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I Moriyasu

Publications and source records attributed to I Moriyasu.

4 recordsLinked to original sources
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↗