Background/Objectives: Beta-lactam antibiotics, derived from penicillin, are the most used class of antimicrobials used for treating bacterial infections. Over the years, microorganisms have developed resistance mechanisms capable of preventing the effect of these drugs. This condition has been a significant public health concern for the 21st century, especially after predictions that antimicrobial resistance could lead to 10 million deaths annually by 2050. The challenge of developing new antimicrobials brings with it the need to ensure the efficacy of existing ones, hence the importance of developing fast and low-cost monitoring techniques. Methods: In this study, we present an alternative based on nanophotonics using Surface-Enhanced Raman Spectroscopy (SERS) mediated by nanoparticles for the detection of antimicrobials, with emphasis on some beta-lactam antibiotics commonly prescribed in cases of critically ill patients. It is a sensitive and accurate technique for drug monitoring, allowing for rapid and specific detection of its molecular signatures. This approach is crucial to address the challenge of antimicrobial resistance and ensure the therapeutic efficacy of existing treatments. Results: Our experiments demonstrate the possibility of identifying spectra with characteristic vibrations (fingerprints) of these antimicrobials via SERS. Conclusions: Our results point to new strategies for molecular monitoring of drugs by optical techniques using unconventional nanoparticles.

We aimed to investigate an outbreak of vancomycin-resistant Enterococcus faecium (VREfm) in paediatric patients from Hospital Pequeno Príncipe. The susceptibility profile was determined, and whole-genome sequencing (WGS) was used to analyse the genetic context of the strains. Five VREfm isolates were recovered from sterile sites and surveillance cultures of two paediatric patients with acute lymphoblastic leukaemia. Species identification was performed using matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS), and the minimum inhibitory concentration (MIC) was assessed according to the European Committee for Antimicrobial Susceptibility Testing (EUCAST). WGS was performed to analyse the genetic context of virulence and resistance genes, and in silico multilocus sequence typing was performed to identify the sequence typing of the strains. High-level vancomycin resistance was observed in all isolates (≥256 mg/L). WGS revealed the presence of mobile genetic elements, such as plasmids (rep₂, rep_11a, rep_US15, rep₁₇, and rep_18a), insertion sequences, and phages. Multiple resistance genes (aac(6')-aph(2"), dfrG, ermB, and vanA) and virulence genes (acm and efaAfm) were identified. All the isolates were assigned to ST117 (ST1133 - via a novel MLST), an important epidemic lineage associated with nosocomial infections and outbreaks. Our results show that the ST117 (ST1133) VREfm isolates are circulating in paediatric patients, which raises a great concern. The development of new drugs as well as the implementation of an antimicrobial stewardship program are necessary for their correct management, limiting the spread of resistance in oncohematological patients.

Antimicrobial resistance (AMR) is a global public health challenge with remarkable impacts on human, animal, and environmental health within the One Health framework. Among the pathogens most frequently associated with healthcare-associated infections are bacteria belonging to the ESKAPEE group, which comprises Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Enterobacter spp., and Escherichia coli. These microorganisms are the main cause of severe infections and difficult-to-treat infections due to multidrug resistance phenotypes driven by complex molecular mechanisms, including enzymatic inactivation, target-site modification, permeability alterations, and biofilm formation. Through a One Health lens, this narrative review synthesizes current evidence on ESKAPEE microorganisms, bridging environmental reservoirs (such as wastewater) with clinical resistance mechanisms, their relevance in hospital settings, and therapeutic strategies. This review highlights the relationship between AMR in ESKAPEE bacteria and the One Health approach, emphasizing the need for integrated strategies to mitigate the spread of resistant pathogens across human, animal, and environmental interfaces.

