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M Tosaka

Publications and source records attributed to M Tosaka.

At least 37 records · Page 2Linked to original sources
PubMed1997

[Laboratory-evaluation of antimicrobial susceptibility testings to detect vancomycin-resistant enterococci].

The emergence and dissemination of vancomycin-resistant enterococci (VRE) emphasizes the need for laboratories to be able to correctly detect them. The study described was conducted to evaluate the test methods presently available in Japan to discriminate between the isolates of VRE and those susceptible (VSE). Among the phenotypic test methods evaluated, an agar screening method which utilized 8 micrograms per ml of vancomycin in Mueller-Hinton agar plate appeared to have a sufficient accuracy. When 23 isolates of vanA positive, 31 of vanB positive, 4 of both positive and 60 of both negative were tested, the sensitivity and specificity to detect VRE were estimated to be 98.3% and 100%, respectively. Also, all the VRE isolates were interpreted as being resistant or intermediate by the E test recently approved in Japan, when the results were read after 48 hr-incubation. Whereas, two disk diffusion tests, Showa disk and NCCLS-based Sensi-disc, were evaluated, but both methods failed to discriminate between VRE and VSE, in particular, between the isolates with vanB positive and negative. The automated system, Vitek GPS-TA produced high frequencies of very major errors; 8.7% for vanA positives and 58% for vanB positives. A total of 1,214 enterococcal isolates from multisite laboratories in Japan, comprising 7 different species, were first tested onto agar screening test plates, but none of isolates represented phenotypic vancomycin resistance. With these results, it can be recommended to detect VRE in clinical microbiology laboratories as follows: First, all the enterococcal isolates will be tested onto the agar screening plates or by the E test. Then, if the isolate is interpreted as being resistant or intermediate, the laboratory should confirm whether it is positive for vanA or vanB by polymerase chain reaction (PCR) specified.

Anti-Bacterial Agents↗
PubMed1997

[Determination of in vitro synergy when amphotericin B is combined with various antimicrobial agents against yeasts by using a colorimetric microdilution checkerboard].

We determined in vitro interactions when amphoteric B (AMPH) is combined with various antimicrobial agents against yeast by using a colorimetric microdilution transfer plate technique, principally based on the current National Committee for Clinical Laboratory Standards (NCCLS) M27-T. An oxidation-reduction dye, sodium resazurin, was used as a color indicator to detect the growth of yeasts, and a standard two-dimensional, two-agent microdilution checkerboard in RPMI 1640 was employed to determine in vitro interactions; synergistic, indifferent or antagonistic. The study included 125 clinical isolates of Candida species and nine reference strains of American Type Culture Collection described in M27-T. Among the 34 antimicrobial agents first tested, polymyxin B (PL), rifampicin (RFP), tetracycline (TC) and erythromycin (EM) showed significant synergism. The fractional inhibitory concentration (FIC) indices of the respective agents were; PL 0.16 to 0.51 (mean, 0.315), RFP 0.13 to 0.56 (0.255), TC 0.06 to 0.75 (0.353) and EM 0.27 to 1.0 (0.550). RFP was the most potent agent, 118 of 125 clinical isolates (94.4%) showing synergism (FIC, < or = 0.5). With these results, we can conclude that several antibacterial agents are potentially effective when combined with AMPH against yeasts, probably due to alteration in the permeability barrier of the surface membrane by AMPH. Antifungal synergism may be promising for more effective, and less toxic therapy, and thus in vivo study will be necessary to determine their clinical significance.

Amphotericin B↗
PubMed1996

Multicenter evaluation of a colorimetric microplate antimycobacterial susceptibility test: comparative study with the NCCLS M24-P.

