Analysis of corticosteroids in samples of animal origin using QuEChERS and ultrahigh-performance liquid chromatography coupled to high-resolution mass spectrometry.

A rapid and sensitive method for the confirmatory analysis of eight synthetic corticosteroids (betamethasone, dexamethasone, prednisolone, 6-methylprednisolone, triamcinolone, flumethasone, beclomethasone, fluocinolone acetonide) is proposed. The method is useful for detecting illegal treatments in different animal species. It consists of an extraction and cleanup using the quick, easy, cheap, effective, rugged, and safe (QuEChERS) strategy. Quantitative determination is achieved by ultrahigh-performance liquid chromatography coupled to high-resolution mass spectrometry with heated electrospray ionization in negative mode. Quantification is performed using surrogate matrix-matched standard calibration curve with dexamethasone-D4 as the internal standard. The method was validated for analyzing liver samples according to the criteria established by Decision 2002/657/EC. Linearity was assessed in the 1-10 µg kg-1 range and linear correlation coefficients were over 0.99 for all the analytes. CCα ranged from 0.04 to 0.16 µg kg-1 for substances without maximum residue limit. The method allows confident quantification and confirmation of corticosteroids in liver samples, and its simplicity makes it suitable for analyzing large numbers of samples.

Human endocarditis on prosthetic valves due to Bartonella vinsonii subsp. berkhoffii.

Bartonella spp. infections are increasingly recognized as causes of zoonotic diseases. One of the most severe infections caused by Bartonella spp. is infective endocarditis, predominantly affecting individuals with underlying valvular heart disease, immunosuppression and homelessness. The microbiological diagnosis of these endocarditis cases is highly challenging due to the fastidious nature of Bartonella spp., requiring specialized serologic and molecular tests in addition to blood cultures, which are usually negative. While B. henselae and B. quintana are the main species associated with these infections, other rarer Bartonella species are increasingly being identified in such cases. Herein, we report the first case of infective endocarditis on prosthetic heart valves caused by Bartonella vinsonii subsp. berkhofii in a 74 year-old shepherd, also being the fourth reported human endocarditis case due to this pathogen. This Bartonella subspecies has been associated with canid exposure, as these animals are believed to be its main reservoir. Interestingly, in our case the bacteria grew in heart-valve culture, allowing for species identification by whole-genome sequencing. Our patient, whose risk factors included canid exposure, cardiac anomalies and immunosuppression, is a clear example of the importance of considering this pathogen in such high-risk populations.

Analysing polypeptide antibiotics residues in animal muscle tissues: The crucial role of HRMS.

A confirmatory method for the determination of polypeptide antibiotics (bacitracin, colistin, and polymyxin B) in muscle samples has been developed. Extraction is performed with acidified methanol, and a clean-up step by solid-phase extraction with polymeric cartridges is applied. Separation by ultra-high performance liquid chromatography (UHPLC) is carried out using a solid core C18 column and gradient elution with water/acetonitrile containing 0.2% formic acid. High-resolution mass spectrometry (HRMS) (Q-Orbitrap) detection using different working modes has proved to be highly advantageous in eliminating interfering signals from endogenous matrix components. The analytical method has been successfully validated according to Commission Regulation 2021/808/EU and is currently used in a public health laboratory involved in veterinary medicines residue surveillance activities.

Direct Prosthetic Joint Infection Diagnosis from Sonication Fluid Inoculated in Blood Culture Bottles by Direct MALDI-TOF Mass Spectrometry.

An accurate and fast microbiological diagnosis is key for a proper management and results when facing prosthetic joint infection (PJI). The purpose of this study is to assess the role of direct Matrix-assisted laser desorption ionization time of flight (MALDI-TOF) mass spectrometry (MS) for early identification of the pathogens causing PJI from sonication fluid inoculated in blood culture bottles (BCB-SF). This prospective multicentric study included 107 consecutive patients from February 2016 to February 2017. Among them, 71 prosthetic joint revision surgeries were undergone for aseptic and 36 for septic reasons. Prostheses were sonicated and the resulting fluid inoculated into blood culture bottles, regardless the suspicion for infection. We assessed the diagnostic performance of direct MALDI-TOF MS identification of the pathogens in BCB-SF and compared it with periprosthetic tissue and conventional sonication fluid cultures. The sensitivity of direct MALDI-TOF MS of BCB-SF (69%) was higher compared to conventional sonication fluid (69% vs. 64%, p > 0.05) or intraoperative tissue cultures (69% vs. 53%, p = 0.04), especially for patients receiving antimicrobial treatment. This approach also reduced the time for identification but the specificity was compromised (100% vs. 94%) and polymicrobial infections were missed. In conclusion, BCB-SF improves the sensitivity and reduces the time of PJI diagnosis when used in combination with conventional cultures under strict sterility conditions.