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During nationwide Fantimicrobial surveillance (Korea Global Antimicrobial Resistance Surveillance System [Kor-GLASS]), the recent emergence of non-oxacillinase (OXA)-23 production by carbapenem-resistant Acinetobacter baumannii (CRAB) isolates was noted. In this study, we evaluated resistance mechanisms other than OXA-23 production to elucidate the shift in considerable CRAB clones. The presence of OXA carbapenemase genes, such as blaOXA-23 , blaOXA-24 , blaOXA-58 , and blaOXA-51-ISAba1, was determined by PCR. Other carbapenemase genes, such as blaIMP , blaVIM , blaNDM , blaKPC , blaGES , and blaOXA-48 , were determined using sequencing. Strains lacking carbapenemase genes were subjected to whole genome sequencing, and resistance genes were analyzed using ResFinder. Four CRAB strains were collected through a Kor-GLASS study in 2022, in which OXA-23 production was not identified. The carbapenemase genotypes of the four CRAB strains lacking blaOXA-23 were blaOXA-51 -ISAba1, blaOXA-66/ACD25 , blaOXA-182, and blaNDM-1 . To the best of our knowledge, this is the first study to identify CRAB producing New Delhi metallo-β-lactamase (NDM)-1 in Korea. In conclusion, domestic CRAB resistance mechanisms may undergo subtle changes. Continuous observations are required to monitor the emergence of new clones.
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Background@#Streptococcus pneumoniae is a serious pathogen causing various infections in humans. We evaluated the serotype distribution and antimicrobial resistance of S. pneumoniae causing invasive pneumococcal disease (IPD) after introduction of pneumococcal conjugate vaccine (PCV)13 in Korea and investigated the epidemiological characteristics of multidrug-resistant (MDR) isolates. @*Methods@#S. pneumoniae isolates causing IPD were collected from 16 hospitals in Korea between 2017 and 2019. Serotyping was performed using modified sequential multiplex PCR and the Quellung reaction. Antimicrobial susceptibility tests were performed using the broth microdilution method. Multilocus sequence typing was performed on MDR isolates for epidemiological investigations. @*Results@#Among the 411 S. pneumoniae isolates analyzed, the most prevalent serotype was 3 (12.2%), followed by 10A (9.5%), 34 (7.3%), 19A (6.8%), 23A (6.3%), 22F (6.1%), 35B (5.8%), 11A (5.1%), and others (40.9%). The coverage rates of PCV7, PCV10, PCV13, and pneumococcal polysaccharide vaccine (PPSV)23 were 7.8%, 7.8%, 28.7%, and 59.4%, respectively. Resistance rates to penicillin, ceftriaxone, erythromycin, and levofloxacin were 13.1%, 9.2%, 80.3%, and 4.1%, respectively. MDR isolates accounted for 23.4% of all isolates. Serotypes 23A, 11A, 19A, and 15B accounted for the highest proportions of total isolates at 18.8%, 16.7%, 14.6%, and 8.3%, respectively. Sequence type (ST)166 (43.8%) and ST320 (12.5%) were common among MDR isolates. @*Conclusions@#Non-PCV13 serotypes are increasing among invasive S. pneumoniae strains causing IPD. Differences in antimicrobial resistance were found according to the specific serotype. Continuous monitoring of serotypes and antimicrobial resistance is necessary for the appropriate management of S. pneumoniae infections.
