Rinsho Biseibutsu Jinsoku Shindan Kenkyukai shi = JARMAM : Journal of the Association for Rapid Method and Automation in Microbiology最新文献

Immunochromatography viral antigen-detection kits have become popular in clinical settings in Japan. Influenza virus detection kit is one of them. It is sometimes used in early phase of the disease, combined with the early treatment with anti-influenza drugs. Most of them are invented to visually read the test line on their kits. However, we should be careful about their reliability of them. Sometimes human errors occur at the visual tests, and they have different sensitivities among the kits from different companies. In this report, we evaluated the sensitivity of BD Veritor System Flu with its reader by comparing with conventional visual tests. A total of 84 people including laboratory technologists were asked to visually read test line and their answers were compared with results of BD Veritor System Reader. This study showed that the lower the concentration of standard sample was applied, the greater the error ratio of visual test became, indicating the stable sensitivity of Veritor System. Moreover, the sensitivity was compared with three other major products approved in Japan, using four influenza viruses: type A of H1N1 seasonal 2009, H1N1 pandemic 2009, H3N2 seasonal 2012 and type B of seasonal 2012. It was indicated that Veritor System had the highest limit of detection from the kits.

Catheter-related bloodstream infection (CRBSI) is an infectious disease requiring special attention. It is a common cause of nosocomial infections; catheter insertion into the central veins particularly increases the risk of infection (CLA-BSI: central line-associated bloodstream infection). We examined the relationship between the number of bacterial colonies cultured from shredded central venous catheter (CVC) tips and from blood cultures in our hospital from 2011 to 2012. Coagulase-negative staphylococci topped the list of microbe isolated from the CVC tip culture, followed by Pseudomonas aeruginosa, Staphylococcus aureus, and Candida spp. S. aureus and Candida spp., with growth of over 15 colony-forming units in the CVC tip culture, were also detected at high rates in the blood culture. However, gramnegative bacilli (Enterobacteriaceae and P. aeruginosa) did not show a similar increase in colony number in the CVC tip culture. Because microbes adhering to shredded catheter tips are readily detected by culture, this method is useful as a routine diagnostic test. In addition, prompt clinical reporting of the bacterial number of serious CLA-BSI-causing S. aureus and Candida spp. isolated from CVC tips could contribute to earlier CLA-BSI diagnosis.

According to aging of population and medical progress, the risk and mortality rate of pneumonia have been increased. In the causative organism inspection, smear-culture examination of sputum is the gold standard. When it is difficult to obtain high quality sputum and to culture the causative organism, or when antibiotics are previously administered, we have no choice but to start the treatment with pathogenic bacteria unknown. In these cases, it is necessary to select an appropriate test method for expecting pathogen. If bacteria are detected in laboratory culture, it is difficult to distinguish whether it is a causative or colonizers. Future development is expected in rapid diagnostic methods.

We have evaluated our new Norovirus rapid detection kit "QuickNavi™-Norovirus2" (Denka Seiken Co., Ltd.). The kit is based on Immunochromatographic method using colored latex particles. In addition to simple preparations giving quick (15 min) results, our newly developed kit enables specimen collection directly from rectum and can also be used with neonatal stool samples, both of which cannot be used with the current version of the kit, "QuickNavi™-Norovirus." Clinical study (stool samples, n=172) shows sensitivity, specificity and accuracy of the test compared to RT-PCR are 92.0%, 98.3%, and 94.2%, respectively. The result also showed good correlation with QuickNavi™-Norovirus. In this study, the new Norovirus rapid detection kit has shown sufficient sensitivity and specificity. Their performance, simple preparation enabling rectal swab samples, and quick results can be useful for day to day clinical practice when diagnosing Norovirus infection.

Because it is not easy to differentiate Influenza virus (Flu) from RS virus (RSV) just by clinical symptoms, to accurately diagnose those viruses in conjunction with patient's clinical symptoms, rapid diagnostic kits has been used separately for each of those viruses. In our new study, we have developed a new rapid diagnostic kit, QuickNavi™-Flu+RSV. The kit can detect Flu A, Flu B, and RSV antigens with a single sample collection and an assay. Total of 2,873 cases (including nasopharyngeal swabs and nasopharyngeal aspirates specimens) in 2010/2011 and 2011/2012 seasons were evaluated with QuickNavi™-Flu+RSV and a commercially available kit. Sensitivity, specificity, and accuracy of Flu type A, type B, and RSV were above 95% when compared to commercially available kits (QuickNavi™-Flu and QuickNavi™-RSV) and considered to be equivalent to the commercially available kits. In 2011/2012 season, RSV infections increased prior to Flu season and continued during the peak of the Flu season. The kit can contribute to accurate diagnosis of Flu and RSV infections since co-infection cases have also been reported during the 2011/2012 season. QuickNavi™-Flu+RSV is useful for differential diagnosis of respiratory infectious diseases since it can detect Flu type A, type B, and RSV virus antigens with a single sample collection.

It was developed that an anti-norovirus single-chain Fv (scFv) antibody for immunochromathographic test kit by using the phage displayed technique and biopanning. To obtain the scFv having wide reactivity for several norovirus genotypes, a mixture of recombinant norovirus capsid proteins, including 11 norovirus genotypes, was used for biopanning. Then, one anti-norovirus scFv antibody that recognized both of norovirus genogroups GI and GII was identified. An immunochromatographic test strip was constructed by using the scFv and demonstrated it to detect norovirus in stool samples. The immunochromatographic strip showed similar sensitivity to a commercially available one on which several monoclonal antibodies are included.

Reports of community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) infections have recently increased in Japan. To determine the status of MRSA infections in our hospital, we investigated their Staphylococcal cassette chromosome mec (SCCmec) types and prevalence of Panton-Valentine leukocidin (PVL). In addition, we investigated the relation between their SCCmec and antimicrobial susceptibility. The 191 strains were isolated from January to July in 2011 and were classified as SCCmec type I (2, 1.0％), type II (136, 71.2％), type IV (36, 18.8％), type V (4, 2.1％) and type VIII (2, 1.0％). Eleven isolates (5.8％) were designated as nontypable. No isolates were PVL-positive in this study. The SCCmec type IV strains were more susceptible to imipenem (MIC90, 0.25 μg/ml) than SCCmec type II strains (MIC90, >16 μg/ml). This difference was also observed between SCCmec type IV and SCCmec type II in susceptibility levels to clarithromycin, clindamycin, minocycline, and levofloxacin, but not to gentamicin. In particular, SCCmec type IV strains were susceptible to imipenem and minocycline. The result indicates these susceptibility is useful to discriminate CA-MRSA from Hospital-associated MRSA (HA-MRSA).