disability in EPIs. The smaller the GA, the higher incidence of neurodevelopmental disability.