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Imipenemase (IMP)-6–producing Pseudomonas aeruginosa sequence type (ST) 235 is a dominant clone of carbapenemase-producing P. aeruginosa (CPPAE) in Korea. As part of the Antimicrobial Resistance Surveillance System in Korea, we found an increase in the carbapenem resistance rate of P. aeruginosa isolates from blood cultures and a shift in the molecular epidemiology of CPPAE. A total of 212 non-duplicated P. aeruginosa blood isolates were obtained from nine general hospitals and two nursing homes. Twenty-four isolates were identified as CPPAE. We observed the emergence of the NDM-1 P. aeruginosa ST 773 clone (N=10), mostly from Gyeongsang Province. The IMP-6 ST 235 clone (N=11) was detected in all provinces. CPPAE isolates showed very high resistance rates to amikacin, and all NDM-1 P. aeruginosa strains carried rmtB. This is the first nationwide surveillance of the recently emerged NDM-1–producing P. aeruginosa ST773 clone in Korea. Continuous surveillance is necessary to prevent the infection and transmission of carbapenem- and amikacin-resistant P. aeruginosa in Korea.
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Background@#Recently, CrpP enzymes have been described as a novel cause of ciprofloxacin resistance. The crpP gene encodes a novel protein that specifically confers resistance to ciprofloxacin through an adenosine triphosphate-dependent mechanism that phosphorylates the antimicrobial. In this study, the current prevalence of the crpP gene in carbapenemaseproducing Pseudomonas aeruginosa blood isolates was evaluated. @*Methods@#During the study of the Antimicrobial Resistance Surveillance System in Korea, 22 blood isolates of carbapenemase-producing P. aeruginosa were collected from nine general hospitals and two nursing homes in the year 2020. Resistance genes and phylogenic trees were analyzed with the whole genome sequencing data. @*Results@#A total of 11 P. aeruginosa blood isolates coharbored the crpP and carbapenemase genes (nine IMP-6 producers and two GES-5-producers). Nine NDM-1-producers coharbored aac(6')-Ib-cr and qnrVC1 . One GES-9-producer also carried aac(6')-Ib-cr, and one NDM-1-producer also carried qnrVC1. The phylogenic tree showed no epidemiologic link among the 22 carbapenemase-producing P. aeruginosa isolates. @*Conclusion@#This is the first report on the current prevalence of the crpP gene in carbapenemaseproducing P. aeruginosa blood isolates in Korea.
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Background@#We compared the antimicrobial resistance rates (AMRs) of major glucose nonfermenting gram-negative bacilli, Acinetobacter baumannii and Pseudomonas aeruginosa, under different clinical conditions. The purpose of the study was to provide useful background data to set up infection control strategies for infection-vulnerable patients. @*Methods@#The AMRs of blood isolates were compared in various clinical conditions, using data from the Antimicrobial Resistance Surveillance System in Korea. @*Results@#A. baumannii blood isolates from patients with healthcare-associated infections, inpatients, or intensive care unit (ICU)-admitted patients consistently exhibited higher AMRs to most antimicrobials, except minocycline, tigecycline, and colistin, compared with those from patients with community-acquired infections, outpatients, or non-ICU-admitted patients, respectively. P. aeruginosa blood isolates from patients with healthcare-associated infections showed higher AMRs to most antimicrobials, except ceftazidime and aztreonam, compared with those from patients with community-acquired infections, but not compared to those from inpatients or ICU-admitted patients. @*Conclusion@#Higher AMRs were associated with A. baumannii bloodstream infections under various clinical conditions, such as healthcare-associated infections and infections in inpatients and ICU-admitted patients. Considering the high AMRs and the limited number of treatment options of A. baumannii, vigorous efforts should be used to prevent the spreading of A. baumannii infections in patients with vulnerable conditions.
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no abstract available.
