Daptomycin Etest MICs for methicillin-resistant Staphylococcus aureus vary among different media.

For optimum activity of daptomycin (DAP) in vitro, medium supplemented with calcium ions at physiological concentration (i.e., 50 mg/l) is required for determination of DAP minimum inhibitory concentration (MIC) in the Clinical and Laboratory Standards Institute (CLSI) broth microdilution (BMD) method. However, our literature review found that Mueller-Hinton agar (MHA) brands used for the DAP Etest had different calcium ion (Ca²âº) concentrations among the reports. For 98 clinical methicillin-resistant Staphylococcus aureus isolates previously unexposed to DAP, MICs were assessed by use of the Etest with MHA plates with different media (MHA-A, MHA-B, and MHA-C) and compared with those from the CLSI reference BMD method. The instructions for the Etest recommend MHA with Ca²âº of 25-40 mg/l for DAP MIC testing; Ca²âº concentrations for each type of MHA were 20.4 mg/l in MHA-A, 45.2 mg/l in MHA-B, and 52.0 mg/l in MHA-C. When the MIC50/MIC90 of the clinical isolates were studied, the Etest MICs for MHA-A were 1-fold dilution higher than for the BMD value. In contrast, for MHA-B they were 1-fold dilution lower, and for MHA-C MIC50 was 1.5-fold dilution lower and MIC90 was 2-fold dilution lower. MICs measured in MHA with higher Ca²âº tended to be lower. Comparison of MICs between BMD and the Etest for each MHA showed they were significantly different (p < 0.0001). The correlation coefficient was 0.6258 (p < 0.0001) for MHA-A, 0.4224 (p < 0.0001) for MHA-B, and 0.2504 (p = 0.0129) for MHA-C. Our results suggest there are differences in DAP MICs between MIC testing methods and differences between Ca²âº concentrations in MHA. For more objective and accurate measurement of DAP MICs, there should be discussion about standardization of Ca²âº in MHA.

[Report of immunoassay control surveys conducted in the past 30 years by the Subcommittee for Radioisotope in vitro Test, the Medical Science and Pharmaceutical Committee, and the Japan Radioisotope Association].

Immunoassay control surveys, were conducted by the Subcommittee for Radioisotope in vitro Test, the Medical Science and Pharmaceutical Committee, and the Japan Radioisotope Association, between 1978 to 2008. A total of 40 analytes for 26 hormones, 14 tumor markers and pharmaceutical drugs were investigated in participating facilities. In the first immunoassay control survey in 1978, samples were measured using only RI kits, however, non-RI kits increased gradually during the next 30 years. In the 30th immunoassay control survey, more than 90% samples were measured using non-RI kits. Coefficient variation (CV) of intra-kits has been decreasing yearly in all analytes for hormones as well as tumor markers. However, improvement of CV in inter-kits has not been seen in the past 30 years by a lack of international standards, although there has been continuous effort over the years for the standardization of immunoassay. Growth hormone (GH) deficiency has been diagnosed using various loading tests. However, the clinical diagnosis varies according to the GH kit used. Standardization for GH measurement has been possible by using recombinant GH as the standard among commercial GH kits. The diagnosis of subclinical Cushing's syndrome also varies according to the cortisol kits being used. Candidate reference measurement procedure and low level cortisol standards have been developed by the Biomedical Standard Section, of the National Metrology Institute of Japan. Standardization of measurement is necessary for improvement of immunoassay.

[Basic and clinical studies for IgG4 measurement by nephelometric immunoassay].

After 2001, many reports have shown that serum IgG4 levels specifically elevate in patients with autoimmune pancreatitis (AIP), suggesting its clinical usefulness in discrimination between AIP and pancreatic cancer. To confirm this, we tried to examine a utility of IgG4 by measuring serum IgG4 levels of patients with healthy human, AIP, chronic pancreatitis, pancreatic cancer and autoimmune disease with nephelometric immunoassay (NIA). The between-assay variation (with coefficient of variation (CV)) in the IgG4 measurement and the within-assay variation were 0.3-3.2% and 1.9-4.5%, respectively. The analytical error was small as shown in 2.9%. Reference range of men and women was 5.6-117.2 mg/dl and 4.3-94.0 mg/dl, respectively, and men showed higher level than women significantly (p<0.05). The median IgG4 level (247.0 mg/dl) of patients with AIP showed significantly high level (p<0.01) compared with each patient group of a chronic pancreatitis (45.0 mg/dl), that of pancreatic cancer (59.6 mg/dl) and that of the autoimmune diseases (54.5 mg/dl). In discrimination between AIP and pancreatic cancer, we found excellent clinical utility showing sufficient sensibility (87.0%) and specificity (93.3%). As a result, we think the measurement of IgG4 is useful for the diagnosis of AIP. However, more popular assay system, such as immunoturbidimetry, will be needed for IgG4 measurement to be prevalent more widely.

