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Monitoring the concentration of antibiotics rapidly and cost-effectively is crucial for accurate clinical medication and timely identification of drug-induced illnesses. Here, we constructed a novel fluorescent assay kit to monitor Zavicefta, an effective antibiotic composed of avibactam (AVI) and ceftazidime (CFZ) to treat carbapenem-resistant gram-negative bacteria infections. AVI can emit fluorescence, but CFZ cannot. To enable simultaneous measurement of both in one kit, we designed molecularly imprinted polymer (MIP) modified quantum dots (QDs) for CFZ determination. MIPs have received significant attention as an artificial antibody due to their exceptional specificity for various targets, particularly drugs with small molecular weight. Under the excitation wavelength of 350 nm, the detection process involves a decrease in QDs' fluorescence signal at 600 nm owing to the "gate effect" between MIP and CFZ and the internal filtration effect between CFZ and QDs. Simultaneously, a fluorescence emission characteristic peak at 420 nm for AVI emerges. In addition, to simplify the operation procedure and improve determination throughput, the detection agents were incorporated into a hydrogel and placed in a 96-well plate, enabling concurrent quantification of AVI and CFZ within the respective range of 80-1000 μM and 1-1000 μM. The developed assay kit successfully determined AVI and CFZ in human serums and therapeutic drug monitoring in a live rabbit model. Recoveries of AVI and CFZ were 92.7-114%, with relative standard deviations below 6.0%. Moreover, a smartphone was employed to read the fluorescence signals, which was beneficial for cost reduction and out-of-lab analysis. This study will deliver a pragmatic resolution to developing high-throughput assay kits for drug determination., (© 2024. The Author(s).)

The impact of penicillin-binding protein 3 (PBP3) modifications that may be identified in Escherichia coli was evaluated with respect to susceptibility to β-lactam/β-lactamase inhibitor combinations including ceftazidime-avibactam, imipenem-relebactam, meropenem-vaborbactam, aztreonam-avibactam, cefepime-taniborbactam, and to cefiderocol. A large series of E. coli recombinant strains producing broad-spectrum β-lactamases was evaluated. While imipenem-relebactam showed a similar activity regardless of the PBP3 background, susceptibility to other molecules tested was affected at various levels. This was particularly the case for ceftazidime-avibactam, aztreonam-avibactam, and cefepime-taniborbactam., Competing Interests: The authors declare no conflict of interest.

Klebsiella pneumoniae carbapenemase-2 (KPC-2) presents a clinical threat as this β-lactamase confers resistance to carbapenems. Recent variants of KPC-2 in clinical isolates contribute to concerning resistance phenotypes. Klebsiella pneumoniae expressing KPC-2 D179Y acquired resistance to the ceftazidime/avibactam combination affecting both the β-lactam and the β-lactamase inhibitor yet has lowered minimum inhibitory concentrations for all other β-lactams tested. Furthermore, Klebsiella pneumoniae expressing the KPC-2 D179N variant also manifested resistance to ceftazidime/avibactam yet retained its ability to confer resistance to carbapenems although significantly reduced. This structural study focuses on the inhibition of KPC-2 D179N by avibactam and relebactam and expands our previous analysis that examined ceftazidime resistance conferred by D179N and D179Y variants. Crystal structures of KPC-2 D179N soaked with avibactam and co-crystallized with relebactam were determined. The complex with avibactam reveals avibactam making several hydrogen bonds, including with the deacylation water held in place by Ω loop. These results could explain why the KPC-2 D179Y variant, which has a disordered Ω loop, has a decreased affinity for avibactam. The relebactam KPC-2 D179N complex revealed a new orientation of the diazabicyclooctane (DBO) intermediate with the scaffold piperidine ring rotated ~150° from the standard DBO orientation. The density shows relebactam to be desulfated and present as an imine-hydrolysis intermediate not previously observed. The tetrahedral imine moiety of relebactam interacts with the deacylation water. The rotated relebactam orientation and deacylation water interaction could potentially contribute to KPC-mediated DBO fragmentation. These results elucidate important differences that could aid in the design of novel β-lactamase inhibitors., Competing Interests: The authors declare no conflict of interest.

