Health care resource utilization associated with treatment of penicillin-susceptible and -nonsusceptible isolates of Streptococcus pneumoniae

Despite failure to correlate in vitro susceptibility with clinical outcomes for respiratory tract infections and bacteremia, resistance affects management of patients with pneumococcal infections. The economic impact of resistance among pneumococci has not been evaluated. We conducted a single-center, retrospective, observational, cohort study of hospitalized patients infected with Streptococcus pneumoniae isolated from blood or a respiratory source between January 1, 1995, and December 31, 1998. Data were collected for 36 days surrounding the day that the first positive culture was collected. Patients were grouped according to isolate penicillin-susceptibility profile [susceptible minimum inhibitory concentration (MIC) ≤ 0.06 μg/ml, nonsusceptible MIC ≥ 0.125 μg/ml), and data were analyzed with respect to health care resource utilization patterns. Of 231 patients identified, 142 and 89 had susceptible and nonsusceptible isolates, respectively. Groups were similar with respect to demographics and comorbidities, except that patients infected with a nonsusceptible isolate were more likely to have the isolate obtained from a respiratory source and to have a history of recent antibiotic therapy. No difference was noted with respect to clinical outcome; however, patients infected with a nonsusceptible isolate had a longer median stay (14 vs 10 days, p<0.05). They also had significantly higher total median costs ($1600, 95% confidence interval $257-2943) due to room and nursing services. Infections caused by penicillin-nonsusceptible pneumococci were not associated with a worse outcome in hospitalized patients but were associated with increased cost of care.