Β-lactamase Inhibitor Research Articles

Evaluation of multidrug resistance in the Gram-negative microbiome of cancer patients and the adverse effects of their metabolites on albino rats and epithelial or fibroblasts cell lines

BackgroundCancer is a significant global health issue due to its high incidence and mortality rates. In recent years, the relationship between the human microbiota and cancer has garnered attention across various medical fields. This includes research into the microbial communities that influence cancer development, tumor-associated microorganisms, and the interactions between the microbiome and tumor, collectively referred to as the oncobiome.MethodsThe negative effects of secondary metabolites extracted from selected multidrug-resistant Gram-negative bacteria within the cancer microbiota were evaluated. These effects included carcinogenicity, mutagenicity, hepatotoxicity, nephrotoxicity, and sperm deformities observed in albino rats after one month of oral ingestion of these microbial extracts.ResultsOur findings in the present investigation revealed that among the bacterial community derived from the microbiota, Gram-negative bacteria accounted for 74.87% the total microbiota (146 out of 195) and their spectrum including Escherichia sp. (n = 36, 24.66%) followed by Acinetobacter sp. (n = 34, 23.29%), Stenotrophomonas sp. (n = 29, 19.86%), Pseudomonas sp. (n = 26, 17.81%) and Serratia sp. (n = 21, 14.38%), as the most prevalent pathogens. All isolates derived from the cancer microbiome exhibited multidrug resistance to a large number of conventional therapies. Out of them Serratia sp. Esraa 1, Stenotrophomonas sp. Esraa 2, Acinetobacter sp. Esraa 3, Escherichia sp. Esraa 4 and Pseudomonas sp. Esraa 5 strains showed multidrug resistant profile against all antibiotic classes under study including penicillins, cephalosporins, carbapenems, fluoroquinolones, β-lactamase inhibitors combinations, folate synthesis pathway inhibitors, phosphonic, aminoglycosides, polymyxins, tetracyclines, macrolides, and chloramphenicol antibiotics. The adverse effects of oral ingestion of their metabolites were evaluated in albino rats. They induced pronounced carcinogenesis along with severe raise in the inflammatory cytokines, hepatotoxicity, nephrotoxicity, mutagenicity along with sperm deformities in treated animals. Moreover, all metabolites showed marked cytotoxicity against human normal cell lines; human mammary epithelial (MCF10A), human lung fibroblasts (WI38) and human dermal fibroblasts (HDFs).ConclusionThese bacterial strains isolated from the cancer microbiome may play significant roles in inducing cancer, inflammation, mutagenesis, hepatotoxicity, nephrotoxicity, and sperm abnormalities, along with histopathological changes in the treated animal groups by orally administrated metabolites in compared to the untreated group.Graphical

Advancements in the fight against globally distributed OXA-48 carbapenemase: evaluating the new generation of carbapenemase inhibitors.

Carbapenemase OXA-48 and its variants pose a serious threat to the development of effective treatments for bacterial infections. OXA-48-producing Enterobacterales are the most prevalent carbapenemase-producing bacteria in large parts of the world. Although these bacteria exhibit low-level carbapenem resistance in vitro, the infections they cause are challenging to treat with conventional therapies, owing to their spread and complex detection in clinical settings. However, numerous β-lactamase inhibitors (BLIs) are currently in the pipeline or late clinical stages. To assess the potential of these compounds, this study compared the efficacy against OXA-48 of novel β-lactamase inhibitors, specifically the 1,6-diazabicyclo[3,2,1]octanes (DBOs) avibactam, relebactam, zidebactam, nacubactam, and durlobactam, along with the cyclic and bicyclic boronates vaborbactam, taniborbactam, and xeruborbactam. The extensive kinetics assays identified xeruborbactam, taniborbactam, and durlobactam, together with the already established avibactam, as BLIs with superior biochemical performance. Susceptibility testing further validated these findings but also demonstrated significantly improved bacterial killing by the DBOs zidebactam, nacubactam, and durlobactam. On the other hand, binding studies demonstrated the superior inhibitory capacity of the BLIs durlobactam and xeruborbactam. Combinations, such as cefepime/zidebactam, meropenem/nacubactam, and sulbactam/durlobactam, show promising activity against OXA-48-producing Enterobacterales, while ceftazidime/avibactam, cefepime/taniborbactam, and meropenem/xeruborbactam combinations also appear highly active, largely due to the excellent kinetics of these new inhibitors. Overall, this comprehensive analysis provides important insights into the effectiveness of new BLIs against OXA-48-producing Enterobacterales, highlighting xeruborbactam, durlobactam, and avibactam as leading candidates. Additionally, BLIs like zidebactam, nacubactam, and taniborbactam also showed potential in addressing the clinical challenges posed by OXA-48-mediated antimicrobial resistance.

