Epidemiological analysis and prevention strategies in response to a shigellosis cluster outbreak: a retrospective case series in an alternative school in the Republic of Korea, 2023.

BACKGROUND: In March 2023, an alternative school in the Republic of Korea reported 12 cases of shigellosis. This study aims to analyze the epidemiological characteristics in order to determine the cause of the cluster outbreak of shigellosis and to develop prevention strategies. METHODS: This study focused on 12 patients with confirmed Shigella infection and investigated their demographics, clinical features, epidemiology, diagnostics, and antimicrobial susceptibility. Following the identification of Shigella, we conducted follow-up rectal smear cultures to manage patients, implementing isolation and control measures. RESULTS: This study investigated the emergence of multidrug-resistant Shigella following missionary activities in Cambodia, documenting a cluster infection within an alternative school in Daejeon, the Republic of Korea. The outbreak affected 56 participants, resulting in the confirmation of 12 cases. The incidence rates varied by gender and occupation, with higher rates among males and teachers. All 12 cases demonstrated multidrug resistance. Challenges included delayed pathogen confirmation and suboptimal adherence to isolation criteria. The incident prompted revisions in the criteria for isolation release, focusing on symptom resolution. The study underscores the necessity for strengthened surveillance, educational initiatives focusing on prevention in endemic areas, and improved oversight of unlicensed educational establishments. CONCLUSION: Successful response strategies included swift situation assessment, collaborative efforts, effective infection control measures, and modified criteria for isolation release. Continued surveillance of multidrug-resistant strains is recommended, especially in regions with a high prevalence.

Unusual enantiomeric separation due to residual amines in chiral crown ether stationary phase linked by long alkyl chain.

A new chiral stationary phase (CSP) in which (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid was linked to a silica gel surface through a long alkyl chain and which did not contain additional aminoundecyl groups was prepared. Generally, when enantiomers containing a primary amine group are optically resolved using a crown-ether-type CSP, a higher resolution is achieved if the surface of the CSP does not contain any residual amine. In this study, the chiral separation factor and resolution factor of a CSP with a long alkyl chain such as the aminoundecyl group were unusually low in the absence of the residual aminoundecyl groups. In this study, a chiral column was prepared by introducing a chiral selector having a long alkyl chain on the surface of silica gel to separate enantiomers of α-amino acids. Furthermore, it was confirmed that the residual-amine-containing CSP, which was easier to synthesize, facilitated more effective enantiomeric separation than the CSP without residual amines.

Characterization of the optical properties of silver nanoparticle films.

To understand the collective properties of nanoparticles, it is necessary to control the particle size, spacing and ordering. Here we describe the chemical synthesis of well-controlled silver nanoparticles, the wet coat preparation and the optical properties of its film. The light incidence angle and polarization dependency of the resonant spectra show distinctive surface plasmon resonance extinction peaks for isolated particles and the coupled modes of neighbouring particles. Furthermore, we discuss the thermal treatment and dielectric surrounding effects on the optical properties of silver nanoparticle film.

Highly active heterogeneous Fenton catalyst using iron oxide nanoparticles immobilized in alumina coated mesoporous silica.

A highly active heterogeneous Fenton catalyst was fabricated by impregnating iron oxide nanoparticles in alumina coated mesoporous SBA-15 silica.

Pediatric radiofrequency catheter ablation: results of initial 100 consecutive cases including congenital heart anomalies.

Radiofrequency catheter ablation (RFCA) has recently become a management option for pediatric tachycardia. We reviewed the records of a total of 100 patients (aged 10 months to 19 yr) who had undergone RFCA, from March 2000 to June 2004. Types of arrhythmia (age, acute success rate) were as follows: atrioventricular reentrant tachycardia (AVRT, 9.0+/-3.7 yr, 66/67), atrioventricular nodal reentrant tachycardia (AVNRT, 13+/-2.5 yr, 16/16), ectopic atrial tachycardia (6.4+/-3.3 yr, 5/5), junctional ectopic tachycardia (10 month, 1/1), ventricular tachycardia (12+/-4.9 yr, 6/6), postsurgical intraatrial reentrant tachycardia (15.6+/-4.1 yr, 2/3), twin node tachycardia (4 yr, 0/1), and His bundle ablation (9 yr, 1/1). The age of AVNRT was older than that of AVRT (p=0.002). Associated cardiac disease was detected in 17 patients, including 6 univentricular patients, and 3 Ebstein's anomaly patients. RFCA for multiple accessory pathways required longer fluoroscopic times than did the single accessory pathway (53.9+/-4.8 vs. 36.2+/-24.1 min; p=0.03), and was associated with a higher recurrence rate (3/9 vs. 3/53; p=0.03). Regardless of the presence or absence of cardiac diseases, the overall acute success rate was 97% without major complications, the recurrence rate was 8.2%, and the final success rate was 97%. This experience confirmed the efficacy and safety of RFCA in the management of tachycardia in children.

Simple synthesis of hierarchically ordered mesocellular mesoporous silica materials hosting crosslinked enzyme aggregates.

Hierarchically ordered mesocellular mesoporous silica materials (HMMS) were synthesized using a single structure-directing agent. The mesocellular pores are synthesized without adding any pore expander; the pore walls are composed of SBA-15 type mesopores. Small-angle X-ray scattering revealed the presence of uniform pore structures with two different sizes. Using HMMS as a nanoscopic template, hierarchically ordered mesocellular mesoporous carbon (HMMC) and polymer (HMMP) materials were synthesized. HMMS was used as a host for enzyme immobilization. To improve the retention of enzymes in HMMS, we adsorbed enzymes, and then employed crosslinking using glutaraldehyde (GA). The resulting crosslinked enzyme aggregates (CLEAs) show an impressive stability with extremely high enzyme loadings. For example, 0.5 g alpha-chymotrypsin (CT) could be loaded in 1 g of silica with no activity decrease observed with rigorous shaking over one month. In contrast, adsorbed CT without GA treatment resulted in a lower loading, which further decreased due to continuous leaching of adsorbed CT under shaking. The activity of crosslinked CT aggregates in HMMS was approximately 10 times higher than that of the adsorbed CT, which represents a 74-fold increase in activity per unit weight of HMMS due to higher CT loading.