Mixed respiratory infections in symptomatic outpatients: A study in community health settings

Mixed respiratory infections in individuals with respiratory symptoms in primary care settings are understudied. This study aims to investigate their epidemiology and determinants.

A cross-sectional study was conducted with 244 consecutive adult patients with respiratory symptoms at Nanlian Community Health Center (January-March 2024). Throat swabs were analyzed for 18 respiratory pathogens and SARS-CoV-2 using multiplex PCR. Hematological parameters, including neutrophil-to-lymphocyte ratio (NLR), were measured from blood counts. The primary outcome was infection status (uninfected, single, or mixed). Multinomial logistic regression models identified factors associated with infection patterns.

The initial cohort included 294 patients and 5,292 pathogen test results, with 319 (6.0 %) positive for at least one of 18 targeted pathogens. The most common pathogens in mixed infections were Influenza A Virus (25.1 %), H3N2 (23.5 %), and Haemophilus influenzae (22.3 %). After excluding 50 cases with incomplete questionnaires, the analytical cohort consisted of 244 participants (83.0 % of total), 56.1 % of whom were female. The largest age group was 19-40 years (71.3 %), and 65 participants (26.6 %) had mixed infections. Higher symptom counts (adjusted OR=1.700, 95 % CI 1.346-2.147) and elevated NLR (adjusted OR=1.232, 95 % CI 1.068-1.422) were linked to mixed infections. SARS-CoV-2 co-infection was negatively associated with mixed infections (adjusted OR=0.141, 95 % CI 0.035-0.575).

Mixed infections correlate with greater symptom burden and higher inflammation markers. The inverse relationship with SARS-CoV-2 warrants further investigation. Findings support targeted pathogen testing in symptomatic patients with elevated NLR.