Kluyvera georgiana Bacteremia Due to Acute Cholangitis: A Report of the First Known Case and a Literature Review

We herein present the first known case of bacteremia caused by Kluyvera georgiana in a 67-year-old female undergoing chemotherapy for recurrent pancreatic cancer. The patient underwent choledochojejunotomy and thereafter developed ascending cholangitis. The diagnosis of K. georgiana was confirmed using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. A literature review of Kluyvera spp. infections indicated potential risk factors including an underlying malignancy and immunosuppression. Although Kluyvera spp. infections are typically sensitive to antibiotics, multidrug resistance is possible. This case highlights the importance of the early diagnosis and treatment of K. georgiana and its associated risk factors.

A case of hypervirulent K1-ST23 Klebsiella pneumoniae endocarditis and papillary muscle rupture secondary to multiple site abscesses

Hypervirulent Klebsiella pneumoniae (hvKP) causes multisite infections and abscesses. However, endocarditis is a rare presentation of hvKP infection. Herein, we report a case of K. pneumoniae native valve infective endocarditis secondary to community-acquired liver and prostate abscesses. The patient developed papillary muscle rupture, leading to mitral regurgitation, and underwent emergent mitral valve replacement. The diagnosis of endocarditis was confirmed microbiologically and histologically. The causative strain belonged to the hypermucoid K1 capsular genotype and possessed the rmpA gene. The genome sequence was deposited in GenBank under the accession number JAQZBZ000000000.

Comparison of phylogenetic and virulence factors between Escherichia coli isolated from biliary tract infections and uropathogenic Escherichia coli

Escherichia coli is a gram-negative intestinal commensal that can also cause various infections, including urinary tract infections, biliary tract infections, neonatal meningitis, and septicemia. Although the characteristics of uropathogenic E. coli and the mechanisms of urinary tract infection have been well studied, the genetic distinctions among E. coli isolates from different types of infections have not yet been determined. This study compared the phylogenetic and virulence factors of E. coli isolates from bacteremic biliary tract infections with those from bacteremic urinary tract infections. The phylogenetic B2 group was the most prevalent in both pathogenic groups (68 % in biliary pathogenic isolates and 85 % in uropathogenic isolates), but the frequency pattern of the phylogenetic group was different. Half of the uropathogenic isolates belonged to ST95 and ST131 (51 %). Among the biliary pathogenic isolates, ST131 was the most prevalent, while the remaining half belonged to other STs outside the four major STs. The frequency of some virulence factors, such as papC, papG2, hlyA, tcpC, fyuA, kpsMT2, sat, and traT, was lower in the biliary pathogenic isolates than in the uropathogenic isolates. The frequency of phylogenetic groups and STs in MLST differed between E. coli isolates from bacteremic biliary tract infections and urinary tract infections. Additionally, some virulence factors, including adhesion and toxin gene groups, showed lower frequencies in the biliary pathogenic group than in the uropathogenic group. Studying the differences in E. coli pathovars from different infection sites is important for developing pathovar-specific targeted therapies such as vaccine therapy.

Association of the Serum Levels of the Nucleocapsid Antigen of SARS-CoV-2 With the Diagnosis, Disease Severity, and Antibody Titers in Patients With COVID-19: A Retrospective Cross-Sectional Study

Background: Several types of laboratory tests for COVID-19 have been established to date; however, the clinical significance of the serum SARS-CoV-2 nucleocapsid (N) antigen levels remains to be fully elucidated. In the present study, we attempted to elucidate the usefulness and clinical significance of the serum N antigen levels.

Methods: We measured the serum N antigen levels in 391 serum samples collected from symptomatic patients with a confirmed diagnosis of COVID-19 and 96 serum samples collected from patients with non-COVID-19, using a fully automated chemiluminescence immunoassay analyzer.

Results: Receiver operating characteristic analysis identified the optimal cutoff value of the serum N antigen level (cutoff index, based on Youden’s index) as 0.255, which yielded a sensitivity and specificity for the diagnosis of COVID-19 of 91.0 and 81.3%, respectively. The serum N antigen levels were significantly higher in the patient groups with moderate and severe COVID-19 than with mild disease. Moreover, a significant negative correlation was observed between the serum N antigen levels and the SARS-CoV-2 IgG antibody titers, especially in patients with severe COVID-19.

Conclusion: Serum N antigen testing might be useful both for the diagnosis of COVID-19 and for obtaining a better understanding of the clinical features of the disease.

