Role of Atypical Bacteria in Hospitalized Patients with Nursing Home-Acquired Pneumonia

Background Nursing home-acquired pneumonia (NHAP) has been identified as one of the leading causes of mortality and hospitalization for long-term care residents. However, current and previous pneumonia guidelines differ on the appropriate management of NHAP in hospitalized patients, specifically in regard to the role of atypical bacteria such as Chlamydia pneumoniae, Mycoplasma pneumoniae, and Legionella. Objectives The purpose of this review is to evaluate clinical trials conducted in hospitalized patients with NHAP to determine the prevalence of atypical bacteria and thus the role for empiric antibiotic coverage of these pathogens in NHAP. Methods Comprehensive MEDLINE (1966-April 2016) and Embase (1980-April 2016) searches were performed using the terms “atypical bacteria”, “atypical pneumonia”, “nursing-home acquired pneumonia”, “pneumonia”, “elderly”, “nursing homes”, and “long term care”. Additional articles were retrieved from the review of references cited in the collected studies. Thirteen published clinical trials were identified. Results In the majority of studies, atypical bacteria were infrequently identified in patients hospitalized with NHAP. However, when an active community-acquired pneumonia (CAP) cohort was available, the rate of atypical bacteria between NHAP and CAP study arms was similar. Only 3 studies in this review adhered to recommended strategies for investigating atypical bacteria; in 2 of these studies, C. pneumoniae was the most common pathogen identified in NHAP cohorts. Conclusion Although atypical bacteria were uncommon in most NHAP studies in this review, suboptimal microbial investigations were commonly performed. To accurately describe the role of atypical bacteria in NHAP, more studies using validated diagnostic tests are needed.