Epidemiological characteristics of New Delhi Metallo-ß-Lactamase-producing Enterobacteriaceae in the Fourth hospital of Hebei Medical University.

The epidemiological characteristics of New Delhi Metallo-ß-Lactamase-Producing (NDM) Enterobacteriaceae were analyzed to provide theoretical support for clarifying the distribution characteristics of carbapenem-resistant Enterobacteriaceae (CRE) in the hospital environment and early identification of susceptible patients. From January 2017 to December 2021,42 strains of NDM-producing Enterobacteriaceae were gathered from the Fourth Hospital of Hebei Medical University, primarily Escherichia coli, Klebsiella pneumoniae, and Enterobacter cloacae. The micro broth dilution method combined with the Kirby-Bauer method was used to determine the minimal inhibitory concentrations (MICs) of antibiotics. The carbapenem phenotype was detected by the modified carbapenem inactivation method (mCIM) and EDTA carbapenem inactivation method (eCIM). Carbapenem genotypes were detected by colloidal gold immunochromatography and real-time fluorescence PCR. The results of antimicrobial susceptibility testing showed that all NDM-producing Enterobacteriaceae were multiple antibiotic resistant, but the sensitivity rate to amikacin was high. Invasive surgery prior to culture, the use of excessive amounts of different antibiotics, the use of glucocorticoids, and ICU hospitalization were clinical characteristics of NDM-producing Enterobacteriaceae infection. Molecular typing of NDM-producing Escherichia coli and Klebsiella pneumoniae was carried out by Multilocus Sequence Typing (MLST), and the phylogenetic trees were constructed. Eight sequence types (STs) and two NDM variants were detected in 11 strains of Klebsiella pneumoniae, primarily ST17, and NDM-1. A total of 8 STs and 4 NDM variants were detected in 16 strains of Escherichia coli, mainly ST410, ST167, and NDM-5. For high-risk patients who have CRE infection, CRE screening should be done as soon as feasible to adopt prompt and efficient intervention measures to prevent outbreaks in the hospital.

Reduced susceptibility to carbapenems in Enterobacteriaceae and antimicrobial resistance profile of Escherichia coli strains isolated from clinical and zoonotic sources in the Bamenda Municipality, Cameroon.

Introduction: food-producing animals harbour pathogenic and antibiotic resistant bacteria which can be transmitted to humans. Resistance to carbapenems may complicate treatment resulting to debilitating consequences. This study aimed at determining the susceptibility of Enterobacteriaceae to carbapenems and to compare the resistant patterns of E. coli strains isolated from clinical and zoonotic sources. Methods: this was a cross-sectional study involving patients presenting at the Bamenda Regional Hospital and abattoir samples. Clinical samples (faeces and urine) and zoonotic samples (cattle faeces) were cultured and isolates identified using API-20E. Enterobacteriaceae isolates were tested for their susceptibility to Carbapenems. The susceptibility of E. coli was tested against eight antibiotics on Mueller Hinton agar. Data was analysed using SPSS version 20. Results: Enterobacteriaceae isolates from clinical specimen showed susceptibility of 93.3% to carbapenems. Out of 208 isolates 14 (6.7%) were Carbapenem-resistant Enterobacteriaceae (CRE) while 30 (14.4%) showed intermediate resistance and 164 (78.9%) were susceptible. The predominant CRE were Proteus (7/16, 43.8%), Providencia (3/15, 20.0%) and E. coli (4/60, 6.7%) with E. coli being the most clinically significant CRE. Multiple drug resistance (MDR) was observed in 83% of E. coli isolates, with the highest resistance being against vancomycin (90, 81.8%), azithromycin (69, 62.7%) and doxycycline (68, 61.8%). Clinical isolates were significantly (P<0.05) more resistant to azithromycin, trimethoprim-suphamethoxazole and gentamicin than zoonotic isolates. Conclusion: CRE were detected among isolates and a high rate of multiple drug resistance was observed among E. coli isolates. Proper antibiotic policies and good hygiene/sanitation measures may curb the development/spread of CRE and MDR E. coli.

Breaking Antimicrobial Resistance: High-Dose Amoxicillin with Clavulanic Acid for Urinary Tract Infections Due to Extended-Spectrum Beta-Lactamase (ESBL)-Producing Klebsiella pneumoniae.

