Prevalence of Carbapenem-Resistant Enterobacteriaceae in Seoul, Korea

The prevalence of carbapenem-resistant Enterobacteriaceae (CRE) is increasing globally. However, a few studies have addressed their epidemiology in Seoul, Korea. In this study, we conducted one-year surveillance of CRE among 1,468 clinical isolates of Enterobacteriaceae at the hospital in Seoul with molecular characterization of carbapenemase genes. About 85% of CRE-positive samples were isolated from the elderly age group (above 60 years). The most common isolated organisms were Klebsiella pneumoniae (K. pneumoniae) (56.5%) and Escherichia coli (E.coli) (17.0%). We detected six different Carbapenemase-producing Enterobacteriaceae (CPE) of blaKPC, blaNDM, blaOXA, blaVIM, blaIMP, and blaGES alone or in combination with other bla genes. Typically, 853 (58.1%) isolates were tested positive for at least one CPE. KPC (K. pneumoniae carbapenemase)-2 was the most common CPE type (46.0%) followed by NDM (New Delhi metallo-β-lactamase)-1 (5.9%). KPC-2 was most commonly found in K. pneumoniae (494/676 isolates [73.1%]) and E.coli (107/676 isolates [15.8%]), whereas NDM-1 was commonly found in Enterobacter cloacae complex (20/86 isolates [23.3%]). Detailed information and molecular characteristics of CPE is essential to prevent the spread of these pathogens.

Mutations in gyrA and parC Genes and Plasmid-Mediated Quinolone Resistance in Non-typhoid Salmonella Isolated from Pediatric Patients with Diarrhea in Seoul

A total of 91 non-typhoid Salmonella isolated from pediatric patients with diarrhea in Seoul from 2003 to 2009 was tested for antimicrobial susceptibility of nalidixic acid (NA). Forty strains of NA resistance or intermediate susceptible non-typhoid Salmonella were identified and their minimum inhibitory concentrations (MICs) of NA, ciprofloxacin (CIP), and norfloxacin (NOR) were determined. Of the 40 isolates, 26 were resistant to NA (MIC >256 microg/ml). Only one isolate was high-level resistant to CIP (12 microg/ml) and NOR (48 microg/ml). Mutations in gyrA and parC genes were studied by PCR and sequencing. All NA-resistant isolates carried point mutations in the gyrA quinolone resistance determining regions (QRDR) at codon 83 or 87 (MICs of NA, >256 microg/ml; MICs of CIP, 0.047~0.25 microg/ml; MICs of NOR, 0.38~1.5 microg/ml). A double change in GyrA was found in one Salmonella Enteritidis (MIC of CIP, 12 microg/ml; MIC of NOR, 48 microg/ml). In respect of the ParC protein, a single change at Thr57-->Ser was found in 3 isolates (MICs of NA, >256 microg/ml; MICs of CIP, 0.19~0.25 microg/ml; MICs of NOR, 1 microg/ml). At the same time, these strains changed from Ser83 to Tyr in the gyrA. The result of the investigation for the prevalence of plasmid-mediated quinolone resistance (PMQR) genes, 14 isolates harbored qnr gene among 40 isolates. All of 14 isolates showed decreased susceptibility at NA (MICs 4~16 microg/ml) and except one strain, all of qnr genes were identified as qnrB. Mutations in the gyrA gene and production of PMQR determinants were critical for quinolone resistance and decreased susceptibility to fluoroquinolone in these isolates.

Molecular Epidemiology of Legionella pneumophila Isolated from Bath Facilities of Public Establishments in Seoul

The genus Legionella is common in aquatic environments. Some species of Legionella are recognized as potential opportunistic pathogens for human, notably Legionella pneumophila that causes Legionellosis. During the summer season between June and August in 2010, we isolated 61 L. pneumophila from the bath facilities of public establishments of 25 wards in Seoul. The existence of 16S rRNA and mip gene of L. pneumophila was confirmed in the genome of the isolated strains by PCR. Among the 61 strains of L. pneumophila, thirty three isolates belong to serogroup 1 (54.1%), 13 isolates were serogroup 6 (21.3%), 9 isolates were serogroup 5 (14.8%), 3 isolates were serogroup 3 (4.9%), and 3 isolates were identified in serogroup 2 (4.9%). On pulsed-field gel electrophoresis (PFGE) analysis using SfiI, genetic types of L. pneumophila were classified into 8 (A to H) patterns by the band similarity with excess of 65%. Our results suggest the existence of serological and genetic diversity among the L. pneumophila isolates.

Surveillance of Acute Gastroenteritis in Seoul, Korea, During May 2004 and June 2007

Acute gastroenteritis (AGE), which is one of the most common diseases worldwide, primarily occurs in infants and young children in both developed and developing countries. To investigate the prevalence of AGE in Korea, 6,788 stool specimens collected from hospitalized patients with AGE in Seoul, Korea from March 2004 to June 2007 were analyzed by enzyme immunoassay, reverse transcription-PCR, DNA sequencing and phylogenetic analysis. Enteric viruses and bacteria were detected in 2,955 (43.5%) and 1,389 (20.5%) specimens, respectively. Among the enteric viruses detected, rotavirus (19.7%) and norovirus (18.9%) were the predominant causative agents, followed by adenovirus (2.5%) and astrovirus (2.4%). Staphylococcus aureus was the most commonly observed bacteria (8.0~19.2%). The epidemic peaks of the enteric viruses were October to December for norovirus, January to May for rotavirus, and August to October for adenovirus. The seasonal activity of rotavirus was shifted from winter to late spring. However, astrovirus did not display seasonal activity in this study. Although viral AGE primarily occurred in patients younger than 5 years of age, the incidence of viral AGE in children aged 6 to 14 years was significant. The results of this study will contribute to the currently available epidemiological data and improve public health and hygiene via amelioration of diagnostic methods and longitudinal surveillance.

Detection of Antibiotic Resistant Genes in Salmonella enterica Serovar Typhimurium Isolated from Foodborne Patients in Seoul Using Multiplex-PCR

The frequency of antibiotic resistance among Salmonella enterica serovar Typhimurium has increased due to the transfer of multiple resistance factors. We detected the 13 antibiotic resistance genes by multiplex-PCR and compared with the results of phage typing and antibiotic disk diffusion for 49 S. typhimurium isolated from food-poisoning outbreaks in Seoul from 1999 to 2002. Resistance genes for tetracycline, streptomycin, ampicillin, sulfonamide, amino-glycoside-modifying enzyme, chloramphenicol, kanamycin, and trimethoprim were detected in 67.3%, 57.1%, 26.5%, 8.1%, 8.1%, 5%, 2.0%, and 0% of isolates, respectively. Overall 28 isolates (57.1%) possessed two or more antibiotic resistance genes. Class 1 integron carrying multidrug resistace genes, ant(3")-IaB, blaPSE, qacE delta1/sul, and tet G were amplified especially in only DT104 isolates. Among the related resistance genes for same antibiotics, strA and strB for streptomycin resistance were simultaneously detected but tetA and tetB for tetracycline were sporadically detected. DT 104 isolates contained only aadA2 and tetG.

Biotype, serotype and antimicrobial susceptibility of yersinia enterocolitica isolated from cattle

No abstract available.