Discrimination of Methicillin-resistant Staphylococcus aureus by MALDI-TOF Mass Spectrometry with Machine Learning Techniques in Patients with Staphylococcus aureus Bacteremia.

Early administration of proper antibiotics is considered to improve the clinical outcomes of Staphylococcus aureus bacteremia (SAB), but routine clinical antimicrobial susceptibility testing takes an additional 24 h after species identification. Recent studies elucidated matrix-assisted laser desorption/ionization time-of-flight mass spectra to discriminate methicillin-resistant strains (MRSA) or even incorporated with machine learning (ML) techniques. However, no universally applicable mass peaks were revealed, which means that the discrimination model might need to be established or calibrated by local strains' data. Here, a clinically feasible workflow was provided. We collected mass spectra from SAB patients over an 8-month duration and preprocessed by binning with reference peaks. Machine learning models were trained and tested by samples independently of the first six months and the following two months, respectively. The ML models were optimized by genetic algorithm (GA). The accuracy, sensitivity, specificity, and AUC of the independent testing of the best model, i.e., SVM, under the optimal parameters were 87%, 75%, 95%, and 87%, respectively. In summary, almost all resistant results were truly resistant, implying that physicians might escalate antibiotics for MRSA 24 h earlier. This report presents an attainable method for clinical laboratories to build an MRSA model and boost the performance using their local data.

A proposed approach to confirm heroin administration - Regional differences in heroin purity is a major factor.

In forensic toxicology, a marker of street heroin use is urgent especially in the absence of urinary 6-monoacetylmorphine. ATM4G, the Glucuronide of Acetylated product of Thebaine compound 4 Metabolite (ATM4), arising from byproducts of street heroin synthesis has been considered as a useful marker in some European studies. However, whether ATM4G is a universal marker particularly in Southeast Asia due to 'street' heroin with high purity, it's still unclear. To investigate putative markers for different regions, ATM4G and other metabolites including the Acetylated product of Thebaine compound 3 Metabolite (ATM3) and thebaol, also originated from thebaine were detected in 552 urine samples from heroin users in Taiwan. Results were compared with that from samples collected in the UK and Germany. Only a sulfo-conjugate of ATM4, ATM4S, was detected in 28 Taiwanese users using a sensitive MS3 method whilst out of 351 samples from the UK and Germany, ATM4G was present in 91. Thebaol-glucuronide was first time detected in 118. No markers were detected in urine following herbal medicine use or poppy seed ingestion. The presence of ATM4S/ATM4G might be affected by ethnicities and heroin supplied in regions. Thebaol-glucuronide is another putative marker with ATM4G and ATM4S for street heroin use.

High Level of Aristolochic Acid Detected With a Unique Genomic Landscape Predicts Early UTUC Onset After Renal Transplantation in Taiwan.

BACKGROUND: The unusual high dialysis prevalence and upper urinary tract urothelial carcinoma (UTUC) incidence in Taiwan may attribute to aristolochic acid (AA), which is nephrotoxic and carcinogenic, exposure. AA can cause a unique mutagenic pattern showing A:T to T:A transversions (mutational Signature 22) analyzed by whole exome sequencing (WES). However, a fast and cost-effective tool is still lacking for clinical practice. To address this issue, we developed an efficient and quantitative platform for the quantitation of AA and tried to link AA detection with clinical outcomes and decipher the genomic landscape of UTUC in Taiwan. PATIENTS AND METHODS: We recruited 61 patients with de novo onset of UTUC after kidney transplantation who underwent radical nephroureterectomy. A liquid chromatography-tandem mass spectrometry (LC-MS/MS) platform was developed for the quantitation of AA. Pearson's chi-square test, Kaplan-Meier method, and Cox proportional hazard model were utilized to assess the correlations among AA detection, clinicopathological characteristics, and clinical outcomes. Seven tumors and seven paired normal tissues were sequenced using WES (approximately 800x sequencing depth) and analyzed by bioinformatic tool. RESULTS: We found that high level of 7-(deoxyadenosin-N6-yl)aristolactam I (dA-AL-I) detected in paired normal tissues was significantly correlated with fast UTUC initiation times after renal transplantation (p = 0.035) and with no use of sirolimus (p = 0.046). Using WES analysis, we further observed that all tumor samples were featured by Signature 22 mutations, apolipoprotein B mRNA-editing enzyme, catalytic polypeptide (APOBEC)-associated gene mutations, p53 mutations, no fibroblast growth factor receptor 3 (FGFR3) mutation, and high tumor mutation burden (TMB). Especially, mammalian target of rapamycin (mTOR) activation predominated in dA-AL-I-detected samples compared with those without dA-AL-I detection and might be associated with UTUC initiation through cell proliferation and suppression of UTUC progression via autophagy inhibition. CONCLUSION: Accordingly, dA-AL-I detection can provide more direct evidence to AA exposure and serve as a more specific predictive and prognostic biomarker for patients with de novo onset of UTUC after kidney transplantation.