Tenosynovitis caused by Mycobacterium marseillense, initially identified as Mycobacterium avium complex using AccuProbe and COBAS TaqMan

Background

Mycobacterium marseillense is a new species of the Mycobacterium avium complex. There has been only a few human infections caused by M. marseillense worldwide.

Case presentation

We report a case of tenosynovitis caused by M. marseillense in an immunocompetent adult in Japan. The isolate was initially identified as M. intracellulare using commercial real time polymerase chain reaction assays and later identified as M. marseillense with sequencing of the the rpoB and hsp65 regions, and matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS).

Conclusions

This is the first case reporting on M. marseillense generating a positive result with commercial real time PCR assays targeting MAC. Human infections associated by M. marseillense might be underreported due to similarities with Mycobacterium intracellulare. To accurately identify M. marseillese, MALDI-TOF MS might provide a rapid and reliable method.

Comparative performance and cycle threshold values of 10 nucleic acid amplification tests for SARS-CoV-2 on clinical samples

Background

A number of nucleic acid amplification tests (NAATs) for SARS-CoV-2 with different reagents have been approved for clinical use in Japan. These include research kits approved under emergency use authorization through simplified process to stabilize the supply of the reagents. Although these research kits have been increasingly used in clinical practice, limited data is available for the diagnostic performance in clinical settings.

Methods

We compared sensitivity, specificity, and cycle threshold (Ct) values obtained by NAATs using 10 kits approved in Japan including eight kits those receiving emergency use authorization using 69 frozen-stored clinical samples including 23 positive samples with various Ct values and 46 negative samples.

Results

Viral copy number of the frozen-stored samples determined with LightMix E-gene test ranged from 0.6 to 84521.1 copies/μL. While no false-positive results were obtained by any of these tests (specificity: 100% [95% CI, 88.9%-100%]), sensitivity of the nine tests ranged from 68.2% [95% CI, 45.1%-86.1%] to 95.5% [95% CI, 77.2%-99.9%] using LightMix E-gene test as the gold standard. All tests showed positive results for all samples with ≥100 copies/μL. Significant difference of Ct values even among tests amplifying the same genetic region (N1-CDC, N2) was also observed.

Conclusion

Difference in the diagnostic performance was observed among NAATs approved in Japan. Regarding diagnostic kits for emerging infectious diseases, a system is needed to ensure both rapidity of reagent supply and accuracy of diagnosis. Ct values, which are sometimes regarded as a marker of infectivity, are not interchangeable when obtained by different assays.

First Reported Human Case of Spondylodiscitis by Staphylococcus condimenti: A Case Report and Literature Review

Staphylococcus condimenti is a Gram-positive coccus that was first isolated from soy sauce mash. Only four cases of human S. condimenti infections have been reported to date. We herein report the first case of spondylodiscitis caused by S. condimenti. A 72-year-old Japanese man complaining of lower back pain and numbness in his legs was diagnosed with spondylodiscitis. A computed tomography (CT)-guided biopsy was performed. A culture of the intravertebral disc aspirate yielded S. condimenti. The result was confirmed using gene sequencing methods. The patient was successfully treated without relapse. This case shows that S. condimenti can be pathogenic and cause invasive infection.

Genetic diversity and epidemiology of accessory gene regulator loci in Clostridioides difficile

Quorum sensing is known to regulate bacterial virulence, and the accessory gene regulator (agr) loci is one of the genetic loci responsible for its regulation. Recent reports examining Clostridioides difficile show that two agr loci, agr1 and agr2, regulate toxin production, but the diversity of agr loci and their epidemiology is unknown. In our study, in silico analysis was performed to research genetic diversity of agr, and C. difficile isolates from clinical samples underwent multilocus sequence typing (MLST) and PCR analysis of agr loci. To reveal the distribution of agr among different strains, phylogenetic analysis was also performed. In our in silico analysis, two different subtypes, named agr2R and agr2M, were found in agr2, which were previously reported. PCR analysis of 133 C . difficile isolates showed that 131 strains had agr1, 61 strains had agr2R, and 26 strains had agr2M; agr2R was mainly found in clade 1 or clade 2 organisms, whereas agr2M was only found in clade 4. With rare exception, agr1-negative sequence types (STs) belonged to clade C-Ⅰ and C-Ⅲ, and one clade 4 strain had agr2R. Our study revealed subtypes of agr2 not previously recognized, and the distribution of several agr loci in C. difficile . These findings provide a foundation for further functional and clinical research of the agr loci.