Spectrophotometric Detection of Beta-Lactamase Inhibition by Plant Extracts

Background: Antibiotic-resistant bacteria have been spreading with increasing frequency over the past several decades. The decreasing effectiveness of therapies in treating bacterial resistance, due to the production of beta-lactamase (EC.3.5.2.6), has led to combining beta-lactamase inhibitors with commonly used beta-lactam antibiotics. Phytochemical compounds produced by plants have varied biological properties such as antioxidant, antimicrobial, antidiabetic, anti-inflammatory, anticancer, antihypertensive and others. Polyphenolics, flavonoids, coumarins, alkaloids, tannins, steroids and terpenoids are the main phytochemicals found in plants extracts. This study aims to assess the inhibitory activity of Annona senegalensis Pers., Terminalia superba Engl. & Diels, Ipomoea batatas Lam., and Psidium guajava L. against a Bacillus cereus beta-lactamase and four beta-lactamases extracted from clinical isolates of Escherichia coli. Methods: Beta-lactamase inhibition was measured using a spectrophotometric assay with benzylpenicillin as the substrate, by a modified acidimetric method. Clavulanic acid was used as the standard beta-lactamase inhibitor. Subsequently, the inhibition of the hydrolysis of other commonly used beta-lactam antibiotics was assessed using a UV spectrophotometric method. Results: Among the tested extracts, Ipomoea batatas showed no effect on the beta-lactamases, whereas Terminalia superba and Annona senegalensis exhibited inhibitory activity against all the beta-lactamases. Psidium guajava inhibited two of the five tested enzymes. The highest percentage of inhibition was observed with Terminalia superba on the beta-lactamase of Bacillus cereus, reaching 75.73%. Regarding the combination of beta-lactam antibiotics with plant extracts, the combination of Terminalia superba and ceftriaxone showed the highest inhibition, with a percentage of 64.90%. The combination of Annona senegalensis and ceftazidime was the least effective, with an inhibition rate of only 12.95%. Conclusion: Two of the tested ethanolic plant extracts showed interesting beta-lactamase inhibitory effects and could contribute to the development of more effective therapies against beta-lactamase-producing bacteria by combining natural inhibitors from plants with existing beta-lactam antibiotics.

Aztreonam-avibactam: a new combination with activity against multidrug-resistant Klebsiella pneumoniae complex.

Klebsiella pneumoniae complex (KPc) is a group of opportunistic pathogens that pose a serious threat to public health. Multidrug resistance is increasing, and limiting therapeutic options. Aztreonam-avibactam (AZA) is a combination of an established β-lactam with a new β-lactamase inhibitor. The aim of this study was to assess the susceptibility of multidrug-resistant KPc strains to AZA. The study included 52 ESβL-positive strains and 152 carbapenemase-positive KPc strains. The susceptibility to AZA was tested using the gradient strip method. AZA showed high activity against KPc, with MICs ranging from 0.032 to 0.75 μg ml-1 for ESβL-positive strains and from 0.016 to 2 μg ml-1 for carbapenemase-positive strains. The lowest MIC50 of AZA was obtained for VIM- and ESβL-positive strains at 0.094 μg ml-1, and MIC90 for ESβL-positive strains was 0.125 μg ml-1. AZA demonstrated excellent in vitro activity against the analysed strains, suggesting that this antibiotic may be an effective therapeutic option for treating infections caused by multidrug-resistant KPc strains.

Metabolomic Profile Modification in the Cerebellum of Mice Repeatedly Exposed to Khat and Treated with β-Lactamase Inhibitor, Clavulanic Acid.

