par Yourassowsky, Eugène 
;Van der Linden, Martial;Lismont, M.J.
Référence Pathologie et biologie, 34, 5, page (381-384)
Publication Publié, 1986
;Van der Linden, Martial;Lismont, M.J.Référence Pathologie et biologie, 34, 5, page (381-384)
Publication Publié, 1986
Article révisé par les pairs
| Résumé : | The antibacterial activity of beta-lactams against H. influenzae is difficult to evaluate as a result of the osmotic-pressure-dependent formation of filaments and spheroplats whose viability is still under debate. The authors compared growth curves obtained by optic density measurements and by UFC/ml counts for H. influenzae in the presence of amoxicillin, cefaclor and cefotaxim in various concentrations. Only the early response to antibiotics, observed during the first six hours of antibiotic-culture contact, was considered. Results showed, for each of the three antibiotics: a) an increase in optic density with formation of abnormal organisms that ocrrelated poorly with antibiotic concentrations; b) a stable number of UFC/ml for more than 90 mn, followed by a slow fall reaching at the most 1.5 Log 10 UFC/ml at the sixth hour. The authors conclude that amoxicillin, cefaclor and cefotaxim in active concentrations rapidly produce the formation of abnormal organisms with an increase in biomass as a result. These abnormal organisms lose their viability slowly, even with concentrations greater than 50 time the MIC. Cefaclor's MIC and MBC are underestimated when results are read only after 24 hours. |
