Risk factors for drug-resistant Streptococcus pneumoniae and antibiotic prescribing practices in outpatient community-acquired pneumonia

Abstract

Objectives: Due to antimicrobial resistance in Streptococcus pneumoniae, national guidelines recommend a respiratory fluoroquinolone or combination antimicrobial therapy for outpatient treatment of community-acquired pneumonia (CAP) associated with risk factors for drug-resistant S. pneumoniae (DRSP). The objectives of this study were to assess the prevalence of these risk factors and antibiotic prescribing practices in cases of outpatient CAP treated in the acute care setting.

Methods: This was a retrospective cohort study of adult outpatients treated for CAP in the emergency department (ED) or urgent care center of an urban, academic medical center from May 1, 2009, through October 31, 2009, and comparison of antibiotic therapy in cases with and without DRSP risk factors.

Results: Of 175 patients, 90 (51%) had at least one DRSP risk factor, most commonly asthma (n = 28, 16%), alcohol abuse (n = 24, 14%), diabetes mellitus (n = 18, 10%), chronic obstructive pulmonary disease (n = 16, 9%), age > 65 years (n = 16, 9%), and use of antibiotics within 3 months (15, 9%). Antibiotic prescriptions were similar among cases with and without DRSP risk factors: a macrolide (62% vs. 59%, respectively, p = 0.65), doxycycline (27% vs. 28%, p = 0.82), or a respiratory fluoroquinolone (9% vs. 9%, p = 0.90). Concordance with national guideline treatment recommendations was significantly lower in cases with DRSP risk factors (9% vs. 87%, p < 0.0001).

Conclusions: DRSP risk factors were present in approximately half of outpatient CAP cases treated in the acute care setting; however, guideline-concordant antibiotic therapy was infrequent. Strict adherence to current guidelines would substantially increase use of fluoroquinolones or combination therapy. Whether the potential risks associated with these broad-spectrum regimens are justified by improved clinical outcomes requires further study.