Catha edulis, commonly known as khat, is used for its psychoactive effects and is considered a natural amphetamine. The current study investigated the metabolomic profile in the cerebellum of mice after repeated exposure to khat and evaluated the effects of clavulanic acid on the metabolomic profile in the cerebellum in khat-treated mice. Male C67BL/6 mice that were 6-9 weeks old were recruited and divided into three groups: the control group was treated with 0.9% normal saline for 17 days; the khat group was given khat extract at a dose of 360 mg/kg via the intraperitoneal (i.p) route for 17 days; and another khat group was treated with khat for 17 days and clavulanic acid at a dose of 5 mg/kg for the last 7 days (days 11-17). At the end of the 17th day, the animals were sacrificed, and their brains were immediately collected and stored at -80 °C. The cerebellum region of the brain was isolated in each group by micropuncture using cryostat and underwent a metabolomics study via Gas Chromatography/Mass Spectroscopy (GC/MS). The total peak area ratios of the selected metabolites in the cerebellum after repeated exposure to the khat extract were significantly reduced (p < 0.05) and treatment of the khat group with clavulanic acid significantly increased (all p < 0.05) the total peak areas ratios of the selected metabolites when compared to their corresponding areas in the alternative khat group. These levels of selected metabolites were further confirmed by observing the metabolite peak area ratios and performing a heat map analysis and a principal compartment analysis of the samples in the cerebellum. A network analysis of altered metabolites in the cerebellum showed a strong correlation between the different metabolites, which showed that an increase in one metabolite can modulate the levels of others. An analysis using the MetaboAnalyst software revealed the involvement of selected altered metabolites like lactic acid in many signaling pathways, like gluconeogenesis, while enrichment analysis data showed altered pathways for pyruvate metabolism and disease pathogenesis. Finally, a network analysis showed that selected metabolites were linked with other metabolites, indicating drug-drug interactions. The present study showed that repeated exposure of mice to khat altered the levels of various metabolites in the cerebellum which are involved in the pathogenesis of different diseases, signaling pathways, and interactions with the pharmacokinetic profile of other therapeutic drugs. The treatment of khat-treated mice with clavulanic acid positively modified the metabolomics profile in the cerebellum and increased the levels of the altered metabolites.

Durlobactam in combination with β-lactams to combat Mycobacterium abscessus.

Mycobacterium abscessus (Mab) presents significant clinical challenges. This study evaluated the synergistic effects of a β-lactam and β-lactamase inhibitor combination against Mab and explored the underlying mechanisms. Synergy was assessed through MIC tests and time-kill studies, and binding affinities of nine β-lactams and BLIs to eight target receptors (L,D-transpeptidases [LDT] 1-5, D,D-carboxypeptidase, penicillin-binding protein [PBP] B, and PBP-lipo) were assessed using mass spectrometry and kinetic studies. Thermal stability and morphological changes were determined. Imipenem demonstrated high binding affinity to LDTs and PBPs, with extremely low inhibition constants (Ki,app; ≤0.002 mg/L for LDT1-2, ≤0.6 mg/L for PBPs), while cephalosporins, sulopenem, tebipenem, and amoxicillin exhibited moderate to low binding affinity. Durlobactam inactivated BlaMab and LDT/PBPs more potently than avibactam. The Ki,apps of durlobactam for PBP B, PBP-lipo, and LDT2 were below clinically achievable unbound concentrations, while avibactam's Ki,app for LDT/PBPs exceeded the clinical concentrations. Single β-lactam treatments resulted in minimal killing (~1 log10 reduction). Although avibactam yielded no effect, combinations with avibactam showed a significant reduction (~4 log10 CFU/mL). Durlobactam alone showed ~2 log10 reduction, and when combined with imipenem or two β-lactams, durlobactam achieved near-eradication of Mab, surpassing the current therapy (amikacin + clarithromycin + imipenem/cefoxitin). Inactivation of PBP-lipo by sulopenem, imipenem, durlobactam, and amoxicillin (with avibactam) led to morphological changes, showing filaments. This study demonstrates the mechanistic basis of combinations therapy, particularly imipenem + durlobactam, in overcoming β-lactam resistance in Mab.

FL058, a novel β-lactamase inhibitor, increases the anti-Mycobacterium abscessus activity of imipenem.

