Evaluation of the synergistic effect of eravacycline and tigecycline against carbapenemase-producing carbapenem-resistant Klebsiella pneumoniae.

BACKGROUND: Carbapenem-resistant Klebsiella pneumoniae (CRKP) poses a substantial healthcare challenge. This study assessed the in vitro efficacy of selected antibiotic combinations against CRKP infections. METHODS: Our research involved the evaluation of 40 clinical isolates of CRKP, with half expressing Klebsiella pneumoniae carbapenemase (KPC) and half producing Metallo-ß-lactamase (MBL), two key enzymes contributing to carbapenem resistance. We determined the minimum inhibitory concentrations (MICs) of four antibiotics: eravacycline, tigecycline, polymyxin-B, and ceftazidime/avibactam. Synergistic interactions between these antibiotic combinations were examined using checkerboard and time-kill analyses. RESULTS: We noted significant differences in the MICs of ceftazidime/avibactam between KPC and MBL isolates. Checkerboard analysis revealed appreciable synergy between combinations of tigecycline (35%) or eravacycline (40%) with polymyxin-B. The synergy rates for the combination of tigecycline or eravacycline with polymyxin-B were similar among the KPC and MBL isolates. These combinations maintained a synergy rate of 70.6% even against polymyxin-B resistant isolates. In contrast, combinations of tigecycline (5%) or eravacycline (10%) with ceftazidime/avibactam showed significantly lower synergy than combinations with polymyxin-B (P < 0.001 and P = 0.002, respectively). Among the MBL CRKP isolates, only one exhibited synergy with eravacycline or tigecycline and ceftazidime/avibactam combinations, and no synergistic activity was identified in the time-kill analysis for these combinations. The combination of eravacycline and polymyxin-B demonstrated the most promising synergy in the time-kill analysis. CONCLUSION: This study provides substantial evidence of a significant synergy when combining tigecycline or eravacycline with polymyxin-B against CRKP strains, including those producing MBL. These results highlight potential therapeutic strategies against CRKP infections.

[Key microbial monitoring and clinical analysis of bloodstream infections and CRO colonization after hematopoietic stem cell transplantation in hematological patients].

Objective: To investigate the distribution and clinical characteristics of pathogenic bacteria following hematopoietic stem cell transplantation (HSCT), as well as to provide a preliminary research foundation for key microbial monitoring, and clinical diagnosis and treatment of infections after HSCT in hematological patients. Methods: We retrospectively analyzed the clinical data of 190 patients who tested positive for microbial testing [G-bacteria blood culture and/or carbapenem-resistant organism (CRO) screening of perianal swabs] at our center from January 2018 to December 2022. Patients were divided into blood culture positive, perianal swab positive, and double positive groups based on the testing results. The three patient groups underwent statistical analysis and comparison. Results: The top four pathogenic bacteria isolated from sixty-three patients with G-bacteria bloodstream infection (BSI) were Escherichia coli (28 strains, 43.75% ), Klebsiella pneumonia (26 strains, 40.63% ), Pseudomonas aeruginosa (3 strains, 4.69% ), and Enterobacter cloacae (3 strains, 4.69% ). The top three pathogenic bacteria isolated from 147 patients with CRO perianal colonization were carbapenem-resistant Klebsiella pneumoniae (58 strains, 32.58% ), carbapenem-resistant Escherichia coli (49 strains, 27.53% ), and carbapenem-resistant Enterobacter cloacae (20 strains, 11.24% ). The 3-year disease-free survival (DFS ) and overall survival (OS) of double positive group patients were significantly lower compared to those in the blood culture and perianal swab positive groups (DFS: 35.6% vs 53.7% vs 68.6%, P=0.001; OS: 44.4% vs 62.4% vs 76.9%, P<0.001), while non-relapse mortality (NRM) was significantly higher (50.0% vs 34.9% vs 10.6%, P<0.001). Failed engraftment of platelets and BSI are independent risk factors for NRM (P<0.001). Using polymyxin and/or ceftazidime-avibactam for more than 7 days is an independent protective factor for NRM (P=0.035) . Conclusion: This study suggests that the occurrence of BSI significantly increases the NRM after HSCT in patients with hematological diseases; CRO colonization into the bloodstream has a significant impact on the DFS and OS of HSCT patients.

Epidemiology and clinical significance of carbapenemases in Australia: a narrative review.

