Epidemiology of carbapenem-resistant Acinetobacter baumannii colonization in neonatal intensive care units:A systematic review and meta-analysis

BACKGROUND The rising prevalence of carbapenem-resistant Acinetobacter baumannii(CRAB)in neonatal intensive care units(NICUs)represents an escalating challenge in healthcare settings,particularly in managing hospital-acquired infections(HAIs).Studies across various World Health Organization regions have documented a significant incidence of CRAB-related HAIs,with rates as high as 41.7 cases per 1000 patients in ICUs,accounting for 13.6%of all HAIs.These infections pose a doubled mortality risk compared to infections with carbapenem-susceptible Acinetobacter baumannii.A particularly concerning aspect of CRAB colonization is its asymptomatic nature,enabling its transmission through healthcare workers(HCWs)or the NICU environment to vulnerable neonates with developing immune systems.AIM To explore the prevalence of CRAB colonization in NICUs,focusing on neonates,healthcare workers,and the environmental samples,to enhance epidemiological understanding and inform targeted interventions.METHODS We conducted according to PRISMA 2020 checklist guidelines,a comprehensive literature search across multiple databases including MEDLINE(Ovid),EMBASE(Ovid),Global Health(Ovid),Web of Science,and Global Index Me-dicus.Studies were selected based on predetermined criteria,primarily involving neonates,HCWs,and environmental swabs,using culture or molecular methods to detect CRAB colonization.We excluded studies that did not specifically focus on NICUs,were duplicates,or lacked necessary data.The study selection and quality assessment were conducted independently by two reviewers.Data extraction involved collecting comprehensive details about each study.Our statistical analysis used a random-effects model to calculate the pooled prevalence and confidence intervals,stratifying results by regional location.We assessed study heterogeneity using Cochran's Q statistic and I²statistic,with regression tests employed to evaluate potential publication bias.RESULTS We analyzed 737 records from five databases,ultimately including 13 studies from ten countries.For neonates,the pooled prevalence was 4.8%(95%CI:1.1%to 10.5%)with the highest rates observed in South-East Asia(10.5%;95%CI:2.4%to 23.3%).Among HCWs,a single Indian study reported a 3.3%prevalence.Environmental samples showed a prevalence of 2.3%(95%CI:0%to 9.3%),with the highest rates in South-East Asia(10%;95%CI:4.2%to 17.7%).Significant heterogeneity was found across studies,and no publication bias was detected.CONCLUSION This systematic review highlights a significant prevalence of CRAB colonization in neonates across various regions,particularly in South-East Asia,contrasting with lower rates in high-income countries.The study reveals a gap in research on HCWs colonization,with only a single study from India reporting moderate prevalence.Environmental samples indicate moderate levels of CRAB contamination,again higher in South-East Asia.These findings underscore the need for more extensive and focused research on CRAB colonization in NICUs,including exploring the roles of HCWs and the environment in transmission,understanding antimicrobial resistance patterns,and developing effective prevention measures.

Rapid and accurate detection of carbapenem-resistance gene by isothermal amplification in Acinetobacter baumannii

Background:Acinetobacter baumannii(A.baumannii)is one of the pivotal pathogens responsible for nosocomial infections,especially in patients with low immune response,and infection with carbapenem-resistant A.baumannii has been increasing in recent years.Rapid and accurate detection of carbapenem-resistance genes in A.baumannii could be of immense help to clinical staff.Methods:In this study,a 15-μL reaction system for recombinase polymerase amplification(RPA)was developed and tested.We collected 30 clinical isolates of A.baumannii from the Burn Institute of Southwest Hospital of Third Military Medical University(Army Medical University)for 6 months and tested antibiotic susceptibility using the VITEK 2 system.A.baumannii was detected based on the blaOXA-51 gene by PCR,qPCR and 15μL-RPA,respectively.Sensitivity and specificity were evaluated.In addition,PCR and 15μL-RPA data for detecting the carbapenem-resistance gene blaOXA-23 were comparatively assessed.Results:The detection limit of the blaOXA-51 gene by 15μL RPA was 2.86 CFU/ml,with sensitivity comparable to PCR and qPCR.No positive amplification signals were detected in non-Acinetobacter isolates,indicating high specificity.However,only 18 minutes were needed for the 15μL RPA assay.Furthermore,an antibiotic susceptibility test showed that up to 90%of A.baumannii strains were resistant to meropenem and imipenem;15μL RPA data for detecting blaOXA-23 showed that only 10%(n=3)of A.baumannii isolates did not show positive amplification signals,and the other 90%of(n=27)isolates were positive,corroborating PCR results.Conclusion:We demonstrated that the new 15μL RPA assay for detecting blaOXA-23 in A.baumannii is faster and simpler than qPCR and PCR.It is a promising alternative molecular diagnostic tool for rapid and effective detection of A.baumannii and drug-resistance genes in the field and point-ofcare testing.