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Purpose@#Streptococcus pneumoniae (S. pneumoniae) causes respiratory tract infections. Its non-vaccine serotypes and multidrug-resistant pneumococcal diseases have increased during the post-pneumococcal vaccination era. Therefore, it is important to understand the regional and age-related antimicrobial susceptibility of S. pneumoniae to select appropriate empirical antimicrobials. @*Materials and Methods@#We retrospectively studied trends in the antimicrobial resistance of S. pneumoniae to commonly prescribed antibiotics in patient groups of various ages at a single teaching hospital in Jeju Island from 2009 to 2018. @*Results@#In total, 1460 S. pneumoniae isolates were obtained during the study period. The overall antimicrobial resistance rates of S. pneumoniae to penicillin, erythromycin, ceftriaxone, levofloxacin, and vancomycin were 16.2%, 84.7%, 25.9%, 3.3%, and 0.0%, respectively, and the MDR rate was 6.7%. Erythromycin and ceftriaxone resistance rates increased by years; however, they were significantly reduced in adult groups. Levofloxacin resistance and MDR rates were also higher in adult groups. Overall, the MDR rate significantly increased during the recent 10 years, as well as in patients with a history of hospitalization within 90 days [odds ratio (OR)=3.58, 95% confidence interval (CI)=1.91–6.71] and sinusitis (OR=4.98, 95% CI=2.07–11.96). @*Conclusion@#Erythromycin and ceftriaxone resistance rates and the MDR rate of S. pneumoniae significantly increased during the recent 10 years; the trends in individual antimicrobial resistance rates significantly differed between the age groups. This study indicates the need for caution when using ceftriaxone as an empirical antimicrobial against pneumococcal infections.
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In June 2017, on Jeju Island, six patients were diagnosed with typhoid fever. All six patients were admitted to our hospital with fever, all of them had been working at the same hotel.The gyrA and gyrB genes of four out of six Salmonella typhi cases were amplified by polymerase chain reaction. The phylogenetic tree of the genes showed that the S. Typhi isolates from Jeju Island in 2017 had the same genotype and were similar to isolates from the United Kingdom.The origin of the isolates of the outbreak was the same, and the disease strain may have been imported from outside of Korea.
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BACKGROUND/AIMS@#Severe fever with thrombocytopenia syndrome (SFTS) is a viral hemorrhagic fever with a high fatality rate. However, effective treatments for SFTS cases not responded to supportive therapy have not been established. Herein, we introduced the therapeutic plasma exchange (TPE) in SFTS patients in a tertiary hospital between 2013 and 2015.@*METHODS@#TPE was performed in patients with rapidly progressing SFTS. Clinical, laboratory, and virological parameters were compared before and after TPE.@*RESULTS@#Among 27 confirmed SFTS patients, two patients were treated with TPE and ribavirin combination in May 2013, then, 14 patients with rapidly progressing SFTS patients were treated with only TPE from June 2013 to September 2015: their median age was 58 years (interquartile range, 50 to 70) and eight (57.1%) were male. Body temperature, pressure-adjusted heart rate, white blood cell and platelet counts, coagulation profile, serum creatinine, and multiple organ dysfunction score improved immediately after TPE. In addition, the mean cyclic threshold value of real-time reverse transcriptase polymerase chain reaction for SFTS virus after TPE (mean ± standard deviation, 31.3 ± 2.9) was significantly higher than that before TPE (26.5 ± 2.9; p < 0.001), indicating that serum viral loads decreased after TPE. Finally, 13 of 14 TPE-treated patients (92.8%) recovered from rapidly progressing SFTS without sequelae.@*CONCLUSIONS@#SFTS patients treated with TPE showed improvements in clinical, laboratory, and virological parameters. These results suggest that TPE would be a therapeutic modality as rescue therapy in patients with rapidly progressing SFTS.
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We compared the serotypes of Streptococcus pneumoniae between the pre-pneumococcal conjugate vaccine (PCV)13 era and post-PCV13 era among homogenous inhabitants of an isolated South Korean island. A total of 325 S. pneumoniae strains were isolated. In the pre-PCV13 era, 19A/F, 15A/F, 19B, and 23A serotypes were identified. In the post-PCV13 era, 15 serotypes were identified. The 19F and 23A serotypes showed the highest prevalence in the pre- and post-PCV13 era, respectively. After PCV13 introduction, the PCV 13 serotype coverage rate was decreased (80.0% and 30.5% in the pre- and post-PCV13 eras, respectively), while the proportion of non-PCV 13 serotypes increased.
