Antimicrobial therapies for pulmonary Klebsiella pneumoniae infection in B6D2F1/J mice immunocompromised by use of sublethal irradiation.

Klebsiella pneumoniae is a common cause of nosocomially acquired pneumonia in immunocompromised patients. Previously, we established a pneumonia model using Klebsiella pneumoniae in B6D2F1/J mice sublethally irradiated with 7-Gy 60Co gamma-radiation and inoculated intratracheally. In the study reported here, we investigated survival of mice following 10 days of antimicrobial therapy with ceftriaxone, gentamicin, gatifloxacin, and a ceftriaxone-gentamicin combination given once daily. Survival was significantly prolonged in response to all therapies. However, survival of mice was 95% when treated with the ceftriaxone-gentamicin combination followed by ceftriaxone alone (75%), and gatifloxacin (80%), whereas survival for controls was 0%. In addition, resistance to any of the treatments did not develop during the study. We conclude that an immunocompromised status does not alter the Infectious Disease Society of America's primary recommendation for treating community-acquired K. pneumoniae pneumonia using a third-generation cephalosporin, with or without an aminoglycoside.