BACKGROUND Carbapenems are the primary treatment for urinary tract infections (UTIs) caused by extended-spectrum beta-lactamase (ESBL)-producing Klebsiella pneumoniae. However, the recurrence rate is high, and patients often require rehospitalization. We present the results of an observational study on patients with recurrent UTIs who were treated in an outpatient setting with maximal therapeutic oral doses of amoxicillin with clavulanic acid. MATERIAL AND METHODS All patients had pyuria and ESBL-producing K. pneumoniae in urine culture. The starting dosage was 2875 g of amoxicillin twice daily and 125 mg of clavulanic acid twice daily. We down-titrated the doses every 7-14 days and continued prophylactic therapy with amoxicillin/clavulanic acid at 250/125 mg for up to 3 months. We defined therapeutic failure as ESBL-positive K. pneumoniae in urine culture during therapy and recurrence as positive urine culture with the same strain within 1 month after the end of treatment. RESULTS We included 9 patients: 7 kidney graft recipients, 1 liver graft recipient, and 1 patient with chronic kidney disease. We observed no therapeutic failures and no recurrences in the study group during the study period. In 1 case, the patient experienced a subsequent UTI caused by ESBL-producing K. pneumoniae 4 months after completing the therapy. CONCLUSIONS In conclusion, it is possible to break the resistance of ESBL-producing K. pneumoniae strains with high doses of oral amoxicillin with clavulanic acid. Such treatment could be an alternative to carbapenems in select cases.

Antimicrobial Activity of Cefiderocol against the Carbapenemase-Producing Enterobacter cloacae Complex and Characterization of Reduced Susceptibility Associated with Metallo-ß-Lactamase VIM-1.

Emergence of cefiderocol resistance among carbapenemase-producing Enterobacterales, particularly those in the Enterobacter cloacae complex (ECC), is becoming of alarming concern; however, the mechanistic basis of this phenomenon remains poorly understood. We describe the acquisition of VIM-1-mediated reduced cefiderocol susceptibility (MICs 0.5 to 4 mg/L) in a collection of 54 carbapenemase-producing isolates belonging to the ECC. MICs were determined by reference methodologies. Antimicrobial resistance genomic analysis was performed through hybrid WGS. The impact of VIM-1 production on cefiderocol resistance in the ECC background was examined at microbiological, molecular, biochemical, and atomic levels. Antimicrobial susceptibility testing yielded 83.3% susceptible isolates and MIC50/90 values of 1/4 mg/L. Decreased susceptibility to cefiderocol was mainly associated with isolates producing VIM-1, with cefiderocol MICs 2- to 4-fold higher than for isolates carrying other types of carbapenemases. E. cloacae and Escherichia coli VIM-1 transformants displayed significantly enhanced cefiderocol MICs. Biochemical assays with purified VIM-1 protein revealed low but detectable cefiderocol hydrolysis. Simulation studies revealed how cefiderocol is anchored to the VIM-1 active site. Additional molecular assays and WGS data analysis highlighted the implication of SHV-12 coproduction and suggested the inactivation of the FcuA-like siderophore receptor as further contributors to the higher cefiderocol MICs. Our findings warn of the potential of the VIM-1 carbapenemase to at least partly limit the activity of cefiderocol in the ECC. This effect is probably enhanced due to combination with additional mechanisms, such as ESBL production and siderophore inactivation, and indicates the need for active surveillance to extend the life span of this promising cephalosporin.

Characteristics of Carbapenem-resistant Klebsiella pneumoniae in sewage from a tertiary hospital in Jilin Province, China.

Carbapenem-resistant Klebsiella pneumoniae (CRKP) infection is a serious problem in hospitals worldwide. We monitored a tertiary hospital in Changchun, Jilin Province, China, and found that CRKP was the major species among the carbapenem-resistant isolates in sewage. Subsequently, we evaluated the drug susceptibility, resistance genes, virulence genes, outer pore membrane protein-related genes (OmpK35 & OmpK 36), multi-locus sequence typing and replicons, biofilm formation capabilities, and resistance to chlorine-containing disinfectants among KP isolates. Identification of drug sensitivity, multiple resistance profiles were observed including 77 (82.80%) multidrug resistant (MDR), 16 (17.20%) extensive drug resistant (XDR). Some antibiotic resistance genes were detected, the most prevalent carbapenemase gene was blaKPC, and 16 resistance genes were associated with other antibiotics. In addition, 3 (3.23%) CRKP isolates demonstrated loss of OmpK-35 and 2 (2.15%) demonstrated loss of OmpK-36. In the detection of multi-locus sequence typing (MLST), 11 ST11 isolates carried virulence genes. The most common replicon type was IncFII. Biofilm-forming capabilities were demonstrated by 68.8% of the isolates, all of which were resistant to chlorine-containing disinfectants. The results of the study showed that antibiotic-resistant isolates, especially CRKP, could resist disinfectants in hospital wastewater, and improper treatment of hospital wastewater may lead to the spread of drug-resistant bacteria and their genes. Thus, these bacteria must be eliminated before being discharged into the municipal sewage system.