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BACKGROUND: Escherichia coli and Klebsiella pneumoniae clinical isolates producing CTX-M extendedspectrum β-lactamases (ESBLs) were assessed for antimicrobial resistance phenotypes varied by group of enzymes. METHODS: A total of 1,338 blood isolates, including 959 E. coli and 379 K. pneumoniae, were studied. All the strains were collected between January and July 2017 from eight general hospitals in South Korea. The species were identified by matrix-assisted laser desorption ionization-time of flight mass spectrometry. Antimicrobial susceptibilities were determined by disk diffusion methods and ESBL phenotypes by double-disk synergy tests using disks containing cefotaxime, ceftazidime, cefepime, aztreonam, and clavulanic acid (CA). The genes for β-lactamases were identified by PCR and sequencing. RESULTS: Of total microbes, 31.6% (303/959) E. coli and 24.0% (91/379) K. pneumoniae were resistant to cefotaxime and 28.1% (269/959) E. coli and 20.1% (76/379) K. pneumoniae were CTX-M-type ESBL producers. Among the detected CTX-M ESBLs, 58.0% (156/269) in E. coli and 86.8% (66/76) in K. pneumoniae belonged to group 1, 46.8% (126/269) in E. coli and 14.5% (11/76) in K. pneumoniae were group 9. Ten E. coli and one K. pneumoniae isolates co-produced both groups of CTX-M ESBL. The group 1 CTX-M producers had a higher level of resistance to cefotaxime, ceftazidime, cefepime, and aztreonam and exhibited stronger synergistic activities when combined with CA compared to group 9. CONCLUSION: ESBL phenotypes differ by CTX-M ESBL group and phenotype testing with drugs including 4th generation cephalosporins and monobactams is critical for screening CTX-M-producers with better sensitivity.
Sujets)
Aztréonam , Céfotaxime , Ceftazidime , Céphalosporines , Acide clavulanique , Diffusion , Escherichia coli , Hôpitaux généraux , Klebsiella pneumoniae , Corée , Dépistage de masse , Spectrométrie de masse , Monobactames , Phénotype , Pneumopathie infectieuse , Réaction de polymérisation en chaîneRésumé
The incidence of vaccine-type Streptococcus pneumoniae carriage and disease have declined in vaccinated children as well as in unvaccinated children and adults. However, diseases caused by non-vaccine type (NVT) S. pneumoniae are increasing. In this study, we report an invasive pneumococcal disease (IPD) caused by NVT multidrug-resistant (MDR) S. pneumoniae transmitted from a vaccinated infant to an unvaccinated healthy woman, and the clinical characteristics of this serotype. A 29-year-old previously healthy woman visited our hospital with fever and headache. She had been breastfeeding her baby for 8 months. She was diagnosed with brain abscess and sinusitis caused by S. pneumoniae. Although the patient had no previous exposure to antibiotics, antibiotic susceptibility test identified the pathogen as MDR. The patient's family members were examined using nasopharyngeal swabs for bacterial culture. The serotype of S. pneumoniae identified from the blood, abscess, and sputum of the patient was 15B/C. After investing the patient's family members, we found that the serotype from nasopharyngeal specimen of her baby was the same. We described an invasive MDR pneumococcal disease in an immunocompetent young adult in the community. IPD likely spread to the patient by close contact with her baby, who harbored S. pneumoniae of NVT. The spread of NVT S. pneumoniae in the post-vaccine era has increased in the community, and resistance pattern for S. pneumoniae of 15B/C changed compared to the pre-pneumococcal conjugate vaccine era. The spread of MDR pathogens causing IPD among family members should be monitored.
