Risk Factors for Community-Onset Pneumonia Caused by Levofloxacin-Nonsusceptible Streptococcus pneumoniae

Background: Fluoroquinolones are antibiotics commonly used in the treatment of infections caused by Streptococcus pneumoniae. However, rates of fluoroquinolone resistance are increasing with their frequent use. We designed this study to verify current fluoroquinolone resistance rates and risk factors for community-onset pneumococcal pneumonia. Methods: A retrospective case-control study was conducted in a tertiary referral hospital. The study population comprised patients admitted for pneumococcal pneumonia between January 2011 and May 2017. The case group included community-onset pneumonia caused by levofloxacin-nonsusceptible S. pneumoniae. The control group consisted of two patients with levofloxacin-susceptible S. pneumoniae who were admitted around the same time as each case. Results: A total of 198 pneumococcal pneumonia cases were identified during the study period. Twenty-five levofloxacin-resistant S. pneumoniae cases and 3 levofloxacin-intermediate S. pneumoniae cases were included in the case group (nonsusceptibility rate=14.1%). Multivariate analysis showed that healthcare-associated factors (odds ratio [OR] 4.78, 95% confidence interval [CI] 1.39-16.43, p=0.013), bronchopulmonary disease (OR 3.79, 95% CI 1.07-13.40, p=0.039), cerebrovascular disease (OR 6.08, 95% CI 1.24-29.75, p=0.026), and exposure to fluoroquinolones within the previous 3 months (OR 5.89, 95% CI 1.21-28.68, p=0.028) were associated with nonsusceptibility to levofloxacin. Conclusion: Independent risk factors for levofloxacin-nonsusceptible pneumococcal pneumonia were recent hospitalization, bronchopulmonary disease, cerebrovascular disease, and prior antibiotic use within 3 months. Careful selection of empirical antibiotics is thus needed in at-risk patients. Similarly, efforts to prevent the interpersonal spread of drug-resistant pathogens in long-term care facilities and to restrict unnecessary fluoroquinolone prescriptions are important.