Burden of severe infections due to carbapenem-resistant pathogens in intensive care unit

Intensive care units(ICU)for various reasons,including the increasing age of admitted patients,comorbidities,and increasingly complex surgical procedures(e.g.,transplants),have become"the epicenter"of nosocomial infections,these are characterized by the presence of multidrug-resistant organisms(MDROs)as the cause of infection.Therefore,the perfect match of fragile patients and MDROs,as the cause of infection,makes ICU mortality very high.Furthermore,carbapenems were considered for years as last-resort antibiotics for the treatment of infections caused by MDROs;unfortunately,nowadays carbapenem resistance,mainly among Gram-negative pathogens,is a matter of the highest concern for worldwide public health.This comprehensive review aims to outline the problem from the intensivist's perspective,focusing on the new definition and epidemiology of the most common carbapenem-resistant MDROs(Acinetobacter baumannii,Pseudomonas aeruginosa and Enterobacterales)to emphasize the importance of the problem that must be permeating clinicians dealing with these diseases.

Association ofβ-lactam antimicrobial's exposure with carbapenem-resistant Pseudomonas aeruginosa infection:a cumulative meta-analysis

Background:Carbapenems are effective against severe Pseudomonas aeruginosa nosocomial infections.Therefore,carbapenem-resistant Pseudomonas aeruginosa is a serious public health threat.An understanding of the risk of inappropriate exposure to different antimicrobials in resistant Pseudomonas aeruginosa infection could help in elucidating the effective approach towards using antimicrobials in vulnerable patients with CRPA infection.Object:To investigate the association between exposure ofβ-lactam antimicrobials and CRPA infection relative to control patients.Methods:The MEDLINE/PubMed and OVID/Embase databases were used to search case-control and cohort studies in English language which reported antimicrobial exposure as risk factors for CRPA infection.The pooled odds ratios(OR)were calculated using a random-effect and fixed-effect model,and forest plots from a cumulative meta-analysis method were used to better show how pooled OR changed as updated evidence accumulated.Results:A total of 24 studies comprising 7039 participants were included for cumulative meta-analysis.A positive correlation was found between development of CRPA infection and exposure of beta-lactam antimicrobials:carbapenems(OR=7.60,95%CI:3.95 to 14.62,P<0.0001),imipenem(OR=9.81,95%CI:5.56 to 17.33),ampicillin(OR=1.86,95%CI:1.14 to 2.41),piperacillin(OR=2.82,95%CI:1.46 to 2.43),penicillins(OR=1.42,95%CI:0.90 to 2.24),cephalosporins(OR=1.88,95%CI:1.46 to 2.43)andβlactamase inhibitors(OR=1.96,95%CI:1.44 to 2.67).Further,exposure of other antimicrobial agents like quinolone(OR=2.35,95%CI:1.78 to 3.10),ciprofloxacin(OR=2.35,95%CI:1.66 to 3.95),aminoglycoside(OR=2.17,95%CI:1.60 to 2.95),amikacin(OR=3.11,95%CI:2.10 to 4.61),glycopeptides(OR=3.02,95%CI:1.92 to 4.75)and vancomycin(OR=3.26,95%CI:1.48 to 7.18),were also found to be positively associated with development of CRPA infection.Conclusions:Exposure of all kinds ofβ-lactams is significantly associated with development of carbapenemresistant Pseudomonas aeruginosa infection.These findings provide an impetus to take a more active approach while usingβ-lactam antimicrobials in patients with resistant Pseudomonas aeruginosa infections.

