Challenges and Trends in Gram-Negative Bacterial Infections in Critically Neonates: A Seven-and-a-Half-Year Observational Study.

OBJECTIVE: Analyze the incidence, risk factors, and fatality rates of bloodstream infections by Gram-negative bacteria (GNB-BSIs) in a Neonatal Intensive Care Unit (NICU). METHODS: This study employs a retrospective cohort design utilizing records of neonates admitted to the NICU between January 2015 and June 2022. RESULTS: Among 1,495 neonates, 5.2% developed GNB-BSIs. The average incidence of infection/1,000 patient-days was 2.9. Primary risk factors for infection included preceeding carbapenem use were significant risk factors (OR=514.4; P<0.01) and 4th generation cephalosporins (OR=66; P<0.01). Among the 85 GNB, 75.3% were fermenters, and 24.7% were non-fermenters. Of the isolates, 14.1% produced extended-spectrum beta-lactamase, and 2.3% carbapenem resistant. Infection correlated with prolonged hospital stays (10 to 39 days) and increased mortality (10% to 29.9%). CONCLUSION: The high incidence of GNB-BSIs was exacerbated by the preceeding use of broad-spectrum antimicrobials, increasing the presence of multidrug-resistant isolates and fatality rates. These findings emphasize the importance of active surveillance.

Ceftazidime-Avibactam Use in a Case Series of Difficult-to-Treat or Recurrent Infections in Pediatric Patients with Complex Chronic Conditions: Effectiveness and Absence of Resistance Development.

The prevalence of multidrug-resistant Gram-negative infections, particularly carbapenem-resistant strains, has become a significant global health concern. Ceftazidime-avibactam (CZA) has emerged as a promising treatment option. However, data on its efficacy and safety in children are scarce, necessitating further investigation. We conducted a descriptive case series at a tertiary hospital in Spain from February 2019 to January 2022. Pediatric patients (<16 years) treated with CZA for confirmed or suspected multidrug-resistant Gram-negative infections were included. The clinical and microbiological characteristics, treatment approaches, and outcomes were examined. Eighteen children received CZA treatment. All had complex chronic conditions, with the most frequent underlying main diseases being liver transplantation (n = 8) and biliary atresia (n = 4). The predominant type of infection for which they received CZA was intra-abdominal infection caused or suspected to be caused by OXA-48-producing Klebsiella pneumoniae. CZA was generally well tolerated. Within the first month of starting CZA therapy, two patients died, with one case directly linked to the infection's fatal outcome. Some patients needed repeated courses of therapy due to recurrent infections, yet no resistance development was noted. In summary, the use of CZA showed effectiveness and safety, while the lack of resistance development highlights CZA's potential as a primary treatment option against OXA-48-producing infections.

Comparison of ERIC carbapenem-resistant Enterobacteriaceae test, BD Phoenix CPO detect panel, and NG-test CARBA 5 for the detection of main carbapenemase types of carbapenem-resistant Enterobacterales.

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

Genetic characteristics of chromosomally integrated carbapenemase gene (blaNDM-1) in isolates of Proteus mirabilis.

OBJECTIVE: This study aims to conduct an in-depth genomic analysis of a carbapenem-resistant Proteus mirabilis strain to uncover the distribution and mechanisms of its resistance genes. METHODS: The research primarily utilized whole-genome sequencing to analyze the genome of the Proteus mirabilis strain. Additionally, antibiotic susceptibility tests were conducted to evaluate the strain's sensitivity to various antibiotics, and related case information was collected to analyze the clinical distribution characteristics of the resistant strain. RESULTS: Study on bacterial strain WF3430 from a tetanus and pneumonia patient reveals resistance to multiple antibiotics due to extensive use. Whole-genome sequencing exposes a 4,045,480 bp chromosome carrying 29 antibiotic resistance genes. Two multidrug-resistant (MDR) gene regions, resembling Tn6577 and Tn6589, were identified (MDR Region 1: 64.83 Kb, MDR Region 2: 85.64 Kbp). These regions, consist of integrative and conjugative elements (ICE) structures, highlight the intricate multidrug resistance in clinical settings. CONCLUSION: This study found that a CR-PMI strain exhibits a unique mechanism for acquiring antimicrobial resistance genes, such as blaNDM-1, located on the chromosome instead of plasmids. According to the results, there is increasing complexity in the mechanisms of horizontal transmission of resistance, necessitating a comprehensive understanding and implementation of targeted control measures in both hospital and community settings.

