Amoxicillin-tolerant Pasteurella multocida strain isolated from chronic dermohypodermitis after suboptimal exposure to amoxicillin is not associated with reduced growth rate

Abstract

Pasteurella multocida is rarely observed in human chronic infections. A Pasteurella multocida strain was isolated from a skin biopsy of chronic dermohypodermitis in a 21-year-old woman without an immunocompromised state. As this strain was viable one month after a cat scratch despite treatment by amoxicillin-clavulanic acid, we compared this strain's growth rate, amoxicillin Minimal Inhibitory and Bactericidal Concentrations (MIC and MBC), resistance to serum and ability to activate neutrophil granulocytes with those of control strains isolated during acute infections in humans without previous antibiotics exposure. This particular strain was not more resistant to serum and did not induce a lower phagocytic activity than control strains. It did not grow more slowly than control strains even after suboptimal exposure to amoxicillin. This particular strain was tolerant to amoxicillin but tolerance did not appear sufficient alone for the induction of a chronic infection in a host without an immunocompromised state.