Control system for the new RIKEN 28-GHz superconducting electron cyclotron resonance ion source for SRILAC

A new RIKEN 28-GHz superconducting electron cyclotron resonance ion source (SC-ECRIS) has been installed for the superconducting RIKEN linear accelerator (SRILAC). The new SC-ECRIS control system mainly consists of programmable logic controllers (PLCs) embedded with the Experimental Physics and Industrial Control System. To improve the reliability as compared with previous control systems, two types of PLC central processing units, sequential and Linux, have been installed in the same unit. Past experience has shown that new types of designs that can rapidly respond to system scalability are key. By connecting PLC stations using star-topology field buses, their rapid and cost-effective response to system changes is realized for the new devices. Furthermore, a unique data acquisition system employing a 920-MHz-band radio was developed to measure analog data such as the temperature at the high-voltage stage.

High intensity vanadium beam for synthesis of new superheavy elements with well-controlled emittance by using "slit triplet"

To provide a very powerful vanadium (V) beam with an intensity of at least 6 particle μA for synthesizing a new superheavy element (SHE) with atomic number Z = 119, we have developed a high-temperature oven (HTO) system to evaporate the metallic V powder inside the new superconducting (SC) electron cyclotron ion source. We successfully extracted a V¹³⁺ beam with a maximum beam intensity of 600 eμA with 2.8-kW microwave power and 900-W heating power of the HTO. Furthermore, from a systematic study of the dependence of the beam intensity on the microwave power and the HTO power, we successfully produced a V¹³⁺ beam of 300 eμA at a consumption rate of 3 mg/h, allowing a one-month duration continuous beam to carry out the SHE synthesis. In addition, to avoid serious damage to newly introduced SC acceleration cavities by beam losses, the beam should be transported with a well-controlled emittance. To efficiently limit the beam emittance, we employed a slit triplet consisting of three pairs of slits installed around the focus point of the low-energy beam transport. The first result of the emittance reduction was observed by a pepper-pot type emittance meter as a function of the acceptance of the slit triplet.

Epidemiology and virulence-associated genes of Clostridioides difficile isolates and factors associated with toxin EIA results at a university hospital in Japan

Introduction

Clostridioides difficile is one of the most important nosocomial pathogens; however, reports regarding its clinical and molecular characteristics from Japan are scarce.

Aims

We studied the multilocus sequence typing (MLST)-based epidemiology and virulence-associated genes of isolates and the clinical backgrounds of patients from whom the isolates had been recovered.

Methods

A total of 105 stool samples tested in a C. difficile toxin enzyme immune assay (EIA) were analysed at the University of Tokyo Hospital from March 2013 to July 2014. PCR for MLST and the virulence-associated genes tcdA, tcdB, cdtA, cdtB and tcdC was performed on C. difficile isolates meeting our inclusion criteria following retrospective review of medical records. EIA-positive and EIA-negative groups with toxigenic strains underwent clinical and molecular background comparison.

Results

The toxigenic strains ST17, ST81, ST2, ST54, ST8, ST3, ST37 and ST53 and the non-toxigenic strains ST109, ST15 and ST100 were frequently recovered. The prevalence rate of tcdA-negative ST81 and ST37, endemic in China and Korea, was higher (11.4%) than that reported in North America and Europe, and hypervirulent ST1(RT027) and ST11(RT078) strains that occur in North America and Europe were not recovered. The linkage between the EIA results and cdt A/B positivity, tcdC deletion, or tcdA variation was absent among toxigenic strains. Compared with the 38 EIA-negative cases, the 36 EIA-positive cases showed that the patients in EIA-positive cases were older and more frequently had chronic kidney disease, as well as a history of beta-lactam use and proton pump inhibitor therapy.

Conclusion

In Japan, the prevalence rates for tcdA-negative strains are high, whereas the cdtA/B-positive strains are rare. EIA positivity is linked to older age, chronic kidney disease and the use of beta-lactams and proton pump inhibitors.

Matrix-assisted laser desorption ionization-time of flight mass spectrometry can be used to identify Helicobacter cinaedi

We examined the applicability of Matrix-assisted laser desorption ionization-time of flight mass spectrometry using 54 Helicobacter cinaedi isolates from humans. In all 54 isolates, MALDI-TOF MS detected H. cinaedi as the best match organism. Our findings suggest that MALDI TOF-MS can be used effectively to identify H. cinaedi.

Progress in high-temperature oven development for 28 GHz electron cyclotron resonance ion source

We have been developing a high-temperature oven using UO2 in the 28 GHz superconducting electron cyclotron resonance ion source at RIKEN since 2013. A total of eleven on-line tests were performed. The longest operation time in a single test was 411 h, and the consumption rate of UO2 was approximately 2.4 mg/h. In these tests, we experienced several problems: the ejection hole of a crucible was blocked with UO2 and a crucible was damaged because of the reduction of tungsten strength at high temperature. In order to solve these problems, improvements to the crucible shape were made by simulations using ANSYS.