Carbapenemase-producing gram-negative bacteria (CP-GNB) infections threaten public health with high mortality, morbidity and treatment costs. Although frequencies remain low in Australia (total number of CP-GNB infections reported was 907 in 2022), blaIMP-4 has established low levels of endemicity in many states. Imipenemase metallo-ß-lactamase types alone accounted for more than half of all carbapenemases in carbapenemase-producing Enterobacterales isolates in Australia, particularly in Enterobacter cloacae complex. New Delhi metallo-ß-lactamase constitutes almost 25% of all carbapenemases in Australia and was identified predominantly in Escherichia coli. The OXA-48-like carbapenemases include almost 10% of all carbapenemases and are mainly seen in Klebsiella pneumoniae and E. coli. Although K. pneumoniae carbapenemase-type carbapenemases are rare in Australia, some local outbreaks have occurred. Most carbapenem-resistant (CR) Pseudomonas aeruginosa strains in Australia do not produce carbapenemases. Finally, OXA-23-like carbapenemases are overwhelmingly positive in CR-Acinetobacter baumannii strains in Australia. Treatment of CR-GNB infections challenges physicians. Of 10 new antibiotics active against at least some CR-GNB infections that are approved by the US Food and Drug Administration, just three are approved for use in Australia. In this context, there is still an unmet need for novel antibacterials that can be used for the treatment of CR-GNB infections in Australia, as well as a pressing requirement for new mechanisms to 'de-link' antibiotic sales from their availability. In this narrative review, we aim to overview the epidemiology and clinical significance of carbapenem resistance in Australia as it pertains to Enterobacterales, P. aeruginosa and A. baumannii.

Clinical characteristics and antimicrobial therapy of healthcare-associated carbapenem-non-susceptible gram-negative bacterial meningitis: a 16-year retrospective cohort study.

OBJECTIVE: Healthcare-associated Gram-negative bacterial meningitis is a substantial clinical issue with poor outcomes, especially for neurosurgical patients. Here, we aimed to study the characteristics and treatment options of patients with healthcare-associated carbapenem-non-susceptible (Carba-NS) Gram-negative bacterial meningitis. METHODS: This observational cohort study was conducted at a teaching hospital from 2004 to 2019. The clinical characteristics of patients with meningitis with Carba-NS and carbapenem-susceptible (Carba-S) bacilli were compared, and the antimicrobial chemotherapy regimens and outcomes for Carba-NS Gram-negative bacterial meningitis were analyzed. RESULTS: A total of 505 patients were included, of whom 83.8% were post-neurosurgical patients. The most common isolates were Acinetobacter spp. and Klebsiella spp., which had meropenem-resistance rates of 50.6% and 42.5%, respectively, and showed a markedly growing carbapenem-resistance trend. Kaplan-Meier curve analysis revealed that Carba-NS Gram-negative bacilli were associated with a significantly higher in-hospital mortality rate (18.8%, 35/186) compared to the Carba-S group (7.4%, 9/122; P = 0.001). For Carba-NS Enterobacterales meningitis, aminoglycoside-based and trimethoprim-sulfamethoxazole-based regimens yielded significantly higher clinical efficacy rates than non-aminoglycoside-based and non-trimethoprim-sulfamethoxazole-based regimens (69.0% vs. 38.7%, P = 0.019 and 81.8% vs. 46.9%, P = 0.036, respectively). For Carba-NS A. baumannii complex meningitis, tetracycline-based (including doxycycline, minocycline, or tigecycline) therapy achieved a significantly higher clinical efficacy rate (62.9%, 22/35) than the non-tetracycline-based therapy group (40.4%, 19/47; P = 0.044). CONCLUSIONS: Our findings revealed that Carba-NS Gram-negative bacilli are associated with higher in-hospital mortality in patients with healthcare-associated meningitis. The combination therapies involving particular old antibiotics may improve patients' outcome. TRIAL REGISTRATION: This study was registered on the Chinese Clinical Trial Register under ChiCTR2000036572 (08/2020).

Carbapenem-resistant Gram-negative bacteria (CR-GNB) in ICUs: resistance genes, therapeutics, and prevention - a comprehensive review.

Intensive care units (ICUs) are specialized environments dedicated to the management of critically ill patients, who are particularly susceptible to drug-resistant bacteria. Among these, carbapenem-resistant Gram-negative bacteria (CR-GNB) pose a significant threat endangering the lives of ICU patients. Carbapenemase production is a key resistance mechanism in CR-GNB, with the transfer of resistance genes contributing to the extensive emergence of antimicrobial resistance (AMR). CR-GNB infections are widespread in ICUs, highlighting an urgent need for prevention and control measures to reduce mortality rates associated with CR-GNB transmission or infection. This review provides an overview of key aspects surrounding CR-GNB within ICUs. We examine the mechanisms of bacterial drug resistance, the resistance genes that frequently occur with CR-GNB infections in ICU, and the therapeutic options against carbapenemase genotypes. Additionally, we highlight crucial preventive measures to impede the transmission and spread of CR-GNB within ICUs, along with reviewing the advances made in the field of clinical predictive modeling research, which hold excellent potential for practical application.

Antimicrobial Use and Carbapenem-Resistant Enterobacterales in Korea: A Nationwide Case-Control Study With Propensity Score Matching.

