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The Journal of the Japanese Society for Clinical Microbiology |
Biblioraphy Information
| ArticleTitle |
Effects of Concomitant Use of Imipenem and Glycopeptides on BIVR and Non-BIVR Strain -Assessment Using Different Amounts of Inoculated Bacteria and Incubation Times- |
| Language |
J |
| AuthorList |
Zenzo Nagasawa, Yukari Nakashima, Megumi Oho, Kouji Kusaba |
| Affiliation |
Department of Clinical Laboratory, Saga University Hospital |
| Publication |
J.J.C.M.: 18 (3), 199-202, 2008 |
| Received |
March 5, 2008 |
| Accepted |
May 28, 2008 |
| Abstract |
The checkerboard method is used to assess antimicrobial combinations for Staphylococcus aureus in vitro and the fractional inhibitory concentration (FIC) index is calculated for evaluation. We selected β-lactam antibiotic induced vancomycin-resistant MRSA (BIVR) strain and a non-BIVR strain and adjusted the inoculum contents (106 cfu/ml, 107 cfu/ml) and incubation periods (24 hours, 48 hours). We evaluated the maximum and minimum FIC indexes obtained from the two combination treatment groups: the imipenem (IPM) and teicoplanin (TEIC) treatment group and the IPM and vancomycin (VCM) treatment group.
In the IPM-TEIC group, the inoculum contents of the BIVR strain and non-BIVR strain made no difference on the FIC index. The maximum and minimum FIC indexes after 24 hour incubation indicated a marked synergistic to additive effect, while after a 48 hour incubation indicated an additive effect or negligible change suggesting a downward trend. On the other hand, in the IPM-VCM group, the minimum FIC indexes after 24 and 48 hour incubation showed a remarkable synergistic to additive effect, while the maximum FIC indexes after 24 and 48 hours of incubation showed an additive to antagonistic effect. These tendencies were slightly more remarkable after inoculation at a concentration of 107 cfu/ml and after inoculation with the BIVR strain. The effect of this combination was found to be shown in various patterns. Consequently, the assessment of the effects of combinations of β-lactam antibiotics and glycopeptide antibiotics using BIVR strains, we should use the drug concentrations that allow for inoculum content, incubation period and FIC index to show their maximum values as well as those that allow FIC index to show its minimum value. |
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