Anti-VIM monoclonal antibody, clone WJ-12

Background: Bacterial resistance to antibiotics has become a major public health concern. This study aimed to determine the resistance mechanisms to carbapenem in clinical isolates of Pseudomonas aeruginosa. Methods: A total of 62 clinical isolates of carbapenem-resistant P aeruginosa (CRPA) were collected from 2015 to 2017. Imipenem (IPM)-EDTA disk synergy test was used to screen strains that produced metallo-beta-lactamase. In addition, the genes for outer membrane protein OprD2, metallo-beta-lactamase and mexR gene were amplified and sequenced. Expression of mexA was detected by real-time PCR. Results: Disk synergy test showed that 51.6% (32/62) of the strains were positive for metallo-beta-lactamase. PCR showed that 84.4% of the strains were SIM-positive (27/32), 15.6% of the strains were IMP-positive (5/32), and 12.5% of the strains were VIM-positive (4/32). SPM-positive and GIM-positive strains were not detected. In addition, 5 of the 62 strains had small deletions and/or point mutations in OprD2. Three strains had a high expression of mexA, while eight strains were positive for the regulatory gene mexR with no mutations detected by DNA sequencing. Conclusion: Expression of metallo-beta-lactamase is the main resistance mechanism of P. aeruginosa to carbapenem. Mutations in OprD2 and/or the overexpression of efflux pump MexAB-OprM may contribute to P aeruginosa resistance to carbapenem.

Decomposition of bodies generates several types of polar volatile organic compounds (VOCs), whose types, patterns and ratios change during the various stages of decomposition and, therefore, their determination has huge potential to provide useful information to disclose events related to the time of death, or body surrounding environment. As sample preparation is a mandatory key-point in a method development, this research aims to develop a simple, accurate and rapid approach to study death-related polar VOCs based on headspace solid-phase microextraction (HS-SPME) combined with comprehensive two-dimensional gas chromatography-time of flight mass spectrometry (GC x GC-ToFMS) analysis. The performance of zwitterionic PIL-based fibers (containing a [VIm(+)C(9)COO(-)] monomer and a [(VIm)(2)Cl-2(2)+]-2Br(-) crosslinker), tailored for polar compounds, was evaluated for a set of 19 analytes associated with the unique odour created by decomposing bodies, and it was compared to the commercially-available fibers: divinylbenzene/carboxen/poly(dimethylsiloxane) - DVB/CAR/PDMS, poly(dimethylsiloxane)/divinylbenzene - PDMS/DVB and polyacrylate (PA). Fibers with absorptive-type mechanism, such as PA and PIL, showed the best results in the balance of the parameters studied, being able to detect analytes at ng level and providing a profile representative of the headspace composition, thus they may represent a useful tool to respond to current challenges in forensic taphonomy. The reproducibility (with relative standard deviation lower than 18%, depending on the analyte) and relative recoveries (higher than 99.1%) were similar and acceptable for both fibers. The zwitterionic PIL, with ca. 4 times smaller film thickness than PA, still has potential to have the best performance, supported by the efforts to obtain thicker sorbent coatings.