Impact of vancomycin use trend change due to the availability of alternative antibiotics on the prevalence of Staphylococcus aureus with reduced vancomycin susceptibility: a 14-year retrospective study.

BACKGROUND: We investigated the trend change in vancomycin-intermediate Staphylococcus aureus (VISA)/heterogeneous VISA (hVISA) prevalence among methicillin-resistant S. aureus (MRSA) bacteremia strains and antistaphylococcal antibiotic use together with mutation studies of vancomycin resistance-related gene loci to evaluate the impact of changes in antibiotic use after new antistaphylococcal antibiotics became available. METHODS: Among 850 healthcare-associated MRSA isolates from 2006 to 2019 at a tertiary hospital in South Korea, hVISA/VISA was determined by modified PAP/AUC analysis, and the identified hVISA/VISA strains were genotyped. Gene mutations at vraSR, graSR, walKR, and rpoB were studied by full-length sequencing. Antistaphylococcal antibiotic use in 2005-2018 was analyzed. RESULTS: Two VISA and 23 hVISA strains were identified. The prevalence rate ratio of hVISA/VISA carrying mutations at the two-component regulatory systems among MRSA was 0.668 (95% CI 0.531-0.841; P = 0.001), and the prevalence rate ratio of hVISA/VISA carrying rpoB gene mutations was 1.293 (95% CI 0.981-1.702; 174 P = 0.068). Annual vancomycin use density analyzed by days of therapy (DOT) per 1,000 patient-days did not decrease significantly, however the annual average length of time analyzed by the number of days vancomycin was administered for each case showed a significantly decreasing trend. CONCLUSIONS: During the 14-year period when the average length of vancomycin therapy decreased every year with the availability of alternative antibiotics, the prevalence of hVISA/VISA did not decrease significantly. This seems to be because the resistant strains carrying the rpoB mutations increased despite the decrease in the strains carrying the mutations at the two-component regulatory systems.

Monitoring of the Binding Between EGFR Protein and EGFR Aptamer Using In-Situ Total Internal Reflection Ellipsometry.

The epidermal growth factor receptor (EGFR) protein has received significant attention in medical biotechnology because it is an important component in cell growth and division. We report the results of a study on the binding between the EGFR protein and the associated aptamer, measured in real time. Aptamers can be used for clinical purposes including macromolecular medicine and basic research. In particular, EGFR aptamers are promising molecular agents for targeting cancer. The data were obtained in-situ with total internal reflection ellipsometry (TIRE), which combines the analytic capability of spectroscopic ellipsometry with the high surface sensitivity of surface plasmon resonance measurements. Our results show that TIRE can be used to determine adsorption of nanoscale biomolecules. Our results are supported by additional data obtained by liquid atomic-force-microscopy.

Development of bio-nanowire networks using phage-enabled assembly for biological sensor application.

This paper proposes a new approach to detect an electrochemical reaction using a working area consisting of bio-nanowires from genetically modified filamentous phages and nanoparticles. Use of the nanomaterials on the working electrode is a vital consideration in biological sensor development, because the biosensor sensitivity heavily depends on the material used. Here we use that fd-tet p8MMM filamentous phages displaying the MMM peptide on the major coat protein pVIII (designated p8MMM phages) were immobilized on the active area of an electrochemical sensor through chemical binding. The bio-nanowires composed of p8MMM phages and silver nanoparticles facilitated sensitive, rapid detection of particular molecules. We performed the experiment for observing electrochemical glucose detection to estimate the possibility of using one or other characterized-biological sensor. The current response of the bio-nanowire sensor reached sufficiently high signals at various glucose concentrations (10(-7) to 10(-4)M). The cyclic voltammetry peak current I(p) and peak potential E(p) were 689microA/cm(2) and 280mV, respectively. The filamentous nanophage-based electrode displayed a high sensitivity and good stability under various pH and temperature in enzyme determination. As a result, it may have wide application in analytical systems, label-free detection and biological sensors.