BACKGROUND: Nationwide research on the association between carbapenem-resistant Enterobacterales (CREs) and antibiotic use is limited. METHODS: This nested case-control study analyzed Korean National Health Insurance claims data from April 2017 to April 2019. Based on the occurrence of CRE, hospitalized patients aged ≥ 18 years were classified into CRE (cases) and control groups. Propensity scores based on age, sex, modified Charlson comorbidity score, insurance type, long-term care facility, intensive care unit stay, and acquisition of vancomycin-resistant Enterococci were used to match the case and control groups (1:3). RESULTS: After matching, the study included 6,476 participants (1,619 cases and 4,857 controls). Multivariable logistic regression analysis revealed that the utilization of broad-spectrum antibiotics, such as piperacillin/tazobactam (adjusted odds ratio [aOR], 2.178; 95% confidence interval [CI], 1.829-2.594), third/fourth generation cephalosporins (aOR, 1.764; 95% CI, 1.514-2.056), and carbapenems (aOR, 1.775; 95% CI, 1.454-2.165), as well as the presence of comorbidities (diabetes [aOR, 1.237; 95% CI, 1.061-1.443], hemiplegia or paraplegia [aOR, 1.370; 95% CI, 1.119-1.679], kidney disease [aOR, 1.312; 95% CI, 1.105-1.559], and liver disease [aOR, 1.431; 95% CI, 1.073-1.908]), were significantly associated with the development of CRE. Additionally, the CRE group had higher mortality (8.33 vs. 3.32 incidence rate per 100 person-months, P < 0.001) and a total cost of healthcare utilization per person-month (15,325,491 ± 23,587,378 vs. 5,263,373 ± 14,070,118 KRW, P < 0.001) than the control group. CONCLUSION: The utilization of broad-spectrum antibiotics and the presence of comorbidities are associated with increasing development of CRE. This study emphasizes the importance of antimicrobial stewardship in reducing broad-spectrum antibiotic use and CRE disease burden in Korea.

Development of a risk prediction model for subsequent infection after colonization with carbapenem-resistant Enterobacterales: a retrospective cohort study.

BACKGROUND: Colonization of carbapenem-resistant Enterobacterale (CRE) is considered as one of vital preconditions for infection, with corresponding high morbidity and mortality. It is important to construct a reliable prediction model for those CRE carriers with high risk of infection. METHODS: A retrospective cohort study was conducted in two Chinese tertiary hospitals for patients with CRE colonization from 2011 to 2021. Univariable analysis and the Fine-Gray sub-distribution hazard model were utilized to identify potential predictors for CRE-colonized infection, while death was the competing event. A nomogram was established to predict 30-day and 60-day risk of CRE-colonized infection. RESULTS: 879 eligible patients were enrolled in our study and divided into training (n = 761) and validation (n = 118) group, respectively. There were 196 (25.8%) patients suffered from subsequent CRE infection. The median duration of subsequent infection after identification of CRE colonization was 20 (interquartile range [IQR], 14-32) days. Multisite colonization, polymicrobial colonization, catheterization and receiving albumin after colonization, concomitant respiratory diseases, receiving carbapenems and antimicrobial combination therapy before CRE colonization within 90 days were included in final model. Model discrimination and calibration were acceptable for predicting the probability of 60-day CRE-colonized infection in both training (area under the curve [AUC], 74.7) and validation dataset (AUC, 81.1). Decision-curve analysis revealed a significantly better net benefit in current model. Our prediction model is freely available online at https://ken-zheng.shinyapps.io/PredictingModelofCREcolonizedInfection/ . CONCLUSIONS: Our nomogram has a good predictive performance and could contribute to early identification of CRE carriers with a high-risk of subsequent infection, although external validation would be required.

A challenging case of carbapenem resistant Klebsiella pneumoniae-related pyogenic liver abscess with capsular polysaccharide hyperproduction: a case report.

