Reviewed by Jose Lucar, MD, The George Washington University
Bottom line: Establishing specific pathogens (i.e. viruses, bacteria) through expanded molecular testing did not reliably predict the duration or severity of illness in adult outpatients presenting with acute cough.
Acute lower respiratory tract infections (LRTIs) are among the most common reasons for healthcare visits in the United States, however, previous studies have revealed challenges in correlating the clinical characteristics of respiratory infections with specific pathogen groups (i.e. bacteria, viruses). Enhancing Antibiotic Stewardship in Primary Care (EAST-PC) is a prospective observational study which aimed to evaluate the clinical characteristics, etiological agents, and the duration and severity of illness in adults presenting to primary and urgent care clinics with acute cough (≤14 days) and symptoms consistent with LRTI [1]. Researchers conducted the study between 2019 and 2023 (paused during the early part of the COVID-19 pandemic) and enrolled adults between 18 and 75 years old with acute cough and at least one associated symptom suggestive of a LRTI. Participants underwent mid-turbinate or anterior nares and pharyngeal sampling for diagnostic testing via a real-time PCR microfluidic array for 46 viruses and bacteria at the Centers for Disease Control and Prevention; results were not used for clinical decision making. Immunocompromised hosts (including people living with HIV), individuals with chronic lung disease, and those who received an antibiotic, antiviral, or corticosteroid in the 28 days prior to screening were excluded. Of 718 patients with complete baseline data, 618 (86%) had valid PCR results, 443 (62%) had complete 28-day symptom follow up data, and 401 (56%) had both complete symptom data and valid PCR results. Of those with valid PCR results, 85% had at least one virus or bacteria detected; 16% had 1+ viruses detected, 34% had 1+ bacteria, and 27% had both. The mean duration of cough was 15 days with viruses, 17 days with bacteria, 17 days with mixed detection, and 18 days for those with negative results. The severity of cough was modestly lower for viral infections. Overall, 29% of participants were prescribed an antibiotic, and a separate publication from the same study showed that antibiotics had no measurable impact on the severity or duration of cough due to acute LRTI [2]. Limitations of this study included missing PCR results and symptom data, the potential influence of the COVID pandemic, the questionable significance of detecting certain organisms, and the potential confounding by indication (i.e. patients with more severe symptoms may have been prescribed an antibiotic). In summary, the first large observational study of outpatients with LRTIs in the US that assessed the link between signs, symptoms, and clinical follow-up and a comprehensive pathogen respiratory panel provided further evidence that questions the clinical benefit of broad pathogen panels and antibiotic therapy in outpatients. Certainly, more evidence is needed before the introduction of broad respiratory pathogen panels into routine clinical care.
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