Klebsiella pneumoniae carbapenemase-producing K. pneumoniae (KPC-Kp) poses a major threat to human health worldwide. Combination therapies of antibiotics with different mechanisms have been recommended in literatures. This study assessed in vitro antibacterial activities and synergistic activities of ceftazidime/avibactam alone and in combinations against KPC-Kp. In total, 70 isolates from 2 hospitals in Beijing were examined in our study. By using the agar dilution method and broth dilution method, we determined the minimum inhibitory concentration (MIC) of candidate antibiotics. Ceftazidime/avibactam demonstrated promising susceptibility against KPC-Kp (97.14%). Synergistic activities testing was achieved by checkerboard method and found ceftazidime/avibactam-amikacin displayed synergism in 90% isolates. Ceftazidime/avibactam-colistin displayed partial synergistic in 43% isolates, and ceftazidime/avibactam-tigecycline displayed indifference in 67% isolates. In time-kill assays, antibiotics at 1-fold MIC were mixed with bacteria at 1 × 105 CFU/ml and Mueller-Hinton broth (MHB). Combinations of ceftazidime/avibactam with amikacin and tigecycline displayed better antibacterial effects than single drug. Ceftazidime/avibactam-colistin combination did not exhibit better effect than single drug. In KPC-Kp infections, susceptibility testing suggested that ceftazidime/avibactam may be considered as first-line choice. However, monotherapy is often inadequate in infection management. Thus, our study revealed that combination therapy including ceftazidime/avibactam colistin and ceftazidime/avibactam tigecycline may benefit than monotherapy in KPC-Kp treatment. Further pharmacokinetic/pharmacodynamic and mutant prevention concentration studies should be performed to optimize multidrug-regimens., Competing Interests: The authors have declared that no competing interests exist.

Ceftazidime-avibactam (CZA) has emerged as a promising solution to the lack of new antibiotics against Pseudomonas aeruginosa infections. Data from in vitro assays of CZA combinations, however, are scarce. The objective of our study was to perform a time-kill analysis of the effectiveness of CZA alone and in combination with other antibiotics against a collection of extensively drug-resistant (XDR) P. aeruginosa isolates. Twenty-one previously characterized representative XDR P. aeruginosa isolates were selected. Antibiotic susceptibility was tested by broth microdilution, and results were interpreted using CLSI criteria. The time-kill experiments were performed in duplicate for each isolate. Antibiotics were tested at clinically achievable free-drug concentrations. Different treatment options, including CZA alone and combined with amikacin, aztreonam, meropenem, and colistin, were evaluated to identify the most effective combinations. Seven isolates were resistant to CZA (MIC ≥ 16/4 mg/liter), including four metallo-β-lactamase (MBL)-carrying isolates and two class A carbapenemases. Five of them were resistant or intermediate to aztreonam (MIC ≥ 16 mg/liter). Three isolates were resistant to amikacin (MIC ≥ 64 mg/liter) and one to colistin (MIC ≥ 4 mg/liter). CZA monotherapy had a bactericidal effect in 100% (14/14) of the CZA-susceptible isolates. Combination therapies achieved a greater overall reduction in bacterial load than monotherapy for the CZA-resistant isolates. CZA plus colistin was additive or synergistic in 100% (7/7) of the CZA-resistant isolates, while CZA plus amikacin and CZA plus aztreonam were additive or synergistic in 85%. CZA combined with colistin, amikacin, or aztreonam was more effective than monotherapy against XDR P. aeruginosa isolates. A CZA combination could be useful for treating XDR P. aeruginosa infections, including those caused by CZA-resistant isolates. IMPORTANCE The emergence of resistance to antibiotics is a serious public health problem worldwide and can be a cause of mortality. For this reason, antibiotic treatment is compromised, and we have few therapeutic options to treat infections. The main goal of our study is to search for new treatment options for infections caused by difficult-to-treat resistant germs. Pseudomonas aeruginosa is a Gram-negative bacterium distributed throughout the world with the ability to become resistant to most available antibiotics. Ceftazidime-avibactam (CZA) emerged as a promising solution to the lack of new antibiotics against infections caused by P. aeruginosa strains. This study intended to analyze the effect of CZA alone or in combination with other available antibiotics against P. aeruginosa strains. The combination of CZA with other antibiotics could be more effective than monotherapy against extensively drug-resistant P. aeruginosa strains.

