Municipal wastewater catchments are significant sources of symbiotic, opportunistic, and drug-resistant bacteria that can acquire or enhance their resistance. This "re-emergence of threats" presents a serious public health issue, especially during crisis conditions (COVID-19). The aim of this study was to propose a sampling algorithm, identify strategically important sites within the wastewater catchment, expand the range of bacterial indicators, and rapidly confirm potential threats using in vitro diagnostics in both raw and treated sewage. A parallel objective was to evaluate the effectiveness of sequencing methods in pre-epidemic studies. The research was conducted as part of a long-term surveillance program at transportation hubs, healthcare facilities, residential complexes, and wastewater treatment plants in Warsaw, Poland. Total nucleic acid (TNA) was isolated from samples, amplified using qPCR kits, and selected samples underwent next-generation sequencing. In raw sewage, the most frequently detected regions included sequences complementary to the bacterial vanB gene, the Integron Verona-encoded metallo-β-lactamase (VIM) gene, and markers for Mycobacterium tuberculosis. Treated environmental effluents primarily contained DNA fragments complementary to the bacterial vanB sequence, along with genes related to resistance against oxacillin and imipenem, as well as the VIM gene and Legionella sp. 16S rRNA sequencing of the sewage samples revealed the presence of 12 promising bacterial indicators relevant to public health and environmental hygiene. The proposed algorithm aligns with the provisions of EU Directive 2024/3019 and in vitro diagnostic tests demonstrated the potential and utility of rapid screening analyses of wastewater during disruptions or crises, as well as in situations involving equipment shortages and logistical challenges in healthcare. The proposed expanded range of bioindicators could expedite decision-making regarding preventive measures and medical support for various counties, hospitals, and transportation hubs in large urban areas. The sequencing results further emphasized the need to broaden the scope of the bacterial indicators for environmental surveillance.

Listeria monocytogenes is one of the leading foodborne pathogens and an increasing public health concern because of the emergence of antimicrobial-resistant strains. This scoping review aimed to synthesize the available evidence on the prevalence and phenotypic antimicrobial resistance profiles of L. monocytogenes in animal-derived foods. The review was conducted following the Joanna Briggs Institute methodology and the PRISMA-ScR guidelines through systematic searches of PubMed/MEDLINE, Scopus, Web of Science, and Embase. Of the 711 records identified, 11 studies met the eligibility criteria. The included studies reported the occurrence of L. monocytogenes in meat and meat products, milk and dairy products, and ready-to-eat foods. The reported prevalence ranged from 0.1% to 60.0% across food matrices; however, the highest estimate (60.0%) was derived from a single ready-to-eat food study with a small sample size (9 positive samples among 15 analyzed) and should therefore be interpreted cautiously. Phenotypic resistance was most frequently reported to specific β-lactams, particularly penicillin, oxacillin, cloxacillin, cefotaxime, ceftriaxone, and piperacillin, as well as to tetracyclines. In contrast, several studies reported preserved susceptibility to ampicillin and amoxicillin, indicating substantial variability in resistance within the β-lactam class across the included studies. This scoping review provides an updated synthesis of the available evidence on the prevalence and phenotypic antimicrobial resistance profiles of L. monocytogenes in animal-derived foods and summarizes the phenotypic antimicrobial resistance patterns reported across the included food matrices.

Over the past few years, considerable scholarly interest has been directed toward the synergistic application of natural compounds alongside conventional antibiotics to address infections stemming from multidrug-resistant (MDR) pathogens. The primary objective of this research is to investigate the efficacy of baicalin (BA), an extract obtained from Scutellaria baicalensis, when used in conjunction with oxacillin sodium (OXS). Specifically, the study evaluates their combined impact on biofilm formation and toxicity reduction in methicillin-resistant Staphylococcus aureus (MRSA) strain USA300. Furthermore, a murine peritonitis model induced by MRSA USA300 was developed to determine the therapeutic potential of this combination therapy against infection. Experimental data indicate that the co-administration of BA and OXS does not induce hemolysis in vitro. In comparison to treatments involving either BA or OXS alone, the combined regimen significantly enhances the accumulation of intracellular reactive oxygen species (ROS) within MRSA USA300. Additionally, this synergistic approach suppresses the production of extracellular polymeric substances (EPSs), decreases the overall protein content within the biofilm matrix, and impairs the metabolic functions of biofilm cells. The investigation also revealed that the synergistic application of BA and OXS intensifies the suppression of key virulence determinants, specifically lipase activity and staphyloxanthin production, while simultaneously downregulating the transcription of sarA (a global regulator of virulence). These findings substantiate the anti-virulence efficacy of the BA-OXS combination. In a murine model of peritonitis established using MRSA USA300, the healthy mice group, the MRSA USA300 group, the BA group, the OXS group, the combined group of BA and OXS, and the VAN group were set up, with eight mice in each group. The results showed that the combined therapy significantly mitigated body weight reduction, decreased the circulating counts of inflammatory cells, including leukocytes and lymphocytes, and suppressed the secretion of pro-inflammatory mediators such as TNF-α, IL-6, and IL-1β, thereby demonstrating potent anti-inflammatory properties. Furthermore, the co-administration of BA and OXS reduced bacterial burden in the abdominal organs of infected mice and alleviated associated histopathological injuries. Importantly, the treatment regimen exhibited no hepatorenal toxicity in the peritonitis mice, effectively maintaining normal levels. In the plasma of mice suffering from peritonitis, the concentration of malondialdehyde (MDA), a marker of oxidative stress, was reduced, while the activities of catalase (CAT) and superoxide dismutase (SOD) were elevated. This modulation contributes to anti-infective effects. These findings offer a theoretical foundation for subsequent investigations into the synergistic application of natural compounds and conventional antibiotics against MRSA.