Modifier-assisted differential mobility-tandem mass spectrometry method for detection and quantification of amphetamine-type stimulants in urine.

An advantage of differential mobility spectrometry (DMS) is it provides an orthogonal mechanism to mass spectrometry (MS). The DMS-MS/MS detects analytes in the gas phase on the basis of differences in ion mobility in low and high electric fields, which makes DMS-MS/MS an alternative to chromatographic separation-MS. One drawback of DMS is its limited resolution and sensitivity, especially for detecting small molecules when using a nonpolar inert gas as the carrier gas. The present work has evaluated the effects on peak capacity of adding chemical modifiers to inert carrier gases (nitrogen, helium, argon and carbon dioxide). Use of a methanol-helium mixture gave improvements in both separation and sensitivity. Nine structurally similar amphetamine-type stimulants were determined in urine without pretreatment of the samples before analysis. After optimization of carrier gas, nature and concentration of chemical modifier, and DMS temperature, limits of detection ranging from 1.1 to 2.7 ng mL-1, with a linear range of three orders of magnitude (5-5000 ng mL-1) were achieved. Precision was <15% and the accuracy of the quality control samples was 87.6-113.7%. For the quantitation of urine samples from drug abusers, data obtained using DMS-MS/MS showed reasonable agreement (within ±19.5%) with that obtained using LC-MS/MS. The analysis time for DMS-MS/MS was only 1.1 min and a paired sample t-test between the two methods gave a p-value of 0.0894, which indicates that DMS-MS/MS is a reliable method, with comparable precision and sensitivity to LC-MS/MS.

Up-and-down-shaker-assisted dispersive liquid-liquid microextraction coupled with gas chromatography-mass spectrometry for the determination of fungicides in wine.

An up-and-down-shaker-assisted dispersive liquid-liquid microextraction (UDSA-DLLME) method coupled with gas chromatography-mass spectrometry was developed for the determination of fungicides (cyprodinil, procymidone, fludioxonil, flusilazole, benalaxyl, and tebuconazole) in wine. The developed method requires 11 µL of 1-octanol without the need for dispersive solvents. The total extraction time was approximately 3 min. Under optimum conditions, the linear range of the method was 0.05-100 µg L(-1) for all fungicides and the limit of detection was 0.007-0.025 µg L(-1). The absolute and relative recoveries were 31-83% and 83-107% for white wine, respectively, and 32-85% and 83-108% for red wine, respectively. The intra-day and inter-day precision were 0.5-7.5% and 0.7-6.1%, respectively. Our developed method had good sensitivity and high extraction efficiency. UDSA-DLLME is a desirable method in terms of performance and speed.

Water with low concentration of surfactant in dispersed solvent-assisted emulsion dispersive liquid-liquid microextraction for the determination of fungicides in wine.

A sample preparation method, dispersive liquid-liquid microextraction assisted by an emulsion with low concentration of a surfactant in water and dispersed solvent coupled with gas chromatography-mass spectrometry, was developed for the analysis of the fungicides cyprodinil, procymidone, fludioxonil, flusilazole, benalaxyl, and tebuconazole in wine. A microsyringe was used to withdraw and discharge a mixture of extraction solvent and 240 µL of an aqueous solution of Triton X-100 (the dispersed agent) four times within 10 s to form a cloudy emulsion in the syringe. This emulsion was then injected into a 5 mL wine sample spiked with all of the above fungicides. The total extraction time was approximately 0.5 min. Under optimum conditions using 1-octanol (12 µL) as extraction solvent, the linear range of the method in analysis of all six fungicides was 0.05-100 µg L(-1), and the limit of detection ranged from 0.013 to 0.155 µg L(-1). The absolute recoveries (n = 3) and relative recoveries (n = 3) were 30-83 and 81-108% for white wine at 0.5, 5, and 5 µg L(-1), and 30-92 and 81-110% for red wine, respectively. The intraday (n = 7) and interday (n = 6) relative standard deviations ranged from 4.4 to 8.8% and from 4.3 to 11.2% at 0.5 µg L(-1), respectively. The method achieved high enrichment factors. It is an alternative sample preparation technique with good performance.