Characterization of blaAFM-1-positive carbapenem-resistant strains isolated in Guangzhou, China.

BACKGROUND: Carbapenemase-producing makes a great contribution to carbapenem resistance in Gram-negative bacilli. BlaAFM-1 gene was first discovered by us in Alcaligenes faecalis AN70 strain isolated in Guangzhou of China and, was submitted to NCBI on 16 November 2018. METHODS: Antimicrobial susceptibility testing was performed by broth microdilution assay using BD Phoenix 100. The phylogenetic tree of AFM and other B1 metallo-ß-lactamases was visualized by MEGA7.0. Whole-genome sequencing technology was used to sequence carbapenem-resistant strains including the blaAFM-1 gene. Cloning and expressing of blaAFM-1 were designed to verify the function of AFM-1 to hydrolyze carbapenems and common ß-lactamase substrates. Carba NP and Etest experiments were conducted to evaluate the activity of carbapenemase. Homology modeling was applied to predict the spatial structure of AFM-1. A conjugation assay was performed to test the ability of horizontal transfer of AFM-1 enzyme. The genetic context of blaAFM-1 was performed by Blast alignment. RESULTS: Alcaligenes faecalis strain AN70, Comamonas testosteroni strain NFYY023, Bordetella trematum strain E202, and Stenotrophomonas maltophilia strain NCTC10498 were identified as carrying the blaAFM-1 gene. All of these four strains were carbapenem-resistant strains. Phylogenetic analysis revealed that AFM-1 shares little nucleotide and amino acid identity with other class B carbapenemases (the highest identity (86%) with NDM-1 at the amino acid sequence level). The spatial structure of the AFM-1 enzyme was predicted to be αß/ßα sandwich structure, with two zinc atoms at its active site structure. Cloning and expressing of blaAFM-1 verified AFM-1 could hydrolyze carbapenems and common ß-lactamase substrates. Carba NP test presented that the AFM-1 enzyme possesses carbapenemase activity. The successful transfer of pAN70-1(plasmid of AN70) to E.coli J53 suggested that the blaAFM-1 gene could be disseminated by the plasmid. The genetic context of blaAFM indicated that the downstream of the blaAFM gene was always adjacent to trpF and bleMBL. Comparative genome analysis revealed that blaAFM appeared to have been mobilized by an ISCR27-related mediated event. CONCLUSIONS: The blaAFM-1 gene is derived from chromosome and plasmid, and the blaAFM-1 gene derived from the pAN70-1 plasmid can transfer carbapenem resistance to susceptible strains through horizontal transfer. Several blaAFM-1-positive species have been isolated from feces in Guangzhou, China.

ESBL in positive hemoculture of a Southern-Brazil Teaching Hospital's Intensive Care Units.

Bloodstream infections are among the most serious and frequent infections, and the people most exposed are patients in the Intensive Care Unit (ICU). ESBL (extended-spectrum beta-lactate) are resistant bacteria to penicillins, cephalosporins and monobactams. It´s necessary to know how often and which microorganisms are involved, checking their susceptibility. This study was carried out at the University Hospital. Data collection was performed in the Adult and Newborn ICUs, with assessment of microorganisms and their resistance profile. During six-month period, 156 samples were studied, and 42 were positive with microorganism isolation. Isolated species include Staphylococcus aureus, Staphylococcus epidermidis and Klebsiella pneumoniae. Many resistant to carbapenem.

Sulbactam-durlobactam: A Step Forward in Treating Carbapenem-Resistant Acinetobacter baumannii (CRAB) Infections.