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Adulte , Enfant , Femelle , Humains , Nourrisson , Jeune adulte , Abcès , Antibactériens , Abcès cérébral , Allaitement naturel , Abcès épidural , Fièvre , Céphalée , Incidence , Pneumopathie infectieuse , Sérogroupe , Sinusite , Expectoration , Streptococcus pneumoniae , Streptococcus , VaccinationRésumé
BACKGROUND: Several factors contribute to differences in Streptococcus pneumoniae serotype distribution. We investigated the serotype distribution and antimicrobial resistance of S. pneumoniae isolated between 2014 and 2016 in Korea. METHODS: We collected a total of 1,855 S. pneumoniae isolates from 44 hospitals between May 2014 and May 2016, and analyzed the serotypes by sequential multiplex PCR. We investigated the distribution of each serotype by patient age, source of the clinical specimen, and antimicrobial resistance pattern. RESULTS: The most common serotypes were 11A (10.1%), followed by 19A (8.8%), 3 (8.5%), 34 (8.1%), 23A (7.3%), and 35B (6.2%). The major invasive serotypes were 3 (12.6%), 19A (7.8%), 34 (7.8%), 10A (6.8%), and 11A (6.8%). Serotypes 10A, 15B, 19A, and 12F were more common in patients ≤5 years old, while serotype 3 was more common in patients ≥65 years old compared with the other age groups. The coverage rates of pneumococcal conjugate vaccine (PCV)7, PCV10, PCV13, and pneumococcal polysaccharide vaccine 23 were 11.8%, 12.12%, 33.3%, and 53.6%, respectively. Of the 1,855 isolates, 857 (46.2%) were multi-drug resistant (MDR), with serotypes 11A and 19A predominant among the MDR strains. The resistance rates against penicillin, cefotaxime, and levofloxacin were 22.8%, 12.5%, and 9.4%, respectively. CONCLUSIONS: There were significant changes in the major S. pneumoniae serotypes in the community. Non-PCV13 serotypes increased in patients ≤5 years old following the introduction of national immunization programs with the 10- and 13-polyvalent vaccines.
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Humains , Céfotaxime , Programmes de vaccination , Corée , Lévofloxacine , Réaction de polymérisation en chaine multiplex , Pénicillines , Vaccins antipneumococciques , Pneumopathie infectieuse , Sérogroupe , Streptococcus pneumoniae , Streptococcus , VaccinsRésumé
BACKGROUND@#Otitis media with effusion (OME) is defined as middle ear effusion without acute signs of infection. OME usually resolves spontaneously; however, persistent OME may require the insertion of a ventilation tube. This study investigated risk factors for persistent OME in children who undergo ventilation tube insertion.@*METHODS@#Children who were admitted to undergo ventilation tube insertion at Jeju National University Hospital between August 2015 and July 2016 were enrolled as the case group. Healthy children without persistent OME from August 2016 to July 2017 were enrolled as the control group. Baseline characteristics and predisposing factor data were collected using an interview questionnaire. Middle ear fluids were collected from the case group.@*RESULTS@#A total of 31 patients underwent ventilation tube insertion. The mean age of the case group was 4.53 years, with a male-to-female ratio of 21:10. Twenty-nine (93.5%) children attended a daycare center, and 21 (67.7%) had experience with bottle feeding. Fifteen (48.4%) children in the case group and 3 (9.7%) in the control group first attended a daycare center at < 1 year of age (odds ratio=9.96; 95% confidence interval=2.44–39.70; p=0.001). No bacteria were found in middle ear fluid collected from the 31 operated children. Nasopharyngeal bacterial colonization was found in 13 (41.9%) and 17 (54.8%) children in the case and control groups, respectively.@*CONCLUSION@#Earlier attendance at a daycare center was the only predisposing factor for ventilation tube insertion in our study. The aseptic nature of middle ear fluids found in children with OME highlights the efficacy of antimicrobial use.
