Clinical and economic evaluation of subsequent infection following intravenous ciprofloxacin or imipenem therapy in hospitalized patients with severe pneumonia

A recent multicentre clinical study evaluated the safety and efficacy of iv ciprofloxacin therapy compared with imipenem-cilastatin in hospitalized patients with severe pneumonia. Monotherapy with iv ciprofloxacin was at least equivalent to imipenem in terms of bacteriological eradication and clinical response. In a single-centre, retrospective, post-therapy evaluation of persistent and subsequent infection, the incidence of Gram-negative infections and associated costs were compared. The main elements of the economic analysis included costs of additional antimicrobial therapy and hospitalization. Thirty-two patients were randomized into the study, of whom 27 were efficacy-valid. The 13 patients randomized into the ciprofloxacin group were not significantly different from the 14 patients in the imipenem group in terms of clinical parameters. Clinical cure occurred in ten of 13 patients (77%) in the ciprofloxacin group and in seven of 14(50%) in the imipenem group. Bacteriological eradication was achieved in 11 of 13 (85%) ciprofloxacin-treated and eight of 14 (57%) imipenem-treated patients. Five of 13 (38%) patients in the ciprofloxacin group and nine of 14(64%) in the imipenem group experienced persistent or subsequent infection requiring post-treatment antimicrobials. In these five ciprofloxacin patients, three had cultures with Gram-positive organisms only and two had cultures with both Gram-positive and Gram-negative organisms. In the nine imipenem-treated patients requiring post-study antimicrobials, all had Gram-negative bacteria and three also had Gram-positive organisms. The incidence of subsequent Gram-negative infection in the two groups (15% vs 64%) was significantly different (P < 0.05). Pseudomonas aeruginosa was isolated from seven patients in the imipenem group but only one in the ciprofloxacin group (P < 0.05). Subsequent costs for post-therapy antimicrobials and hospital stay while receiving study and post-study drug therapy were evaluated; the cost per patient cure was US$29,000 for ciprofloxacin and US$76,000 for imipenem. Initial treatment of severe pneumonia with ciprofloxacin resulted in significantly less subsequent Gram-negative infection and was associated with substantially lower curative costs.