BACKGROUND: Carbapenem-resistant Klebsiella pneumoniae (CRKP) infections are a major public health problem, necessitating the administration of polymyxin E (colistin) as a last-line antibiotic. Meanwhile, the mortality rate associated with colistin-resistant K. pneumoniae infections is seriously increasing. On the other hand, importance of administration of carbapenems in promoting colistin resistance in K. pneumoniae is unknown. CASE PRESENTATION: We report a case of K. pneumoniae-related pyogenic liver abscess in which susceptible K. pneumoniae transformed into carbapenem- and colistin-resistant K. pneumoniae during treatment with imipenem. The case of pyogenic liver abscess was a 50-year-old man with diabetes and liver transplant who was admitted to Abu Ali Sina Hospital in Shiraz. The K. pneumoniae isolate responsible for community-acquired pyogenic liver abscess was isolated and identified. The K. pneumoniae isolate was sensitive to all tested antibiotics except ampicillin in the antimicrobial susceptibility test and was identified as a non-K1/K2 classical K. pneumoniae (cKp) strain. Multilocus sequence typing (MLST) identified the isolate as sequence type 54 (ST54). Based on the patient's request, he was discharged to continue treatment at another center. After two months, he was readmitted due to fever and progressive constitutional symptoms. During treatment with imipenem, the strain acquired blaOXA-48 and showed resistance to carbapenems and was identified as a multidrug resistant (MDR) strain. The minimum inhibitory concentration (MIC) test for colistin was performed by broth microdilution method and the strain was sensitive to colistin (MIC < 2 µg/mL). Meanwhile, on blood agar, the colonies had a sticky consistency and adhered to the culture medium (sticky mucoviscous colonies). Quantitative real-time PCR and biofilm formation assay revealed that the CRKP strain increased capsule wzi gene expression and produced slime in response to imipenem. Finally, K. pneumoniae-related pyogenic liver abscess with resistance to a wide range of antibiotics, including the last-line antibiotics colistin and tigecycline, led to sepsis and death. CONCLUSIONS: Based on this information, can we have a theoretical hypothesis that imipenem is a promoter of resistance to carbapenems and colistin in K. pneumoniae? This needs more attention.

An Intra-Hospital Spread of Colistin-Resistant K. pneumoniae Isolates-Epidemiological, Clinical, and Genetic Analysis.

Background and Objective: Klebsiella pneumoniae appears to be a significant problem due to its ability to accumulate antibiotic-resistance genes. After 2013, alarming colistin resistance rates among carbapenem-resistant K. pneumoniae have been reported in the Balkans. The study aims to perform an epidemiological, clinical, and genetic analysis of a local outbreak of COLr CR-Kp. Material and Methods: All carbapenem-resistant and colistin-resistant K. pneumoniae isolates observed among patients in the ICU unit of Military Medical Academy, Sofia, from 1 January to 31 October 2023, were included. The results were analyzed according to the EUCAST criteria. All isolates were screened for blaVIM, blaIMP, blaKPC, blaNDM, and blaOXA-48. Genetic similarity was determined using the Dice coefficient as a similarity measure and the unweighted pair group method with arithmetic mean (UPGMA). mgrB genes and plasmid-mediated colistin resistance determinants (mcr-1, mcr-2, mcr-3, mcr-4, and mcr-5) were investigated. Results: There was a total of 379 multidrug-resistant K. pneumoniae isolates, 88% of which were carbapenem-resistant. Of these, there were nine (2.7%) colistin-resistant isolates in six patients. A time and space cluster for five patients was found. Epidemiology typing showed that two isolates belonged to clone A (pts. 1, 5) and the rest to clone B (pts. 2-4) with 69% similarity. Clone A isolates were coproducers of blaNDM-like and blaOXA-48-like and had mgrB-mediated colistin resistance (40%). Clone B isolates had only blaOXA-48-like and intact mgrB genes. All isolates were negative for mcr-1, -2, -3, -4, and -5 genes. Conclusions: The study describes a within-hospital spread of two clones of COLr CR-Kp with a 60% mortality rate. Clone A isolates were coproducers of NDM-like and OXA-48-like enzymes and had mgrB-mediated colistin resistance. Clone B isolates had only OXA-48-like enzymes and intact mgrB genes. No plasmid-mediated resistance was found. The extremely high mortality rate and limited treatment options warrant strict measures to prevent outbreaks.

Ineffectiveness of colistin monotherapy in treating carbapenem-resistant Acinetobacter baumannii Pneumonia: A retrospective single-center cohort study.

BACKGROUND: Acinetobacter baumannii, a common carbapenem-resistant gram-negative bacillus, usually causes nosocomial infections. Colistin has been used for carbapenem-resistant A. baumannii (CRAB) infections; however, only a few studies have evaluated colistin as a treatment option compared to appropriate controls. We investigated the effectiveness of colistin monotherapy in treating CRAB pneumonia compared to those treated without an active drug. METHODS: Adult patients (≥ 18 years) with CRAB isolated from respiratory specimens were screened from September 2017 to August 2022. Only patients with pneumonia treated with colistin monotherapy (colistin group) were included and compared to those without any active antibiotics (no active antibiotics [NAA] group). The primary and secondary outcomes were 30-day all-cause mortality and acute kidney injury within 30 days. The inverse probability of the treatment-weighted Cox proportional hazard model was used to compare mortality between groups. RESULTS: Among the 826 adult patients with CRAB in their respiratory specimens, 45 and 123 patients were included in the colistin and NAA groups, respectively. Most of the CRAB pneumonia (91.1%) cases were hospital-acquired pneumonia. The 30-day all-cause mortality rates in the colistin and NAA groups were 58.3% and 56.1%, respectively, and no difference was observed after adjustments (adjusted hazard ratio, 0.74; 95% CI, 0.47-1.17). The incidence of acute kidney injury was higher in the colistin group (65.3%) compared to the NAA group (39.0%) (P = 0.143). CONCLUSIONS: Colistin monotherapy did not significantly improve treatment outcomes for CRAB pneumonia. The development and evaluation of new antimicrobials for CRAB pneumonia should be advocated in clinical practice.