β-lactams are crucial for anti-Mycobacterium abscessus complex (MABC) therapy. Treating infections is challenging since MABC produces a class A β-lactamase (BlaMab) , which is capable of hydrolyzing β-lactams thus causing drug resistance. Diazabicyclooctane (DBO) β-lactamase inhibitors (BLIs) can inhibit BlaMab. FL058 is a novel DBO BLI; the anti-MABC activity of FL058 combined with β-lactams remains unknown. The activities of ten β-lactams (imipenem, meropenem, faropenem, tebipenem, cefoxitin, cefepime, ceftazidime, cefdinir, cefuroxime, and amoxicillin) combined with three DBO BLIs (FL058, avibactam, and relebactam) toward two MABC reference strains were determined by broth microdilution assay. The anti-MABC activities of imipenem combined with three BLIs against 193 clinical isolates were also evaluated. The activity of imipenem combined with FL058 was also tested against intracellular MABC residing in macrophages and in a mouse model. Finally, the BlaMab mutations in clinical isolates were analyzed using sequence alignment to determine whether BlaMab mutations are associated with DBO BLIs sensitivity. FL058, avibactam and relebactam significantly increased the anti-MABC activity of β-lactams, especially imipenem, against reference strains and clinical isolates. The anti-MABC activity of imipenem combined with FL058 was superior to its activity when combined with either avibactam or relebactam. The combination of imipenem and FL058 significantly reduced the numbers of intracellular organisms in cultured macrophages, and of viable bacteria in the lungs of MABC-infected mice. Rough morphotypes tended to be more resistant than smooth morphotype. A BlaMab T141A mutation may reduce the susceptibility of MABC to imipenem-BLIs. The elevated anti-MABC activity exhibited by imipenem combined with FL058 suggests a potential new approach to treating MABC infections.

Utilizing machine learning-based QSAR model to overcome standalone consensus docking limitation in beta-lactamase inhibitors screening: a proof-of-concept study

In virtual drug screening, consensus docking is a standard in-silico approach consisting of a combined result from optimized docking experiments, a minimum of two results combination. Therefore, consensus docking is subjected to a lower success rate than the best docking method due to its mathematical nature, an unavoidable limitation. This study aims to overcome this drawback via random forest, an ensemble machine learning model. First, in vitro beta-lactamase inhibitory screening was performed using an in-house chemical library. The in vitro results were later used as a validation. Consequently, we optimized docking protocols for AutoDock Vina and DOCK6 programs. With an appropriate scoring function, we found that DOCK6 could identify up to 70% of all active molecules, double the inappropriate. Further consensus analysis reduced the success rate to 50%. Simultaneously, a false positive rate was down to 16%, which was experimentally favorable for a drug search. Finally, we trained two quantitative structure-activity relationship (QSAR) models using logistic regression as a reference model and a random forest as a test model. After combining consensus docking results, random forest-based QSAR outperformed a logistic regression by restoring the success rate to 70% and maintaining a low false positive rate of around 21%. In conclusion, this study demonstrated the benefit of using a random forest (machine learning)-based QSAR model to overcome a standard consensus docking limitation in beta-lactamase inhibitor search as a proof-of-concept.

PH/H2O2 dual-responsive macrophage-targeted chitosaccharides nanoparticles to combat intracellular bacterial infection.

Antibiotic resistance combined with bacteria internalization result in recurrent infections that seriously threaten human health. To overcome these problems, a pH/H2O2 dual-responsive nanoparticle (COSBN@CFS@PS) that can target macrophages, exhibiting synergistic antibiotic and β-lactamase inhibitor activity, is reported. Chitosaccharides (COS) is covalently bound with benzenboronic acid pinacol ester and assemble with cefoxitin sodium salt (CFS) to form COSBN@CFS nanoparticles. Then, COSBN@CFS was encapsulated with phosphatidylserine (PS), which aimed to targeted uptake by macrophages. After the uptake, the pH/H2O2 dual-responsive nanoparticle could effectively inhibit β-lactamase activity by release boronic acid (β-lactamase inhibitor), and then reinforced the antibacterial activity of CFS. Meanwhile, the resultant nanoparticles could significantly inhibit the growth of CFS-resistant bacteria. Furthermore, these nanoparticles could eliminate intracellular bacteria in vivo through the synergistic activities of antibiotic and β-lactamase inhibitor. The excellent biocompatibility and outstanding bactericidal activity promise COSBN@CFS@PS have great potential for diverse intracellular bacterial infection therapy.

