ABSTRACT
PURPOSE: Staphylococcus aureus is one of the most common pathogens causing bloodstream infection. A rapid characterisation of resistance to methicillin and, occasionally, to aminoglycosides for particular indications, is therefore crucial to quickly adapt the treatment and improve the clinical outcomes of septic patients. Among analytical technologies, targeted liquid chromatography-tandem mass spectrometry (LC-MS/MS) has emerged as a promising tool to detect resistance mechanisms in clinical samples. METHODS: A rapid proteomic method was developed to detect and quantify the most clinically relevant antimicrobial resistance effectors in S. aureus in the context of sepsis: PBP2a, PBP2c, APH(3')-III, ANT(4')-I, and AAC(6')-APH(2''), directly from positive blood cultures and in less than 70 min including a 30-min cefoxitin-induction step. The method was tested on spiked blood culture bottles inoculated with 124 S.aureus, accounting for the known genomic diversity of SCCmec types and the genetic background of the strains. RESULTS: This method provided 99% agreement for PBP2a (n = 98/99 strains) detection. Agreement was 100% for PBP2c (n = 5/5), APH(3')-III (n = 16/16), and ANT(4')-I (n = 20/20), and 94% for AAC(6')-APH(2'') (n = 16/17). Across the entire strain collection, 100% negative agreement was reported for each of the 5 resistance proteins. Additionally, relative quantification of ANT(4')-I expression allowed to discriminate kanamycin-susceptible and -resistant strains, in all strains harbouring the ant(4')-Ia gene. CONCLUSION: The LC-MS/MS method presented herein demonstrates its ability to provide a reliable determination of S. aureus resistance mechanisms, directly from positive blood cultures and in a short turnaround time, as required in clinical laboratories.
ABSTRACT
BACKGROUND: The clinical results following regenerative endodontic procedures (REPs) vary according to numerous parameters, including the presence of bacteria. This limitation reduces the indications for REPs and calls for the development of next generation antibacterial strategies (NGAS) providing alternatives to current antibacterial strategies (CAS) such as double or triple antibiotic paste (DAP/TAP) and (Ca(OH)2). OBJECTIVES: The present scoping review aims to describe the current trends regarding the use of such strategies and highlight future perspectives. METHODS: Four databases (PUBMed, Cochrane, ClinicalTrials and Science Direct) were searched until 1st May 2023. RESULTS: A total of 918 records were identified, 133 were screened and assessed for eligibility, and 87 articles were included. The findings show that (1) clinical studies are only available for CAS, (2) although next generation strategies are the most studied approach since 2017, they are all at the pre-clinical stage, (3) most of the next generation strategies use galenic forms which offer cell support and colonization and which simultaneously contain antibacterial molecules as alternatives to CAS and to antibiotics in general, (4) standardization is required for future research, specifically regarding the bacterial strains studied, the use of biofilm studies and the cellular behaviour assessments. CONCLUSION: Although NGAS are promising strategies to improve REPs in the context of infection, the current evidence is mostly limited to pre-clinical studies. Further methodological improvement is required to allow relevant comparisons between studies and to reduce the time from bench to bedside.
