Epidemiology and Clonal Spread Evidence of Carbapenem-Resistant Organisms in the Center of Care and Protection of Orphaned Children, Vietnam

Objective: To determine the prevalence of colonization and transmission of carbapenem-resistant Gram-negative organisms in order to develop of an effective infection prevention program. Design: Cross-sectional study with carbapenem-resistant organisms (CRO) colonization detection from the fecal specimens of 20 Health Care Workers (HCWs) and 67 residents and 175 random environment specimens from September 2022 to September 2023. Setting: A Care and Protection Centre of Orphaned Children in South of HCM City. Participants: It included 20 HCWs, 67 residents, and 175 randomly collected environmental specimens. Method: Rectal and environmental swabs were collected from 20 HCWs, 67 residents (most of them were children), and 175 environmental specimens. MELAB Chromogenic CARBA agar plates, Card NID, and NMIC-500 CPO of the BD Phoenix TM Automated Microbiology System and whole genome sequencing (WGS) were the tests to screen, confirm CROs, respectively and determine CRO colonization and transmission between HCWs, residents, and the environment. Result: We detected 36 CRO isolates, including 6, 11 and 19 CROs found in 6 HCWs, 10 residents and 19 environments. The prevalence of detectable CRO was 30% (6/20) in HCWs, 14.92% (10/67) in residents, and 10.86% (19/175) in environmental swabs in our study. WGS demonstrated CRO colonization and transmission with the clonal spread of E. coli and A. nosocomialis, among HCWs and residents (children). Conclusion: Significant CRO colonization and transmission was evident in HCWs, residents, and the center environment. Cleaning and disinfection of the environment and performing regular hand hygiene are priorities to reduce the risk of CRO colonization and transmission.

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.

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.

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.

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.

Bloodstream Infection with Carbapenem-resistant Klebsiella Pneumoniae and Multidrug-resistant Acinetobacter Baumannii:a Case Report

IN the presence of septic shock, every hour in delaying the administration of effective antibiotics is associated with a measurable increase in mortality. This is especially true for neutropenic patients with septic shock. As there is a higher incidence of involving multi-drug resistant pathogens for neutropenic patients, the decision on antibiotics regime remains a challenge for physicians.2 Immunosuppression and previous antibacterial use are factors that promote the spread of multi-drug resistant pathogens, and the possibility of co-existing multi-drug resistant pathogens should be suspected when treating patients with these risk factors who developed refractory shock. Here we present a case with neutropenic fever and refractory shock whose blood culture yielded multi-drug resistant Acinetobacter baumannii and carbapenem- resistant Klebsiella pneumoniae.

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.

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.

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.

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.

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.

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.

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.

耐碳青霉烯类肺炎克雷伯菌血流感染的预后分析

目的了解耐碳青霉烯类肺炎克雷伯菌血流感染的情况及预后分析。方法选取中国人民解放军第202医院发生血流感染并检出肺炎克雷伯菌的患者127例,进行血液细菌培养及药物敏感试验,对碳青霉烯类抗生素敏感患者和耐碳青霉烯类抗生素患者进行调查分析。结果耐碳青霉烯类抗生素患者的院内死亡率、感染相关死亡率、感染后住院天数和总住院天数显著高于碳青霉烯类抗生素敏感患者(P<0.01),耐碳青霉烯类抗生素的血流感染患者生存率显著低于碳青霉烯类抗生素敏感患者(P<0.01)。结论耐碳青霉烯类肺炎克雷伯菌血流感染患者预后较差,是血流感染患者院内死亡的独立危险因素之一。

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.

23株血液分离产KPC-2肺炎克雷伯菌毒力及同源性研究

目的了解肺炎克雷伯菌对碳青霉烯类抗菌药物的主要耐药基因携带情况、毒力、分子分型及同源性。方法收集六安市人民医院2018年1月~2019年12月分离自血培养的非重复CRKP菌株共23株,拉丝试验筛查高毒力菌株;Wzi分型检测荚膜血清型别;聚合酶链式反应检测荚膜多糖合成调节基因(rmpA)、毒力基因及常见碳青霉烯酶基因;多位点序列分型对菌株进行分子分型;脉冲场凝胶电泳技术进行同源性分析。结果23株菌均携带KPC-2基因,18株拉丝试验阳性且携带rmpA的高毒力菌株。Wzi分型22株为K14.64型,1株为K19型。多位点序列分型为ST11型18株、ST307型4株和ST15型1株,脉冲场凝胶电泳技术进一步将18株ST11型菌株分为3个型别。结论本研究中肺炎克雷伯菌对碳青霉烯类抗菌药物耐药机制主要是携带KPC-2基因,主要荚膜血清型为K14.64,优势序列型为ST11型,可能存在院内暴发流行。

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.

Antibacterial activity evaluation of a novel K3-specific phage against Acinetobacter baumannii and evidence for receptor-binding domain transfer across morphologies

Acinetobacter baumannii(A.baumannii)poses a serious public health challenge due to its notorious antimicrobial resistance,particularly carbapenem-resistant A.baumannii(CRAB).In this study,we isolated a virulent phage,named P1068,from medical wastewater capable of lysing CRAB,primarily targeting the K3 capsule type.Basic characterization showed that P1068 infected the A.baumannii ZWAb014 with an optimal MOI of 1,experienced a latent period of 10 min and maintained stability over a temperature range of 4–37C and pH range of 3–10.Phylogenetic and average nucleotide identity analyses indicate that P1068 can be classified as a novel species within the genus Obolenskvirus of the Caudoviricetes class as per the most recent virus classification released by the International Committee on Taxonomy of Viruses(ICTV).Additionally,according to classical morphological classification,P1068 is identified as a T4-like phage(Myoviridae).Interestingly,we found that the tail fiber protein(TFP)of P1068 shares 74%coverage and 88.99%identity with the TFP of a T7-like phage(Podoviridae),AbKT21phiIII(NC_048142.1).This finding suggests that the TFP gene of phages may undergo horizontal transfer across different genera and morphologies.In vitro antimicrobial assays showed that P1068 exhibited antimicrobial activity against A.baumannii in both biofilm and planktonic states.In mouse models of intraperitoneal infection,P1068 phage protected mice from A.baumannii infection and significantly reduced bacterial loads in various tissues such as the brain,blood,lung,spleen,and liver compared to controls.In conclusion,this study demonstrates that phage P1068 might be a potential candidate for the treatment of carbapenem-resistant and biofilmforming A.baumannii infections,and expands the understanding of horizontal transfer of phage TFP genes.