A colorimetric test method using the microplate culture technique for the determination of susceptibility of Mycobacterium tuberculosis against antimycobacterial agents was developed and evaluated by the multicenter study. The test method utilizes an oxidation-reduction dye, 2,3-diphenyl-5-thienyl-(2)-tetrazolium chloride (STC), as an indicator of mycobacterial growth. When compared to the presently available test method, some modifications were also included; lower inoculum density (10-fold dilution), inclusion of an inoculum diluted 1:100 as a growth control, and the preparation of inoculum preincubated in Middlebrook 7H9 broth and spectrophotometrically adjusted to McFarland #1 turbidity. The test method evaluated was highly precise and reliable to detect antimycobacterial resistances when the ATCC reference strains were tested. Also, the interpretations of the test result were highly comparable to those determined by the method of NCCLS M24-P, the % agreements ranging from 76.1% (ethambutol) to 91.3% (streptomycin). The test results were also comparable to those determined by Ogawa media; > 90% agreed with susceptible, intermediate, or resistant. The appearance of mycobacterial colonies on the test media was easily read, and the test results were more comparable to those of NCCLS M24-P. With these results, it can be concluded that the colorimetric microplate susceptibility test method described will be more suitable for clinical mycobacteriology laboratories.

Antitubercular Agents↗
PubMed1996

[Colorimetric broth microdilution for antifungal susceptibility testing].

A colorimetric broth microdilution modification of the National Committee for Clinical Laboratory Standards (NCCLS) for antifungal susceptibility testing was developed and evaluated. The test method modification includes; air-dried microdilution trays, in which serial two-fold dilutions of three antifungal agents, amphotericin B (AMPH), flucytosine (5-FC) and fluconazole (FCZ) were first prepared and evaporated, then reconstituted by adding 100 microliters of yeast inocula, and an oxidation-reduction color indicator (sodium resazurin, Sigma) added to RPMI 1640 medium buffered to pH7.0 with 0.165M morpholinepropanesulfonic acid. The trays were incubated in air at 35 degrees C and were inspected after 24 and 48hr of incubation. The MICs were defined as the lowest concentration of the respective agents; no color change (blue) for AMPH, and slight color change (blue to purple) for 5-FC and FCZ. The MICs of AMPH, 5-FC and FCZ were determined for four reference strains and 100 clinical isolates, in comparison with the NCCLS macrodilution method. The four reference strains were tested seven times each by macrodilution method (MACRO) and 14 times each against all three antifungal agents by microdilution method (MICRO). Overall, 100% of MICs determined by MACRO, 96% of those determined at 24hr incubation by MICRO, and 93% of those determined at 48hr incubation by MICRO fell within the 3-log2 dilutions, although 20 to 33% were out of the acceptable MIC ranges of the NCCLS M27-P proposal. Excellent reproducibility in determining growth endpoint by color change was also demonstrated, giving 99 to 100% agreements in duplicated dilutions. When the MICs determined for 100 clinical isolates against three antifungal agents were compared, those determined at 24hr incubation by MICRO gave 61.7% of agreement within the 3-log2 dilutions of the NCCLS MACRO, and those determined at 48hr incubation by MICRO were 86.2%. The MICRO read at 24hr trended to the lower MICs, except for 5-FC. While the MICs of MICRO read at 48hr were mostly comparable (78 to 97% agreement) to those of MACRO, especially against 5-FC (97%) and AMPH (85%), but the discrepant MICs of Candida tropicalis against FCZ were noted. With these results, it can be concluded that the resazurin colorimetric broth microdilution method is easy to perform and highly precise, and may provide MICs comparable to those determined by the reference NCCLS macrodilution method.

Amphotericin B↗
PubMed1996

[Determination of antimycobacterial activities of fluoroquinolones against clinical isolates of Mycobacterium tuberculosis: comparative determination with egg-based Ogawa and agar-based Middlebrook 7H10 media].

The minimum inhibitory concentrations (MICs) to the fluoroquinolones, ofloxacin (OFLX), ciprofloxacin (CPFX), sparfloxacin (SPFX), norfloxacin (NFLX), balofloxacin (BLFX) and CS-940, were determined in 100 clinical isolates of Mycobacterium tuberculosis. The MICs were determined with 1% egg-based Ogawa or agar-based Middlebrook 7H10 and each of them supplemented with oxidation-reduction color dye, 2,3-diphenyl-5-thienyl-(2)-tetrazolium chloride (STC) by using the microculture technique. The MICs determined with Ogawa medium were approximately two- to four-fold higher when compared to those determined with Middlebrook agar medium. The supplement with STC slightly increased the MICs, probably as a result of easily recognizing small initial colonies. Among the six fluoroquinolones, CS-940 and SPFX showed the greatest antimycobacterial activities with inhibition of 50% of all the isolates at the concentrations between 0.25 to 0.5 microgram/ml. OFLX, CPFX and BLFX followed in potency at 0.5 to 2.0 micrograms /ml. NFLX was less potent requiring 8 to 16 micrograms/ml to inhibit 50% of the isolates.

