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Jpn J Antibiot. 1991 Dec;44(12):1376-85.

[Biological types and drug-sensitivities of multiple strains of freshly isolated methicillin-resistant Staphylococcus aureus].

[Article in Japanese]

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Section of Studies, Tokyo Clinical Research Center.


Biological studies were done on numbers of methicillin-resistant strains of Staphylococcus aureus (MRSA) either clinically isolated at medical institutes nationwide and sent to us or isolated and identified by us from samples obtained in the year 1990 from patients with various infections. The results of the studies are summarized as follows. 1. The origins of the 1,047 strains used in our studies included arterial and venous blood samples (6.9%), samples from the respiratory tract (43.3%), surgical and dermatological samples (30.2%), otorhinolaryngological and ophthalmological samples (3.8%), urological samples (7.2%), fecal samples (5.1%) and others (3.6%), thus samples from the respiratory tract were the most frequent. 2. The strains were classified according to coagulase types into type II (76.4%), type III (2.1%), type IV (15.4%), type VII (5.3%) and other types (0.8%), thus type II strains were the most numerous. When classified according to their origins, type II strains were found in a significantly high frequency in respiratory tract samples, and type IV strains appeared to be present at relatively high frequencies in the surgical, dermatological, otorhinolaryngological and ophthalmological samples. Some coagulase types were found more frequently in samples from some institutes than in others, but coagulase type distributions were similar in different localities. 3. The strains were classified according to their enterotoxin types into type A (22.8%), type B (10.5%), type C (54.9%) and other types (11.7%), thus type C strains were the most frequent. Significant correlations were observed between enterotoxin type C and coagulase type II, and type A and type IV. 4. Defining strains with minimum inhibitory concentrations (MICs) of greater than or equal to 100 micrograms/ml as high MRSA and less than or equal to 50 micrograms/ml as moderate MRSA, 94.8% of coagulase type II strains were high MRSA and 78.9% of coagulase type IV strains were moderate MRSA, thus coagulase type II strains tended to be high in methicillin resistance. 5. MIC50 and MIC90 of vancomycin (VCM) against many of these strains of MRSA were 0.78 and 1.56 micrograms/ml, respectively, suggesting that VCM has also a potent antibacterial activity against recent isolates of MRSA in Japan.

[Indexed for MEDLINE]

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