Complete sequence of carbapenem-resistant Ralstonia mannitolilytica clinical isolate co-producing novel class D ß-lactamase OXA-1176 and OXA-1177 in Japan.

In 2020, the Ralstonia mannitolilytica strain JARB-RN-0044 was isolated from a midstream urine sample of an elderly hospitalized patient in Japan and was highly resistant to carbapenem (i.e., imipenem, meropenem, and doripenem). Whole-genome sequencing revealed that the complete genome consists of two replicons, a 3.5-Mb chromosome and a 1.5-Mb large non-chromosomal replicon which has not been reported in R. mannitolilytica, and referred to as the "megaplasmid" in this study based on Cluster of Orthologous Group of proteins functional analysis. The strain JARB-RN-0044 harbored two novel OXA-60 and OXA-22 family class D ß-lactamase genes blaOXA-1176 and blaOXA-1177 on the megaplasmid. Cloning experiments indicated that Escherichia coli recombinant clone expressing blaOXA-1176 gene showed increased minimum inhibitory concentrations (MICs) of imipenem, meropenem, and doripenem, indicating that blaOXA-1176 gene encodes carbapenemase. In contrast, E. coli recombinant clone expressing blaOXA-1177 gene showed increased MICs of piperacillin and cefazolin, but not of carbapenem. Interestingly, the 44.6 kb putative prophage region containing genes encoding phage integrase, terminase, head and tail protein was identified in the downstream region of blaOXA-1176 gene, and comparative analysis with some previously reported R. mannitolilytica isolates revealed that the prophage region was unique to strain JARB-RN-0044. The existence of a highly carbapenem-resistant R. mannitolilytica isolate may raise human health concerns in Japan, where the population is rapidly aging.IMPORTANCERalstonia mannitolilytica is an aerobic non-fermenting Gram-negative rod commonly found in aquatic environments and soil. The bacteria can occasionally cause severe hospital-acquired bloodstream infections in immunocompromised patients and it has been recently recognized as an emerging opportunistic human pathogen. Furthermore, some R. mannitolilytica isolates are resistant to various antimicrobial agents, including ß-lactams and aminoglycosides, making antimicrobial therapy challenging and clinically problematic. However, clinical awareness of this pathogen is limited. To our knowledge, in Japan, there has been only one report of a carbapenem-resistant R. mannitolilytica clinical isolate from urine by Suzuki et al. in 2015. In this study, whole-genome sequencing analysis revealed the presence and genetic context of novel blaOXA-1176 and blaOXA-1177 genes on the 1.5 Mb megaplasmid from highly carbapenem-resistant R. mannitolilytica isolate and characterized the overall distribution of functional genes in the chromosome and megaplasmid. Our findings highlight the importance of further attention to R. mannitolilytica isolate in clinical settings.

Acute Exacerbation of Chronic Obstructive Pulmonary Disease Due to Carbapenem-Resistant Klebsiella pneumoniae-Induced Pneumonia: Clinical Features and Prognostic Factors.

Purpose: Carbapenem-resistant Klebsiella pneumoniae (CRKP) is closely related to respiratory tract infection. The aim of this study was to investigate the clinical features and prognostic factors of CRKP-induced pneumonia in acute exacerbation of chronic obstructive pulmonary disease (AECOPD) patients. Methods: A single-centre, retrospective case-control study on COPD patients hospitalized for acute exacerbation and CRKP-induced pneumonia was conducted from January 1, 2016, to December 31, 2022. The mortality rate of acute exacerbation due to CRKP-induced pneumonia was investigated. The patients were divided into the CRKP-induced pneumonic acute exacerbation (CRKPpAE) group and the non-CRKP-induced pneumonic acute exacerbation (non-CRKPpAE) group, and the clinical characteristics and prognostic factors were compared using univariate analysis and multivariate analysis. Results: A total of 65 AECOPD patients were included, composed of 26 patients with CRKPpAE and 39 patients with non-CRKPpAE. The mortality rate of CRKPpAE was 57.69%, while non-CRKPpAE was 7.69%. Compared with non-CRKPpAE, a history of acute exacerbation in the last year (OR=8.860, 95% CI: 1.360-57.722, p=0.023), ICU admission (OR=11.736, 95% CI: 2.112-65.207, p=0.005), higher NLR levels (OR=1.187, 95% CI: 1.037-1.359, p=0.013) and higher D-dimer levels (OR=1.385, 95% CI: 1.006-1.905, p=0.046) were independently related with CRKPpAE. CRKP isolates were all MDR strains (26/26, 100%), and MDR strains were also observed in non-CRKP isolates (5/39, 12.82%). Conclusion: Compared with non-CRKPpAE, CRKPpAE affects the COPD patient's condition more seriously and significantly increases the risk of death.

