Evaluation of the Usefulness of Anti-Cyclic Citrullinated Peptide Antibodies Measured by an Automated Enzyme Immunoassay / 임상검사와정도관리

BACKGROUND: Rheumatoid arthritis (RA) is the most common autoimmune rheumatic disease, but sensitive and specific test for its diagnosis is lack. This study evaluated the analytical performance and diagnostic role of a new automated ELISA anti-cyclic citrullinated peptide (anti-CCP) antibody test. METHODS: Anti-CCP antibody test was done with the enzyme-linked immunosorbent assay (ELISA) in serum samples from 49 RA patients and 104 non-RA patients, and 51 healthy subjects. Serum pools were used to determine its precision and linearity. The optimal cut-off values were determined by the receiver-operator characteristics (ROC) curve. The rheumatoid factor (RF) by turbidimetry was also assayed in every samle and the results were compared to anti-CCP for sensitivity and specificity. RESULTS: The total imprecision (CV%) was 4.8%, 7.6% for serum pools with low (mean concentration: 2.7 U/mL) and high (mean concentration :82.2 U/mL) concentration, respectively. Linearity data were acceptable (R2=0.9907). At each optimal cut-off value, the sensitivity of anti-CCP was higher than that of RF (81.6 % vs 69.4%), but statistical significance was not defined. Specificity of anti-CCP was higher than that of RF (95.5% vs 75.5%, p<0.001). A combination of anti-CCP and RF increased sensitivity and specificity to 87.7%, 98.0%, respectively. Nine of 15 (60.0%) sera from RF negative RA patients were positive for anti-CCP. CONCLUSIONS: Anti-CCP ELISA antibody test, we examined on a fully automated enzyme immunoassay, is easy to assay in routine laboratory, and showed good analytical performance. And anti-CCP antibody test also showed higher diagnostic specificity than RF. So, anti-CCP antibody may be useful serologic marker for diagnosis and monitoring of RA, if performed concomitantly with RF assay.

Molecular Typing of Salmonella typhi by Random Amplified Polymorphic DNA Analysis / 대한임상미생물학회지

BACKGROUND: In the year 1996, there were some outbreaks of Salmonella typhi infection in Pusan and therefore, the incidence of S. typhi infection was markedly increased in comparison with the previous year. To differentiate the isolates epidemiologically, a random amplified polymorphic DNA(RAPD) fingerprinting method has been developed. METHODS: A total of 9 arbitrary primers were screened with S. typhi strains isolated in Pusan, 1996. This allowed selection of a panel of primers capable of detecting DNA polymorphisms among S. typhi isolates. This panel was used to examine 54 strains of S. typhi, which had been isolated in Pusan including the cases of outbreaks that was previously characterized by phage typing. RESULTS: Four single primers and one combination of two primers were selected to discriminate the S. typhi isolates. RAPD analysis resolved the 54 strains into 20 different subtypes. At least two outbreaks were found by RAPD analysis. The isolates of E1 phage type, which are the most common in Korea, were perfectly differentiated with each other, except the strains isolated within the outbreaks. CONCLUSION: The RAPD approach is the useful epidemiologic tool to S. typhi subtyping, which is providing high discriminatory power. There were at least two outbreaks when the epidemic Salmonella infections of Pusan in 1996 had been occurred. The primers or their comb ination capable to discriminate the S. typhi isolates were described.