MALDI-TOF MS Based Bacterial Antibiotics Resistance Finger Print for Diabetic Pedopathy

Diabetes mellitus has become a major global health issue. Currently, the use of antibiotics remains the best foundational strategy in the control of diabetic foot infections. However, the lack of accurate identification of pathogens and the empirical use of antibiotics at early stages of infection represents a non-targeted treatment approach with a poor curative effect that may increase the of bacterial drug resistance. Therefore, the timely identification of drug resistant bacteria is the key to increasing the efficacy of treatments for diabetic foot infections. The traditional identification method is based on bacterial morphology, cell physiology, and biochemistry. Despite the simplicity and low costs associated with this method, it is time-consuming and has limited clinical value, which delays early diagnosis and treatment. In the recent years, MALDI-TOF MS has emerged as a promising new technology in the field of clinical microbial identification. In this study, we developed a strategy for the identification of drug resistance in the diagnosis of diabetic foot infections using a combination of macro-proteomics and MALDI MS analysis. The macro-proteomics result was utilized to determine the differential proteins in the resistance group and the corresponding peptide fragments were used as the finger print in a MALDI MS analysis. This strategy was successfully used in the research of drug resistance in patients with diabetic foot infections and achieved several biomarkers that could be used as a finger print for 4 different drugs, including ceftazidime, piperacillin, levofloxacin, and tetracycline. This method can quickly confirm the drug resistance of clinical diabetic foot infections, which can help aid in the early treatment of patients.

Combining MALDI-MS with Machine Learning for Metabolomic Characterization of Lung Cancer Patient Sera

An increasing amount of evidence have proven that serum metabolites can instantly reflect disease states. Therefore, sensitive and reproducible detection of serum metabolites in a high-throughput way is urgently desirable...

Ultrasensitive and rapid identification of ESRI developer- and piperacillin/tazobactam-resistant Escherichia coli by the MALDIpiptaz test

The excessive use of piperacillin/tazobactam (P/T) has promoted the emergence of P/T-resistant Enterobacterales. We reported that in Escherichia coli, P/T contributes to the development of extended-spectrum resistance to β-lactam/β-lactamase inhibitor (BL/BLI) (ESRI) in isolates that are P/T susceptible but have low-level resistance to BL/BLI. Currently, the detection of P/T resistance relying on conventional methods is time-consuming. To overcome this issue, we developed a cost-effective test based on MALDI-MS technology, called MALDIpiptaz, which aims to detect P/T resistance and ESRI developers in E. coli. We used automated Clover MS Data Analysis software to analyse the protein profile spectra obtained by MALDI-MS from a collection of 248 E. coli isolates (91 P/T-resistant, 81 ESRI developers and 76 P/T-susceptible). This software allowed to preprocess all the spectra to build different peak matrices that were analysed by machine learning algorithms. We demonstrated that MALDIpiptaz can efficiently and rapidly (15 min) discriminate between P/T-resistant, ESRI developer and P/T-susceptible isolates and allowed the correct classification between ESRI developers from their isogenic resistance to P/T. The combination of excellent performance and cost-effectiveness are all desirable attributes, allowing the MALDIpiptaz test to be a useful tool for the rapid determination of P/T resistance in clinically relevant gram-negative bacteria.

Interleukin-13 overexpressing mice represent an advanced pre-clinical model for detecting the distribution of anti-mycobacterial drugs within centrally necrotizing granulomas

The Mycobacterium tuberculosis (Mtb)-harboring granuloma with a necrotic center surrounded by a fibrous capsule is the hallmark of tuberculosis (TB). For a successful treatment, antibiotics need to penetrate these complex structures to reach their bacterial targets. Hence, animal models reflecting the pulmonary pathology of TB patients are of particular importance to improve the pre-clinical validation of novel drug candidates. Mtb-infected interleukin-13 overexpressing (IL-13 tg ) mice develop a TB pathology very similar to patients and, in contrast to other mouse models, also share pathogenetic mechanisms. Accordingly, IL-13 tg animals represent an ideal model for analyzing the penetration of novel anti-TB drugs into various compartments of necrotic granulomas by matrix-assisted-laser-desorption/ionization-mass spectrometry imaging (MALDI MS imaging). In the present study, we evaluated the suitability of BALB/c IL-13 tg mice for determining the antibiotic distribution within necrotizing lesions. To this end, we established a workflow based on the inactivation of Mtb by gamma irradiation while preserving lung tissue integrity and drug distribution, which is essential for correlating drug penetration with lesion pathology. MALDI MS imaging analysis of clofazimine, pyrazinamide and rifampicin revealed a drug-specific distribution within different lesion types including cellular granulomas, developing in BALB/c wild-type mice, and necrotic granulomas of BALB/c IL-13 tg animals, emphasizing the necessity of pre-clinical models reflecting human pathology. Most importantly, our study demonstrates that BALB/c IL-13 tg mice recapitulate the penetration of antibiotics into human lesions. Therefore, our workflow in combination with the IL-13 tg mouse model provides an improved and accelerated evaluation of novel anti-TB drugs and new regimens in the pre-clinical stage.

MALDI MS-Based Investigations for SARS-CoV-2 Detection

The urgent need to fight the COVID-19 pandemic has impressively stimulated the efforts of the international scientific community, providing an extraordinary wealth of studies. After the sequence of the virus became available in early January 2020, safe and effective vaccines were developed in a time frame much shorter than everybody expected. However, additional studies are required since viral mutations have the potential of facilitating viral transmission, thus reducing the efficacy of developed vaccines. Therefore, improving the current laboratory testing methods and developing new rapid and reliable diagnostic approaches might be useful in managing contact tracing in the fight against both the original SARS-CoV-2 strain and the new, potentially fast-spreading CoV-2 variants. Mass Spectrometry (MS)-based testing methods are being explored, with the challenging promise to overcome the many limitations arising from currently used laboratory testing assays. More specifically, MALDI-MS, since its advent in the mid 1980s, has demonstrated without any doubt the great potential to overcome many unresolved analytical challenges, becoming an effective proteomic tool in several applications, including pathogen identification. With the aim of highlighting the challenges and opportunities that derive from MALDI-based approaches for the detection of SARS-CoV-2 and its variants, we extensively examined the most promising proofs of concept for MALDI studies related to the COVID-19 outbreak.