Antimicrobial resistance in gram-negative pathogens, such as Acinetobacter baumannii, is a serious threat to human health. Sulbactam-durlobactam, a unique ß-lactam and a ß-lactamase inhibitor combination, is a novel agent targeted against carbapenem-resistant A. baumannii. This supplement provides a summary of the development of SUL-DUR, discussing its unique features and role in treating infections caused by CRAB pathogens.

Pathogen-Targeted Clinical Development to Address Unmet Medical Need: Design, Safety, and Efficacy of the ATTACK Trial.

There is a crucial need for novel antibiotics to stem the tide of antimicrobial resistance, particularly against difficult to treat gram-negative pathogens like Acinetobacter baumannii-calcoaceticus complex (ABC). An innovative approach to addressing antimicrobial resistance may be pathogen-targeted development programs. Sulbactam-durlobactam (SUL-DUR) is a ß-lactam/ß-lactamase inhibitor combination antibiotic that is being developed to specifically target drug-resistant ABC. The development of SUL-DUR culminated with the Acinetobacter Treatment Trial Against Colistin (ATTACK) trial, a global, randomized, active-controlled phase 3 clinical trial that compared SUL-DUR with colistin for treating serious infections due to carbapenem-resistant ABC. SUL-DUR met the primary noninferiority endpoint of 28-day all-cause mortality. Furthermore, SUL-DUR had a favorable safety profile with a statistically significant lower incidence of nephrotoxicity compared with colistin. If approved, SUL-DUR could be an important treatment option for infections caused by ABC, including carbapenem-resistant and multidrug-resistant strains. The development program and the ATTACK trial highlight the potential for pathogen-targeted development programs to address the challenge of antimicrobial resistance.

Navigating Available Treatment Options for Carbapenem-Resistant Acinetobacter baumannii-calcoaceticus Complex Infections.

Carbapenem-resistant Acinetobacter baumannii-calcoaceticus complex (CRAB) is one of the top-priority pathogens for new antibiotic development. Unlike other antibiotic-resistant threats, none of the available therapies have been shown to consistently reduce mortality or improve patient outcomes in clinical trials. Antibiotic combination therapy is routinely used in clinical practice; however, the preferred combination has not been defined. This narrative review focuses on evidence-based solutions for the treatment of invasive CRAB infections. We dissect the promise and perils of traditional agents used in combination, such as colistin, sulbactam, and the tetracyclines, and offer clinical pearls based on our interpretation of the available data. Next, we investigate the merits of newly developed ß-lactam agents like cefiderocol and sulbactam-durlobactam, which have demonstrated contrasting results in recent randomized clinical trials. The review concludes with the authors' perspective on the evolving treatment landscape for CRAB infections, which is complicated by limited clinical data, imperfect treatment options, and a need for future clinical trials. We propose that effective treatment for CRAB infections requires a personalized approach that incorporates host factors, the site of infection, pharmacokinetic-pharmacodynamic principles, local molecular epidemiology of CRAB isolates, and careful interpretation of antibiotic susceptibility testing results. In most clinical scenarios, a dose-optimized, sulbactam-based regimen is recommended with the addition of at least one other in vitro active agent. Should sulbactam-durlobactam receive regulatory approval, recommendations will need to be re-evaluated with the most recent evidence.

Streptothricin F is a bactericidal antibiotic effective against highly drug-resistant gram-negative bacteria that interacts with the 30S subunit of the 70S ribosome.

The streptothricin natural product mixture (also known as nourseothricin) was discovered in the early 1940s, generating intense initial interest because of excellent gram-negative activity. Here, we establish the activity spectrum of nourseothricin and its main components, streptothricin F (S-F, 1 lysine) and streptothricin D (S-D, 3 lysines), purified to homogeneity, against highly drug-resistant, carbapenem-resistant Enterobacterales (CRE) and Acinetobacter baumannii. For CRE, the MIC50 and MIC90 for S-F and S-D were 2 and 4 µM, and 0.25 and 0.5 µM, respectively. S-F and nourseothricin showed rapid, bactericidal activity. S-F and S-D both showed approximately 40-fold greater selectivity for prokaryotic than eukaryotic ribosomes in in vitro translation assays. In vivo, delayed renal toxicity occurred at >10-fold higher doses of S-F compared with S-D. Substantial treatment effect of S-F in the murine thigh model was observed against the otherwise pandrug-resistant, NDM-1-expressing Klebsiella pneumoniae Nevada strain with minimal or no toxicity. Cryo-EM characterization of S-F bound to the A. baumannii 70S ribosome defines extensive hydrogen bonding of the S-F steptolidine moiety, as a guanine mimetic, to the 16S rRNA C1054 nucleobase (Escherichia coli numbering) in helix 34, and the carbamoylated gulosamine moiety of S-F with A1196, explaining the high-level resistance conferred by corresponding mutations at the residues identified in single rrn operon E. coli. Structural analysis suggests that S-F probes the A-decoding site, which potentially may account for its miscoding activity. Based on unique and promising activity, we suggest that the streptothricin scaffold deserves further preclinical exploration as a potential therapeutic for drug-resistant, gram-negative pathogens.

