1997 Volume 60 Issue 3 Pages 221-231
I studied the OFLX resistant mechanisms of anaerobic Gram-negative bacilli originating from odontogenic infections because new quinolone resistant bacteria are being isolated from these infections treated with ofloxacin (OFLX). The bacterial strains used were Prevotella buccae (P. buccae) ATCC 33574 (OFLX susceptible strain), P. buccae 31-8 (low level OFLX resistant strain, isolated from a closed dentoalveolar abscess), and P. buccae 31-8-R4 and 31-8-R5 (high level OFLX resistant strains), both selected from P. buccae 31-8 using OFLX.
The DNAs of the two high level resistant strains were highly hybridized with that of the parent strain. Enzymatic productivity was confirmed between the parent strain and the high level resistant strains. The MICs of six new quinolones (OFLX, levofloxacin, sparfloxacin, lomefloxacin, tosufloxacin and norfloxacin) were 1-8 μg/ml for P. buccae ATCC 33574, 0.5-16 μg/ml for P. buccae 31-8, 16-64 μg/ml for P. buccae 31-8-R4, and 16〜＞128 μg/ml for P. buccae 31-8-R5, respectively, using agar dilution at 106 CFU/ml of inoculum. The growth of OFLX resistant strains was suppressed with OFLX (1/32-1/2 MIC) and 2.5μg/ml carbonyl cyanide m-chlorophenylhydrazon (CCCP). Furthermore, the growth suppression of OFLX resistant strains was observed among the other five new quinolones (1/8 MIC) and 2.5 μg/ml CCCP. Accumulation of OFLX was not detected in OFLX susceptible P. buccae ATCC 33574 cells with 2.5 μg/ml CCCP. However, this accumulation was recognized in low and high level OFLX resistant P. buccae 31-8-R4 and 31-8-R5 cells. The value of these accumulations with CCCP increased by 1.07 to 1.24 times in comparison to that without CCCP. The 75.8 kDa outer membrane protein detected from the OFLX susceptible strain was not detected in the SDS-PAGE pattern from low and high level OFLX resistant strains. Also, 29.4 and 63.2 kDa outer membrane proteins appeared in the OFLX resistant strains, and the bands of 35.2 and 47.3 kDa from the outer membrane proteins in OFLX resistant strains were wider than those from the susceptible strain.
These results suggest the possibility that the efflux of new quinolone and the obstruction of outer membrane permeability are related to the OFLX resistant mechanism of P. buccae. Shika Igaku (J Osaka Odontol Soc) 1997 Sept； 60(3)：221-231．