Anti-Infective Agents↗
PubMed1994

The first case of polymyositis associated with interferon therapy.

A 54-year-old man with renal cell carcinoma was treated with interferon (IFN)-gamma for 3 weeks soon after nephrectomy. Three months later he received IFN-alpha therapy for 8 weeks due to chronic active hepatitis C. He subsequently contracted polymyositis (PM): proximal muscle weakness, an elevation of muscle enzymes, myogenic patterns on the electromyograph and histologically specific findings in biopsied muscle specimens. After discontinuation of IFN his muscular weakness gradually recovered.

Carcinoma, Renal Cell↗
PubMed1994

[Multi-center evaluation to discriminate between the strains of methicillin-resistant Staphylococcus aureus (MRSA) and those susceptible (MSSA) by Showa oxacillin and methicillin disk susceptibility tests].

The Showa disk susceptibility test using two penicillinase-resistant penicillins, oxacillin and methicillin, was evaluated to discriminate between the strains of Staphylococcus aureus resistant to methicillin (MRSA) and those susceptible (MSSA) in the multi-center trials. The study included 651 clinical isolates of S. aureus, comprising of 329 MRSA and 322 MSSA isolates. The inhibitory zone diameters by Showa disks to oxacillin and methicillin highly correlated with minimum inhibitory concentrations (MICs) determined by standard agar dilutions with 0.961 and 0.930 correlation coefficients, respectively. Of 651 duplicate MIC determinations, 79.9% (oxacillin) and 80.3% (methicillin) were within +/- 1 log2 dilutions with each other. When Showa oxacillin and methicillin disks were incubated at 35 degrees C, sensitivity and specificity of oxacillin to detect MRSA were 95.4% and 98.1%, and those of methicillin were 94.8% and 95.2%. When tested on agar plates supplemented with 5% NaCl, sensitivity and specificity markedly improved to > 97%. Also, when incubated at 30 degrees C, sensitivity and specificity became to nearly 100%. Of 329 MRSA isolates, the interpretive criteria combined with incubation at 30 degrees C and testing onto 5% NaCl supplemented agar plates could correctly identify 324 (98.5%) and 329 (100%) isolates, respectively. In conclusion, when the Showa oxacillin and methicillin disk susceptibility tests were employed exactly according to the manufacturer's instruction, the test performances to detect MRSA were enough reliable to screen MRSA isolates in clinical microbiology laboratories.

Methicillin↗
PubMed1994

[Multi-center evaluation of Showa ceftizoxime disk susceptibility test to discriminate between the strains of methicillin-resistant Staphylococcus aureus (MRSA) and those susceptible (MSSA)].

An increasing prevalence of methicillin-resistant Staphylococcus (S.) aureus (MRSA) has a serious therapeutic problem, and accurate methods to detect such strains are needed. We studied the antimicrobial susceptibility of S. aureus to ceftizoxime, in comparison with those to four other cephems (cefazolin, cefoxitin, latamoxef and cefmenoxime), by broth microdilutions and disk susceptibility tests, and also evaluated whether the reagents, in replace of penicillinase-resistant penicillins (PRPs), could discriminate between the strains of MRSA and those susceptible to PRPs (MSSA). A total of 651 clinical isolates of S. aureus were collected from six geographically different hospitals. All the strains collected were first classified into either MRSA (n = 329) or MSSA (n = 322) according to the interpretations of MRSA screening agar, minimum inhibitory concentrations (MICs) to oxacillin and methicillin (NCCLS M7-A2), and the presence or absence of mecA gene by polymerase chain reaction. In broth microdilution tests, the MICs of MRSA to ceftizoxime ranged > or = 64 micrograms/ml, whereas all the MSSA were at the concentration of < or = 16 micrograms/ml. The results of Showa disk diffusion tests highly correlated with those of MIC determinations. The distribution of inhibitory zone diameters to ceftizoxime were clearly divided into two groups; 99.2% (sensitivity) of MRSA had inhibitory zones of < or = 20 mm and 98.9% (specificity) of MSSA produced > or = 21 mm. It was concluded that the Showa ceftizoxime disk susceptibility test was useful and enough reliable to screen MRSA isolates in clinical laboratories.