Susceptibility of various Gram-negative bacteria to antibacterial agents: SMART in China 2019–2020

BackgroundThe Study for Monitoring Antimicrobial Resistance Trends (SMART) is an international surveillance program longitudinally monitoring aerobic and facultative Gram-negative bacteria (GNB) involvement in infections and their antimicrobial resistance profiles. Here the incidence and resistance patterns of Chinese GNB isolates from bloodstream infections (BSI), intraabdominal infections (IAI), respiratory tract infections (RTI) and urinary tract infections (UTI) to commonly used antibacterial agents has been updated. 4,975 GNB isolates collected from 22 hospitals across 7 regions of China from 2019 to 2020 were analyzed. Antimicrobial minimum inhibitory concentrations were assessed using broth microdilution, and susceptibility interpretations followed the breakpoints of European Committee on Antimicrobial Susceptibility Testing 2022 or Clinical and Laboratory Standards Institute.ResultsThis study affirmed that Escherichia coli (Ec) was the most commonly identified GNB (32.1%) and then Klebsiella pneumoniae (Kp) (25.3%), Pseudomonas aeruginosa (Pa) (13.9%) and Acinetobacter baumannii (10.5%). The detection rates of carbapenem-resistant (CR) Enterobacterales varied across major infection sites, ranging from 10.3% in UTI to 18.9% in RTI. Specifically, the detection rates of CR-Kp and CR-Pa ranged from 16.2% in IAI to 35.8% in UTI and from 16.1% in UTI to 38.0% in RTI, respectively. Extended-spectrum β-lactamases (ESBL)-producing Ec and Kp bacteria exhibited over 91.7% susceptibility to carbapenems and at least 87.8% susceptibility to amikacin and colistin, but showed lower susceptibility to piperacillin/tazobactam (57.5–86.2%), levofloxacin (10.8–39.7%) and aztreonam (15.3–27.6%) across different infection sources. Amikacin showed higher efficacy against CR strains compared to other commonly used antibacterial drugs, with 80.0% susceptibility against CR-Ec and 82.3% susceptibility against CR-Pa, while only 36.3% susceptibility was observed against CR-Kp.ConclusionsThe study found varying incidences of CR isolates in Chinese hospitals. Treatment options remained limited due to resistance to multiple antibacterial agents. Carbapenems demonstrated effective antimicrobial in vitro activity against ESBL-producing Enterobacterales found in BSI, IAI, UTI and RTI, outperforming broad-spectrum cephalosporins and other β-lactamase inhibitors.

Invention of Enmetazobactam: An Indian Triumph in Antimicrobial Drug Discovery.

The discovery of antimicrobials was an inflection point in human existence since it contributed enormously to the extension of the human lifespan. Among others, the invention of Enmetazobactam marks a significant milestone in the field of antimicrobial development, especially for India. It is a novel beta-lactamase inhibitor invented by scientists at Orchid Pharma in Chennai, India, and has garnered international attention for its potential to address antimicrobial resistance. It became the first new chemical entity invented in India, clinically developed by Allecra Therapeutics GmbH, to be approved by the U.S. Food & Drug Administration, with additional approvals from the European Medical Agency, the U.K.'s Medicine & Healthcare Products Regulatory Agency, and the Drug Controller General of India.

Imipenem pharmacokinetics/pharmacodynamics in preclinical hollow fiber model, dose-finding in virtual patients, and clinical evidence of efficacy for Mycobacterium abscessus lung disease.

Guideline-based therapy (GBT) for Mycobacterium abscessus (Mab) lung disease achieves sputum culture conversion rates (SCC) of 35%. This poor GBT efficacy is mirrored in the hollow fiber system model of Mab (HFS-Mab). While imipenem is part of GBT, biological effect with or without β-lactamase inhibitors, is unproven. We performed imipenem/relebactam minimum inhibitory concentration (MIC) in 122 Mab isolates, and an exposure-response study in the HFS-Mab using human intrapulmonary pharmacokinetics. The % time that concentration persisted above MIC (TMIC) mediating maximal effect in the HFS-Mab was used as the exposure target in 10,000 virtual subjects Monte Carlo experiment (MCE)-based dose-finding. For real-world evidence, we performed a patient, intervention (imipenem), comparison (no β-lactam), and outcome (SCC) (PICO) analysis. Imipenem killed 1.32 log10 CFU/mL below day 0 in HFS-Mab. Imipenem target exposure was TMIC=47.9±9.77%. 1g infusion, every 6h, achieved the target in >90% of virtual patients in MCEs. The pharmacokinetics/pharmacodynamics MIC breakpoint was 1mg/L. In PICO analyses, median days-to-SCC were 470 in comparators, 311 for imipenem added on failing regimen, and 37 in newly treated (p=0.049). The odds ratio for SCC when imipenem was part of the initial regimen versus comparators was 12.5 (95% confidence interval: 1.47 to 84.55). Patients on imipenem experienced no treatment-limiting adverse event, while 2/7 comparators did (p=0.0457). Middlebrook 7H9 broth MIC distribution, read at 24 hours, correlated better with patient responses than cation-adjusted Mueller Hinton broth. Imipenem demonstrated biologic effect in the HFS-Mab and in patients. Imipenem/relebactam doses of 1g every 6h are recommended.