Improving the treatment of bacterial infections caused by multidrug-resistant bacteria through drug repositioning.

Drug repurposing (repositioning) is a dynamically-developing area in the search for effective therapy of infectious diseases. Repositioning existing drugs with a well-known pharmacological and toxicological profile is an attractive method for quickly discovering new therapeutic indications. The off-label use of drugs for infectious diseases requires much less capital and time, and can hasten progress in the development of new antimicrobial drugs, including antibiotics. The use of drug repositioning in searching for new therapeutic options has brought promising results for many viral infectious diseases, such as Ebola, ZIKA, Dengue, and HCV. This review describes the most favorable results for repositioned drugs for the treatment of bacterial infections. It comprises publications from various databases including PubMed and Web of Science published from 2015 to 2023. The following search keywords/strings were used: drug repositioning and/or repurposing and/or antibacterial activity and/or infectious diseases. Treatment options for infections caused by multidrug-resistant bacteria were taken into account, including methicillin-resistant staphylococci, multidrug-resistant Mycobacterium tuberculosis, or carbapenem-resistant bacteria from the Enterobacteriaceae family. It analyses the safety profiles of the included drugs and their synergistic combinations with antibiotics and discusses the potential of antibacterial drugs with antiparasitic, anticancer, antipsychotic effects, and those used in metabolic diseases. Drug repositioning may be an effective response to public health threats related to the spread of multidrug-resistant bacterial strains and the growing antibiotic resistance of microorganisms.

Molecular epidemiology and risk factors for carbapenem-resistant Enterobacteriaceae infections during 2020-2021 in Northwest China.

OBJECTIVES: Severe infection caused by Carbapenem-resistant Enterobacteriaceae (CRE) is a challenge for clinical anti-infective therapy, and clinical intervention to improve control of CRE is of great significance. The study aims to determine the molecular epidemiology and risk factors of CRE infections to provide evidence for effective control of nosocomial infection in patients with CRE. METHODS: A total of 192 non-repetitive CRE strains were collected from January 2020 to December 2021 in Northwest China. To explore the risk factors of CRE infection by univariate and Logistic regression analysis, 1:1 case-control study was used to select Carbapenem sensitive Enterobacteriaceae (CSE) infection patients at the same period as the control group. RESULTS: Among the 192 CRE strains, the most common isolates included Klebsiella pneumoniae (Kpn) and Enterobacter cloacae (Ecl). The CRE strain showed the lowest rate of resistance to amikacin at 58.3. 185 CRE strains carried carbapenemase resistance genes of concern in this study. KPC-2 (n=94) was the most common carbapenemase, followed by NDM-1 (n=69), NDM-5 (n=22) and IMP-4 (n=5). OXA-48 and VIM were not detected. And KPC-2 was the most common in all strains. Logistic regression analysis implicated days of invasive ventilator-assisted ventilation (OR=1.452; 95 % CI 1.250～1.686), antibiotic combination therapy (OR=2.149; 95 % CI 1.128～4.094), hypoalbuminemia (OR=6.137; 95 % CI 3.161～11.913), history of immunosuppressant use (OR=25.815; 95 % CI 6.821～97.706) and days of hospitalization (OR=1.020; 95 % CI 1.006～1.035) as independent risk factors associated with CRE infection. Age (OR=0.963; 95% CI 0.943～0.984) and history of hormone use (OR=0.119; 95 % CI 0.028～0.504) were protective factors for CRE infection (P < 0.05). CONCLUSIONS: The resistance of commonly used antibiotics in clinical is severe, and CRE strains mainly carry KPC-2 and NDM-1. Multiple risk factors for CRE infection and their control can effectively prevent the spread of CRE.

Eternal Hunt: Unravelling the Challenge of CRE, the Quest for Perfection Continues!

How to cite this article: Salotagi S, Kannan A, Jindal A. Eternal Hunt: Unravelling the Challenge of CRE, the Quest for Perfection Continues! Indian J Crit Care Med 2024;28(5):513-514.

Proton pump inhibitors increase the risk of carbapenem-resistant Enterobacteriaceae colonization by facilitating the transfer of antibiotic resistance genes among bacteria in the gut microbiome.