A comprehensive evaluation of risk factors for mortality, infection and colonization associated with CRGNB in adult solid organ transplant recipients: a systematic review and meta-analysis.

BACKGROUND: The burden of carbapenem-resistant gram-negative bacteria (CRGNB) among solid organ transplant (SOT) recipients has not been systematically explored. Here, we discern the risk factors associated with CRGNB infection and colonization in SOT recipients. METHODS: This study included observational studies conducted among CRGNB-infected SOT patients, which reported risk factors associated with mortality, infection or colonization. Relevant records will be searched in PubMed, Embase and Web of Science for the period from the time of database construction to 1 March 2023. RESULTS: A total of 23 studies with 13,511 participants were included, enabling the assessment of 27 potential risk factors. The pooled prevalence of 1-year mortality among SOT recipients with CRGNB was 44.5%. Prolonged mechanical ventilation, combined transplantation, reoperation and pre-transplantation CRGNB colonization are salient contributors to the occurrence of CRGNB infections in SOT recipients. Renal replacement therapy, post-LT CRGNB colonization, pre-LT liver disease and model for end-stage liver disease score increased the risk of infection. Re-transplantation, carbapenem use before transplantation and ureteral stent utilization increaesd risk of CRGNB colonization. CONCLUSION: Our study demonstrated that SOT recipients with CRGNB infections had a higher mortality risk. Invasive procedure may be the main factor contribute to CRGNB infection.

Carbapenem-Resistant Enterobacteriaceae in Urinary Tract Infections: From Biological Insights to Emerging Therapeutic Alternatives.

Urinary tract infections (UTIs) are the second most frequent type of infection observed in clinical practice. Gram-negative Enterobacteriaceae are common pathogens in UTIs. Excessive antibiotic use in humans and animals, poor infection control, and increased global travel have accelerated the spread of multidrug-resistant strains (MDR). Carbapenem antibiotics are commonly considered the last line of defense against MDR Gram-negative bacteria; however, their efficacy is now threatened by the increasing prevalence of carbapenem-resistant Enterobacteriaceae (CRE). This comprehensive review aims to explore the biological mechanisms underlying carbapenem resistance and to present a focus on therapeutic alternatives currently available for complicated UTIs (cUTIs). A comprehensive bibliographic search was conducted on the PubMed/MEDLINE, Scopus, and Web of Science databases in December 2023. The best evidence on the topic was selected, described, and discussed. Analyzed with particular interest were the clinical trials pivotal to the introduction of new pharmacological treatments in the management of complicated cUTIs. Additional suitable articles were collected by manually cross-referencing the bibliography of previously selected papers. This overview provides a current and comprehensive examination of the treatment options available for CRE infections, offering a valuable resource for understanding this constantly evolving public health challenge.

Understanding blaNDM-1 gene regulation in CRKP infections: toward novel antimicrobial strategies for hospital-acquired pneumonia.

BACKGROUND: The escalating challenge of Carbapenem-resistant Klebsiella pneumoniae (CRKP) in hospital-acquired pneumonia (HAP) is closely linked to the blaNDM-1 gene. This study explores the regulatory mechanisms of blaNDM-1 expression and aims to enhance antibacterial tactics to counteract the spread and infection of resistant bacteria. METHODS: KP and CRKP strains were isolated from HAP patients' blood samples. Transcriptomic sequencing (RNA-seq) identified significant upregulation of blaNDM-1 gene expression in CRKP strains. Bioinformatics analysis revealed blaNDM-1 gene involvement in beta-lactam resistance pathways. CRISPR-Cas9 was used to delete the blaNDM-1 gene, restoring sensitivity. In vitro and in vivo experiments demonstrated enhanced efficacy with Imipenem and Thanatin or Subatan combination therapy. RESULTS: KP and CRKP strains were isolated with significant upregulation of blaNDM-1 in CRKP strains identified by RNA-seq. The Beta-lactam resistance pathway was implicated in bioinformatics analysis. Knockout of blaNDM-1 reinstated sensitivity in CRKP strains. Further, co-treatment with Imipenem, Thanatin, or Subactam markedly improved antimicrobial effectiveness. CONCLUSION: Silencing blaNDM-1 in CRKP strains from HAP patients weakens their Carbapenem resistance and optimizes antibacterial strategies. These results provide new theoretical insights and practical methods for treating resistant bacterial infections.

Clinical success of anti-infective combination therapy compare to monotherapy in patients with carbapenem-resistant Pseudomonas aeruginosa infection: a 10-years retrospective study.