Molecular characteristics of carbapenem-resistant gram-negative bacilli in pediatric patients in China.

BACKGROUND: Carbapenem-resistant gram-negative bacilli (CR-GNB) have been increasingly reported in China. However, dynamic monitoring data on molecular epidemiology of CR-GNB are limited in pediatric patients. RESULTS: 300 CR-GNB isolates (200 Carbapenem-resistant K. pneumoniae (CRKP), 50 carbapenem-resistant A.baumannii (CRAB) and 50 carbapenem-resistant P. aeruginosa (CRPA)) were investigated. The predominant carbapenemase gene was blaNDM-1 (73%) and blaKPC-2 (65%) in neonates and non-neonates. Meanwhile, the predominant STs were ST11 (54%) in neonates and ST17 (27.0%) and ST278 (20.0%) in non-neonates. Notably, a shift in the dominant sequence type of CRKP infections from ST17 /ST278-NDM-1 to ST11-KPC-2 was observed during the years 2017-2021 and KPC-KP showed relatively higher resistance to aminoglycosides and quinolones than NDM-KP.BlaOXA-23 was isolated from all the CRAB isolates while only one isolate expressing blaBIC and 2 isolates expressing blaVIM-2 were found in CRPA isolates. ST195 (22.0%) and ST244 (24.0%) were the most common in CRAB and CRPA isolates and all the STs of CRAB belonged to CC92 while CRPA presents ST types with diversity distribution. CONCLUSION: CRKP showed different molecular phenotypes in neonates and non-neonates and was changing dynamically and high-risk clone of ST11 KPC-KP should be paid more attention. Most CRKP and CRAB strains shared the same CCs, suggesting that intrahospital transmission may occur, and large-scale screening and more effective measures are urgently needed.

One Health Approach for Reporting Veterinary Carbapenem-Resistant Enterobacterales and Other Bacteria of Public Health Concern.

A carbapenem-resistant Enterobacterales outbreak at a veterinary teaching hospital in the United States increased urgency for improved communication among diagnostic laboratories, public health authorities, veterinarians, and pet owners. Kansas State University, University of Missouri, Kansas Department of Health and Environment, and Veterinary Laboratory Investigation and Response Network created a surveillance, storage, and reporting protocol for veterinary antimicrobial-resistant bacteria; determined frequency of those bacteria in companion animals during 2018-2021; and created educational flyers for veterinarians and pet owners. We recommend a One Health strategy to create efficient surveillance programs to identify and report antimicrobial-resistant bacteria and educate veterinarians and pet owners about transmission risks.

The C5α-Methyl-Substituted Carbapenem NA-1-157 Exhibits Potent Activity against Klebsiella spp. Isolates Producing OXA-48-Type Carbapenemases.

The wide spread of carbapenem-hydrolyzing ß-lactamases in Gram-negative bacteria has diminished the utility of the last-resort carbapenem antibiotics, significantly narrowing the available therapeutic options. In the Enterobacteriaceae family, which includes many important clinical pathogens such as Klebsiella pneumoniae and Escherichia coli, production of class D ß-lactamases from the OXA-48-type family constitutes the major mechanism of resistance to carbapenems. To address the public health threat posed by these enzymes, novel, effective therapeutics are urgently needed. Here, we report evaluation of a novel, C5α-methyl-substituted carbapenem, NA-1-157, and show that its MICs against bacteria producing OXA-48-type enzymes were reduced by 4- to 32-fold when compared to meropenem. When combined with commercial carbapenems, the potency of NA-1-157 was further enhanced, resulting in target potentiation concentrations ranging from 0.125 to 2 µg/mL. Kinetic studies demonstrated that the compound is poorly hydrolyzed by OXA-48, with a catalytic efficiency 30- to 50-fold lower than those of imipenem and meropenem. Acylation of OXA-48 by NA-1-157 was severely impaired, with a rate 10,000- to 36,000-fold slower when compared to the commercial carbapenems. Docking, molecular dynamics, and structural studies demonstrated that the presence of the C5α-methyl group in NA-1-157 creates steric clashes within the active site, leading to differences in the position and the hydrogen-bonding pattern of the compound, which are incompatible with efficient acylation. This study demonstrates that NA-1-157 is a promising novel carbapenem for treatment of infections caused by OXA-48-producing bacterial pathogens.