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BACKGROUND: Otitis media with effusion (OME) is defined as middle ear effusion without acute signs of infection. OME usually resolves spontaneously; however, persistent OME may require the insertion of a ventilation tube. This study investigated risk factors for persistent OME in children who undergo ventilation tube insertion.METHODS: Children who were admitted to undergo ventilation tube insertion at Jeju National University Hospital between August 2015 and July 2016 were enrolled as the case group. Healthy children without persistent OME from August 2016 to July 2017 were enrolled as the control group. Baseline characteristics and predisposing factor data were collected using an interview questionnaire. Middle ear fluids were collected from the case group.RESULTS: A total of 31 patients underwent ventilation tube insertion. The mean age of the case group was 4.53 years, with a male-to-female ratio of 21:10. Twenty-nine (93.5%) children attended a daycare center, and 21 (67.7%) had experience with bottle feeding. Fifteen (48.4%) children in the case group and 3 (9.7%) in the control group first attended a daycare center at < 1 year of age (odds ratio=9.96; 95% confidence interval=2.44–39.70; p=0.001). No bacteria were found in middle ear fluid collected from the 31 operated children. Nasopharyngeal bacterial colonization was found in 13 (41.9%) and 17 (54.8%) children in the case and control groups, respectively.CONCLUSION: Earlier attendance at a daycare center was the only predisposing factor for ventilation tube insertion in our study. The aseptic nature of middle ear fluids found in children with OME highlights the efficacy of antimicrobial use.
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Enfant , Humains , Bactéries , Alimentation au biberon , Études cas-témoins , Causalité , Côlon , Oreille moyenne , Ventilation de l'oreille moyenne , Otite moyenne sécrétoire , Otite moyenne , Otite , Facteurs de risque , VentilationRésumé
A 20-year-old Cambodian male living in Korea for 2 years as a foreign worker visited our gastroenterology outpatient clinic. He had a small farm in Cambodia. He complained of postprandial upper abdominal pain with nausea and vomiting for 2 years. Gastroduodenoscopy showed hyperemic mucosa near the major papilla in the duodenum and two small and slender reddish worms. These were removed with endoscopic biopsy forceps. Under microscopy, these were identified as Ancylostoma duodenale by the characteristic morphology of 2 pairs of cutting teeth in the buccal cavity and 3 lobes in the copulatory bursa. After removal of two worms, his symptom improved. Soil-transmitted helminths (STH) present a global health problem. In the Republic of Korea, STH, including hookworms, were highly prevalent until the 1970s. With mass fecal examination followed by selective mass chemotherapy with anthelmintics from 1969 to 1995, the prevalence of STH has rapidly decreased since the 1980s. Since 2004, no hookworms have been found in nationwide surveys on the prevalence of intestinal parasitic infection. Therefore, we report a case of in vivo endoscopic removal of A. duodenale in a patient with abdominal pain.
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Humains , Mâle , Jeune adulte , Douleur abdominale , Agriculture , Établissements de soins ambulatoires , Ancylostoma , Ancylostomatoidea , Anthelminthiques , Asiatiques , Biopsie , Cambodge , Traitement médicamenteux , Duodénum , Endoscopie , Gastroentérologie , Santé mondiale , Helminthes , Corée , Microscopie , Muqueuse , Nausée , Maladies parasitaires , Prévalence , République de Corée , Instruments chirurgicaux , Dent , VomissementRésumé
Mycoplasma pneumoniae is the major pathogen of community-acquired pneumonia in children. The prevalence of macrolide-resistant M. pneumoniae (MRMP) is important owing to the limited alternative therapies for children. We analyzed 111 M. pneumoniae obtained from 107 children admitted for lower respiratory tract infection at Jeju National University Hospital between 2010 and 2015. Macrolide resistance of M. pneumoniae was searched for using polymerase chain reaction (PCR) and sequencing. Of 107 clinical M. pneumoniae, 11 (10.3%) carried macrolide resistance mutations in the 23S rRNA gene. All macrolide resistance mutations were A2063G transitions. We found an acquired A2063G mutation of M. pneumoniae from a patient during macrolide treatment. Patients' characteristics and clinical severity did not differ between those with MRMP and macrolide-sensitive M. pneumoniae, with the exception of frequent pleural effusion in the MRMP group. The prevalence of MRMP (10.3%) in Jeju Island was relatively lower than those of surrounding countries in East Asia. Previous antimicrobial usage and timing of diagnostic test should be considered when determining of macrolide resistance of M. pneumoniae.