Ceftizoxime↗
PubMed1993

Prevalence of enterococcal high-level aminoglycoside resistance in Japan. Comparative detection by three methods.

A total of 250 strains of enterococci isolated in Kumamoto University Hospital, Japan, during the period from January to March 1992 were tested for high-level aminoglycoside resistance. Brain-heart infusion (BHI) agar plates supplemented with 1000 micrograms/ml of gentamicin or 2000 micrograms/ml of streptomycin detected 164 (66%) isolates resistant to either gentamicin or streptomycin alone, or both, and consisted of 107 (43%) resistant to gentamicin and 96 (38%) resistant to streptomycin. The Vitek Gram-Positive Susceptibility card (GPS-TA) revealed high correlations with those by agar screens, the results indicating a sensitivity of 100% and 99% to gentamicin and streptomycin, respectively, and 100% specificity to both. Also, the microdilution tests of the National Committee for Clinical Laboratory Standards (NCCLS) showed 100% and 92% sensitivity to gentamicin and streptomycin, respectively, and no false resistance (100% specificity) when compared with the results by agar screens.

Aminoglycosides↗
PubMed1993

Gastric non-Hodgkin's lymphoma associated with Behçet's disease.

The first case of primary gastric lymphoma associated with Behçet's disease is reported. A 43-year-old woman, who had been treated for Behçet's disease for 15 years, was diagnosed as low-grade and small lymphocytic malignant lymphoma of the stomach. Although the patient had been treated for Behçet's disease, chemotherapy was performed and a complete remission of gastric lymphoma was achieved. The literature regarding the association of malignant diseases with Behçet's disease is briefly reviewed.

Adult↗
PubMed1992

Thoracic extramedullary hematopoiesis associated with hereditary spherocytosis.

A 54-year-old man was diagnosed with hereditary spherocytosis. An X-ray of the chest disclosed bilateral round masses in the upper and lower posterior mediastinum. CT showed homogeneous round masses of soft tissue density in the posterior mediastinum. A needle biopsy of the mass showed hyperplastic erythroid bone marrow. Fatty metamorphosis of the masses was observed in CT 2 years after splenectomy but showed no change in size.

Hematopoiesis, Extramedullary↗
PubMed1992

[An autopsied case of progressive systemic sclerosis with anti Wa antibody who showed a rapid progression].

An anti Wa antibody was reported as a new t-RNA related protein antibody in 1986. This autoantibody is now considered specific for the diagnosis of progressive systemic sclerosis (PSS). Up to date only 5 cases with anti Wa antibody have been identified. We report here an autopsied case of PSS with this antibody. A 53 years old female was admitted to our hospital because of dry cough and dyspnea in Sep 1987. There were fine crackles and chest X ray revealed interstitial pneumonia. The progressive respiratory failure was treated by steroid pulse therapy effectively. Sclerotic skin changes of hand began to appear in Sep 1988 and rapidly progressed to arms, chest and forehead by Dec 1988. A skin biopsy confirmed PSS changes. An anti Wa antibody was detected by double immunodiffusion and the protein antigen was associated with t-RNA when immunoprecipitation was conducted. She died of heart failure in July 1989. An autopsy revealed the diffuse fibrotic change of the heart and the lung. Cases with anti Wa antibody were shortly reviewed from the literature.

Autoantibodies↗
PubMed1992

[Isolation and antimicrobial susceptibility of methicillin-resistant Staphylococcus aureus (MRSA) at Kumamoto University Hospital].

