Non-typhoidal salmonellosis remains a pressing public health problem worldwide. Quinolones, particularly fluoroquinolones, are widely used to treat various infections, including non-typhoidal salmonellosis, which can be a serious illness. The emergence of fluoroquinolone-resistant Salmonella has resulted in treatment failure and high mortality rates. In this study, we estimated the presence of plasmid-mediated quinolone resistance (PMQR) genes in Salmonella enterica isolated from human salmonellosis patients in South Korea from 2016 to 2019. We evaluated the association of these genes with fluoroquinolone susceptibility. Antimicrobial susceptibility tests for Salmonella isolates were performed using the Vitek II system, and the minimum inhibitory concentrations (MIC) of ciprofloxacin and levofloxacin were determined using the E-test method. Plasmid-mediated quinolone resistance (PMQR) genes were detected by PCR amplification and quinolone resistance-determining regions (QRDRs) of the gyrA and parC genes were analyzed following Sanger sequencing of the PCR products. Thirty-four Salmonella strains with reduced susceptibility to fluoroquinolones (ciprofloxacin MIC ≥ 0.125 µg/mL and levofloxacin MIC ≥ 0.25 µg/mL) were selected from 208 human clinical Salmonella isolates. Among them, 22 Salmonella strains harbored one PMQR gene (qnrA, qnrB, or qnrS), and three Salmonella strains carried two PMQR genes (qnrS and aac(6′)-Ib-cr or qnrA and qnrB). qnrS was the most common PMQR gene. Serotyping revealed that Salmonella 4,[5]12:i:- (32.4%, 11/34) and Salmonella Typhimurium (29.4%, 10/34) were the two most predominant serovars, and Multi-locus sequence typing (MLST) showed that ST19 and ST34 were the most frequent sequence types. In conclusion, qnr gene-positive Salmonella 4,[5],12:i:- and Salmonella Typhimurium were the main serovars responsible for reduced susceptibility to fluoroquinolones. Therefore, our findings suggest that PMQR-positive Salmonella strains, which can be isolated from various samples including human, food, and the environment, should be carefully monitored.

This study was conducted to evaluate the microbiological hazard on nursery school children's hands and to investigate the reduction effect of hand washing education. A total of 59 nursery school children's hands were tested. The average number of total aerobic bacteria was 3.72 ± 0.38 log CFU/hand. Five children's hands(2 male and 3 female) were positive(14.3%) for the coliform bacteria. These results showed that hand washing education are required repetitively. Among the pathogenic bacteria tested in this study, Staphylococcus aureus and Bacillus cereus were detected in 9(25.7%) and 16(45.7%) out of 35 their hands, respectively. Twelve out of sixteen B. cereus isolates(70.0%) produced enterotoxin. The results indicate that the hand hygiene of nursery school children needs to be improved. Comparing before and after hand washing in educated and non-educated group, the reduction effect of total aerobic bacteria on their hands was 0.42 and 0.60 log CFU/hand, respectively. The educated group showed 0.18 log CFU/hand higher reduction effect than non-educated group but microorganism did not eliminate perfectly. From the results, using a hand sanitizer after washing with soap and the continuous hand washing education are required to control the contaminated bacteria on nursery school children's hands.

An acute gastroenteritis (AGE) outbreak was reported in May 2013 in Gyeonggi Province, South Korea. Eight students who had eaten breakfast on 21 May 2013 at a high-school restaurant exhibited AGE symptoms. Our case-control study showed that a strong association was observed between AGE symptoms and fermented oyster consumption. Virological studies also indicated that noroviruses (NoVs) were detected from both clinical samples and fermented oyster samples, and multiple different genotypes (genogroups GII.4, GII.11 and GII.14) of NoVs were present in both samples. The nucleotide sequence similarity between the strains found in the clinical samples and those in the fermented oysters was more than 99·5%. Therefore, to prevent further outbreaks, proper management of raw oysters is necessary and the food industry should be aware of the risk of viral gastroenteritis posed by fermented oysters contaminated with NoVs.

This study was conducted to survey the epidemiological characteristics and the isolated strains for pathogenic E. coli which was the major causative organisms for food poisoning occurred at school food services in the Gyeonggi-do area during the past three years. We investigated 19 accidents of food-borne disease outbreaks by pathogenic E. coli at school food services from 2010 to 2012. Food-borne disease outbreaks by pathogenic E. coli were usually occurred at direct management type (18 accidents, 95%) and high schools. For the seasonal factors, 13 accidents (65%) were occurred in June to September, especially the end of August and September after the summer holidays. The first patients were occurred on Wednesday (7 accidents, 37%) and Thursday (7 accidents, 37%), and they were mainly reported on Thursday (7 accidents, 37%) and Friday (5 accidents, 26%). The exposure of risk was estimated in Monday (4 accidents, 21%), Tuesday (7 accidents, 37%) and Wednesday (4 accidents, 21%), and kimchi (5 accidents, 50%) was estimated as the food of the high risk responsible for the outbreaks. 98 isolates of pathogenic E. coli consisted of PEC (50%), ETEC (34%), EAEC (15%), and EHEC (1%). The antibiotic resistance of pathogenic E. coli showed in the descending order of ampicilline (40%), nalidixic acid (37%), trimethoprim/sulfamethoxazole (24%), and tetracycline (19%). The antibiotics of second and third generation cephalosporins, cabarpenem, aminoglycosides, and second generation quinolones had antimicrobial susceptibilities and cefalotin, ampicillin/sulbactam and chloramphenicol showed medium resistance at 29%, 25%, and 6% respectively, and 70% of isolates were resistant to more than one antibiotic. By the PFGE analysis, they were classified into nine major groups and 31 profiles with 57% pattern similarity. It was very difficult to find the correlation of antimicrobial susceptibilities and genotype in the small scale-food poisoning, but the similarity of antimicrobial resistance and PFGE patterns in the large scale-food poisoning enabled the outbreaks to estimate the same pathotype of E. coli derived from identical origins.

Campylobacter jejuni is one of important food-borne pathogens causing human gastroenteritis. We isolated 42 strains of C. jejuni from diarrhea patients and 4 food-poisoning outbreaks in 2010, Gyeonggi-do. In this study, 42 strains were tested for genetic characteristics, the serotype distribution and antimicrobial resistant rate. The presence of hipO (100%), cdtB (100%), and mutated gyrA (