Anti-bacterial mechanism of baicalin-tobramycin combination on carbapenem-resistant Pseudomonas aeruginosa

BACKGROUND Pseudomonas aeruginosa(P.aeruginosa)is an important cause of nosocomial infections,and contributes to high morbidity and mortality,especially in intensive care units.P.aeruginosa is considered a'critical'category bacterial pathogen by the World Health Organization to encourage an urgent need for research and development of new antibiotics against its infections.AIM To investigate the effectiveness of baicalin combined with tobramycin therapy as a potential treatment method for carbapenem-resistant P.aeruginosa(CRPA)infections.METHODS Polymerase chain reaction(PCR)and RT-PCR were used to detect the expression levels of drug-resistant genes(including VIM,IMP and OprD2)and biofilmrelated genes(including algD,pslA and lasR)in CRPA that confer resistance to tobramycin,baicalin and tobramycin combined with baicalin(0,1/8,1/4,1/2 and 1MIC).RESULTS There was a correlation between biofilm formation and the expression of biofilmrelated genes.In addition,VIM,IMP,OprD2,algD,pslA and lasR that confer biofilm production under different concentrations in CRPA were significantly correlated.The synergistic effect of baicalin combined with tobramycin was a significant down-regulation of VIM,IMP,algD,pslA and lasR.CONCLUSION Baicalin combined with tobramycin therapy can be an effective treatment method for patients with CRPA infection.

Klebsiella pneumoniae infections after liver transplantation:Drug resistance and distribution of pathogens,risk factors,and influence on outcomes

BACKGROUND Liver transplantation(LT)is the only curative treatment for end-stage liver disease.However,LT recipients are susceptible to infection,which is the leading cause of early mortality after LT.Klebsiella pneumoniae infections(KPIs)in the bloodstream are common in LT recipients.We hypothesized that KPIs and carbapenemresistant Klebsiella pneumoniae(CRKP)infections may affect the outcomes of LT recipients.AIM To assess KPI incidence,timing,distribution,drug resistance,and risk factors following LT and its association with outcomes.METHODS This retrospective study included 406 patients undergoing LT at The Third Xiangya Hospital of Central South University,a tertiary hospital,from January 2015 to January 2023.We investigated the risk factors for KPIs and assessed the impact of KPIs and CRKP infections on the prognosis of LT recipients using logistic regression analysis.RESULTS KPI incidence was 7.9%(n=32),with lung/thoracic cavity the most frequent site of infection;the median time from LT to KPI onset was 7.5 d.Of 44 Klebsiella pneumoniae isolates,43(97.7%)and 34(77.3%)were susceptible to polymyxin B or ceftazidime/avibactam and tigecycline,respectively;>70%were resistant to piperacillin/tazobactam,ceftazidime,cefepime,aztreonam,meropenem,and levofloxacin.Female sex[odds ratio(OR)=2.827,95%confidence interval(CI):1.256-6.364;P=0.012],pre-LT diabetes(OR=2.794,95%CI:1.070-7.294;P=0.036),day 1 post-LT alanine aminotransferase(ALT)levels≥1500 U/L(OR=3.645,95%CI:1.671-7.950;P=0.001),and post-LT urethral catheter duration over 4 d(OR=2.266,95%CI:1.016-5.054;P=0.046)were risk factors for KPI.CRKP infections,but not KPIs,were risk factors for 6-month all-cause mortality post-LT.CONCLUSION KPIs occur frequently and rapidly after LT.Risk factors include female sex,pre-LT diabetes,increased post-LT ALT levels,and urethral catheter duration.CRKP infections,and not KPIs,affect mortality.