Control system renewal for efficient operation in RIKEN 18 GHz electron cyclotron resonance ion source

A RIKEN 18 GHz electron cyclotron resonance ion source (18 GHz ECRIS) is used as an external ion source at the Radioactive Ion Beam Factory (RIBF) accelerator complex to produce an intense beam of medium-mass heavy ions (e.g., Ca and Ar). In most components that comprise the RIBF, the control systems (CSs) are integrated by the Experimental Physics and Industrial Control System (EPICS). On the other hand, a non-EPICS-based system has hardwired controllers, and it is used in the 18 GHz ECRIS CS as an independent system. In terms of efficient and effective operation, the 18 GHz ECRIS CS as well as the RIBF CS should be renewed using EPICS. Therefore, we constructed an 18 GHz ECRIS CS by using programmable logic controllers with embedded EPICS technology. In the renewed system, an operational log system was developed as a new feature, for supporting of the 18 GHz ECRIS operation.

Note: Effect of hot liner in producing 40,48Ca beam from RIKEN 18-GHz electron cyclotron resonance ion source

In order to produce a high-intensity and stable (48)Ca beam from the RIKEN 18-GHz electron cyclotron resonance ion source, we have begun testing the production of a calcium beam using a micro-oven. To minimize the consumption rate of the material ((48)Ca), we introduced the "hot liner" method and investigated the effect of the liner on the material consumption rate. The micro-oven was first used to produce the (48)Ca beam for experiments in the RIKEN radioisotope beam factory, and a stable beam could be supplied for a long time with low consumption rate.

Evaluation of a simple phenotypic method for the detection of carbapenemase-producing Enterobacteriaceae

We investigated the performance of a phenotypic test, the Carbapenemase Detection Set (MAST-CDS), for the identification of carbapenemase-producing Enterobacteriaceae. Our results indicated that MAST-CDS is rapid, easily performed, simple to interpret, and highly sensitive for the identification of carbapenemase producers, particularly imipenemase producers.

Implementation of an operator intervention system for remote control of the RIKEN 28 GHz superconducting electron cyclotron resonance ion source

The control system for the RIKEN 28 GHz superconducting electron cyclotron resonance ion source (28 GHz SC-ECRIS) consists of a distributed control system based on the experimental physics and industrial control system. To maintain the beam quality for the long beam-service time at the radioactive isotope beam factory, beam tuning to prevent subtle changes in the 28 GHz SC-ECRIS conditions is required. Once this is achieved, it should then be possible to check conditions and operate the ion source at any time. We have designed a web-based operational interface to remotely control the ion source, but for access and control from several locations, suitable access security, policies, and methods are required. We thus implemented an operator intervention system that makes it possible to safely access the network externally with the permission of on-site accelerator operators in the control room.

Recent development of RIKEN 28 GHz superconducting electron cyclotron resonance ion source

Over the past two years, we have tried to improve the performance of the RIKEN superconducting electron cyclotron resonance ion source using several methods. For the production of U vapor, we chose the sputtering method because it is possible to install a large amount of material inside the plasma chamber and thus achieve long-term operation without a break, although it is assumed that the beam intensity is weaker than in the oven technique. We also used an aluminum chamber instead of a stainless steel one. Using these methods, we successfully produced ∼180 eμA of U(35+) and ∼230 eμA of U(33+) at the injected radio frequency (RF) power of ∼4 kW (28 GHz). Very recently, to further increase the beam intensity of U(35+), we have started to develop a high temperature oven and have successfully produced a highly charged U ion beam. In this contribution, we report on the beam intensity of highly charged U ions as a function of various parameters (RF power and sputtering voltage) and discuss the effects of these parameters on the beam stability in detail.

Development of a high-temperature oven for the 28 GHz electron cyclotron resonance ion source

We have been developing the 28 GHz ECR ion source in order to accelerate high-intensity uranium beams at the RIKEN RI-beam Factory. Although we have generated U(35+) beams by the sputtering method thus far, we began developing a high-temperature oven with the aim of increasing and stabilizing the beams. Because the oven method uses UO2, a crucible must be heated to a temperature higher than 2000 °C to supply an appropriate amount of UO2 vapor to the ECR plasma. Our high-temperature oven uses a tungsten crucible joule-heated with DC current of approximately 450 A. Its inside dimensions are ϕ11 mm × 13.5 mm. Since the crucible is placed in a magnetic field of approximately 3 T, it is subject to a magnetic force of approximately 40 N. Therefore, we used ANSYS to carefully design the crucible, which was manufactured by machining a tungsten rod. We could raise the oven up to 1900 °C in the first off-line test. Subsequently, UO2 was loaded into the crucible, and the oven was installed in the 28 GHz ECR ion source and was tested. As a result, a U(35+) beam current of 150 μA was extracted successfully at a RF power of approximately 3 kW.

