Patients hospitalized with flu, CAP frequently have bacterial coinfection
Around 10% of patients hospitalized for influenza and community-acquired pneumonia also had a community-onset bacterial coinfection, and these patients experienced worse outcomes and higher costs, according to a large U.S. study.
“Little is known about the microbiology of bacterial coinfection in seasonal influenza pneumonia,” Patricia S. Bartley, MD, MSc, an infectious disease specialist at the Cleveland Clinic, told Healio. “We wanted to fill in this gap to help direct empiric antibiotic choices for patients hospitalized with influenza pneumonia.”
According to Bartley, limited information available for patients hospitalized with pandemic influenza indicates that “influenza pneumonia leads to bacterial colonization, an increased risk of bacterial coinfection and poor outcomes, including increased mortality.”
“We also wanted to make available these microbiological data, which support the most recent community-acquired pneumonia (CAP) guidelines by the Infectious Diseases Society of America and the influenza treatment guidelines from the CDC. Both recommend that patients with influenza pneumonia receive empiric treatment with antibiotics targeting the usual pathogens for community-acquired pneumonia,” Bartley said.
For the study, Bartley and colleagues used data from adults admitted with CAP and tested for influenza between 2010 and 2015 at 179 U.S. hospitals to assess the relationships between coinfection and inpatient mortality, ICU admission, length of stay and cost.
Among 38,665 patients hospitalized with CAP and tested for influenza who were included in the study, 4,313 (11.2%) were positive for influenza. Bartley and colleagues found that in the first 3 hospital days, patients with influenza were less likely to have a positive culture than those without (10.3% vs. 16.2%; P < .001), and cultures were more likely to contain Staphylococcus aureus (34.2% vs. 28.2%; P = .007) and less likely to contain Streptococcus pneumoniae (24.9% vs. 31%; P = .008).
The study demonstrated that 42.8% of S. aureus isolates from patients with influenza were methicillin resistant compared with 53.2% from those without influenza (P = .01).
Additionally, the researchers found that bacterial coinfection was associated with increased odds of in-hospital mortality (adjusted OR = 3; 95% CI, 2.17-4.16), late ICU transfer (aOR = 2.83; 95% CI, 1.98-4.04) and higher cost (risk-adjusted mean multiplier = 1.77; 95% CI, 1.59-1.96).
According to Bartley, the findings can help guide empiric antibiotic choices in patients with influenza pneumonia and suspected coinfection.
“Specifically, they support an antibiotic regimen that does not include coverage for MRSA, as recommended by the most recent American Thoracic Society/IDSA CAP guidelines, reserving MRSA coverage for patients with known risk factors for MRSA,” she said. “Once a patient had been in the hospital for 4 days, we found no difference in bacterial pathogens between patients admitted with influenza pneumonia and those without influenza. Thus, if a patient with influenza begins to deteriorate after 3 days, clinicians should initiate treatment for hospital-acquired pneumonia, including coverage of MRSA and Pseudomonas.”