Molecular Epidemiology and Risk Factors of Carbapenem-Resistant Klebsiella Pneumoniae Bloodstream Infections in Wuhan,China

Objective:The clinical characteristics and microbiological data of patients with K.pneumoniae bloodstream infections(BSI)from January 2018 to December 2020 were retrospectively analyzed to study the molecular epidemiology of Carbapenem-resistant Klebsiella pneumoniae(CRKP).We also aimed to identify the risk factors for the development of CRKP BSI.Methods:This retrospective study was conducted at Renmin Hospital of Wuhan University from January 2018 to December 2020.The date of non-duplicate K.pneumoniae isolates isolated from blood samples was identified using the microbiology laboratory database.The data from patients diagnosed with K.pneumoniae BSI were collected and analyzed.

Treatment of Donor-derived Carbapenem-resistant Klebsiella pneumoniae Infection after Renal Transplantation with Tigecycline and Extended-infusion Meropenem

Objective Donor-derived carbapenem-resistant Klebsiella pneumoniae(CRKP)infection has recently emerged as a critical early complication after renal transplantation.Although CRKP is usually sensitive to tigecycline,monotherapy with this drug is often less than effective.We investigated the efficacy of a combined regimen of tigecycline with high-dose,extended-infusion meropenem in the treatment of donor-derived CRKP infection after kidney transplantation.Methods From Jan.2016 to Dec.2017,a total of 12 CRKP isolates were detected from cultures of the organ preservation solution used for soaking the donor kidneys at our institute.Probable or possible donor-derived infection(DDI)was identified in 8 transplant recipients.Clinical data were retrospectively analyzed.Results Klebsiella pneumoniae carbapenemase-2(KPC-2)-producing CRKP was reported to be positive in organ preservation solution cultures at 3.5±0.9 days after transplantation,leading to surgical site(n=3),urinary tract(n=4),and/or bloodstream(n=2)infections in 8 recipients.The drug susceptibility tests showed that CRKP was sensitive to tigecycline,but resistant to meropenem.In 7 patients who received tigecycline combined with high-dose extended-infusion meropenem,DDIs were successfully cured.The length of hospital stay was 31(18–129)days,and the serum creatinine at discharge was 105.8±16.7µmol/L.The one remaining patient who received tigecycline combined with intravenous-drip meropenem died of septic shock.A median follow-up of 43 months(33–55)showed no recurrence of new CRKP infection in the 7 surviving recipients.Conclusion It was suggested that a prompt and appropriate combination therapy using tigecycline with high-dose extended-infusion meropenem is effective in treating donor-derived KPC-2-producing CRKP infection after renal transplantation.

Isolation of Leclercia adecarboxylata Producing Carbapenemases in A Newborn Female

Leclercia adecarboxylata is a Gram-negative bacterium belonging to the Enterobacteriaceae family.To our knowledge,this is the first report of a carbapenem-resistant L.adecarboxylata strain isolated from a healthy newborn.The L.adecarboxylata strain isolated in this study carried four plasmids that may serve as reservoirs for antibiotic resistance genes.Plasmids 2 and 4 did not harbor any antimicrobial resistance genes.Plasmid 3 is a novel plasmid containing three resistance genes.The bla IMP gene harbored in the strain was most similar to bla IMP-79 at the nucleotide level,with a similarity of 99.4%(737/741).This case highlights the importance of considering L.adecarboxylata as a potential cause of infections in children.

Newly Detected Transmission of bla_(KPC-2) by Outer Membrane Vesicles in Klebsiella Pneumoniae

Objective The prevalence of carbapenem-resistant Klebsiella pneumoniae(CR-KP)is a global public health problem.It is mainly caused by the plasmid-carried carbapenemase gene.Outer membrane vesicles(OMVs)contain toxins and other factors involved in various biological processes,includingβ-lactamase and antibiotic-resistance genes.This study aimed to reveal the transmission mechanism of OMV-mediated drug resistance of Klebsiella(K.)pneumoniae.Methods We selected CR-KP producing K.pneumoniae carbapenemase-2(KPC-2)to study whether they can transfer resistance genes through OMVs.The OMVs of CR-KP were obtained by ultracentrifugation,and incubated with carbapenem-sensitive K.pneumoniae for 4 h.Finally,the carbapenem-sensitive K.pneumoniae was tested for the presence of bla_(KPC-2)resistance gene and its sensitivity to carbapenem antibiotics.Results The existence of OMVs was observed by the electron microscopy.The extracted OMVs had bla_(KPC-2)resistance gene.After incubation with OMVs,bla_(KPC-2)resistance gene was detected in sensitive K.pneumoniae,and it became resistant to imipenem and meropenem.Conclusion This study demonstrated that OMVs isolated from KPC-2-producing CR-KP could deliver bla_(KPC-2)to sensitive K.pneumoniae,allowing the bacteria to produce carbapenemase,which may provide a novel target for innovative therapies in combination with conventional antibiotics for treating carbapenem-resistant Enterobacteriaceae.

