Chapter 109: Influenza

Content Update

March 12, 2019

Updated IDSA Guidelines on Seasonal Influenza: The Infectious Diseases Society of America (IDSA) updated the 2009 clinical practice guidelines for the diagnosis, treatment, chemoprophylaxis, and institutional outbreak management of seasonal influenza. The document provides new information and recommendations on diagnostic testing, use of antivirals, and testing for antiviral resistance. It also presents evidence on harm associated with routine use of corticosteroids. These updated guidelines should be adopted by all primary care providers.

Patient Care Process for Influenza Infection Treatment

Collect

• Patient characteristics; age; health conditions; occupation; travel; lifestyle, current health status, present & past medical history; allergies

• Medication history (include prescription, nonprescription and other substances); vaccination history; pregnancy status

• Microbiologic results from rapid respiratory viral panel and secondary bacterial infection. Bacterial susceptibility tests when available. (see Clinical Presentation: Diagnosis of Infection)

• Laboratory results for infection, major organ function (particularly kidney and liver), immune status, lactate

Assess

• Assess for medication contraindications and drug interactions

• Determine severity of illness based on vital signs, acute organ dysfunction, source control (or lack thereof)

• Determine likely pathogens for secondary bacterial infection of the respiratory tract, patient's microbiologic history, previous antibiotic exposure, and response to current therapy

• Determine if other conditions are present such as chronic lung disease likely to affect outcomes of infection.

• Estimate creatinine clearance for drug dosing.

Plan

• Strongly recommend future influenza vaccine if no contraindication is present (Table 109-2)

• Initiate treatment neuraminidase therapy—oral, inhaled, or IV, based on severity of illness (Table 109-5 and 6)

• Determine influenza treatment goals of therapy with monitoring parameters for each goal.

• Determine appropriate antibiotic therapy for secondary bacterial infection and monitoring plan

• Establish antimicrobial monitoring goals for efficacy (e.g., resolution of infection, clearance of bacteria from blood cultures) and drug toxicity

• Check for drug interactions and dose adjustments based on end-organ function

Implement

• Initiate a neuraminidase inhibitor and continue for ~7 days after identification of illness onset in the last patient (prophylaxis for community outbreak) or 5 days (treatment) or establish tentative stop date for severely ill patients.

• If secondary bacterial infection suspected, initiate empiric antimicrobial regimen, and deescalate antimicrobial therapy to more narrow-spectrum agents as appropriate based on response and microbiologic data.

• Assess patient as needed for response to antiviral medications, and other treatments.

• Use measures to minimize adverse events to medications and assess for occurrence of adverse events.

Follow-up: Monitor and Evaluate

• Refer patient for follow-up services to their primary care provider or another provider (provide patient with documentation of referral)

• Determine if patient shows improvement in the signs and symptoms of infection within 48 hours after neuraminidase inhibitor is initiated

• Monitor for emergence of resistant virus

• Monitor for occurrence of secondary bacterial pneumonia

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