An increasing prevalence of methicillin-resistant Staphylococcus aureus (MRSA) has created a serious therapeutic problem. During the period from July to December 1987, the prevalence of MRSA was only 72 strains (35.8%) of 201 total staphylococcal isolates. Since then, the frequency of MRSA has markedly increased to 67.3% in 1989, and at that time it was estimated that 30 patients (3.5%) of 850 total inpatients became infected with MRSA. In an early study in 1987, the majority of the MRSA came from post-operative patients; however in 1989, nearly 40% of MRSA were from internal medicine, mainly from immunocompromised patients. The major source of MRSA isolates was sputum (40%) throughout the years, but the MRSA from blood cultures was first recovered in 1989. Also, the major coagulase serotype of MRSA was type IV (18 of 30) in the 1987-study, then shifted to type II (24 of 40) in 1989. Among the several antimicrobials evaluated, four agents; erythromycin, minocycline, ofloxacin, and gentamicin revealed increasing MICs when compared with the results obtained for the MRSA isolates in 1987 and 1989. In particular, the most of the MICs to minocycline and ofloxacin were categorized to be highly susceptible (less than or equal to 0.39 micrograms/ml) or resistant (greater than or equal to 25 micrograms/ml). Vancomycin, currently licensed for the MRSA infection, will be highly effective both in vitro and in vivo; however, it examinative of the MRSA isolates in the clinical laboratories, especially to prevent hospital-acquired infections and to follow up the vancomycin susceptibility will be required.

Anti-Bacterial Agents↗
PubMed1991

[Multi-center evaluation of Showa disk susceptibility to presumptively determine minimum inhibitory concentrations through linear regression analysis].

To confirm the reliability of minimum inhibitory concentrations (MICs) determined by use of predefined linear regressions to bacterial growth inhibitory zone diameter on Showa disk susceptibility test, the multi-center evaluation along daily routines was performed in comparison with the standard agar dilution method. In total, 4,107 (89.0%) of 4,613 testings gave comparable MICs with 4-fold or less differences to those determined by the standard agar dilutions. The agreement of MICs (less than or equal to 4-fold differences) for gram-negative rods, excluding Pseudomonas aeruginosa, against 10 antimicrobial agents was estimated to 92.1%, and those for gram-positive cocci against 9 agents and for the strains of Pseudomonas aeruginosa against 8 agents were 84.5% and 81.7%, respectively. With these results, we can conclude that, under the well-controlled test procedures, the MIC correlates determined by Showa disk susceptibility test are enough comparable to those determined by the standard agar dilution method.

Anti-Bacterial Agents↗
PubMed1991

[Detection of methicillin-resistant Staphylococcus aureus by the Showa disk].

The Showa disk susceptibility test using two penicillinase-resistant penicillins (PRPs: methicillin and oxacillin) and four cephalosporins (cefazolin, cefmetazole, ceftizoxime, and latamoxef) was evaluated to discriminate between the strains of Staphylococcus aureus resistant to methicillin (MRSA) and those susceptible (MSSA). Among 129 MRSA and 112 MSSA strains, significant numbers of MRSA found to be false-susceptible to PRPs, especially when incubated at 37 degrees C. Using agar plates supplemented with 5% NaCl, oxacillin disk correctly categorized all the MRSA and MSSA strains, but two MSSA strains were mischaracterized with methicillin disk. All the MSSA strains found to be susceptible against cephalosporins tested, but significant numbers of MRSA were also interpreted to be susceptible. Only the result of ceftizoxime disk susceptibility test highly correlated with methicillin resistance, when incubated at 35 degrees C. All the MRSA did not produce any significant bacterial growth inhibitory zone around the disk, whereas all the MSSA found to be susceptible (19 mm or more), e.g., 100% correlation. With these data, we recommend that ceftizoxime disk susceptibility test, incubated at 35 degrees C, provides a more reliable method to characterize the strains of MRSA and MSSA. The interpretive breakpoint would be used as; less than or equal to 16 mm (greater than or equal to 25 micrograms/ml) for MRSA.

Methicillin Resistance↗