Symptoms Associated With Detection of Viral Versus Bacterial Pathogens in Outpatients With Lower Respiratory Infections

PURPOSE: This study aims to identify symptoms that predict a high likelihood of viral infection, so these patients could be triaged for home care to avoid antibiotics. METHODS: We recruited adults presenting to US primary or urgent care sites with a chief complaint of cough and symptoms consistent with LRTI. Data collected included demographics, comorbidities, symptoms, and 46 viral and bacterial respiratory pathogens by PCR. Chi-square tests were done to evaluate the association between individual symptoms and viral versus bacterial infections. Symptoms with a p < 0.10 for the association were retained for logistic regression. We created four regression models using stepwise backward elimination at p < 0.20, with viral infection, bacterial infection, and mixed infection as the dependent variables. A simple risk score was created assigning positive and negative points for viral and bacterial symptoms. RESULTS: We enrolled 718 adults with acute cough and obtained valid PCR specimens for 618. Four symptoms were significantly more likely with viral infections and less common in bacterial: coryza, confusion, fever, and chest congestion. Three symptoms were more likely with bacterial infections and less likely with viral infections: presence of sputum, sputum that is colored, and double-sickening (feeling better but then worsening). A simple risk score identified patients with a low (29%), moderate (56%), or high (79%) likelihood of having only viral pathogens detected. CONCLUSIONS: Seven symptoms were identified that could help primary care clinicians distinguish between viral and bacterial LRTI. A simple risk score is proposed but requires prospective validation.