A two-dimensional photonic crystal hydrogel biosensor for colorimetric detection of penicillin G and penicillinase inhibitors.

A simple penicillinase functionalized two-dimensional photonic crystal hydrogel (2DPPCH) biosensor was developed for colorimetric detection of penicillin G and penicillinase inhibitors. The penicillinase can specifically recognize penicillin G and catalyze it to produce penicilloic acid, which decreases the pH of the hydrogel microenvironment and shrinks the pH-sensitive hydrogel. The particle spacing decrease of the 2D photonic crystal array induced by the hydrogel shrinkage further causes a blue-shift in the diffraction wavelength. While the hydrolysis reaction is repressed upon treatment with clavulanate potassium (a kind of penicillinase inhibitor), no significant change in the diffraction wavelength is found. The detection of targets can be achieved by measuring the Debye diffraction ring diameter or observing the structural color change in the visible region. The lowest detectable concentrations for penicillin G and clavulanate potassium are 1 µM and 0.1 µM, respectively. Moreover, the 2DPPCH is proved to exhibit high selectivity and an excellent regeneration property, and it shows satisfactory performance for penicillin G analysis in real water samples.

A novel fluorescent probe for the detection of AmpC beta-lactamase and the application in screening beta-lactamase inhibitors.

The rapid detection of ß-lactamases (Blas) and effective screening of Bla inhibitors are critically important and urgent for solving antibiotic resistance and improving precision medicine. Here a novel fluorescent probe CDC-559 was designed and synthesized, which can be used for the selective and direct detection of AmpC Blas. More importantly, it can realize screening the Bla inhibitors with sulbactam sodium and tazobactam as model compounds, and the half-maximal inhibitory concentration are 0.279 µM and 0.053 µM, respectively. CDC-559 can be applied not only to examine the resistance of bacterial strains, but also to categorize its mode of action specifically, which is consistent with the essential result of the Blas. The research suggests that CDC-559 probe has tremendous potential in the rapid detection of AmpC Blas as well as the strains with AmpC-encoded gene, which is instructive in promoting better antibiotic stewardship practices and developments.

Crystallographic analyses of isoquinoline complexes reveal a new mode of metallo-ß-lactamase inhibition.

Crystallographic analyses of the VIM-5 metallo-ß-lactamase (MBL) with isoquinoline inhibitors reveal non zinc ion binding modes. Comparison with other MBL-inhibitor structures directed addition of a zinc-binding thiol enabling identification of potent B1 MBL inhibitors. The inhibitors potentiate meropenem activity against clinical isolates harboring MBLs.

Label-Free Photonic Crystal-Based ß-Lactamase Biosensor for ß-Lactam Antibiotic and ß-Lactamase Inhibitor.

A simple, label-free, and visual photonic crystal-based ß-lactamase biosensor was developed for ß-lactam antibiotic and ß-lactamase inhibitor in which the penicillinase (a ß-lactamase) was immobilized on the pH-sensitive colloidal crystal hydrogel (CCH) film to form penicillinase colloidal crystal hydrogel (PCCH) biosensing film. The hydrolysis of penicillin G (a ß-lactam antibiotic) can be catalyzed by penicillinase to produce penicilloic acid, leading to a pH decrease in the microenvironment of PCCH film, which causes the shrink of pH-sensitive CCH film and triggers a blue-shift of the diffraction wavelength. Upon the addition of ß-lactamase inhibitor, the hydrolysis reaction is suppressed and no clear blue-shift is observed. The concentrations of ß-lactam antibiotic and ß-lactamase inhibitor can be sensitively evaluated by measuring the diffraction shifts. The minimum detectable concentrations for penicillin G and clavulanate potassium (a ß-lactamase inhibitor) can reach 1 and 0.1 µM, respectively. Furthermore, the proposed method is highly reversible and selective, and it allows determination of penicillin G in fish pond water samples.

Safety and Tolerability of Nebulized Amoxicillin-Clavulanic Acid in Patients with COPD (STONAC 1 and STONAC 2).

The safety and tolerability of nebulized amoxicillin clavulanic acid were determined in patients with stable COPD and during severe exacerbations of COPD. Nine stable COPD patients received doses ranging from 50:10 mg up to 300:60 mg amoxicillin clavulanic acid and eight patients hospitalised for a COPD exacerbation received fixed doses 200/40 mg twice daily. Safety was evaluated by spirometry before and after inhalation. Tolerability was evaluated by questionnaire. Plasma and expectorated sputum samples were assayed for amoxicillin content. Seventeen patients underwent in total 100 nebulizations with amoxicillin clavulanic acid. In this safety and tolerability study no clinically relevant deteriorations in FEV1 were observed. Nebulized amoxicillin clavulanic acid produces sputum concentrations well above the Minimal Inhibiting Concentration of 90% for potential pathogenic micro-organisms, with low concentrations in the central compartment (low systemic exposure). Based on spirometry and reported side effects, inhalation of nebulized amoxicillin clavulanic acid seems to be safe and well tolerated, both in stable patients with COPD as in those experiencing a severe exacerbation. Levels of amoxicillin were adequate.

[Simultaneous determination of three beta-lactamase inhibitor residues in dairy products by high performance liquid chromatography].

An improved method has been developed for the determination of clavulanate potassium, tazobactam and sulbactam in dairy products. High performance liquid chromatography with photodiode array detector (HPLC-PAD) was used in this method. The separation was performed on a CAPCELL PAK MG-C18 column (150 mm x 4.6 mm, 5 microm). The mobile phase was 0.03% (volume fraction unless otherwise specified) phosphate-acetonitrile. This method offered effective sample preparation procedures including dissolution with water, protein isolation with acetone, clean-up and enrichment by solid-phase extraction (SPE) with PWAX cartridges (60 mg/3 mL) under weak acidic condition and further elution with 0.05% ammonia-methanol solution. The analytical method was well validated and good results were obtained with the RSDs of 2.2% - 7.4% and the recoveries of 84.6% - 101.7%. The detection limits of clavulanate potassium, tazobactam and sulbactam were 0.03 mg/L. All of the target compounds exhibited good linearities (r > 0.999) over the mass concentration range of 0.05 - 5 mg/L. With the advantages of good purification effect, high sensitivity, good recovery and repeatability, the method is suitable for the detection of beta-lactamase inhibitors in dairy products.