Carbapenem-resistant Enterobacteriaceae (CRE) pose a global health threat; however, there is still limited understanding of the risk factors and underlying mechanisms of CRE colonization in the gut microbiome. We conducted a matched case-control study involving 282 intensive care unit patients to analyze influencing covariates on CRE colonization. Subsequently, their effects on the gut microbiome were analyzed in a subset of 98 patients (47 CRE carriers and 51 non-CRE carriers) using whole metagenome sequences. The concomitant use of proton pump inhibitors (PPIs) and antibiotics was a significant risk factor for CRE colonization. The gut microbiome differed according to PPI administration, even within the CRE and non-CRE groups. Moreover, the transfer of mobile genetic elements (MGEs) harboring carbapenem resistance genes (CRGs) between bacteria was higher in the PPI-treated group than in the PPI-not-treated group among CRE carriers. The concomitant use of PPIs and antibiotics significantly alters the gut microbiome and increases the risk of CRE colonization by facilitating the transfer of CRGs among bacteria of the gut microbiome. Based on these findings, improved stewardship of PPIs as well as antibiotics can provide strategies to reduce the risk of CRE colonization, thereby potentially improving patient prognosis.

Antimicrobial resistance of Enterobacteriaceae and Staphylococcus spp. isolated from raw cow's milk from healthy, clinical and subclinical mastitis udders.

Mastitis is the most common disease of dairy cattle and can be manifested in clinical and subclinical forms. The overuse of antimicrobials in the treatment and prevention of mastitis favours antimicrobial resistance and milk can be a potential route of dissemination. This study aimed to evaluate the biological quality of bulk tank milk (BTM) and the microbiological quality and signs of mastitis of freshly milked raw milk. In addition, to evaluate antimicrobial resistance in Enterobacteriaceae and Staphylococcus spp. isolated from freshly milked raw milk. None of the farms were within the official Brazilian biological quality limits for BTM. Freshly milked raw milk with signs of clinical (CMM), subclinical (SCMM) and no signs (MFM) of mastitis were detected in 6.67%, 27.62% and 65.71% samples, respectively. Most samples of freshly milked raw milk showed acceptable microbiological quality, when evaluating the indicators total coliforms (78.10%), Escherichia coli (88.57%) and Staphylococcus aureus (100%). Klebsiella oxytoca and S. aureus were the most prevalent microorganisms in SCMM and MFM samples. Antimicrobial resistance and multidrug resistance (MDR) were observed in 65.12% and 13.95% of Enterobacteriaceae and 84.31% and 5.88% of Staphylococcus spp., respectively, isolated from both SCMM and MFM samples. Enterobacteriaceae resistant to third-generation cephalosporin (3GCR) (6.98%) and carbapenems (CRE) (6.98%) and methicillin-resistant S. aureus (MRSA) (4.88%) were observed. Antimicrobial-resistant bacteria can spread resistance genes to previously susceptible bacteria. This is a problem that affects animal, human and environmental health and should be evaluated within the one-health concept.

3-O-Substituted Quercetin: an Antibiotic-Potentiating Agent against Multidrug-Resistant Gram-Negative Enterobacteriaceae through Simultaneous Inhibition of Efflux Pump and Broad-Spectrum Carbapenemases.

The discovery of safe and efficient inhibitors against efflux pumps as well as metallo-ß-lactamases (MBL) is one of the main challenges in the development of multidrug-resistant (MDR) reversal agents which can be utilized in the treatment of carbapenem-resistant Gram-negative bacteria. In this study, we have identified that introduction of an ethylene-linked sterically demanding group at the 3-OH position of the previously reported MDR reversal agent di-F-Q endows the resulting compounds with hereto unknown multitarget inhibitory activity against both efflux pumps and broad-spectrum ß-lactamases including difficult-to-inhibit MBLs. A molecular docking study of the multitarget inhibitors against efflux pump, as well as various classes of ß-lactamases, revealed that the 3-O-alkyl substituents occupy the novel binding sites in efflux pumps as well as carbapenemases. Not surprisingly, the multitarget inhibitors rescued the antibiotic activity of a carbapenem antibiotic, meropenem (MEM), in NDM-1 (New Delhi Metallo-ß-lactamase-1)-producing carbapenem-resistant Enterobacteriaceae (CRE), and they reduced MICs of MEM more than four-fold (synergistic effect) in 8-9 out of 14 clinical strains. The antibiotic-potentiating activity of the multitarget inhibitors was also demonstrated in CRE-infected mouse model. Taken together, these results suggest that combining inhibitory activity against two critical targets in MDR Gram-negative bacteria, efflux pumps, and ß-lactamases, in one molecule is possible, and the multitarget inhibitors may provide new avenues for the discovery of safe and efficient MDR reversal agents.

