Etiology and Clinical Outcomes of Acute Respiratory Virus Infection in Hospitalized Adults

BACKGROUND: Etiologies and clinical profiles of acute respiratory viral infections need to be clarified to improve preventive and therapeutic strategies. MATERIALS AND METHODS: A retrospective observational study at a single, university-affiliated center was performed to evaluate the respiratory viral infection etiologies in children compared to that in adults and to document the clinical features of common viral infections for adults from July 2009 to April 2012. RESULTS: The common viruses detected from children (2,800 total patients) were human rhinovirus (hRV) (31.8%), adenovirus (AdV) (19.2%), respiratory syncytial virus (RSV) A (17.4%), RSV B (11.7%), and human metapneumovirus (hMPV) (9.8%). In comparison, influenza virus A (IFA) had the highest isolation rate (28.5%), followed by hRV (15.5%), influenza virus B (IFB) (15.0%), and hMPV (14.0%), in adults (763 total patients). Multiple viruses were detected in single specimens from 22.4% of children and 2.0% of adults. IFA/IFB, RSV A/B, and hMPV exhibited strong seasonal detection and similar circulating patterns in children and adults. Adult patients showed different clinical manifestations according to causative viruses; nasal congestion and rhinorrhea were more common in hRV and human coronavirus (hCoV) infection. Patients with RSV B, hRV, or AdV tended to be younger, and those infected with RSV A and hMPV were likely to be older. Those with RSV A infection tended to stay longer in hospital, enter the intensive care unit more frequently, and have a fatal outcome more often. The bacterial co-detection rate was 26.5%, and those cases were more likely to have lower respiratory tract involvement (P = 0.001), longer hospital stay (P = 0.001), and higher mortality (P = 0.001). CONCLUSIONS: The etiologic virus of an acute respiratory infection can be cautiously inferred based on a patient's age and clinical features and concurrent epidemic data. Large-scale prospective surveillance studies are required to provide more accurate information about respiratory viral infection etiology, which could favorably influence clinical outcomes.

Clinical and Epidemiologic Characteristics of Mycoplasma pneumoniae Pneumonia in Adults During 2011 Epidemic

BACKGROUND: Recent data regarding the clinical epidemiologic characteristics of Mycoplasma pneumoniae pneumonia in Korean adults are insufficient. This study was conducted in order to compare epidemics in different ages and to identify the clinical characteristics in adults. MATERIAL AND METHODS: We investigated patients who visited Korea University Guro Hospital from January to December 2011 due to community acquired pneumonia and underwent mycoplasma antibody tests. M. pneumoniae pneumonia was diagnosed if mycoplasma antibody titer was > or =1:320 at any time, seroconversion or 4-fold rise was seen at convalescent phase. Patients under the age of 19 were classified as child and adolescent, otherwise adult. We investigated the number of monthly cases in all patients and reviewed the medical records of adult patients. RESULTS: A total of 249 young patients aged < or =18 years and 29 adults were diagnosed with M. pneumoniae pneumonia. Among young patients, 75.5% were concentrated in the 0-6 years age group and 58.6% of adults belonged to the 26-40 years age group. The number of young patients began to increase in July and continued to increase in December, while the number of adult patients began to increase in August and occurred continuously until December. The correlation coefficient of the epidemic trend between the two groups was 0.682 (P=0.015). Median age of adult patients was 33.3 years. Fever was observed in all patients and 25 patients (86.2%) complained of purulent sputum. The average white blood cell count was 7,066/mm3. The average values for aspartate aminotransferase, alanine aminotransferase, creatinine, and sodium were within the normal range. In chest X-ray study, ipsilateral lower patchy consolidation was found in 24 patients (82.8%). Twenty one adult patients (72.4%) were hospitalized. The mean duration of hospitalization was 7.3 days. Twenty three patients (79.3%) were initially treated with combinations of third generation cephalosporin and macrolide. Among them, five patients (17.2%) showed poor responses. Six cases (20.7%) were initially treated with quinolone, and treatment was maintained until the end without changing antibiotics. Development of cryptogenic organizing pneumonia occurred in one case and there was no occurrence of death. CONCLUSIONS: When M. pneumoniae pneumonia is epidemic among children and adolescents, it should also be suspected in adult patients with community-acquired pneumonia. Some patients showed poor responses to macrolide. Overall, it appears that additional studies are needed for evaluation of the effectiveness of macrolide in treatment of M. pneumoniae pneumonia in adults.