[Drug-resistance patterns and biological properties of MRSA isolated from different geographical areas of Japan].
One hundred isolates of methicillin-resistant Staphylococcus aureus (MRSA) collected from hospitals located in different geographical areas of Japan were used in the present study. The susceptibilities of the strains to gentamicin (GM), erythromycin (EM), tetracycline (TC) and ofloxacin (OFLX) were determined and classified into twelve groups according to their differences in the patterns of the resistance to the four drugs. Of the 100 strains tested, 75 belonging to the main four groups were investigated for the relationships between their patterns of the drug-resistance and biological properties such as coagulase, enterotoxin and phage types, TSST-1 and beta-lactamase producibilities, and percentages of the strains carrying plasmids of large size (> or = 20,000 bp). The main four patterns of drug resistance of the 75 strains were as follows: the first group (33 strains resistant to GM, EM, TC and OFLX), the second group (15 strains resistant to EM, TC and OFLX), the third group (11 strains resistant to GM, EM and OFLX) and the fourth group (16 strains resistant to EM and OFLX) and the remaining 25 strains were divided into further groups. A considerable number of the strains in the third group differed markedly in some biological properties from those in the other groups; coagulase typing (III type-50%: the other groups-II type), enterotoxin typing (64%-non-production: the other groups-C type), TSST-1 producibility (36%-production: the other groups-76 to 88%-production) and phage typing (55%-non-typable: the other groups-80 to 97%-non-typable). In beta-lactamase and plasmids of large size, the first group consisted of the strains with beta-lactamase producibility at the ratio of 50:50, but the other groups consisted of most of the strains with the beta-lactamase producibility. Most of the strains belonging to the second and fourth groups carried large size of plasmids, but 36 and 46% of those belonging to the first and third groups did not carry them. On the other hand, our results of the susceptibility test for the 100 strains showed that a considerable number of strains were susceptible to GM (35%) and TC (42%) at therapeutically significant concentrations.
Kanayama
A
A
Chemotherapy Division, Mitsubishi Kagaku Bio Clinical Laboratories, Inc., Japan.
Saika
T
T
Hasegawa
M
M
Kobayashi
I
I
Nishida
M
M
D000900:Anti-Bacterial Agents / Q000494:pharmacology; D004352:Drug Resistance, Microbial; D007564:Japan; D016106:Methicillin Resistance; D013211:Staphylococcus aureus / Q000145:classification / Q000187:drug effects* / Q000302:isolation & purification
D000900:Anti-Bacterial Agents