Operational test of micro-oven for 48Ca beam

In order to supply a high-intensity and stable (48)Ca beam from the RIKEN 18-GHz electron cyclotron resonance ion source, we are conducting operational tests of a micro-oven. A mixture of CaO and Al powders is placed into the crucible of the micro-oven and heated to produce metallic calcium by a reductive reaction. The successful production of a calcium beam was confirmed. In addition, we reduced the material consumption rate by using a so-called "hot liner," and we enhanced the beam intensity by applying a negative voltage bias to the micro-oven, the effect of which is similar to the effect of a "biased disk."

Pyogenic discitis due to Abiotrophia adiacens

INTRODUCTION

Abiotrophia species have been referred to as nutritionally variant streptococci because of their fastidious nutritional requirements for growth. Abiotrophia species are difficult to identify with conventional solid culture.

PRESENTATION OF CASE

A 48-year-old woman was admitted to our hospital with severe low back pain and body temperature of 38.2 °C. Magnetic resonance imaging revealed edema and contrast enhancement of the L4 and L5 vertebral bodies with high signal intensity in the L3-4 and L4-5 intervertebral discs on the T2-weighted images. The patient underwent needle biopsy of the L3-4 disk. Cultures of disk biopsy samples and blood yielded gram positive cocci in short chains with scanty growth on chocolate agar. Further subculture with supplemented medium and subsequent 16S ribosomal RNA gene sequencing identified the pathogen as Abiotrhophia adiacens. The patient was treated with intravenous ampicillin. At 6-month follow-up, the patient was free of symptoms.

DISCUSSION

Causative microorganisms remain unidentified in 25–40% of spinal infection cases. Abiotrophia species grow poorly on conventional solid media, and require pyridoxal or thiol group supplementation. Use of Brucella HK agar or GAM agar plate is helpful for detection of Abiotrophia species. We first confirmed the diagnosis by direct identification of Abiotrophia adiacens from infected disk. Abiotrophia species are one of the major pathogens of infective endocarditis accounting for 5% of cases. Considering their fastidious nature, it is likely that most cases of Abiotrophia discitis are falsely classified as culture-negative discitis; therefore, their role in pyogenic discitis may be underestimated.

CONCLUSION

Subculture using nutritionally supplemented media is crucial for their identification.

Production of a highly charged uranium ion beam with RIKEN superconducting electron cyclotron resonance ion source

A highly charged uranium (U) ion beam is produced from the RIKEN superconducting electron cyclotron resonance ion source using 18 and 28 GHz microwaves. The sputtering method is used to produce this U ion beam. The beam intensity is strongly dependent on the rod position and sputtering voltage. We observe that the emittance of U(35+) for 28 GHz microwaves is almost the same as that for 18 GHz microwaves. It seems that the beam intensity of U ions produced using 28 GHz microwaves is higher than that produced using 18 GHz microwaves at the same Radio Frequency (RF) power.

Results of RIKEN superconducting electron cyclotron resonance ion source with 28 GHz

We measured the beam intensity of highly charged heavy ions and x-ray heat load for RIKEN superconducting electron cyclotron resonance ion source with 28 GHz microwaves under the various conditions. The beam intensity of Xe(20+) became maximum at B(min) ∼ 0.65 T, which was ∼65% of the magnetic field strength of electron cyclotron resonance (B(ECR)) for 28 GHz microwaves. We observed that the heat load of x-ray increased with decreasing gas pressure and field gradient at resonance zone. It seems that the beam intensity of highly charged heavy ions with 28 GHz is higher than that with 18 GHz at same RF power.

