ceftazidime and Sepsis

We evaluated the efficacy of NXL104, a novel β-lactamase inhibitor, in combination with ceftazidime (CAZ) in two murine infection models (septicemia and thigh infection). We chose two KPC-producing Klebsiella pneumoniae strains (VA-361 and VA-406) showing MICs of CAZ of ≥256 μg/ml. Septicemia was induced by the intraperitoneal injection of KPC-producing K. pneumoniae followed 30 min later by a single subcutaneous treatment with CAZ alone or CAZ-NXL104 in ratios of 2:1, 4:1, 8:1, and 16:1. In this model, the median effective doses for 50% (ED(50)) of the animals for CAZ alone versus VA-361 and VA-406 were 1,578 and 709 mg/kg of body weight, respectively. When combined with NXL104 at 2:1, 4:1, 8:1, and 16:1 ratios, the CAZ ED(50)s for VA-361 and VA-406 were reduced to 8.1 and 3.5 mg/kg, 15.1 and 3.8 mg/kg, 16.9 and 7.2 mg/kg, and 29.5 and 12.1 mg/kg, respectively. For thigh infection, neutropenia was induced by the intraperitoneal injection of cyclophosphamide at days -4 and -1 preinfection. Infection was established by the intramuscular injection of KPC-producing K. pneumoniae into the right thigh. Mice were treated 1.5 h postinfection with either CAZ alone or CAZ-NXL104 at constant ratios of 4:1. When thighs were removed at 24 h postinfection, a >2-log CFU reduction was observed for mice treated with CAZ-NXL104 at doses of ≥128:32 mg/kg. In contrast, CAZ doses of ≥1,024 mg/kg were unable to reduce the numbers of CFU. Despite resistance to CAZ and possessing a complex β-lactamase background, NXL104 combined with CAZ proved to be very effective in murine models of infection due to contemporary highly resistant KPC-producing K. pneumoniae isolates.

Topics: Animals; Anti-Bacterial Agents; Azabicyclo Compounds; Ceftazidime; Disease Models, Animal; Female; Klebsiella Infections; Klebsiella pneumoniae; Mice; Microbial Sensitivity Tests; Sepsis

The Capnocytophaga sputigena isolate NOR, responsible for septicemia, was resistant to amoxicillin and narrow-spectrum cephalosporins. In a cloning experiment, a new gene, bla(CSP-1), was identified; this gene encodes a novel extended-spectrum beta-lactamase (ESBL) that shares only 52% and 49% identities with the CME-1 and VEB-1 beta-lactamases, respectively. The G+C content of this gene, its genetic environment, the absence of conjugation transfer, and its detection in two reference strains suggested that it was an intrinsic resistance gene located on the chromosome.

Topics: Amino Acid Sequence; Amoxicillin; Anti-Bacterial Agents; beta-Lactam Resistance; beta-Lactamases; Capnocytophaga; Cephalosporins; Gram-Negative Bacterial Infections; Humans; Microbial Sensitivity Tests; Molecular Sequence Data; Sepsis