Pharmacokinetic/pharma-codynamic study of pralurbactam (FL058) combined with meropenem in a neutropenic murine thigh infection model.

Pralurbactam (FL058) is a novel β-lactamase inhibitor with good inhibitory activity on class A, C, and D β-lactamases. This study aimed to evaluate the pharmacokinetic/pharmacodynamic (PK/PD) relationship of pralurbactam/meropenem in a neutropenic murine thigh infection model. After 2-h infection, neutropenic mice was treated with meropenem every 2 h alone or in combination with pralurbactam at different dosing frequencies for 24 h, and the colony count in the thighs was determined before and after treatment. The maximum effect model was fit to the PK/PD relationship to determine the PK/PD index and targets for pralurbactam in combination with meropenem resulting in a static effect and 1-log10 kill. The plasma drug concentration-time data demonstrated that the PK profiles of pralurbactam were consistent with a one-compartment model. Pralurbactam demonstrated a linear PK profile in mice plasma. The percent time of free drug above 1 mg/L (%fT > 1 mg/L) was the PK/PD index that best described the bacterial killing effect of pralurbactam/meropenem over 24 h. When the PK/PD index %fT > 1 mg/L reached 38.4% and 63.6%, pralurbactam/meropenem combination would achieve bacteriostatic effect and 1-log10 reduction against Klebsiella pneumoniae in thigh bioburden, respectively. These PK/PD data derived from mouse thigh infection models will be used to inform the optimal dosing regimen of pralurbactam/meropenem combination in clinical trials.

Characterization of Metallo β-Lactamase Producing Enterobacterales Isolates with Susceptibility to the Aztreonam/Avibactam Combination.

Background/Objectives: Metallo-β-lactamases (MBLs) in Enterobacterales and other Gram-negative organisms pose significant public health threats due to their association with multidrug resistance (MDR). Although aztreonam (AZT) can target MBL-producing organisms, its efficacy is compromised in organisms expressing additional β-lactamases that inactivate it. Combining AZT with the β-lactamase inhibitor avibactam (AVI) may restore its activity against MBL-producing isolates. Methods: AZT-AVI, along with other clinically relevant antimicrobials, was tested against thirteen MBL-producing clinical isolates of Enterobacterales (nine Klebsiella pneumoniae, three Enterobacter cloacae, and one Providencia stuartii) using whole-genome sequencing (WGS) for genetic characterization. Results: AZT-AVI demonstrated full susceptibility across all isolates, whereas aztreonam alone was ineffective. The newer β-lactam/β-lactamase inhibitor combinations imipenem/relebactam and meropenem/vaborbactam were inactive in 100% and 92.3% of isolates, respectively. WGS-based analysis revealed multiple resistance mechanisms consistent with MDR phenotypes, including high-risk K. pneumoniae clones (ST147 and ST11). Conclusions: AZT-AVI is effective against MDR MBL-producing Enterobacterales, highlighting its therapeutic potential for challenging infections. While WGS does not replace phenotypic testing, it provides valuable insights for antimicrobial stewardship and the monitoring of resistance gene dissemination.

Evaluating the in vitro activity of cefoperazone-sulbactam against Gram negative pathogens in blood stream infections using automated systems.

