β-Lactamase Activity and Outer Membrane Permeability of β-Lactam Antibiotic Resistant Prevotella in Saliva of Elementary School Children

Abstract

     We studied the relation between the resistance to β-lactam antibiotics and β-lactamase activity, and the role of the outer membrane permeability of β-lactam antibiotic resistant Prevotella in the saliva of four elementary school children (case A, B, C and D). Strains which had a higher antibiotic minimum inhibitory concentration (MIC) also had high β-lactamase activity. The number of strains was calculated that had both a MIC of 50 μg/ml or greater and β-lactamase activity of 30 mU/mg or more. The percentage of these strains was 17-57% for penicillin G (PCG), 0-61% for ampicillin (ABPC), 50-83% for cefaclor (CCL), 0-57% for cefazolin (CEZ) and 0-50% for aztreonam. However, the percentages for cefmetazole, latamoxef and cefteram-pivoxil (CFTM-PI) were low, and the value for imipenem was zero. In about 20% of the strains tested, the MIC for PCG, ABPC, CER, CCL, CFTM-PI with EDTA was one fourth or less than the MIC without EDTA.
     These results suggest that β-lactamase plays on important role in the mechanism of β-lactam antibiotic resistance in the Prevotella tested, and that outer membrane permeability is related to this mechanism in some of the strains.