A rapid, antibiotic susceptibility test for multidrug-resistant, Gram-negative bacterial uropathogens using the biochemical assay, DETECT

Enzymatic Antimicrobial Susceptibility Testing with Bacteria Identification in 30 min

Rapid antimicrobial susceptibility testing (AST) with the ability of bacterial identification is urgently needed for evidence-based antibiotic prescription. Herein, we propose an enzymatic AST (enzyAST) that employs β-d-glucuronidase as a biomarker to identify pathogens and profile phenotypic susceptibilities simultaneously. EnzyAST enables to offer binary AST results within 30 min, much faster than standard methods (>16 h). The general applicability of enzyAST was verified by testing the susceptibility of two Escherichia coli strains to three antibiotics with different action mechanisms. The pilot study also shows that the minimal inhibitory concentrations can be determined by enzyAST with the statistical analysis of enzymatic activity of the bacteria population exposed to varying antibiotic concentrations. With further development of multiple bacteria and sample treatment, enzyAST could be able to evaluate the susceptibility of pathogens in clinical samples directly to facilitate the evidence-based therapy.

Association of multidrug resistance behavior of clinical Pseudomonas aeruginosa to pigment coloration

Pseudomonas aeruginosa is an adaptable bacterial pathogen that infects a variety of organs, including the respiratory tract, vascular system, urinary tract, and central nervous system, causing significant morbidity and mortality. As the primary goal of this study, we wanted to determine how pigment color production differed between clinical strains of P. aeruginosa, and whether or not that variation was associated with multidrug resistance or the ability to form biofilms. We screened in total 30.1% of yellow, 39.8% green and 30.1% of no pigment-producing P. aeruginosa strains from a total of 143 various clinical isolates. Yellow pigment-producing strains presented significant resistance to antibiotics groups, including β-lactam (91.5%), aminoglycosides (70.5%), and carbapenems (51.9%) compared to green and non-pigmented strains. Notably, 16.3% of yellow pigment-producing strains were resistant to colistin which is used as a last-resort treatment for multidrug-resistant bacteria, whereas only 2.3% of non-pigmented and 1.8% of green pigmented strains were resistant to colistin. Aside from that, yellow pigment-producing strains were frequent producers of enzymes belonging to the lactamase family, including ESBL (55.6%), MBL (55.6%), and AmpC (50%). Compared to the green groups (7.14%) and non-pigmented groups (28.5%), they had a higher frequency of efflux positive groups (64.2%). Notably, when compared to non-pigmented groups, green pigment-producing strains also displayed antibiotic susceptibility behavior similar to yellow pigment-producing strains. The majority of yellow pigment-producing strains outperformed the green and non-pigmented strains in terms of MIC levels when compared to the other two groups of strains. Despite the fact that previous studies have demonstrated a direct correlation between multidrug resistance behaviors and biofilm production, no such statistically significant association between pigment and biofilm formation was found in our investigation. Our research has demonstrated that the correlation of bacterial pigments on their susceptibility to antimicrobial agents. Yellow pigment-producing P. aeruginosa strains posed a significant problem due to the lack of alternative agents against such transformed strains, which may be associated with the development of multidrug resistance.

A self-immolative linker that releases thiols detects penicillin amidase and nitroreductase with high sensitivity via absorption spectroscopy

This article reports the synthesis and characterization of a novel self-immolative linker, based on thiocarbonates, which releases a free thiol upon activation via enzymes. We demonstrate that thiocarbonate self-immolative linkers can be used to detect the enzymes penicillin G amidase (PGA) and nitroreductase (NTR) with high sensitivity using absorption spectroscopy. Paired with modern thiol amplification technology, the detection of PGA and NTR were achieved at concentrations of 160 nM and 52 nM respectively. In addition, the PGA probe was shown to be compatible with both biological thiols and enzymes present in cell lysates.

Application of a solid-phase microextraction-gas chromatography-mass spectrometry/metal oxide sensor system for detection of antibiotic susceptibility in urinary tract infection-causing Escherichia coli - A proof of principle study

PURPOSE

Antibiotic resistance is widespread throughout the world and represents a serious health concern. There is an urgent need for the development of novel tools for rapidly distinguishing antibiotic resistant bacteria from susceptible strains. Previous work has demonstrated that differences in antimicrobial susceptibility can be reflected in differences in the profile of volatile organic compounds (VOCs) produced by dissimilar strains. The aim of this study was to investigate the effect of the presence of cephalosporin antibiotics on the VOC profile of extended spectrum beta-lactamase (ESBL) and non-ESBL producing strains of Escherichia coli.

MATERIAL AND METHODS

In this study, VOCs from strains of Escherichia coli positive and negative for the most commonly encountered ESBL, CTX-M in the presence of cephalosporin antibiotics were assessed using solid-phase microextraction (SPME) coupled with a combined gas chromatography-mass spectrometry/metal oxide sensor (GC-MS/MOS) system.

RESULTS

Our proof-of-concept study allowed for distinguishing CTX-M positive and negative bacteria within 2 ​h after the addition of antibiotics. One MOS signal (RT: 22.6) showed a statistically significant three-way interaction (p ​= ​0.033) in addition to significant two-way interactions for culture and additive (p ​= ​0.046) plus time and additive (p ​= ​0.020). There were also significant effects observed for time (p ​= ​0.009), culture (p ​= ​0.030) and additive (p ​= ​0.028). No effects were observed in the MS data.

CONCLUSIONS

The results of our study showed the potential of VOC analysis using SPME combined with a GC-MS/MOS system for the early detection of CTX-M-producing, antibiotic-resistant E. coli, responsible for urinary tract infections (UTIs).

Activity-Based Diagnostics: Recent Advances in the Development of Probes for Use with Diverse Detection Modalities

Abnormal enzyme expression and activity is a hallmark of many diseases. Activity-based diagnostics are a class of chemical probes that aim to leverage this dysregulated metabolic signature to produce a detectable signal specific to diseased tissue. In this Review, we highlight recent methodologies employed in activity-based diagnostics that provide exquisite signal sensitivity and specificity in complex biological systems for multiple disease states. We divide these examples based upon their unique signal readout modalities and highlight those that have advanced into clinical trials.