Salmonellosis outbreaks linked to eggs at 2 gimbap restaurants in the Republic of Korea.

Objectives: Salmonellosis outbreaks occurred at 2 restaurants 2 days apart, and an epidemiological investigation was conducted to determine whether the outbreaks were connected. Methods: Case studies were conducted for both outbreaks. Stool samples were collected from individuals, and food samples were collected from the restaurants. Pulsed-field gel electrophoresis (PFGE) and whole-genome sequencing analyses were performed on outbreak-related Salmonella enterica serovar Enteritidis (Salmonella Enteritidis) isolates. Traceback investigations were also conducted for the ingredients from gimbap restaurants A and B. Results: In total, 106 people from gimbap restaurant A and 5 from gimbap restaurant B met the case definition. Salmonella Enteritidis was detected in samples from 2 food handlers, 22 patients, and 1 food (iceberg lettuce) at gimbap restaurant A and from 1 patient at gimbap restaurant B. According to PFGE, all isolates were identified as SEGX01.089. The molecular typing of all isolates showed the same pattern, and the genetic distance was close according to phylogenetic analysis. Eggs were the only food ingredient that was supplied to both gimbap restaurants. Conclusion: The outbreaks were caused by Salmonella Enteritidis, and the source of infections was suspected to be contaminated eggs. To prevent foodborne outbreaks of Salmonella, restaurants should heat eggs sufficiently, and egg farms need to establish management systems that prevent Salmonella infections.

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.

Distribution of Extended-Spectrum-ß-Lactamase-Producing Diarrheagenic Escherichia coli Clonal Complex 10 Isolates from Patients with Diarrhea in the Republic of Korea.

ESBL-producing E. coli is a public health concern in healthcare settings and the community. Between 2009 and 2018, a total of 187 ESBL-producing pathogenic E. coli isolates were identified, and clonal complex (CC) 10 was the predominant clone (n = 57). This study aimed to characterize the ESBL-producing pathogenic E. coli CC10 strains obtained from patients with diarrhea to improve our understanding of CC10 distribution in the Republic of Korea. A total of 57 CC10 strains were selected for comprehensive molecular characterization, including serotype identification, the analysis of antibiotic resistance genes, the investigation of genetic environments, the determination of plasmid profiles, and the assessment of genetic correlations among CC10 strains. Among the CC10 isolates, the most prevalent serotype was O25:H16 (n = 21, 38.9%), followed by O6:H16 (10, 19.6%). The most dominant ESBL genes were blaCTX-M-15 (n = 31, 55%) and blaCTX-M-14 (n = 15, 27%). Most blaCTXM genes (n = 45, 82.5%) were located on plasmids, and these incompatibility groups were confirmed as IncB/O/K/Z, IncF, IncI1, and IncX1. The mobile elements located upstream and downstream mainly included ISEcp1 (complete or incomplete) and IS903 or orf477. Phylogenetic analysis showed that the CC10 strains were genetically diverse and spread among several distinct lineages. The results of this study show that ESBL-producing pathogenic E. coli CC10 has been consistently isolated, with CTX-M-15-producing E. coli O25:H16 isolates being the major type associated with the distribution of CC10 clones over the past decade. The identification of ESBL-producing pathogenic E. coli CC10 isolates underscores the possible emergence of resistant isolates with epidemic potential within this CC. As a result, continuous monitoring is essential to prevent the further dissemination of resistant ESBL-producing E. coli CC10 strains.

Dissemination of the high-risk cloneST147 carbapenem-resistant klebsiella pneumoniae from a local tertiary care hospital in the Republic of Korea.