Purpose: The objective of this communication was to determine the intravenous compatibility of ceftazidime/avibactam and aztreonam using simulated and actual Y-site administration., Methods: Ceftazidime-avibactam was reconstituted and diluted to concentrations of 8, 25, and 50 mg/mL in 0.9% sodium chloride. Aztreonam was reconstituted and diluted to concentrations of 10 and 20 mg/mL. Each combination of concentrations was tested for compatibility using visual, Tyndall beam, microscopy, turbidity, and pH assessments. Microscopy results were compared to those from sodium chloride 0.9% in water, pH was compared to that at time 0, and turbidity of combinations was compared to that of individual agents. Actual Y-site mixing was conducted over 2-h infusions with samples collected at 0, 1, and 2 h. Test results were evaluated at 0, 1, 2, 4, 8, and 12 h after mixing. All experiments were completed in triplicate., Findings: Across simulated and actual Y-site experiments, no evidence of incompatibility between combinations of ceftazidime-avibactam + aztreonam was observed. Visual and microscopic tests revealed no particulate matter, color changes, or turbidity. Tyndall beam tests were negative with all combinations. No evidence of incompatibility was observed in turbidity testing. The pH values were consistent across each of the 6 combinations, from immediately after mixing until 12 h after mixing. When the addition of agents was reversed in simulated Y-site experiments, no differences in compatibility were observed. No differences in compatibility between actual and simulated Y-site administration were observed, and there was minimal variability across all replicate experiments., Implications: Ceftazidime-avibactam, at concentrations of 8, 25, and 50 mg/mL, appeared compatible with aztreonam at concentrations of 10 and 20 mg/mL., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Class D β-lactamases exhibit very heterogeneous hydrolysis activity spectra against the various types of clinically useful β-lactams. Similarly, and according to the available data, their sensitivities to inactivation by avibactam can vary by a factor of more than 100. In this paper, we performed a detailed kinetic study of the interactions between two ceftazidime-hydrolyzing OXA enzymes and showed that they were significantly more susceptible to avibactam than several other class D enzymes that do not hydrolyze ceftazidime. From a clinical point of view, this result is rather interesting if one considers that avibactam is often administered in combination with ceftazidime.

Ceftazidime-avibactam is a combination of a third-generation cephalosporin and a novel non-beta-lactam beta-lactamase inhibitor. This combination was recently recommended for the treatment of complicated urinary tract infections, including acute pyelonephritis, in adults with limited or no alternative treatment options. The current review is aimed to determine activity, efficacy and safety of ceftazidime-avibactam in the treatment of patients with complicated urinary tract infections.

Avycaz combines an older cephalosporin antibiotic, ceftazidime, and the β-lactamase inhibitor avibactam. Ceftazidime targets penicillin-binding proteins (PBPs) in the bacterial periplasm that are required for cell wall synthesis. Avibactam blocks β-lactamases (β-L) in the periplasm, which would otherwise inactivate the antibiotics resulting in drug resistance., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Purpose: Gram-negative resistance continues to rise with treatment options becoming more limited. Ceftazidime/avibactam was recently approved in the United States and Europe, which combines an established third-generation cephalosporin with a new, unique, non-β-lactam β-lactamase inhibitor. This review conducts a thorough examination of structure, pharmacology, spectrum of activity, pharmacokinetics/pharmacodynamics, in vitro and clinical efficacy and safety/tolerability of ceftazidime/avibactam, as well as detailed future directions for the agent., Methods: Pubmed and clinicaltrials.gov searches, as well as abstracts from the 2015 Interscience Conference on Antimicrobial Agents and Chemotherapy/International Society of Chemotherapy (ICAAC/ICC) and ID Week meetings and the 2016 American Society of Microbiology Microbe meeting, were conducted from January 2004 - September 2016. Relevant search terms included ceftazidime, ceftazidime/avibactam, avibactam, NXL104 and AVE1330A. The US package insert for ceftazidime/avibactam (02/2015) and European public assessment report (06/2016) were also reviewed., Results: In vitro susceptibility for ceftazidime/avibactam displayed potent activity against many Enterobacteriaceae including extended-spectrum-β-lactamase (ESBL) and carbapenemase-producing strains, as well as Pseudomonas aeruginosa. Phase II clinical trials utilized for approval demonstrated comparable safety and efficacy to imipenem/cilistatin for treatment of complicated urinary tract infections (70.4% vs. 71.4%) and combined with metronidazole compared to meropenem in complicated intra-abdominal infections (91.2% vs 93.4%). Phase III data displayed non-inferior efficacy of ceftazidime/avibactam compared to doripenem for complicated urinary tract infections (70.2% vs 66.2%) and combined with metronidazole compared to meropenem in complicated intra-abdominal infections (82.5% vs 84.9%), as well as comparable safety. Ceftazidime/avibactam was well-tolerated but does require renal adjustments. Additionally, 3 case series and a single case report have demonstrated the potential for ceftazidime/avibactam against multidrug resistant organisms for compassionate use or failure after previous therapy., Conclusion: By adding avibactam to ceftazidime, clinicians' antimicrobial armamentarium is expanded, potentially increasing the ability to combat multi-drug resistant gram-negative pathogens, particularly ESBL and carbapenemase-producing organisms, as well as Pseudomonas aeruginosa. This article is open to POST-PUBLICATION REVIEW. Registered readers (see "For Readers") may comment by clicking on ABSTRACT on the issue's contents page.

