Synergistic activity of apalcillin and gentamicin in a combination therapy in experimental Pseudomonas bacteraemia of neutropenic mice.

The therapeutic activity of a combination of apalcillin and gentamicin was evaluated in experimental Pseudomonas aeruginosa infection in neutropenic mice. Mice made neutropenic by administration of cyclophosphamide were more susceptible to P. aeruginosa infection than normal mice. At both challenge levels of 2LD50 and 20LD50, therapy with gentamicin alone was more effective than that with apalcillin or piperacillin. However, therapy with apalcillin-gentamicin combinations was significantly more effective than that by either component alone, and was as active as that with piperacillin-gentamicin. These in-vivo findings correlated with those of in-vitro studies, thus establishing a synergistic effect when apalcillin and gentamicin were combined. The results show that apalcillin when combined with gentamicin is effective in treating serious P. aeruginosa bacteraemia in neutropenic mice.