Characterization of carbapenem-resistant Escherichia coli and Klebsiella: a role for AmpC-producing isolates.

Aim: This study aimed to investigate the role of AmpC enzymes in carbapenem resistance among AmpC/extended-spectrum ß-lactamase (ESBL)-producing clinical isolates of Escherichia coli and Klebsiella spp. Methods: Fifty-six bacterial strains that were AmpC producers were examined. The antibiotic susceptibility test was performed by the disk diffusion and E-test. The prevalence of the plasmid carbapenemase was determined using PCR. Results: The resistance to meropenem in the AmpC+/ESBL+ group was 64%, higher than that reported for the AmpC-/ESBL+ group. Ten isolates of the carbapenem-resistant AmpC producers were negative for carbapenemase-encoding genes. Conclusion: Carbapenem resistance among AmpC-producing isolates with negative results for carbapenemase-encoding genes potentially demonstrates the role of AmpC enzymes among these isolates.

Comparative study of polymyxin B and colistin sulfate in the treatment of severe comorbid patients infected with CR-GNB.

BACKGROUND: With the difficulties in choosing colistin sulfate and polymyxin B sulfate (PBS) for carbapenem-resistant gram-negative bacteria (CR-GNB), we compared the efficacy and safety of these two old polymyxins in treatment of critically ill patients infected with CR-GNB infection. METHODS: One hundred four patients infected with CR-GNB in ICU were retrospectively grouped by PBS (68 patients) or colistin sulfate (36 patients). Clinical efficacy including symptoms, inflammatory parameters, defervescence, prognosis and microbial efficacy were analyzed. Hepatotoxicity, nephrotoxicity, and hematotoxicity were evaluated by TBiL, ALT, AST, creatinine, and thrombocytes. RESULTS: Demographic characteristics between colistin sulfate and PBS were not significantly different. Most of the CR-GNB were cultured in respiratory tract (91.7% vs 86.8%), and almost all were polymyxin-sensitive (98.2% vs 100%, MIC ≤ 2 µg/ml). The microbial efficacy in colistin sulfate (57.1%) was significantly higher than PBS (30.8%) (p = 0.022), however, no significant difference in clinical success was seen in both groups (33.8% vs 41.7%), as well as mortality, defervescence, imaging remission, days in the hospital, microbial reinfections, and prognosis, and almost all patients defervesce within 7 days (95.6% vs 89.5%). CONCLUSIONS: Both polymyxins can be administrated in critically ill patients infected with CR-GNB and colistin sulfate is superior to PBS in microbial clearance. These results highlight the necessity of identifying CR-GNB patients who may benefit from polymyxin and who are at higher risk of mortality.

Hypermucoviscous Carbapenem-Resistant Klebsiella pneumoniae ST25 Infect Human Intestinal Epithelial Cells and Induce Moderate Inflammation.

Klebsiella pneumoniae is an opportunistic pathogen that can produce moderate and severe infections in immunosuppressed hosts. In recent years, an increase in the isolation of hypermucoviscous carbapenem-resistant K. pneumoniae with sequence type 25 (ST25) in hospitals in Norwest Argentina was observed. This work aimed to study the virulence and inflammatory potential of two K. pneumoniae ST25 strains (LABACER01 and LABACER27) in the intestinal mucosa. The human intestinal Caco-2 cells were infected with the K. pneumoniae ST25 strains, and their adhesion and invasion rates and changes in the expression of tight junction and inflammatory factors genes were evaluated. ST25 strains were able to adhere and invade Caco-2 cells, reducing their viability. Furthermore, both strains reduced the expression of tight junction proteins (occludin, ZO-1, and claudin-5), altered permeability, and increased the expression of TGF-ß and TLL1 and the inflammatory factors (COX-2, iNOS, MCP-1, IL-6, IL-8, and TNF-α) in Caco-2 cells. The inflammatory response induced by LABACER01 and LABACER27 was significantly lower than the one produced by LPS or other intestinal pathogens, including K. pneumoniae NTUH-K2044. No differences in virulence and inflammatory potential were found between LABACER01 and LABACER27. In line with these findings, no major differences between the strains were found when the comparative genomic analysis of virulence factors associated with intestinal infection/colonization was performed. This work is the first to demonstrate that hypermucoviscous carbapenem-resistant K. pneumoniae ST25 infects human intestinal epithelial cells and induces moderate inflammation.