Antimicrobial approach of abdominal post-surgical infections

Abdominal surgical site infections(SSIs)are infections that occur after abdominal surgery.They can be superficial,involving the skin tissue only,or more profound,involving deeper skin tissues including organs and implanted materials.Currently,SSIs are large global health problem with an incidence that varies significantly depending on the United Nations’Human Development Index.The purpose of this review is to provide a practical update on the latest available literature on SSIs,focusing on causative pathogens and treatment with an overview of the ongoing studies of new therapeutic strategies.

Epidemiology and Mechanisms of Ceftazidime-Avibactam Resistance in Gram-Negative Bacteria

Carbapenem resistance presents a major challenge for the global public health network, as clinical infections caused by carbapenem-resistant organisms(CRO) are frequently associated with significant morbidity and mortality. Ceftazidime–avibactam(CAZ–AVI) is a novel cephalosporin/β-lactamase inhibitor combination offering an important advance in the treatment of CRO infections. CAZ–AVI has been reported to inhibit the activities of Ambler classes A, C, and some class D enzymes. However, bacterial resistance has been emerging shortly after the introduction of this combination in clinical use, with an increasing trend. Understanding these resistance mechanisms is crucial for guiding the development of novel treatments and aiding in the prediction of underlying resistance mechanisms. This review aims to systematically summarize the epidemiology of CAZ–AVI-resistant strains and recently identified resistance mechanisms of CAZ–AVI, with a focus on the production of β-lactamase variants, the hyperexpression of β-lactamases, reduced permeability, and overexpressed efflux pumps. The various mechanisms of CAZ–AVI resistance that have emerged within a short timescale emphasize the need to optimize the use of current agents, as well as the necessity for the surveillance of CAZ–AVI-resistant pathogens.

Spontaneous bacterial peritonitis due to carbapenemase-producing Enterobacteriaceae:Etiology and antibiotic treatment

Carbapenem antibiotics were first introduced in the 1980s and have long been considered the most active agents for the treatment of multidrug-resistant gramnegative bacteria.Over the last decade,carbapenem-resistant Enterobacteriaceae(CRE)have emerged as organisms causing spontaneous bacterial peritonitis.Infections caused by CRE have shown a higher mortality rate than those caused by bacteria sensitive to carbapenem antibiotics.Current antibiotic guidelines for the treatment of spontaneous bacterial peritonitis are insufficient,and rapid deescalation of empiric antibiotic treatment is not widely recognized.This review summarizes the molecular characteristics,epidemiology and possible treatment of spontaneous bacterial peritonitis caused by CRE.

Incidence of Oxa23 and Oxa51 Genes Associated with Bacterial Isolated from Patients with Urosepsis: Single Centre Prespective