BACKGROUND: The emergence of carbapenem-resistant Enterobacterales (CRE) infections is rapidly increasing and represents a serious public threat. In 2020, a total of 16,883 carbapenemase-producing Enterobacterales strains were collected; among these isolates, 21 strains were repeatedly isolated in a local tertiary care hospital. METHODS: Antimicrobial susceptibility testing was performed using the broth microdilution method. All 21 strains of CRKP were analyzed by PFGE after XbaI digestion. The 21 CRKP strains were sequenced on the Illumina Miseq and Oxford Nanopore GridION platforms. RESULTS: These 21 CRKP isolates showed an identical antimicrobial resistance profile, including resistance to ampicillin, carbapenems, cephems, chloramphenicol, fluoroquinolone, macrolides and trimethoprim/sulfamethoxazole. Based on whole-genome analysis, these 21 CRKP isolates shared a common genetic structure (ISAba125-IS630-blaNDM-1-bleMBL) and harbored additional resistance determinants (blaOXA-1, blaCTX-M-15, blaSHV-11, blaSHV-67, aac(6')-Ib-cr, qnrS1, OqxA, OqxB, catB3, mph(A), sul1, and dfrA12) and mutations in the quinolone resistance-determining regions of gyrA (S83I) and parC (S80I). These isolates belonged to the ST147 and KL64 capsular types, which were carried on IncFIB replicon plasmids. The 21 CRKP strains collected from one hospital were divided into five PFGE patterns, and they were closely related with a minimum similarity value of 95.2%. These isolates were found to be highly related based on the presence of between 2 and 27 SNPs. CONCLUSIONS: These findings indicate that NDM-1-producing K. pneumoniae ST147 may have been introduced via a common source, implying nosocomial transmission; furthermore, continuous monitoring is necessary to prevent endemic transmission.

Evaluation of MGIT 960 System for the Second-Line Drugs Susceptibility Testing of Mycobacterium tuberculosis.

Many laboratories validate DST of the second-line drugs by BACTEC MGIT 960 system. The objective of this study is to evaluate the critical concentration and perform DST for the 2nd line drugs. We evaluated 193 clinical strains of M. tuberculosis isolated from patients in South Korea. Testing the critical concentration of six second-line drugs was performed by MGIT 960 and compared with L-J proportion method. The critical concentration was determined to establish the most one that gave the difference between drug resistance and susceptibility in MGIT960 system. Good agreement of the following concentrations was found: Concordance was 95% for 0.5 µ g/mL of moxifloxacin; 93.6%, 1.0 µ g/mL of levofloxacin; 97.5%, 2.5 µ g/mL of kanamycin; 90.6%, 2.5 µ g/mL of capreomycin; 86.2%, 5.0 µ g/mL of ethionamide; and 90.8%, 2.0 µ g/mL of ρ-aminosalicylic acid. The critical concentrations of the four drugs, moxifloxacin, levofloxacin, kanamycin, and capreomycin, were concordant and reliable for testing 2nd line drug resistance. Further study of ethionamide and ρ -aminosalicylic acid is required.

Nationwide surveillance study of vancomycin intermediate Staphylococcus aureus strains in Korean hospitals from 2001 to 2006.

We investigated the prevalence and the molecular characteristics of vancomycin-intermediate Staphylococcus aureus (VISA) among methicillin-resistant Staphylococcus aureus (MRSA) strains isolated from clinical samples at tertiary or general hospitals participating in a nationwide surveillance program for VISA and vancomycin-resistant Staphylococcus aureus (VRSA) in Korea during an 8-week period in each year from 2001 to 2006. Of 41,639 MRSAs isolated, 37,856 were screened and 169 grew on brain heart infusion agar supplemented with 4 microg/ml vancomycin. A vancomycin MIC of 4 microg/ml was confirmed for 33 VISA isolates of the 169 isolates. Eighteen of the 33 isolates were classified as hetero-VISA (hVISA) by the population analysis profile (PAP) method. All VISA isolates were susceptible to linezolid, tigecycline, and quinupristin-dalfopristin. Most VISA isolates (MIC 4 microg/ml) showed a PFGE C pattern with sec, seg, and sei enterotoxin genes, including ST5-SCCmec type II, or a PFGE A pattern with sea, including ST239-SCCmec type III.