[Evaluation of the reference range of retinol-binding protein (RBP) levels by the latex turbidimetric immunoassay].

Retinol-binding-protein (RBP) has a short half-life, and a physiological change and intra-individual variation are small, so it is used as nutrition assessment protein. The measurement of RBP levels has nephelometric immunoassay (NIA) and latex turbidimetric immunoassay (LTIA), and the reference range was demanded by NIA, but it is noted it to vary by the LTIA. Thus we found a reference value in the LTIA and estimated intra-individual variation and analytical error by analysis of variance. Therefore we demanded intra-individual variation amplitude and reference range in the turbidimetric immunoassay. As for RBP, the intra-individual variations(with coefficient of variation (CV)) was 4.3% and 13.3% for males and females, respectively. The analytical error (CV) is very small in 1.2% and there are less them than half of the intra-individual variation for evaluation of inaccuracy. The reference range of the RBP was 2.65-6.00 mg/dl (n=525) in male and 1.90-4.61 mg/dl (n=565) in female, respectively. This reference range became the low level in comparison with the value of the NIA which was already reported. As a result of mutual measurement of the calibrator and the control of NIA and LTIA, a tendency similar to the difference of the reference range was found, so it seemed to be due to the difference of the calibrator.

[Evaluation of samples that indicated the difference of immunoglobulin values between different assays].

Since the immunoglobulin levels of survey samples for the survey of Japanese Association of Medical Tech7ologists in 2003, especially the IgA and IgM, became different by the immunological methods (LAIA [latex agglutination immunoassay] and TIA [turbidimetric immunoassay]), the cause of difference was investigated. From the results of gel filtration and immunoblotting analysis, it was suggested that profiles of the reaction of purified IgA and IgM polymers in survey samples were different on each method. In the case of M protein, also, there were higher levels of IgM and IgA type M protein by TIA and SRID methods than other methods even though the precipitation curve was obscure. Similarly, several samples from patients with M protein demonstrated higher values by SRID method than that of other methods. When these samples were analyzed by gel filtration and immunoblotting, they did not indicate the presence of the polymeric IgM. It will be suggested that non-specific reactions on TIA (weak reaction) and SRID (unusual precipitin line) methods were present. Furthermore, in a case of IgM type M protein, IgM level was twice higher by LAIA than that by TIA. However, it did not indicate any polymer or fragment of IgM by gel filtration and immunoblotting. Accordingly, it was assumed that the difference in measured values between the methods was attributable to the difference of the reaction to the samples.

Prevalence of tuberculosis in small pulmonary nodules obtained by video-assisted thoracoscopic surgery.

The prevalence of tuberculosis in small solitary lesions of the lung obtained by video-assisted thoracoscopic surgery (VATS) is still unclear. Of 103 lung lesions resected by VATS in 98 patients (47 men, 51 women), 19 were identified macroscopically as inflammatory changes, 78 were neoplastic, and 6 were undefined. Presumptive diagnosis based on microscopic analysis of fresh specimen smears treated with Papanicolaou stain was performed in 19 lesions. Of these, 11 lesions had epithelioid cells, granulomas with caseous necrosis and Langerhans-type giant cells. The 6 undefined lesions were non-inflammatory benign changes. Isolation and identification of tuberculosis were based on microscopic findings of fresh material smears and sections of fixed specimens stained with Ziehl-Neelsen's dye, cultivation using egg-based Ogawa medium, and in situ hybridization between polymerase chain reaction (PCR) products of each of the 11 lesions and specific DNA sequences for Mycobacterium tuberculosis, M. avium, and M. intracellulare. Of these 11 lesions, M. tuberculosis was confirmed in one (0.96%) by PCR and M. avium was confirmed in four by culture and PCR. Of the 78 malignant lesions, final pathologies were primary lung cancer (n=59, 70.2%) and pulmonary metastatic cancer (n=19, 22.6%). The most frequent primary malignant cancer was adenocarcinoma, which was found in 19 men and 28 women in the present study. Eight lesions in 8 men were squamous cell carcinomas. The results of the present study suggested that even though the prevalence of lung tuberculosis is low, attention should be paid to the presence of M. tuberculosis in specimens obtained by VATS.