Background: Urosepsis is one of the most common infections that require empirical broad spectrum antibiotics immediately after diagnosis. This has led to development of bacterial resistance by acquiring the capability to destroy the β-lactam ring. Methodology: This is a cross-sectional hospital-based study. The study was conducted from 2019 to 2020 at Gezira Hospital for Renal diseases and surgery (GHRDS). A hundred patients were diagnosed clinically with urosepsis and the isolated organisms were Escherichia coli, Staphylococcus aureus, Proteus mirabilis, Klebsiella pneumonia and Pseudomonas aeruginosa. The susceptibility test was conducted by Kirby Bauer disc diffusion technique according to clinical laboratory standard institute (CLSI) guidelines. Seventy eight samples of bacterial genomic DNA were confirmed by 16srRNA and multiplex PCR, were performed for genotypic blaOXA-51 and blaOXA-23 gene characterization of isolated bacteria. Then gel electrophoresis was used to identify the presence or absence of (blaOXA-51 and blaOXA-23) genes. Results: 88.5% (69/78) in 16srRNA detected. Using multiplex PCR, the frequencies of blaOXA-51 and blaOXA-23 genes were 13% and 10.1%, respectively. The percentages of isolates which yielded both blaOXA-51 and blaOXA-23 among P. aeruginosa was 25% (1/4), among K. pneumonia was 17% (1/6), and among E. coli was 8% (3/37). Only blaOXA-51 was detected in P. mirabilis 10% (1/10) and only blaOXA-23 was detected in S. aureus 5% (1/18). Conclusion: In this study, the presence of blaOXA-51 and blaOXA-23 genes was increased in the isolated bacteria.

Severe COVID-19-associated sepsis is different from classical sepsis induced by pulmonary infection with carbapenem-resistant klebsiella pneumonia (CrKP)

Purpose::COVID-19 is also referred to as a typical viral septic pulmonary infection by 2019-nCoV.However,little is known regarding its characteristics in terms of systemic inflammation and organ injury,especially compared with classical bacterial sepsis.This article aims to investigate the clinical characteristics and prognosis between COVID-19-associated sepsis and classic bacterial-induced sepsis.Methods::In this retrospective cohort study,septic patients with COVID-19 in the intensive care unit(ICU)of a government-designed therapy center in Shenzhen,China between January 14,2020 and March 10,2020,and septic patients induced by carbapenem-resistant klebsiella pneumonia(CrKP)admitted to the ICU of the Second People's Hospital of Shenzhen,China between January 1,2014 and October 30,2019 were enrolled.Demographic and clinical parameters including comorbidities,critical illness scores,treatment,and laboratory data,as well as prognosis were compared between the two groups.Risk factors for mortality and survival rate were analyzed using multivariable logistic regression and survival curve,respectively.Results::A total of 107 patients with COVID-19 and 63 patients with CrKP were enrolled.A direct comparison between the two groups demonstrated more serious degrees of primary lung injury following 2019-nCoV infection(indicated by lower PaO 2/FiO 2),but milder systemic inflammatory response,lower sequential organ failure assessment score and better functions of the organs like heart,liver,kidney,coagulation,and circulation.However,the acquired immunosuppression presented in COVID-19 patients was more severe,which presented as lower lymphocyte counts(0.8×109/L vs.0.9×109/L).Moreover,the proportion of COVID-19 patients treated with corticosteroid therapy and extracorporeal membrane oxygenation was larger compared with CrKP patients(78.5%vs.38.1%and 6.5%vs.0,respectively)who required less invasive mechanical ventilation(31.6%vs.54.0%).The incidence of hospitalized mortality and length of ICU stay and total hospital stay were also lower or shorter in viral sepsis(12.1%vs.39.7%,6.5 days vs.23.0 days and 21.0 days vs.33.0 days,respectively)(all p<0.001).Similar results were obtained after being adjusted by age,gender,comorbidity and PaO2/FiO2.Lymphocytopenia and high acute physiology and chronic health evaluation II scores were common risk factors for in-hospital death.While the death cases of COVID-19 sepsis mostly occurred at the later stages of patients’hospital stay.Conclusion::Critical COVID-19 shares clinical characteristics with classical bacterial sepsis,but the degree of systemic inflammatory response,secondary organ damage and mortality rate are less severe.However,following 2019-nCoV infection,the level of immunosuppression may be increased and thus induce in more death at the later stage of patients’hospitalstay.