Clinical distribution of carbapenem genotypes and resistance to ceftazidime-avibactam in Enterobacteriaceae bacteria.

Introduction: Bacterial resistance is a major threat to public health worldwide. To gain an understanding of the clinical infection distribution, drug resistance information, and genotype of CRE in Dongguan, China, as well as the resistance of relevant genotypes to CAZ-AVI, this research aims to improve drug resistance monitoring information in Dongguan and provide a reliable basis for the clinical control and treatment of CRE infection. Methods: VITEK-2 Compact automatic analyzer was utilized to identify 516 strains of CRE collected from January 2017 to June 2023. To determine drug sensitivity, the K-B method, E-test, and MIC methods were used. From June 2022 to June 2023, 80 CRE strains were selected, and GeneXpert Carba-R was used to detect and identify the genotype of the carbapenemase present in the collected CRE strains. An in-depth analysis was conducted on the CAZ-AVI in vitro drug sensitivity activity of various genotypes of CRE, and the results were statistically evaluated using SPSS 23.0 and WHONET 5.6 software. Results: This study identified 516 CRE strains, with the majority (70.16%) being K.pneumoniae, followed by E.coli (18.99%). Respiratory specimens had highest detection rate with 53.77% identified, whereas urine specimens had the second highest detection rate with 17.99%. From June 2022 to June 2023, 95% of the strains tested using the CRE GeneXpert Carba-R assay possessed carbapenemase genes, of which 32.5% were blaNDM strains and 61.25% blaKPC strains. The results showed that CRE strains containing blaKPC had a significantly higher rate of resistance to amikacin, cefepime, and aztreonam than those harboring blaNDM. Conclusions: The CRE strains isolated from Dongguan region demonstrated a high resistance rate to various antibiotics used in clinical practice but a low resistance rate to tigecycline. These strains produce Class A serine carbapenemases and Class B metals ß-lactamases, with the majority of them carrying blaNDM and blaKPC. Notably, CRE strains with blaKPC and blaNDM had significantly lower resistance rates to tigecycline. CAZ-AVI showed a good sensitivity rate with no resistance to CRE strains carrying blaKPC. Therefore, CAZ-AVI and tigecycline should be used as a guide for rational use of antibiotics in clinical practice to effectively treat CRE.

[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.

When the Trojan horse is unable to reach inside the city: investigation of the mechanism of resistance behind the first reported cefiderocol-resistant E. coli in Canada.

Gram-negative metallo-ß-lactamase-producing bacteria can be extremely problematic, especially when found to be extensively drug-resistant (XDR). Cefiderocol is a novel antimicrobial that has been shown to overcome most carbapenemases, with very rare resistance reported to date. Within our institution, two multidrug-resistant and one XDR strains were isolated from a patient who recently emigrated from India. Each isolate underwent whole-genome sequencing to resolve plasmids and determine phylogenetics, strain typing, and mechanisms of resistance. The XDR E. coli was ST167, harbored NDM-5, cirA and PBP3 mutations, consistent with cefiderocol resistance. Our study suggests that the NDM region is required in conjunction with cirA and PBP3 mutations. It is not clear why; however, our study did determine a potential novel iron-transport region unique to the cefiderocol-resistant isolate. This is the first characterized cefiderocol-resistant E.coli reported from Canada. Health centers should be on alert for this clone.IMPORTANCEThe development of cefiderocol, a novel siderophore cephalosporin, has provided additional options to the treatment of extensively drug-resistant (XDR) Gram-negative bacteria. Resistance to cefiderocol is poorly understood and only recently described. Here, we describe a case of a patient with recent travel to India harboring three Escherichia coli isolates, one resistant and two susceptible to cefiderocol. Two isolates are highly similar genetically, allowing the mechanism of resistance to be described more closely. The importance of this manuscript contributes both globally to the understanding of cefiderocol resistance in E. coli as well as nationally as this is the first resistant case reported in Canada. This is especially concerning as cefiderocol is not currently approved in Canada. The implications of reporting emerging resistance to new antimicrobials for XDR Gram negatives are impactful to infectious disease specialists, clinical microbiologists, physicians, and public health.