Background/Objectives: The emergence of methicillin-resistant Staphylococcus aureus (MRSA) highlights the need for new antibacterial agents. Here, we report the identification and evaluation of a novel Gram-positive selective antibacterial: NDM-552. Methods: Antibacterial activity was determined by broth microdilution against a panel of Gram-positive and Gram-negative pathogens. Mechanistic studies included BOCILLIN-FL competition assays, microscale thermophoresis (MST), and antibiotic interaction with oxacillin and moenomycin. Additionally, time-kill analyses, frequency-of-resistance measurements, cytotoxicity assays, plasma stability studies, and a murine wound infection model were performed to characterize NDM-552. Results: NDM-552 exhibits activity against Gram-positive pathogens including S. aureus, Enterococcus faecium, and Staphylococcus epidermidis, with minimum inhibitory concentrations (MICs) of 1-2 µg/mL. NDM-552 displays no activity against Gram-negative bacteria. NDM-552 displays bacteriostatic activity against MRSA and additive interactions with oxacillin and moenomycin. The frequency of resistance in MRSA is low (2.39 × 10[-9]). BOCILLIN-FL competition assays and MST binding analysis identify the essential penicillin-binding protein 2 (PBP2) as the potential target of NDM-552. NDM-552 demonstrates acceptable cytotoxicity, favorable plasma stability, and reduces bacterial burden in a murine wound infection model. Conclusions: NDM-552 is a potent Gram-positive selective antibacterial agent that potentially targets PBP2-associated cell wall biosynthesis and exhibits in vivo efficacy against MRSA. Findings establish NDM-552 as a promising scaffold for the development of new antibacterial agents.

Lactococcosis is an important bacterial disease affecting farmed fish worldwide and is primarily associated with Lactococcus garvieae, Lactococcus petauri, and Lactococcus formosensis. In Thailand, information on L. garvieae infection in tilapia remains limited, particularly regarding genome-based identification, virulence determinants, and antimicrobial resistance profiles. This study characterized two L. garvieae isolates, AAHM-LG2501 and AAHM-LG2509, recovered from a lactococcosis outbreak in cage-cultured Nile tilapia (Oreochromis niloticus) in Ubon Ratchathani province, Thailand. Both isolates exhibited typical phenotypic characteristics of L. garvieae, including Gram-positive cocci, alpha hemolysis, positive capsule staining, and positive carbohydrate fermentation. Whole-genome sequencing confirmed both isolates as L. garvieae, with genome sizes of approximately 1.95 Mb and a G + C content of 38.9%. Genome-based taxonomic analysis supported species identification based on dDDH and ANI values, and both isolates were assigned to sequence type ST95 and serotype I. Virulence factor analysis identified 288 virulence-associated genes representing 97 virulence factors across 14 functional categories. Capsule-associated genes were prominent, together with genes involved in heme uptake, adhesion, hemolysis, stress survival, biofilm formation, and host adaptation. Ten capsule biosynthesis genes, including cpsABCFGKO, cps4A, and cps4I, as well as LPxTG cell wall anchor protein genes, were detected. Antimicrobial susceptibility testing showed resistance to nalidixic acid, oxolinic acid, and oxacillin, while reduced inhibition zones were observed for enrofloxacin and sulfamethoxazole-trimethoprim. Genome analysis identified predicted antimicrobial resistance determinants, including lsaD, vanT, vanY, and mdtA. Resistance-associated protein variants were detected in gyrA and gyrB, suggesting that target alteration may contribute to fluoroquinolone resistance. Overall, this study provides genome-level evidence of virulence and antimicrobial resistance determinants in L. garvieae from Thai tilapia and highlights the importance of whole-genome sequencing for accurate diagnosis, epidemiological surveillance, and disease management in aquaculture.

Nocardia farcinica is a highly virulent opportunistic pathogen with a marked propensity to cause disseminated infection in immunocompromised hosts. Its clinical manifestations are often nonspecific, conventional empirical anti-infective therapy may be ineffective, and both misdiagnosis and mortality rates remain high. We report the case of a 20-year-old man with membranous nephropathy who developed multiple cutaneous and deep soft-tissue abscesses, fever, and pulmonary infiltrates after 7 months of dual immunosuppressive therapy with methylprednisolone and tacrolimus. Initial empirical treatment with oxacillin plus moxifloxacin failed to control the infection, and the patient continued to experience high fever with persistently elevated inflammatory markers. Direct smear examination of pus specimens showed weakly acid-fast, branching filamentous organisms, and culture followed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) identified the pathogen as Nocardia farcinica. According to antimicrobial susceptibility testing, therapy was adjusted to trimethoprim-sulfamethoxazole (SMZ-TMP) combined with amoxicillin/clavulanate potassium. The patient subsequently became afebrile, the abscesses gradually decreased in size, and inflammatory markers improved substantially. After clinical stabilization, he was discharged on continued oral anti-infective therapy and showed no evidence of recurrence during 12 months of outpatient follow-up. Together with a review of the literature, this report discusses the clinical features, etiological diagnostic strategies, and susceptibility-guided anti-infective regimens for disseminated Nocardia farcinica infection in immunosuppressed patients, with the aim of providing a practical reference for clinical diagnosis and treatment.