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

purposeThis 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.

methodsWe 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.

resultsWe 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.

conclusionsSeven 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.