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Enfant , Humains , Thérapies complémentaires , Tests diagnostiques courants , Extrême-Orient , Gènes d'ARN ribosomique , Mycoplasma pneumoniae , Mycoplasma , Épanchement pleural , Pneumopathie infectieuse , Pneumopathie à mycoplasmes , Réaction de polymérisation en chaîne , Prévalence , Infections de l'appareil respiratoireRésumé
Several evidences suggested that Toll-like receptor 9 (TLR9) plays an important role in atherosclerosis and neuroprotection but the association between the TLR9 and risk for stroke or outcomes after stroke has not been investigated. The aim of the present study was to investigate the association between TLR9 polymorphisms and the risk for ischemic stroke using a case-control study design. We also explored the correlation between the polymorphisms and outcomes after stroke. We enrolled consecutive Korean stroke patients and controls without history of stroke. Four polymorphisms, namely c.-1486T>C, c.-1237C>T, c.1174A>G, and c.2848G>A were examined using polymerase chain reaction followed by direct sequencing. Initially we examined 193 stroke patients and the same number of healthy adults who had no history of stroke as controls. Due to deviation from Hardy-Weinberg equilibrium of initial controls, we performed genetic analysis of two polymorphisms (c.1174A>G and c.2848G>A) for additional 165 controls. The genotype frequency of four polymorphisms did not differ significantly between stroke patients and controls in unadjusted analysis. The variant allele (C) in c.-1486 locus was associated with significantly increased chance of favorable functional outcome at three month after stroke (OR 2.32, 95% CI 1.02~5.26, p = 0.043).
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Adulte , Humains , Allèles , Athérosclérose , Études cas-témoins , Génotype , Réaction de polymérisation en chaîne , Accident vasculaire cérébral , Récepteur-9 de type Toll-like , Récepteurs de type TollRésumé
BACKGROUND AND OBJECTIVES: Residual platelet reactivity in patients who are taking clopidogrel is commonly measured with VerifyNow assay, which is based on the principle of light transmission aggregometry. However, to evaluate the residual platelet reactivity, it would be more accurate if the reactivity of platelet glycoprotein (GP) IIb/IIIa is directly monitored. In this study, PAC1, a monoclonal antibody against activated platelet GP IIb/IIIa, was used to measure the residual platelet reactivity. SUBJECTS AND METHODS: Twenty seven patients with coronary artery disease taking clopidogrel were enrolled. Platelets in whole blood were stained with fluorescein isothiocyanate (FITC)-conjugated PAC1. Mean fluorescence intensity (MFI) and % positive platelets (PP) were measured with flow cytometry, and the binding index (BI; MFI x %PP/100) was calculated. P2Y12 reaction unit (PRU) and % inhibition of VerifyNow assay were also measured in the usual manner. RESULTS: PRU of VerifyNow assay correlated significantly with MFI, %PP, and BI at 10 microM (r=0.59, 0.73, and 0.60, respectively, all p<0.005) and 20 microM of adenosine diphosphate (ADP; r=0.61, 0.75, and 0.63, respectively, all p<0.005). The % inhibition also correlated significantly with MFI, %PP, and BI at 10 microM (r=-0.60, -0.69, and -0.59, respectively, all p<0.005) and 20 microM of ADP (r=-0.63, -0.71, and -0.62, respectively, all p<0.005). CONCLUSION: Direct measurements of the reactivity of platelet GP IIb/IIIa were feasible using PAC1 and flow cytometry in patients taking clopidogrel. Further clinical studies are required to determine the cut-off values which would define high residual platelet reactivity in patients on this treatment protocol.