Comparative effectiveness and mortality of colistin monotherapy versus colistin-fosfomycin combination therapy for the treatment of carbapenem-resistant Enterobacteriaceae (CRE) infections: A propensity score analysis.

BACKGROUND: Carbapenem-resistant Enterobacteriaceae (CRE) infections pose a significant threat to global health due to limited treatment options and high mortality rates. Colistin-based regimens have emerged as a primary treatment approach, but the effectiveness and mortality outcomes of colistin monotherapy versus colistin-fosfomycin combination therapy remain uncertain. This study aims to compare the effectiveness and mortality of colistin monotherapy and colistin-fosfomycin combination therapy for CRE infections. Notably, our study is the first to undertake a comprehensive examination of the effectiveness and mortality outcomes between colistin monotherapy and colistin-fosfomycin combination therapy in the context of CRE infections. METHODS: A retrospective cohort study was conducted using data from patients diagnosed with carbapenem-resistant Enterobacteriaceae (CRE) infections at Nakornping Hospital during 2015 to 2022. Inverse probability weighting (IPW) was employed to create balanced cohorts of patients receiving either colistin monotherapy or colistin-fosfomycin combination therapy. The primary outcome measure was treatment effectiveness, assessed by 30-day mortality. Secondary outcome measures included clinical response, mortality at the end of treatment, and microbiologic response. Univariate and multivariate logistic regression analysis were employed after applying propensity score weighting using inverse probability of weighting (IPW). RESULTS: A total of 220 patients were included in the analysis, with 67 receiving colistin monotherapy and 153 receiving colistin-fosfomycin combination therapy. Propensity score weighting using IPW balanced the baseline characteristics between the two groups. The effectiveness of treatment, as measured by 30-day mortality, was not significantly different between the colistin monotherapy group and the colistin-fosfomycin combination therapy group (adjusted odds ratio [aOR] = 1.51, 95% confidence interval [CI]: 0.60-3.78, p = 0.383). Similarly, no significant difference was observed in the mortality at the end of treatment between the two groups (aOR = 1.26, 95% CI: 0.55-2.90, p = 0.576). The clinical response (aOR = 1.48, 95% CI: 0.61-3.59, p = 0.383) and microbiologic response (aOR = 0.66, 95% CI: 0.18-2.38, p = 0.527) were similar between the colistin monotherapy and colistin-fosfomycin combination therapy groups. CONCLUSION: The propensity score analysis among 220 matched patients showed comparable treatment effectiveness and mortality between colistin monotherapy and colistin-fosfomycin combination therapy for CRE infections. These results suggest that colistin monotherapy may be as effective as combination therapy. More prospective randomized controlled trials are needed to confirm these findings and establish optimal CRE treatment strategies.

Case report: Long-term follow-up of patients who received a FimCH vaccine for prevention of recurrent urinary tract infections caused by antibiotic resistant Enterobacteriaceae: a case report series.

Urinary tract infections (UTI) caused by carbapenem-resistant Enterobacteriaceae (CRE) are considered one of the most urgent health threats to humans according to the Centers for Disease Control (CDC), and the World Health Organization (WHO). A FimCH Vaccine expanded access study is being conducted in patients with a history of antibiotic resistant UTIs who are considered to be at risk for development of CRE UTI. This case series describes the clinical, safety and immunogenicity findings for four participants who received a FimCH four-vaccine series. Participants were followed for 12 months after administration of the fourth vaccine for safety, general health status and UTI occurrence. The study was later amended to allow additional follow-up of up to five years post vaccine administration to assess long-term health status, UTI occurrences and to obtain blood samples for anti-FimH antibody testing. In our population of 4 study participants, the number of symptomatic UTI occurrences caused by gram-negative bacteria in the 12-month period following peak anti-FimH antibody response were approximately 75% lower than the 12-month period preceding study enrollment. These results are consistent with the 30-patient cohort of a Phase 1 study with the same FimCH Vaccine. UTI occurrences increased during the long-term follow-up period for all 4 participants but did not reach the rate observed pre-vaccination. No new safety concerns related to the FimCH Vaccine were identified during long-term follow-up. This case series has clinical importance and public health relevance since it examines and reports on UTI frequency and recurrence following vaccination with the FimCH Vaccine in a high-risk population of patients with recurrent UTI. Additionally, participants described improved well-being following vaccination which was maintained in the long-term follow-up period.