First results from the new RIKEN superconducting electron cyclotron resonance ion source (invited)

The next generation heavy ion accelerator facility, such as the RIKEN radio isotope (RI) beam factory, requires an intense beam of high charged heavy ions. In the past decade, performance of the electron cyclotron resonance (ECR) ion sources has been dramatically improved with increasing the magnetic field and rf frequency to enhance the density and confinement time of plasma. Furthermore, the effects of the key parameters (magnetic field configuration, gas pressure, etc.) on the ECR plasma have been revealed. Such basic studies give us how to optimize the ion source structure. Based on these studies and modern superconducting (SC) technology, we successfully constructed the new 28 GHz SC-ECRIS, which has a flexible magnetic field configuration to enlarge the ECR zone and to optimize the field gradient at ECR point. Using it, we investigated the effect of ECR zone size, magnetic field configuration, and biased disk on the beam intensity of the highly charged heavy ions with 18 GHz microwaves. In this article, we present the structure of the ion source and first experimental results with 18 GHz microwave in detail.

[The fundamental evaluation of COBAS TaqMan48 using clinical specimens]

PURPOSE

When smear test is positive for acid-fast bacilli, it is important to differentiate between Mycobacterium tuberculosis complex and nontuberculosis mycobacteria (NTM) in healthcare associated infection (HAI) control. The aim of this study is to evaluate between COBAS TaqMan48 (TaqMan) and COBAS Amplicor (COBAS).

MATERIAL AND METHOD

Tenfold dilution series of 5 x 10(4) cfu/mL of Mycobacterium bovis (ATCC19210) were used for evaluating the limit of detection (LOD) and reproducibility. 73 frozen clinical specimens (34 M. tuberculosis complex and 39 NTM) stored at below -20 degrees C before its use that were treated with NALC-NaOH were used to determine the agreement between two methods. Divided reaction reagents (include Master mix solution, Internal control and Mg2+) of TaqMan for 3 and 6 tests per batch used to evaluate reagents stability.

RESULT

The LOD of both kits were 5 X102 cfu/mL. Regarding reproducibility, the same result was obtained when tested 3 times. The agreement rate between TaqMan and culture method was 58.8%, and between COBAS and culture method was 67.6%. When limited to smear positive eleven specimens, the agreement between TaqMan and culture method was 81.8%, and between COBAS and culture method was 90.9%. Reagents divided for 3 tests and 6 tests and stored at 4 degrees C in dark, both test reagents stability was confirmed maximum for 16 days.

CONCLUSION

As the results of the evaluation of TaqMan, the LOD, reproducibility and the agreement were similar to COBAS results. However, in low colony forming unit of clinical specimen raise the possibility that results may contain false negative.

Measurement of plasma potential of liquid-He-free superconducting electron cyclotron resonance ion source

The plasma potential of liquid-He-free superconducting electron cyclotron resonance ion source was measured as a function of minimum strength of mirror magnetic field (B(min)) and gas pressure with the method based on the retarding electric field. We observed that the plasma potential decreased with increasing B(min) up to 0.5 T and then gradually increased again. The plasma potential increased with increasing gas pressure. When we add the O(2) gas to the Ar plasma (gas mixing method), plasma potential gradually decreased with increasing the O(2) gas pressure.

New superconducting electron cyclotron resonance ion source for RIKEN RI beam factory project

For RIKEN radio isotope beam project, we started to construct the new superconducting electron cyclotron resonance ion source (SC-ECRIS), which has an operational frequency of 28 GHz, in 2007. The main feature of this ion source is that we can produce large size of resonance zone with six sets of solenoid coils. Before starting, we intensively studied the effect of several key parameters of ECRIS (magnetic field configuration, microwave power density, negatively biased disk) on the plasma. In this article, we describe the effect of key parameters on the plasma and detailed structure of the new SC-ECRIS.

Production of U beam from RIKEN 18 GHz electron cyclotron resonance ion source

For the RIKEN radio isotope factory (RIBF) project, we produced the multicharged uranium beam with two methods. To produce lower charge state U ion beams (14+-20+) we used the UF(6) gas as an ionized gas. The typical beam intensity of U(14+-20+) was 2-1 particle microA at the extraction voltage of 14 kV. To produce higher charge state U ion beam (U(35+)), we chose the sputtering method. The beam intensity was 70 particle nA at the extraction voltage of 5.4 kV. Using this method, we successfully produced multicharged U beam continuously for one month without break for RIBF commissioning.

