Exploring the role of respiratory virus infections in aspiration pneumonia: a comprehensive analysis of cases with lower respiratory tract infections.

Background: While respiratory virus infection has been implicated in the onset of bacterial pneumonia, no research has investigated the association of respiratory viruses with the onset of aspiration pneumonia (AP). This study aimed to investigate the role of respiratory virus infections in AP.

Methods: Patients presenting with acute respiratory symptoms and undergoing influenza antigen testing at the emergency department of Okinawa Chubu Hospital from February 2020 to January 2021, and diagnosed with lower respiratory tract infections, were included. Cases were categorized into AP, pneumonia other than AP (non-AP), and acute bronchitis (AB) based on physician diagnoses recorded in medical records. The residual nasal swab specimens were further tested with multiplex PCR tests for respiratory viruses.

Results: A total of 209 subjects were included in the study: 59 in the AP group, 118 in the non-AP group, and 32 in the AB group. The AP group was characterized by older age, higher rates of nursing home residency, a greater prevalence of comorbidities such as cerebrovascular disease and dementia, a lower sputum culture positivity rate, and a different spectrum of causative pathogens compared to the other groups. The virus positivity rate in the AP group was 47%, compared to 50% in the non-AP group and 53% in the AB group, with no significant difference observed. The AP group exhibited the highest rate of only respiratory viruses detected and the lowest rate of both respiratory viruses and bacteria detected among the groups. There was no significant difference in the types of viruses detected between the AP group and the other groups, with rhinovirus being the most frequently detected virus across all groups. In the AP group, virus-negative cases were significantly older on average. No other significant differences in background, symptoms, or clinical data were observed between virus-positive and virus-negative cases within the AP group.

Conclusion: In the AP group, the rate of respiratory virus detections was comparable to that of the non-AP and AB groups. This suggests a potential link between respiratory virus infections and the development of AP, emphasizing the need for novel preventive strategies. While distinguishing between AP patients with and without respiratory virus detections based on clinical findings was challenging, recognizing the frequent involvement of respiratory virus infections in AP highlights the importance of enhanced infection control and awareness in its management.