Preclinical characterization and in silico safety assessment of three virulent bacteriophages targeting carbapenem-resistant uropathogenic Escherichia coli.

Phage therapy has recently been revitalized in the West with many successful applications against multi-drug-resistant bacterial infections. However, the lack of geographically diverse bacteriophage (phage) genomes has constrained our understanding of phage diversity and its genetics underpinning host specificity, lytic capability, and phage-bacteria co-evolution. This study aims to locally isolate virulent phages against uropathogenic Escherichia coli (E. coli) and study its phenotypic and genomic features. Three obligately virulent Escherichia phages (øEc_Makalu_001, øEc_Makalu_002, and øEc_Makalu_003) that could infect uropathogenic E. coli were isolated and characterized. All three phages belonged to Krischvirus genus. One-step growth curve showed that the latent period of the phages ranged from 15 to 20 min, the outbreak period ~ 50 min, and the burst size ranged between 74 and 127 PFU/bacterium. Moreover, the phages could tolerate a pH range of 6 to 9 and a temperature range of 25-37 °C for up to 180 min without significant loss of phage viability. All phages showed a broad host spectrum and could lyse up to 30% of the 35 tested E. coli isolates. Genomes of all phages were approximately ~ 163 kb with a gene density of 1.73 gene/kbp and an average gene length of ~ 951 bp. The coding density in all phages was approximately 95%. Putative lysin, holin, endolysin, and spanin genes were found in the genomes of all three phages. All phages were strictly virulent with functional lysis modules and lacked any known virulence or toxin genes and antimicrobial resistance genes. Pre-clinical experimental and genomic analysis suggest these phages may be suitable candidates for therapeutic applications.

Analysis of the transmission chain of carbapenem-resistant Enterobacter cloacae complex infections in clinical, intestinal and healthcare settings in Zhejiang province, China (2022-2023).

Considerable attention is given to intensive care unit-acquired infections; however, research on the transmission dynamics of multichain carbapenemase-resistant Enterobacter cloacae complex (CRECC) outbreaks remains elusive. A total of 118 non-duplicated CRECC strains were isolated from the clinical, intestinal, and hospital sewage samples collected from Zhejiang province of China during 2022-2023. A total of 64 CRECC strains were isolated from the hospital sewage samples, and their prevalence increased from 10.0 % (95 % confidence interval, CI = 0.52-45.8 %) in 2022 to 63.6 % (95 % CI = 31.6-87.6 %) in 2023. Species-specific identification revealed that Enterobacter hormaechei was the predominant CRECC species isolated in this study (53.4 %, 95 % CI = 44.0-62.6 %). The antimicrobial susceptibility profiles indicated that all 118 CRECC strains conferred high-level resistance to ß-lactam antibiotics, ceftacillin/avibactam, and polymyxin. Furthermore, all CRECC strains exhibited resistance to ß-lactams, quinolones, and fosfomycin, with a higher colistin resistance rate observed in the hospital sewage samples (67.2 %, 95 % CI = 54.2-78.1 %). Several antibiotic resistance genes were identified in CRECC strains, including Class A carbapenemases (blaKPC-2) and Class B carbapenemases (blaNDM-1/blaIMP), but not Class D carbapenemases. The WGS analysis showed that the majority of the CRECC strains carried carbapenemase-encoding genes, with blaNDM-1 being the most prevalent (86.9 %, 95 % CI = 77.4-92.9 %). Furthermore, sequence typing revealed that the isolated CRECC strains belonged to diverse sequence types (STs), among which ST418 was the most prevalent blaNDM-positive strain. The high risk of carbapenemase-producing ST418 E. hormaechei and the blaNDM-harboring IncFIB-type plasmid (81.4 %, 95 % CI = 72.9-87.7 %) were detected and emphasized in this study. This study provides valuable insights into the prevalence, antimicrobial resistance, genomic characteristics, and plasmid analysis of CRECC strains in diverse populations and environments. The clonal relatedness analysis showed sporadic clonal transmission of ST418 E. hormaechei strains, supporting inter-hospital transmission.

Evaluation of Phenotypic Tests for Carbapenemase Detection in Enterobacteriaceae in Tunisia.