The incidence of multidrug-resistant, Gram-negative organisms, isolated as the etiological agents of infections is ascending. The advent of novel antibiotics poses significant challenges, necessitating the optimization and utilization of extant antimicrobial agents. Cefoperazone, a third-generation cephalosporin and β-lactam antimicrobial, when combined with sulbactam, an irreversible β-lactamase inhibitor, mitigates the vulnerability of cefoperazone to β-lactamase-producing organisms. Nonetheless, regional data on the susceptibility patterns for this pharmacological combination remains scarce. The primary objective of this investigation was to assess the efficacy of the cefoperazone-sulbactam combination against prevalent Gram-negative bacteria isolated from blood cultures. A total of 700 Gram-negative isolates, comprising Escherichia coli, Klebsiella pneumoniae, Acinetobacter species, and Pseudomonas aeruginosa, were procured using the BacT/Alert 3D system. The identification and susceptibility testing for cefoperazone-sulbactam were performed using the VITEK Compact ID and AST system. Comparative analysis was conducted against other tested antibiotics. The study revealed that cefoperazone-sulbactam exhibited commendable in-vitro activity against Gram-negative pathogens isolated from blood, surpassed only by colistin and tigecycline. Cefoperazone-sulbactam demonstrates robust activity against the most frequently encountered clinical pathogens, suggesting its potential as an efficacious therapeutic agent. The findings underscore the imperative for ongoing surveillance of resistance patterns and trends among commonly used antimicrobials.

Frequencies and mechanisms of mutational resistance to ceftibuten/avibactam in Enterobacterales.

Antibiotic resistance complicates treatment of urinary infections, particularly when these ascend above the bladder, with few oral options remaining. New oral β-lactamase inhibitor combinations present a potential answer, with ceftibuten/avibactam-now undergoing clinical trials-widely active against strains with ESBLs and serine carbapenemases. To inform its development we undertook mutant selection studies. Single-step mutants were sought from Enterobacterales (n = 24) with AmpC, ESBL, OXA-48 and KPC β-lactamases. MICs were determined by CLSI agar dilution. Illumina WGS of selected mutants (n = 50) was performed. Even at low MIC multiples, mutant frequencies were mostly only c. 10-8. β-Lactamase structural mutants were obtained only from KPC and AmpC enzymes. The KPC mutants had Trp105Arg or Ser130Thr substitutions, causing only small MIC shifts; the AmpC mutant had an Asn346Trp replacement, as previously selected with other avibactam combinations. No ESBL mutants were obtained. Rather, from Escherichia coli, we predominantly selected mutants with modifications to ftsI, encoding penicillin-binding protein (PBP) 3. From Klebsiella pneumoniae and Enterobacter cloacae we predominantly obtained variants with modification of uptake and efflux components or their regulators. ftsI mutants lacked cross-resistance to other avibactam combinations; uptake mutants had broader MIC rises. A few putative mutants had other lesion(s) of uncertain significance, or grew as small, stressed colonies lacking detectable lesions. There seems little risk of ESBLs mutating to confer ceftibuten/avibactam resistance, though some risk may apply for KPC and AmpC enzymes. The propensity to select E. coli ftsI/PBP3 mutants is notable and was not seen with other avibactam combinations.

Highly Sensitive In Vivo Imaging of Bacterial Infections with a Hydrophilicity-Switching, Self-Immobilizing, Near-Infrared Fluorogenic β-Lactamase Probe Enriched within Bacteria.

The emergence of antibiotic resistance, particularly bacterial resistance to β-lactam antibiotics, the most widely prescribed therapeutic agents for infectious diseases, poses a significant threat to public health worldwide. The discovery of effective therapies against antibiotic-resistant pathogens has become an urgent need, necessitating innovative approaches to accelerate the identification and development of novel antibacterial agents. On the other hand, the expression of the β-lactam-hydrolyzing enzyme (β-lactamase), the major cause of bacterial resistance to β-lactam antibiotics, provides a distinctive opportunity to visualize bacterial infection, evaluate the efficacy of existing antibiotics, screen for novel antibacterial agents, and optimize drug dosing regimens in live animals. Herein, a hydrophilicity-switching, self-immobilizing, near-Infrared fluorogenic β-lactamase probe for the highly sensitive imaging of bacterial infection in live mice is reported. This probe, in addition to a significant increase in fluorescence upon selective hydrolysis by β-lactamases as conventional β-lactamase probes, also massively enriches within β-lactamase-expressing bacteria (over 1500-folds compared to the incubation medium), which renders excellent sensitivity in the imaging of bacterial infections in living animals. This agent has proven to enable the assessment of antibiotic therapeutic efficacy and potency of β-lactamase inhibitors in living animals in a non-invasive and much more convenient manner.

Simulated achievement rate of β-lactams/nacubactam treatment in humans using instantaneous MIC-based PK/PD analysis.

