20１１ネン カラ ２０１３ネン ノ ヤマガタケン ニ オケル ミッツ ノ コトナル イデンシガタ ノ ハイエン マイコプラズマ ノ チイキテキ ヒロガリ ト マクロライド タイセイ カブ シュツゲン ノ タイミング ニ カンスル ケントウ

Background: We previously revealed that several multiple-locus variable-number tandem-repeat analyses（MLVA）and P1 types of Mycoplasma pneumoniae（M. pneumoniae）cocirculated between 2011 and 2013 in Yamagata, Japan. However, the regional spread of M. pneumoniae infection by genotype is not reported yet. It remains unclear whether there is a difference in the spread of macrolide-resistant M. pneumoniae among genotypes. Methods: Genotypes were labeled according to 4-locus（Mpn 13, 14, 15, and 16）MLVA and P1 types. A total of 208 strains belonging to three major genotypes, i.e., type 4-5-7-2, 1; 4-5-7-3, 1; and 3-5-6-2, 2c, were analyzed by combining with the information of macrolide resistance-associated mutation and the patients’ information including residence. Results and Discussion: The three genotypes were widely distributed over more than four cities and towns in Yamagata Prefecture, cocirculating between late 2011 and early 2013, and there was little difference in the duration of their epidemics. Timing of macrolide-resistant strain appearance during the epidemic period differed between type 4-5-7-2, 1 and type 4-5-7-3, 1, and it did not appear throughout type 3-5-6-2, 2c epidemic. These genotypic differences can account for the variation in the prevalence of macrolide resistance-associated mutations in each of the studied areas

Comparison of virus isolation using the Vero E6 cell line with real-time RT-PCR assay for the detection of human metapneumovirus

Abstract Background The use of cell culture for the diagnosis of human metapneumovirus (hMPV) infection is uncommon at present and molecular method such as reverse-transcription PCR (RT-PCR) has been widely and most commonly used as the preferred test. We aimed to compare the results of virus isolation using Vero E6 cells with real-time RT-PCR for the detection of hMPV, since such a comparison data is not available. Methods Between December 2007 and July 2008, we obtained 224 nasopharyngeal swab specimens from patients with acute respiratory infection and tested by the two methods. Results Forty-three (19.2%) were found positive by cell culture and 62 (27.7%) by real-time RT-PCR. Cell cultures were positive for 42 of 62 specimens found positive by real-time RT-PCR (67.7% sensitivity) and for 1 of 162 specimens found negative by real-time RT-PCR (99.4% specificity), respectively. The sensitivity of the cell culture was 76.2-87.5% (mean 81.8%) when specimens were collected within 3 days after the onset of symptoms, and the sensitivity decreased to 50% or less thereafter. Among specimens collected within 3 days after symptom onset, all of the real-time RT-PCR positive specimens having a viral load of more than 1.25×105 copies/ml were found positive by cell culture. Conclusions Cell culture using Vero E6 cell line has 81.8% sensitivity compared with the real-time RT-PCR method, when specimens are collected within 3 days after the onset of symptoms. Thus, this method is a useful method for epidemiological and virological research even in facilities with minimal laboratory resources.</p

Evaluation of a New Rapid Antigen Test Using Immunochromatography for Detection of Human Metapneumovirus in Comparison with Real-Time PCR Assay▿

A new rapid human metapneumovirus (hMPV) detection kit using immunochromatography (SAS hMPV test) was compared to real-time PCR for 224 nasal swab specimens, 96.4% of which were obtained from children of <15 years of age. The overall sensitivity and specificity were 82.3% and 93.8%, respectively, suggesting that this test is useful for pediatricians to diagnose hMPV infection in a clinical setting

A two-year survey of the oseltamivir-resistant influenza A(H1N1) virus in Yamagata, Japan and the clinical effectiveness of oseltamivir and zanamivir

Abstract Background Oseltamivir is the preferred antiviral drug for influenza, but oseltamivir-resistant A(H1N1) viruses have circulated worldwide since the 2007-2008 influenza season. We aimed to determine the rate of oseltamivir resistance among A(H1N1) isolates from Yamagata, Japan, to compare the virological characteristics between isolates from the 2007-2008 and 2008-2009 seasons, and to evaluate the clinical effectiveness of oseltamivir. Results Oseltamivir resistance, determined by detecting the H275Y mutation in the neuraminidase (NA) gene, was observed in 2.5% (2 of 79) and 100% (77 of 77) of isolates from the 2007-2008 and 2008-2009 seasons, respectively. Antigenic analysis suggested that antigenically different variants of A(H1N1) viruses circulated in the 2008-2009 season. Growth testing demonstrated that the ability of the 2008-2009 isolates to replicate in MDCK cells was similar to those of the oseltamivir-susceptible isolates from the 2007-2008 season. A phylogenetic analysis revealed that two oseltamivir-resistant viruses isolated in the 2007-2008 season were closely related to other oseltamivir-susceptible viruses in Yamagata but were different from oseltamivir-resistant viruses isolated in Europe and North America in the 2007-2008 season. The oseltamivir-resistant viruses isolated in Japan in the 2008-2009 season were phylogenetically similar to oseltamivir-resistant isolates from Europe and North America during the 2007-2008 season. Furthermore, the median duration of fever after the start of oseltamivir treatment was significantly longer in oseltamivir-resistant cases (2 days; range 1-6 days) than in oseltamivir-susceptible cases (1.5 days: range 1-2 days) (P = 0.0356). Conclusion Oseltamivir-resistant A(H1N1) isolates from Yamagata in the 2007-2008 season might have acquired resistance through the use of oseltamivir, and the 2008-2009 oseltamivir-resistant isolates might have been introduced into Japan and circulated throughout the country. Influenza surveillance to monitor oseltamivir-resistance would aid clinicians in determining an effective antiviral treatment strategy.</p