Vancomycin-gingerol encapsulated niosomal formulation against carbapenem-resistantKlebsiella pneumoniae.

Alternatives to conventional antibiotics are critical in light of the increasing prevalence of antibiotic-resistant bacteria, posing a serious threat to humanity and imposing a financial burden on the community. The current study aimed to develop a Vancomycin (Van) and Gingerol (Gin) co-encapsulated in a niosomal (Nio-Gin/Van) formulation and to assess the optimized formulation as a potent antibacterial agent against carbapenem-resistantKlebsiella pneumoniae(CRKP) strains. The prepared Nio-Gin/Van was characterized via scanning electron microscopy (SEM), transmission electron microscopy (TEM), and dynamic light scattering (DLS) and Fourier-transform infrared spectroscopy (FTIR) techniques. The F4 formulation was selected as the optimal formulation due to its low polydispersity index (PDI) (0.221 ± 0.023), small size (222.8 ± 6.35 nm), and suitable entrapment efficiency (EE%) (83.73 ± 1.12 for Gin and 66.25 ± 1.34 for Van). The Nio-Gin/Van had a sustained drug release up to 72 h and posed great stability to 60 d at 4 °C with low alterations in size, PDI and EE%, which introduced it as an appropriate candidate for medicinal utilization. The antibacterial activities of Nio-Gin/Van against CRKPs isolates were investigated using a MIC assay, which revealed MIC values of between 7.81/100-125/100 µg ml-1. Microtiter-plate assays and real-time polymerase chain reaction (PCR) were used to evaluate the antibiofilm properties of Nio-Gin/Van. A microtiter-plate assay indicated that approximately 53% of 15 CRKP isolates (n= 8) produced strong biofilms, while 26.6% (n= 4) produced moderate biofilms. Additionally, real-time PCR analysis revealed that Nio-Gin/Van significantly reduced the expression of thefimH, blaKPC, mrkD, andOmpk36genes in all CRKP isolates examined. It was concluded that encapsulating Gin-Van in niosome enhances their antibacterial and antibiofilm activity against CRKP strains and these preparations could be considered as a novel strategy for targeted drug delivery.

Characterisation of pellicle-forming ability in clinical carbapenem-resistant Acinetobacter baumannii.

Background: Acinetobacter baumannii was reported to have resistance towards carbapenems and the ability to form an air-liquid biofilm (pellicle) which contributes to their virulence. The GacSA two-component system has been previously shown to play a role in pellicle formation. Therefore, this study aims to detect the presence of gacA and gacS genes in carbapenem-resistant Acinetobacter baumannii (CRAB) isolates recovered from patients in intensive care units and to investigate their pellicle forming ability. Methods: The gacS and gacA genes were screened in 96 clinical CRAB isolates using PCR assay. Pellicle formation assay was performed in Mueller Hinton medium and Luria Bertani medium using borosilicate glass tubes and polypropylene plastic tubes. The biomass of the pellicle was quantitated using the crystal violet staining assay. The selected isolates were further assessed for their motility using semi-solid agar and monitored in real-time using real-time cell analyser (RTCA). Results: All 96 clinical CRAB isolates carried the gacS and gacA genes, however, only four isolates (AB21, AB34, AB69 and AB97) displayed the ability of pellicle-formation phenotypically. These four pellicle-forming isolates produced robust pellicles in Mueller Hinton medium with better performance in borosilicate glass tubes in which biomass with OD570 ranging from 1.984 ± 0.383 to 2.272 ± 0.376 was recorded. The decrease in cell index starting from 13 hours obtained from the impedance-based RTCA showed that pellicle-forming isolates had entered the growth stage of pellicle development. Conclusion: These four pellicle-forming clinical CRAB isolates could be potentially more virulent, therefore further investigation is warranted to provide insights into their pathogenic mechanisms.