Nacubactam (NAC), a new diazabicyclooctane β-lactamase inhibitor, is being developed for use together with aztreonam (AZT) and cefepime (CFPM). However, the effective clinical dosages of AZT/NAC and CFPM/NAC have not yet been established. We have previously shown that free time above instantaneous MIC (fT > MICi) is a valuable pharmacokinetic (PK)/pharmacodynamic parameter for β-lactam (BL)/NAC in a mouse thigh infection model. This study simulated the fT > MICi (%) for AZT/NAC and CFPM/NAC against carbapenemase-producing Enterobacterales (CPE) with different MIC in humans to estimate the clinical efficacy at practically achievable combination doses of AZT/NAC and CFPM/NAC. Using previously reported PK parameters of each drug in humans and chequerboard MIC data, we calculated the fT > MICi (%) for AZT/NAC and CFPM/NAC in 10 000 simulated patients to predict the percentages of target attainment of bacteriostatic and bactericidal efficacies at various combined doses. The results predicted that both BL/NAC combinations could achieve 100% 2 log10-kill against CPE strains at the lowest combination dose (0.5 g/0.5 g q8h). Additionally, in MIC studies examining BLs/NAC at a 1:1 ratio, the dosage regimen for strains with MICcomb ≤ 1 mg/L was expected to offer 100% bactericidal efficacy (2 log10-kill) at 0.5 g/0.5 g q8h or higher doses. For strains with 1 mg/L < MICcomb ≤ 16 mg/L, BLs/NAC at a 2 g/2 g q8h was predicted to produce bactericidal efficacy (1 log10-kill). At MICcomb = 32 mg/L, some bacteriostatic effect was expected at high BL doses. AZT/NAC and CFPM/NAC are bactericidal against CPE at practically achievable dosages.

Prevalence, Antibiotic Resistant Pattern and Genotypic Detection of Acinetobacter baumannii Isolated from Different Clinical Specimens of Patients Admitted at a Tertiary Care Hospital in Bangladesh

Background: Acinetobacter baumannii infection treatment has become a clinical challenge due to the increasing resistance of the bacteria to different classes of antimicrobial agents and it needs to be identified before exposure to patients. Objective: This study aimed to determine the prevalence of Acinetobacter baumannii with its antibiotic-resistant patterns. Methodology: The study was a cross-sectional study that was done from 1st January 2019 to 31st December 2019 at the Microbiology Department of Dhaka Medical College. Clinical samples including endotracheal aspirates, blood, urine, sputum, wound swabs, and pus were collected from the patients from the intensive care unit, burn unit, general wards, and outpatient department of Dhaka Medical College and Hospital. Acinetobacter baumannii organisms were identified by biochemical tests and Gram staining, and the resistance pattern was determined by using the disc diffusion method for all antibiotics except for colistin, which was determined by minimum inhibitory concentration. Results: Among 500 clinical samples, 13.31% Acinetobacter baumannii were identified. Most of these showed resistance to fluoroquinolones, carbapenem, amikacin, the extended spectrum of cephalosporin, β-lactam, and β-lactamase inhibitors. However, the least resistant drug was tigecycline (8.88%). About 62.22% MDR, 28.89% A. baumannii were identified. Conclusion: Acinetobacter baumannii is showing increasing resistance to colistin and tigecycline. Bangladesh Journal of Medical Microbiology, January 2024;18(1):37-43

Fusobacterium necrophorum septic arthritis of the hip: A case-report and literature review.

Fusobacterium necrophorum is a rare but significant cause of septic arthritis, typically following oropharyngeal infections in adolescents. This anaerobic pathogen, commonly associated with Lemierre's syndrome, can lead to joint infections, posing risks for severe morbidity if diagnosis and treatment are delayed. Awareness and timely intervention are essential for preventing long-term joint damage. We report the case of a 19-year-old woman who developed high fever and acute right hip pain one week after a sore throat. Imaging revealed septic arthritis, with F. necrophorum identified in both blood and synovial fluid cultures. She received intravenous piperacillin/tazobactam, followed by outpatient parenteral therapy through an elastomeric pump, achieving full recovery. This case adds to the 42 cases documented in our literature review, reinforcing the need for prompt antimicrobial therapy. Fusobacterium-induced septic arthritis, though uncommon, should be considered in young patients presenting with joint infections post-pharyngitis. Early diagnosis and targeted antimicrobial therapy, particularly with β-lactamase inhibitors, are critical for effective management and preventing joint sequelae.