Pneumonia: The impact of risk factors on the outcome of treatment with meropenem and ceftazidime

This analysis comprises data pooled from two clinical trials of meropenem (0.5 g 8-hourly) versus ceftazidime (1 g 8-hourly) in hospitalized patients with community-acquired pneumonia. The clinical and bacteriological responses to treatment were assessed in relation to a range of risk factors previously linked to a poor clinical outcome. 393 patients (198 meropenem, 195 ceftazidime) were clinically evaluable while 230 (113 meropenem, 117 ceftazidime) were bacteriologically evaluable. Meropenem was highly effective, independent of associated risk factors, producing overall satisfactory clinical and bacteriological response rates at the end of therapy of 91.4% and 94.7%, respectively, similar to those produced by ceftazidime (90.3% and 92.3%, respectively). Clinical and bacteriological treatment outcome were similar in patients with up to three of the following key risk factors: age greater than or equal to 65 years, male gender, serum urea >7 mmol/L, serum albumin <35 g/L and difficult-to-treat pathogens. Meropenem also achieved high clinical (85.7%) and bacteriological (89.3%) success rates in patients requiring ventilation, as did ceftazidime (81.6% and 87.1%, respectively). Both agents were highly effective against both Gram-negative and Gram-positive causative pathogens, including those organisms normally considered difficult to treat and typical of nosocomial pneumonia (e.g. Enterobacteriaceae, Staphylococcus aureus, Pseudomonas aeruginosa). Thus, meropenem and ceftazidime were highly effective in patients hospitalized with community-acquired pneumonia, irrespective of a number of concurrent risk factors (including those regarded as key risk factors). Furthermore, the analysis points to a role for meropenem 0.5 g 8-hourly in the treatment of nosocomial pneumonias that do not require intensive care unit admission and/or mechanical ventilation. Overall, this novel analysis of trial data suggests that incorporation of key risk factor endpoints into the initial design of pneumonia studies may prove to be a useful approach in defining appropriate antibiotic treatment for specific patient groups.