Avibactam, a novel β-lactamase inhibitor, has recently been co-formulated with ceftazidime and approved for use in patients with complicated intra-abdominal and urinary tract infections, where no better treatment alternative exists. The basis for its FDA approval has been the extensive clinical experience with ceftazidime and the demonstration in vitro and in animal models that the addition of avibactam reverses resistance to ceftazidime in extended-spectrum β-lactamase and some carbapenemase-producing Enterobacteriaceae. Early clinical data are promising, with efficacy demonstrated in patients with complicated intra-abdominal and urinary tract infections. This review will summarize the in vitro, animal and clinical data available on this agent to date.

Aim: Avibactam, a novel non-β-lactam β-lactamase inhibitor co-administrated with the β-lactam antibiotic ceftazidime, is in clinical development. The need to evaluate its PK and PD requires accurate and reliable bioanalytical methods., Methods: We describe LC-MS/MS methods for the determination of avibactam and ceftazidime in human plasma. Avibactam was extracted using weak anionic exchange solid-phase extraction and analyzed on an amide column. Ceftazidime was extracted using protein precipitation and analyzed on a C18 column. Calibration curves were established over 10-10,000 ng/ml (avibactam) and 43.8-87,000 ng/ml (ceftazidime)., Results & Conclusion: Method validation, cross-validation between three laboratories and incurred sample re-analysis demonstrated method robustness. The methods were successfully applied to multiple clinical studies.

Avibactam (formerly NXL104, AVE1330A) is a synthetic non-β-lactam, β-lactamase inhibitor that inhibits the activities of Ambler class A and C β-lactamases and some Ambler class D enzymes. This review summarizes the existing data published for ceftazidime-avibactam, including relevant chemistry, mechanisms of action and resistance, microbiology, pharmacokinetics, pharmacodynamics, and efficacy and safety data from animal and human trials. Although not a β-lactam, the chemical structure of avibactam closely resembles portions of the cephem bicyclic ring system, and avibactam has been shown to bond covalently to β-lactamases. Very little is known about the potential for avibactam to select for resistance. The addition of avibactam greatly (4-1024-fold minimum inhibitory concentration [MIC] reduction) improves the activity of ceftazidime versus most species of Enterobacteriaceae depending on the presence or absence of β-lactamase enzyme(s). Against Pseudomonas aeruginosa, the addition of avibactam also improves the activity of ceftazidime (~fourfold MIC reduction). Limited data suggest that the addition of avibactam does not improve the activity of ceftazidime versus Acinetobacter species or most anaerobic bacteria (exceptions: Bacteroides fragilis, Clostridium perfringens, Prevotella spp. and Porphyromonas spp.). The pharmacokinetics of avibactam follow a two-compartment model and do not appear to be altered by the co-administration of ceftazidime. The maximum plasma drug concentration (C(max)) and area under the plasma concentration-time curve (AUC) of avibactam increase linearly with doses ranging from 50 mg to 2,000 mg. The mean volume of distribution and half-life of 22 L (~0.3 L/kg) and ~2 hours, respectively, are similar to ceftazidime. Like ceftazidime, avibactam is primarily renally excreted, and clearance correlates with creatinine clearance. Pharmacodynamic data suggest that ceftazidime-avibactam is rapidly bactericidal versus β-lactamase-producing Gram-negative bacilli that are not inhibited by ceftazidime alone.Clinical trials to date have reported that ceftazidime-avibactam is as effective as standard carbapenem therapy in complicated intra-abdominal infection and complicated urinary tract infection, including infection caused by cephalosporin-resistant Gram-negative isolates. The safety and tolerability of ceftazidime-avibactam has been reported in three phase I pharmacokinetic studies and two phase II clinical studies. Ceftazidime-avibactam appears to be well tolerated in healthy subjects and hospitalized patients, with few serious drug-related treatment-emergent adverse events reported to date.In conclusion, avibactam serves to broaden the spectrum of ceftazidime versus ß-lactamase-producing Gram-negative bacilli. The exact roles for ceftazidime-avibactam will be defined by efficacy and safety data from further clinical trials. Potential future roles for ceftazidime-avibactam include the treatment of suspected or documented infections caused by resistant Gram-negative-bacilli producing extended-spectrum ß-lactamase (ESBL), Klebsiella pneumoniae carbapenemases (KPCs) and/or AmpC ß-lactamases. In addition, ceftazidime-avibactam may be used in combination (with metronidazole) for suspected polymicrobial infections. Finally, the increased activity of ceftazidime-avibactam versus P. aeruginosa may be of clinical benefit in patients with suspected or documented P. aeruginosa infections.