BACKGROUND: Carbapenem-resistant Pseudomonas aeruginosa (CRPA) infection has become a major public health concern. The recommendations for monotherapy and combination therapy in the current guidelines lack sufficient evidence to support them. The primary objective of this study is to determine the effectiveness of anti-Infective combination therapy compared to monotherapy in achieving clinical success in patients with CRPA infection and risk factors of clinical failure of monotherapy. METHODS: A retrospective study from Medical Information Mart for Intensive Care IV (MIMIC-IV) was conducted. We included adults with infections caused by CRPA. The outcomes of this study were clinical success, complete clinical success, and 28-day all-cause mortality. RESULTS: A total of 279 subjects were finally enrolled. The rate of clinical success for combination therapy was higher than that for monotherapy (73.1% versus 60.4%, p=0.028). Compared to clinical failure patients, patients in the clinical success group were more likely to die within 28 days after CRPA was found (48.3% versus 3.6%, p<0.001). In a multivariate logistic regression analysis, monotherapy was found to be significantly correlated with clinical success (OR, 0.559, 95% CI, 0.321-0.976; p = 0.041). CONCLUSION: Combination therapy is more effective for CRPA infection patients, especially those whose SOFA score is ≥ 2 or whose Charlson comorbidity index is ≥ 6.

Carbapenem-producing Enterobacteriaceae in mothers and newborns in southeast Gabon, 2022.

Introduction: Infections caused by carbapenemase-producing Enterobacteriaceae (CPE) pose a significant threat, leading to severe morbidity and mortality among newborns. Methods: This study, conducted at Franceville hospital's maternity and neonatology wards from February 22nd to June 20th, 2022, investigated the prevalence of CPE in 197 parturients and 203 newborns. Rectal swabs were taken from parturients before delivery and from newborns 30 minutes after birth. Blood culture samples were collected if signs of infection were observed in newborns during a 28-day follow-up. A total of 152 environmental samples were obtained, comprising 18 from sinks, 14 from incubators, 27 from cradles, 39 from maternal beds, 14 from tables and desks, four from the two baby scales and 36 from bedside furniture. Results: None of the 203 newborns were found to be CPE carriers 30 minutes after delivery. CPE carriage was found in 4.6% of mothers. When comparing colonized and uncolonized parturients, well-established risk factors for CPE carriage, such as recent hospitalization and antibiotic therapy, were more frequently observed among CPE carriers (33.3 vs 10.6% for hospitalization in the past 15 days; 55.5 vs 30.3% for hospitalization during pregnancy, and 55.5 vs 35.1% for antibiotic therapy during pregnancy). Notably, the prevalence of treatment with amoxicillin and clavulanic acid was 44.4% in CPE carriers compared to 17.0% in non-carriers. The incidence density of CPE-associated bloodstream infection was 0.49 per 100 newborns, accounting for a fatal case of CPE-associated bacteremia identified in one of the 203 newborns. Seven environmental samples returned positive for CPE (5 sinks and two pieces of furniture). Whole genome sequencing, performed on the 25 CPE isolates, revealed isolates carrying blaNDM-7 (n=10), blaNDM-5 (n=3), blaOXA181 (n=10), blaOXA48 (n=2) or blaOXA244 (n=1), along with genetic traits associated with the ability to cause severe and difficult-to-treat infections in newborns. Core genome comparison revealed nine CPE belonging to three international high-risk clones: E. coli ST410 (four mothers and a sink), two E. coli ST167 (a mother and a piece of furniture), and K. pneumoniae ST307 (a sink and a piece of furniture), with highly similar genetic backgrounds shared by maternal and environmental isolates, suggesting maternal contamination originating from the environment. Discussion: Our study reveals key findings may guide the implementation of infection control measures to prevent nosocomial infections in newborns: the prevalence of CPE carriage in one out of 20 parturients, an infection occurring in one out of 400 newborns, substantial contamination of the care environment, clinical and environmental CPE isolates possessing genetic traits associated with the ability to cause severe and challenging infections, and clonal relationships between clinical and environmental isolates suggesting CPE spread within the wards, likely contributing to the acquisition and colonization of CPE by parturients during pregnancy.

Cefiderocol either in monotherapy or combination versus best available therapy in the treatment of carbapenem-resistant Acinetobacter baumannii infections: A systematic review and meta-analysis.