Changes in drug susceptibility and toxin genes in Staphylococcus aureus isolated from blood cultures at a university hospital

We studied changes in toxin-producing genes and drug susceptibility in Staphylococcus aureus isolated from blood cultures at the University of Tokyo Hospital between 1980-1984 (six mecA gene-positive methicillin resistant S. aureus [MRSA] strains and 20 mecA gene-negative methicillin-susceptible S. aureus [MSSA] strains) and 1999 (11 MRSA and 20 MSSA strains). The prevalence of strains with toxin-producing genes increased from 66.7% to 90.9% in MRSA, and from 30.0% to 55.0% in MSSA during the interval. Among toxin-producing gene-positive S. aureus, the dominant strains shifted from those with the enterotoxin (ET) - A gene in 1980-1984 to those with both the toxic shock syndrome toxin-1 and the ET-C genes in 1999. All strains were susceptible to vancomycin and teicoplanin. Mupirocin and arbekacin inhibited all strains at concentrations of less than or equal to 0.5 micro g/ml and 4 micro g/ml, respectively. More than half of the MRSA strains in 1999 were considered to be nonsusceptible to flomoxef. Because almost all MRSA and more than half of MSSA among recently isolated strains possessed the toxin-producing genes, we should pay attention to whether toxin-related diseases caused by MRSA and MSSA are increasing.

[Reliability of Amplicor Mycobacteria Kit for detection of Mycobacterium tuberculosis complex and Mycobacterium intracellulare: results of cooperative study among 331 laboratories in 2000]

Amplicor Mycobacterium Kit (Roch Diagnostics: Japan) is the most widely used kit in Japan for the diagnosis of mycobacteria infections, especially those caused by Mycobacterium tuberculosis, Mycobacterium avium and Mycobacterium intracellulare. We evaluated the reliability of the kit in co-operation with 331 laboratories using the kit in routine examination. We distributed specially prepared 4 test samples to each laboratories. The negative sample was NALC-NaOH treated sputum which showed "negative" when tested by this kit and positive samples were NALC-NaOH treated sputum containing M. bovis or M. intracellurare. False-positive results were reported in 6 out of 331 laboratories (1.8%) and false-negative results were reported from 7 laboratories (2.1%). (The details were 1 out of 331 labs for TB-H sample, 5 out of 331 labs for TB-L sample and 1 out of 316 in MIN sample.) Statistical significance between MWP method and COBAS method was not significant. After receiving and evaluating the test results on the 4 samples, the follow up questionnaires were sent out to 22 laboratories which reported incorrect results and low optical density (O.D.) on positive control. Results of this questionnaire suggested that it was important to follow the package insert instructions and to follow the correct procedures for PCR assay. These results suggested that Amplicor Mycobacterium Kit is reliable for rapid diagnosis of Mycobacteria infections.

Effectiveness of fosfomycin combined with other antimicrobial agents against multidrug-resistant Pseudomonas aeruginosa isolates using the efficacy time index assay

We investigated the effectiveness of fosfomycin combined with other antibiotics, such as piperacillin, cefepime, ceftazidime, imipenem, meropenem, aztreonam, gentamicin, or levofloxacin, against 30 Pseudomonas aeruginosa strains, including multidrug-resistant strains, isolated from clinical specimens, using the efficacy time index (ETI) assay. The assay refers to the result of pharmacokinetics obtained from adult men volunteers, and yields an ETI to evaluate the effect of a combination of antimicrobial agents. With the ETI, based on serum concentration 3 h after the administration of two antimicrobial agents, the effectiveness of antimicrobial combinations was evaluated as follows: poor, ETI < 0.5; fair, 0.5 < or = ETI < 1; good, 1 < or = ETI < 8; and excellent, ETI > or = 8. The combination of fosfomycin and cefepime (efficacy rate [excellent plus good], 76.7%) and fosfomycin/aztreonam (efficacy rate, 76.7%) appeared to be the most effective, followed by fosfomycin/meropenem (efficacy rate, 76.6%), fosfomycin/imipenem (efficacy rate, 73.3%), fosfomycin/ceftazidime (efficacy rate, 70%), fosfomycin/gentamicin (efficacy rate, 70%), fosfomycin/piperacillin (efficacy rate, 66.7%), and fosfomycin/levofloxacin (efficacy rate, 66.7%). Fosfomycin/cefepime, fosfomycin/aztreonam, and fosfomycin/meropenem may be clinically useful in selected patients, particularly for P. aeruginosa. The ETI assay provided information on the minimum inhibitory concentration (MIC) of many pairs of combined antimicrobial agents simultaneously. The ETI assay may be a useful technique with which to investigate the effect of combinations of antimicrobial agents against P. aeruginosa, including multidrug-resistant strains.

