[Beta-lactam combinations with new quinolones]

The combination of new quinolones with beta-lactam antibiotics can be an alternative to the classical use of aminoglycoside-beta-lactam antibiotic combinations. In vitro studies, in particular using cefotaxime-pefloxacin or ofloxacin combinations against Enterobacteria and cefsulodin or ceftazidime with pefloxacin or ofloxacin against P. aeruginosa rarely show evidence of synergistic antibacterial activity when the "static" checker board method is used. In contrast, kinetic bactericidal studies very often show a notable increase in the rapidity of bactericidal activity as well as the disappearance of the frequent secondary regrowth seen after 6 hours with the antibiotics used alone. Techniques studying the development of resistance in vitro show that the combination of pefloxacin-cefotaxime against enterobacteria and pefloxacin-cefsulodin against P. aeruginosa are capable of inhibiting the emergence of resistant variants. These promising results require confirmation by studies using animal models and, above all, by the clinico-microbiological analysis of the results of clinical trials.