Proactive infection control measures to prevent nosocomial transmission of carbapenem-resistant Enterobacteriaceae in a non-endemic area

Background Identification of hospitalized carbapenem-resistant Enterobacteriaceae （CRE）-positive patient is important in preventing nosocomial transmission.The objective of this study was to illustrate the implementation of proactive infection control measures in preventing nosocomial transmission of CRE in a healthcare region of over 3200 beds in Hong Kong between October 1,2010 and December 31,2011.Methods The program included active surveillance culture in patients with history of medical tourism with hospitalization and surgical operation outside Hong Kong within 12 months before admission,and ＂added test＂ as an opportunistic CRE screening in all fecal specimens submitted to the laboratory.Outbreak investigation and contact tracing were conducted for CRE-positive patients.Serial quantitative culture was performed on CRE-positive patients and the duration of fecal carriage of CRE was analyzed.Results During the study period,a total of 6533 patients were screened for CRE,of which 76 patients were positive （10 from active surveillance culture,65 from ＂added test＂,and 1 secondary case from contact tracing of 223 patients with no nosocomial outbreak）,resulting in an overall rate of CRE fecal carriage of 1.2％.The median time of fecal carriage of CRE was 43 days （range,13-119 days）.Beta-lactam-beta-lactamase-inhibitors,cephalosporins,and fluoroquinolones were associated significantly with high fecal bacterial load when used 90 days before CRE detection,while use of cephalosporins,carbapenems,and fiuoroquinolones after CRE detection are significantly associated with longer duration of carriage.The duration of fecal carriage of CRE also correlates significantly with the initial fecal bacterial load （Pearson correlation：0.53; P=0.02）.Conclusion Proactive infection control measures by enhanced surveillance program identify CRE-positive patients and data obtained are useful for the planning of and resource allocation for CRE control.

高毒力碳青霉烯耐药肺炎克雷伯菌的院内播散与分子进化

高毒力碳青霉烯耐药肺炎克雷伯菌(Hv-CRKP)已成为全球公共卫生领域的重大挑战.该研究报告了2017年至2022年浙江一家三甲医院Hv-CRKP分离株的定植和传播情况.对来自72名患者的90个不同的CRKP菌株进行测序分析,发现院内感染Hv-CRKP的流行主要依赖于ST11-K64克隆传播.对11个代表性分离株进行了全基因组测序,得到了31个完整的质粒基因序列,其中包括12个携带KPC-2耐药基因的质粒和10个携带rmpA毒力基因的质粒.除了二元质粒外,还发现了两种可介导rmpA和KPC-2共同传播的融合质粒.研究人员通过捕获其祖先质粒,提出了该融合质粒的形成机制.此外,发现了五种rmpA启动子变异体(P9T到P13T),其活力与地理分布存在差异.通过CRISPR/Cas9基因编辑技术,证实活跃的“P11T-rmpA”调控子是“高风险”ST11-K64/CRKP克隆群的生物标志物.该研究拓展了对ST11-K64/Hv-CRKP流行性克隆的播散和临床演进的认知.

Identification of a phage-derived depolymerase specific for KL47 capsule of Klebsiella pneumoniae and its therapeutic potential in mice

Klebsiella pneumoniae is one of the major pathogens causing global multidrug-resistant infections.Therefore,strategies for preventing and controlling the infections are urgently needed.Phage depolymerase,often found in the tail fiber protein or the tail spike protein,is reported to have antibiofilm activity.In this study,phage P560isolated from sewage showed specific for capsule locus type KL47 K.pneumoniae,and the enlarged haloes around plaques indicated that P560 encoded a depolymerase.The capsule depolymerase,ORF43,named P560dep,derived from phage P560 was expressed,purified,characterized and evaluated for enzymatic activity as well as specificity.We reported that the capsule depolymerase P560dep,can digest the capsule polysaccharides on the surface of KL47 type K.pneumoniae,and the depolymerization spectrum of P560dep matched to the host range of phage P560,KL47 K.pneumoniae.Crystal violet staining assay showed that P560dep was able to significantly inhibit biofilm formation.Further,a single dose(50μg/mouse)of depolymerase intraperitoneal injection protected 90%–100%of mice from lethal challenge before or after infection by KL47 carbapenem-resistant K.pneumoniae.And pathological changes were alleviated in lung and liver of mice infected by KL47 type K.pneumoniae.It is demonstrated that depolymerase P560dep as an attractive antivirulence agent represents a promising tool for antimicrobial therapy.