Search Results (3)

Backgrunod/Objectives: Routine identification of common bacterial pathogens is typically efficient, utilizing standardized, cost-effective methods. However, the diagnostic process becomes significantly more complex when dealing with rare or unexpected microorganisms, especially as they can be considered colonizers in many cases. Methods: This study presents diagnostic details of an uncommon pathogen, Vibrio alginolyticus, isolated from auricular discharge in a patient with non-Hodgkin lymphoma diagnosed with persistent otitis externa and explores its identification through both conventional and modern laboratory approaches. Sequential ear discharge cultures resulted in phenotypically similar but genomically different Vibrio alginolyticus isolates. We complemented classical methods like conventional culture (on Columbia agar and CLED agar), Vitek2 Compact identification, and EUCAST disk diffusion antimicrobial susceptibility testing (following the EUCAST version 12.0 guidelines) with MALDI-TOF mass spectrometry and Illumina/Nanopore whole genome sequencing. Comparative analysis of the genomes was performed with the PeGAS pipeline, Unicycler, and 1928Diagnostics SNP analysis. Results: The Vitek2 analysis identified both isolates as V. alginolyticus with 99% confidence, and this was supported by the MALDI-TOF MS results. The first isolate (A) was fully susceptible to the antibiotics tested, while the second (B) showed resistance to ciprofloxacin. Whole genome sequencing revealed 99.23% and 98.60% nucleotide identity to the V. alginolyticus reference genome for isolates A and B, respectively, with a 99.8% match between them. Isolate B acquired a gyrA (c.1870C>T) mutation that correlates with the ciprofloxacin resistance (MIC > 0.5 mg/L). Both genomes carry hlyA (hemolysin), toxR (cholera toxin regulator), genes involved in biofilm formation (rpoN, relA, spoT, opp), luxS (motility), proA, vacB (virulence factors), and tet(34) (oxytetracycline resistance). A core genome SNP distance of <100 indicates clonal relatedness. Our integrated (phenotypic and genomic) diagnostic approach confirmed V. alginolyticus and documented host resistance evolution, with a virulence repertoire that could explain the clinical evolution. Conclusions: This case highlights the utility of molecular methods in confirming species identity, detecting resistance markers, characterizing virulence determinants, and differentiating a pathogen from a colonizer, supporting targeted clinical management. Full article

USA300 is a predominant community-associated methicillin-resistant Staphylococcus aureus strain which carries an arginine catabolic mobile element (ACME). ACME contains potential virulence factors including an arginine deiminase (arc) pathway and an oligopeptide permease (opp-3) system, which are proposed to play a role in bacterial virulence and transmission. However, the role of ACME in evolution and pathogenicity of USA300 remains to be elucidated. ACME and arcA deletion mutants were created by allelic replacement from a USA300 clinical isolate. By comparing wild type and isogenic ACME deletion USA300 strains, ACME was shown not to contribute to bacterial survival on plastic surfaces, and mouse skin surfaces. ACME did not contribute to bacterial virulence in cell invasion and cytotoxicity assays, invertebrate killing assays and a mouse skin infection model. Wild-type ACME negative USA300 clinical isolates showed similar associations with invasive anatomic sites as ACME positive isolates. Our experiments also demonstrated that ACME can spontaneously excise from the bacterial chromosome to generate an ACME deletion strain at a low frequency. Our results do not support that the ACME element alone is a significant factor in the transmission and virulence of USA300 strain, and ACME may have been coincidently incorporated into the genome of USA300. Full article

“City” could be viewed as an integration of various service systems with relocated social, economic, and environmental capitals under urbanization. It was evidential in Hsinchu City, Taiwan, where once the biggest market, Dongmen Market (DMM), declined because the replacement of urban consumption patterns along with the setup of high tech science park bringing new residences. This research took the perspectives of Service-Dominant Logic (S-DL) and Actor Network Theory (ANT) to study the development of new service systems and how they were sustained through the revitalization by a two-year ethnographic study. We explain how stakeholders propose and receive value within and among service systems. A unique actor called obligatory passage point (OPP) was formed in the translation phases of actor networks, delivering the co-created value by stakeholders with different interests. Four identified OPPs indicated that their “evolution process” drove the revitalization of DMM toward a sustainable service system. A framework of open innovation practice was formulated as iterative cycles with four phases: (1) actor interacting; (2) value co-creating; (3) relationship modeling; and (4) OPP transforming, which operationalized the OPP evolution from its destruction to construction. The application of the OPP evolution process to revitalizing urban service systems contributes to practitioners in social innovation to sustain urban service systems in addition to the theoretical formation of OPP evolution. Full article