[Detection methods for drug-resistant bacteria in routine examination--MRSA]

Since methicillin-resistant Staphylococcus aureus(MRSA) is resistant not only to methicillin but also to multiple species of antibacterial drugs, there are cases where infections with MRSA are difficult to treat. For laboratory identification of MRSA, S. aureus is first identified, then an oxacillin (MPIPC) sensitivity test, PCR detection of the S. aureus mecA gene and an agglutination test using the latex sensitized with an anti-PBP-2' monoclonal antibody are usually utilized. However, the detection of MRSA does not necessarily indicate MRSA infection, and many cases only demonstrate MRSA colonization. Thus, a clinical investigation is indispensable for establishing the diagnosis of MRSA infection. In addition, recent reports also suggested a current trend toward decreasing sensitivity to Bactroban(MUP, mupirocin, an anti-intranasal MRSA antibacterial drug). Taking these into consideration, surveillance of the trend in patient's sensitive to various species of antibacterial drugs including MUP must continue further.

Molecular epidemiological investigation using a randomly amplified polymorphic DNA assay of Burkholderia cepacia isolates from nosocomial outbreaks

We experienced two Burkholderia cepacia outbreaks over a 1-year period. During this period, 28 B. cepacia isolates were obtained from clinical specimens, and 2 were obtained from environmental specimens (i.e., from a nebulizer solution and a nebulizer tube). These 30 isolates were subjected to the PCR-based randomly amplified polymorphic DNA (RAPD) assay as well as to pulsed-field gel electrophoresis (PFGE). In the first outbreak, in which eight patients hospitalized in the Trauma and Critical Care Center were involved, the RAPD assay revealed that all 20 isolates obtained from clinical specimens and the 2 isolates from environmental specimens had identical DNA profiles. These RAPD data enabled us to pinpoint a possible source and to take countermeasures to prevent further spread of the epidemic-causing strain. In the second outbreak, two consecutive B. cepacia infection/colonization cases were seen in the surgery ward. The RAPD profiles of four isolates obtained were again identical, but they were distinct from those seen in the first outbreak, clearly indicating that the second outbreak was not related to the first. Thus, our experience demonstrated that the RAPD assay is a useful and reliable tool for epidemiological studies of B. cepacia isolates from nosocomial outbreaks. Since the RAPD assay could provide discriminatory potential and reproducibility comparable to those of the widely used PFGE assay with less complexity and in a shorter time, the introduction of the RAPD assay into hospital microbiology laboratories as a routine technique may help prevent nosocomial outbreaks.

[The in vitro antibacterial activity of cefozopran against clinically isolated bacteria]

The in vitro antibacterial activity of cefozopran (CZOP) against recent clinical isolates was evaluated and compared with those of ceftazidime (CAZ), cefpirome (CPR), cefepime (CFPM), cefotaxime (CTX), sulbactam/cefoperazone (S/C), imipenem (IPM), oxacillin (MPIPC), and flomoxef (FMOX). MIC80 values of CZOP for methicillin-susceptible Staphylococcus aureus (MSSA, n = 41), methicillin-resistant Staphylococcus aureus (MRSA, n = 57), Streptococcus pneumoniae (n = 45), Enterococus faecalis (n = 49), Enterobacter cloacae (n = 50), Citrobacter freundii (n = 45), Serratia marcescens (n = 45), and Pseudomonas aeruginosa (n = 100) were 1, 32, 2, 16, 4, 1, 0.25, 8 micrograms/ml, respectively. CZOP was more active than CPR against P. aeruginosa and exhibited similar activity to CPR against other species. CZOP was especially active against S. marcescens with MIC values lower than 1 microgram/ml against all strains tested. CZOP was similarly active to or more active than CFPM against all species except for C. freundii. CZOP was not active against MRSA. Thus, we investigated the in vitro combination effects of CZOP/vancomycin (VCM) and CZOP/arbekacin (ABK) using the checkerboard method. The interaction between CZOP and VCM ranged from additive activity (0.5 < FIC index < or = 1.00, n = 37) to synergistic activity (FIC index < 0.50, n = 1), except for one strain showing indifference (1.00 < FIC index < or = 2.00). The interaction between CZOP and ABK ranged from additive activity (n = 22) to synergistic activity (n = 1). These date suggest the potential effect of combination therapy of (CZOP) and VCM or ABK against MRSA. The combined therapy is suggested to be useful to reduce side effects in patients with impared renal function, to reduce the administration dose of VCM or to treat infections of sites where achievable drug concentrations are lower than those commonly achieved in the bloodstream. We also investigated the combination effects of CZOP/AMK and CZOP/GM against CZOP-resistant P. aeruginosa (MIC > 16 micrograms/ml). The combination of CZOP/AMK showed additive activity (n = 9) to synergistic activity (n = 2). The combination of CZOP/GM showed additive activity (n = 5). These results suggest that combinations of CZOP with AMK or GM are effective in treating P. aeruginosa.