Introduction: Resistance to carbapenems in Enterobacteriaceae is a challenge for public health. Carbapenemase production is the leading mechanism. This work aims to evaluate four phenotypic methods for carbapenemase detection in comparison with a molecular method. Materials and Methods: Thirty-seven nonrepeating Enterobacteriaceae strains with decreased susceptibility to ertapenem were included. Imipenem MIC, Modified Hodge Test (MHT), Neo-Rapid Carb Kit® and KPC, MBL, and OXA-48 Confirm Kit® were performed. Isolates were tested for blaOXA-48, blaNDM, and blaVIM genes by end-point polymerase chain reaction. The results of the molecular study were used as a reference test to determine the performances of the phenotypic tests. Results: Imipenem resistance does not seem to be a good marker for carbapenemase production with a sensitivity of 54% (95% CI: 38-71). MHT showed 82% sensitivity (95% CI: 65-91). Overall, the enzymatic test showed the best performances for carbapenemase detection with 100% sensitivity (95% CI: 89-100) and the best turnaround time. The characterization of carbapenemases classes by the combined discs test demonstrated 88% overall sensitivity (95% CI: 72-95). Conclusion: The results of this study support the combination of the enzymatic and the combined disc tests for carbapenemase detection in Enterobacteria.

Raman spectrum combined with deep learning for precise recognition of Carbapenem-resistant Enterobacteriaceae.

Carbapenem-resistant Enterobacteriaceae (CRE) is a major pathogen that poses a serious threat to human health. Unfortunately, currently, there are no effective measures to curb its rapid development. To address this, an in-depth study on the surface-enhanced Raman spectroscopy (SERS) of 22 strains of 7 categories of CRE using a gold silver composite SERS substrate was conducted. The residual networks with an attention mechanism to classify the SERS spectrum from three perspectives (pathogenic bacteria type, enzyme-producing subtype, and sensitive antibiotic type) were performed. The results show that the SERS spectrum measured by the composite SERS substrate was repeatable and consistent. The SERS spectrum of CRE showed varying degrees of species differences, and the strain difference in the SERS spectrum of CRE was closely related to the type of enzyme-producing subtype. The introduced attention mechanism improved the classification accuracy of the residual network (ResNet) model. The accuracy of CRE classification for different strains and enzyme-producing subtypes reached 94.0% and 96.13%, respectively. The accuracy of CRE classification by pathogen sensitive antibiotic combination reached 93.9%. This study is significant for guiding antibiotic use in CRE infection, as the sensitive antibiotic used in treatment can be predicted directly by measuring CRE spectra. Our study demonstrates the potential of combining SERS with deep learning algorithms to identify CRE without culture labels and classify its sensitive antibiotics. This approach provides a new idea for rapid and accurate clinical detection of CRE and has important significance for alleviating the rapid development of resistance to CRE.

High rates of intestinal colonization with carbapenemase producing Enterobacteriaceae in hematopoietic stem cell transplant recipients.

Carbapenem resistant Enterobacteriaceae (CRE) are major human pathogens because, these cause high number of difficult-to-treat infections. Allogeneic hematopoietic stem cell transplant (AHSCT) recipients are highly exposed to these type of bacteria. The aim of our study was to investigate prevalence of CRE colonization in AHSCT patients and to determine genes encoding carbapenem resistance. A retrospective study conducted between January 2015 and December 2019, involved 55 patients colonized with CRE strains. We determined the rate of antibiotic resistance according to European Committee on Antimicrobial Susceptibility Testing (EUCAST) and the carbapenem resistance genes by PCR assays for genes encoding most frequent ß-lactamases namely, blaGES, blaKPC, blaIMI, blaNDM, blaVIM, blaIMP and blaOXA-48. Eighty-one episodes of CRE colonization were recorded in 55 patients, mainly suffering from acute leukaemia (30%) and aplastic anemia (26%). History of hospitalization was noted in 80 episodes. Prior antibiotic treatment, severe neutropenia and corticosteroid therapy were respectively found in 94%, 76% and 58% of cases. Among the 55 patients, six patients (11%) developed a CRE infection. The CRE responsible for colonization were carbapenemase producers in 90% of cases. They belonged mostly to Klebsiella pneumoniae (61/81) and Escherichia coli species (10/81). Antibiotic resistance rates were 100% for ertapenem, 53% for imipenem, 42% for amikacin, 88% for ciprofloxacin and 27% for fosfomycin. Molecular study showed that blaOXA-48 gene was the most frequent (60.5%), followed by blaNDM (58%). Thirty-five (43%) strains were co-producers of carbapenemases. In our study, we report a high rate of CRE intestinal colonization in AHSCT recipients of our center.