Methicillin-resistant Staphylococcus aureus (MRSA) is a leading cause of hospital- and community-acquired infections (HA-MRSA and CA-MRSA, respectively). Although this microorganism is associated with childhood bacteremia, its epidemiology and predictive factors are not well established. In this study, the susceptibility profiles and molecular characteristics of 46MRSA isolates obtained from blood samples and other sterile fluids of pediatric patients between January 2017 and May 2022 were characterized. The isolates were identified using matrix-assisted laser desorption ionization-time of flight mass spectrometry. After that, their antimicrobial susceptibility profiles were assessed trough broth microdilution, and their molecular characteristics was performed by whole genome sequencing. Antibiotic susceptibility tests showed that the isolates were 100% sensitive to vancomycin, linezolid, and sulfamethoxazole-trimethoprim. In terms of SCCmec, types IV and II were the most prevalent, accounting for 47.82% (22/44) and 47.72% (21/44) of the isolates, respectively, whereas type I was identified in just one isolate (2.27%). Thus, 50% of infections were caused by CA-MRSA and HA-MRSA. Sequencing analysis revealed polyclonal spread, with several sequence types (STs) identified. Five STs belonging to the CC5 clonal complex (ST5, ST105, ST1649, ST1176, and ST1307) accounted for most of the isolates (n=38). The detected virulence genes were sak, tst-1, ACME, hlgA, lukF-PV/lukS-PV, and lukD/lukE. The Panton–Valentine Leukocidin (PVL) toxin gene was found in nine isolates, all of which were CA-MRSA and carried SCCmec type IV. Several antimicrobial resistance genes encoding resistance to different antibiotic classes were identified. In conclusion, we conclude that CA-MRSA strains are currently ubiquitous in hospital environments, causing serious infections, with CC5 being predominant over the past five years.

Persistent candidemia (PC) in children can lead to unfavorable outcomes. However, its risk factors and clinical impact remain poorly understood. This study aimed to identify risk factors associated with PC in pediatric patients. We conducted a retrospective analysis of 141 children (0–17 years) diagnosed with candidemia at a children’s hospital in Brazil between 2016 and 2022. Clinical data were collected from medical records. Microorganisms were identified by MALDI-TOF MS, tested for biofilm production, and sensitivity profile. Molecular typing was performed on the three most prevalent species, and ERG11 mutation screening was carried out on fluconazole-resistant isolates. PC was identified in 34.8% (n = 49) patients. Independent risk factors included early non-removal of the central venous catheter, parenteral nutrition, and cancer. The overall 30-day mortality was 23.4%, and the candidemia-related mortality was 16.3%. C. parapsilosis was the prevalent species. All isolates except one produced biofilm. One isolate of C. tropicalis, which had the missense mutation Y257H in ERG11, was resistant to fluconazole. Isolates showed high genetic diversity. PC was associated with host factors and clinical management rather than aspects of the etiological agent, highlighting the importance of early patient monitoring.

Background/Objectives: Acute lymphoblastic leukemia (ALL) is the most common childhood malignancy. Understanding its epidemiological characteristics is essential for guiding public health strategies. In this study, we characterized the epidemiological profiles that may contribute to the risk of ALL in children in southern Brazil. Methods: Clinical and epidemiological data from 71 children (1–15 years old) admitted and newly diagnosed with ALL at four hospitals in Curitiba, Paraná, Brazil, were retrieved and analyzed. Results: Among the 71 children with ALL, the majority were male (n = 43, 60.6%), with an age range of 1–3 years (n = 26, 36.6%), self-identified as White (n = 47, 66.2%), and were born in Paraná state (n = 61, 85.9%). Nearly half had a family history of cancer (n = 33, 46.5%), primarily among grandparents (n = 36, 61%). Parental environmental exposures included smoking (n = 30, 42.3%) and occupational exposure to chemicals or radiation (n = 17, 23.9%). At diagnosis, most patients (n = 43, 60.5%) had a bone marrow blast count > 70%, and 27 patients (38%) had a peripheral blood blast count > 70%. B-cell ALL was the predominant subtype (n = 61, 85.9%). In B-cell ALL cases, the most frequent molecular subtype was high hyperdiploidy (n = 17, 23.9%). White blood cell counts differed significantly between the B-cell ALL and T-cell ALL groups (p = 0.029). Conclusions: Our findings provide insights into ALL epidemiology in southern Brazil and highlight regional differences across the country.