BACKGROUND: The best treatment for carbapenem-resistant Acinetobacter baumannii (CRAB) infections is still a matter of debate. OBJECTIVES: To describe the outcomes of patients treated with cefiderocol for CRAB infections, and to compare the efficacy of cefiderocol versus best available therapy (BAT). DATA SOURCES: We searched MEDLINE, the Cochrane Library and EMBASE to screen original reports published up to September 2023. STUDY ELIGIBILITY CRITERIA: Randomized controlled trials (RCTs) and observational studies investigating 30-day mortality, clinical failure, microbiological failure or rate of adverse drug reactions of patients treated with cefiderocol or BAT. PARTICIPANTS: Patients with infections due to CRAB. INTERVENTIONS: Cefiderocol in monotherapy or in combination with other potentially active agents or BAT. ASSESSMENT OF RISK OF BIAS: We used the Cochrane Risk of Bias Tool for RCTs, and the Newcastle Ottawa scale for observational studies. METHODS OF DATA SYNTHESIS: We conducted a meta-analysis pooling risk ratios (RRs) through random effect models. RESULTS: We screened 801 original reports, and 18 studies (2 RCTs, 13 cohort studies and 3 case-series) were included in the analysis, for a total 733 patients treated with cefiderocol, and 473 receiving the BAT. Among patients receiving cefiderocol, the 30-day mortality rate was 42% (95% CI 38-47%), the rate of microbiological failure 48% (95% CI 31-65%), the clinical failure rate 43% (95% CI 32-55%), and the rate of ADRs was 3% (95% CI 1-6%). A lower mortality rate was observed among patients receiving cefiderocol monotherapy as compared to those treated with combination regimens (RR: 0.64; 95% CI: 0.43-0.94, p = 0.024). We found a significantly lower mortality rate (RR: 0.74; 95% CI: 0.57-0.95, p = 0.02) and a lower rate of ADRs (RR: 0.28; 95% CI: 0.09-0.91, p = 0.03) in the group treated with cefiderocol as compared to BAT. No difference was observed in microbiological and clinical failure rate. CONCLUSIONS: Our data strengthen the efficacy and safety profile of cefiderocol in CRAB infections.

Risk factors and outcome associated with the acquisition of MDR linezolid-resistant Enterococcus faecium: a report from tertiary care centre.

OBJECTIVE: The aim of the study was to determine the resistance profile of linezolid-resistant Enterococcus faecium (LREfm) and to investigate risk factors and outcomes associated with LREfm infections. MATERIAL AND METHODS: A prospective case-control study was undertaken (2019 to 2022) and included 202 patients with LREfm infections (cases) and 200 controls with LSEfm infections. Clinical data was prospectively collected and analysed for risk factors and outcomes. Antimicrobial susceptibility was performed, and resistance profile was studied using WHOnet. RESULTS: Risk factors associated with LREfm infection were site of infection UTI (OR 5.87, 95% CI 2.59-13.29, p ≤ 0.001), prior use of carbapenem (OR 2.85 95% CI 1.62-5.02, p ≤ 0.001) and linezolid (OR 10.13, 95% CI 4.13-24.82, p ≤ 0.001), use of central line (OR 5.54, 95% CI 2.35-13.09, p ≤ 0.001), urinary catheter (OR 0.29, 95% CI 0.12-0.70, p ≤ 0.001) and ventilation (OR 14.87, 95% CI 7.86-28.11, p ≤ 0.007). The hospital stay 8-14 days (< 0.001) prior to infection and the mortality rate (p = 0.003) were also significantly high among patients with LREfm infections. Linezolid and vancomycin resistance coexisted; further, MDR, XDR and PDR phenotypes were significantly higher among LREfm. CONCLUSION: This study provided insight into epidemiology of MDR LREfm in a setting where linezolid use is high. The main drivers of infections with LREfm are multiple, including use of carbapenems and linezolid. Invasive procedures and increased hospital stay facilitate spread through breach in infection control practises. As therapeutic options are limited, ongoing surveillance of LREfm and VRE is critical to guide appropriate use of linezolid and infection control policies.

Effect of different strategies for excluding duplicate cultures on the correlation between hospital resistance rates and antibiotic consumption.

INTRODUCTION: Studies may underestimate the impact of antibiotics on bacterial resistance when correlating hospital antibiotic use with resistance rates (RRs) that exclude duplicate cultures as duplicates usually include more resistant isolates. Comparing correlations between antibiotic consumption and RRs resulting from different strategies for excluding duplicates could help explore how their exclusion affects such correlations. METHODS: We obtained antibiotics consumption and Pseudomonas aeruginosa susceptibility data from 2017 to 2021 for seven antibiotics and for carbapenems as a group in a university hospital. We calculated RRs using seven different time criteria for excluding duplicates. We assessed the correlations of antibiotic consumption to the same-year and next-year RR rates for the three most distinct rates. RESULTS: Duplicate cultures represented 53.45% of total cultures. RRs were higher when duplicates were included. We compared RRs resulting from excluding all duplicates, excluding duplicates monthly or admitting one culture per day. All antibiotics except meropenem showed a correlation with same-year RRs, either positive or negative, whereas all antibiotics showed a positive correlation with next-year RRs. For same-year and next-year correlations, the criteria with fewer duplicates (and therefore fewer resistant strains) found more correlations. However, the inclusion of duplicates taken at least 1 month apart found the most correlations. Admitting one culture per day found the fewest correlations. CONCLUSIONS: Excluding duplicates from RRs affects the correlation of antibiotics consumption with RRs in P. aeruginosa. Including at least some duplicate cultures in correlation analyses, such as those taken 1 month apart, should be considered.