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Do not attempt to collect a throat specimen for culture if acute epiglottitis is suspected because trauma from the swab may cause increased edema, resulting in airway occlusion.undefined#ref11">11
Collect oropharyngeal and nasopharyngeal specimens within 3 days of symptom onset if possible but no later than 7 days of symptom onset and before the start of antimicrobial therapy.4
Pregnant patients, young children, or older adults may require transfer and admission to an acute care facility if the illness is severe of if respiratory distress is suspected.
Influenza is a febrile illness affecting the respiratory system caused by an infection of the influenza virus.8 Seasonal epidemics occur yearly due to the spread of influenza A and influenza B. There are multiple classifications of influenza, with the two most common strains being influenza A and influenza B. Influenza affects all ages and all levels of health. The patients most at risk for serious complications from influenza are infants, young children, and older adults as well as patients who are immunocompromised, have comorbid chronic illnesses, have morbid obesity, or are pregnant.8
Influenza is transmitted through droplets when an infected person coughs or sneezes and the virus comes in contact with a susceptible person’s mucus membranes. Transmission can also be spread through autoinoculation. This occurs when a susceptible person comes in contact with a contaminated surface and then becomes contaminated by touching mucus membranes.1 Adults may be considered contagious starting 1 day before symptom onset and up to 5 to 7 days after, whereas pediatric patients may be considered contagious for more than 7 days.1
Classic signs and symptoms of influenza virus include an abrupt onset of high fever, myalgia, headache, anorexia, fatigue, cough, prominent rhinorrhea, and congestion.8 In pediatric patients, the symptoms may be more gastrointestinal related, such as nausea, vomiting, and diarrhea. These signs and symptoms are not common in adults with influenza. Some signs and symptoms tend to last as long as 2 weeks.8
The influenza virus is present year-round, but the peak season is fall through winter. According to the Centers for Disease Control and Prevention (CDC), over the last 36 years, the month of February has had the highest percentage of influenza infections.5
During a seasonal epidemic, a history and physical are normally sufficient for a diagnosis, but a rapid influenza diagnostic test (RIDT) or nasopharyngeal swab may be performed to aid in diagnosis confirmation.10 RIDT results can be obtained within 10 to 15 minutes.3 An RIDT that results positive is considered a diagnosis for influenza A or influenza B because of the high specificity.10 Negative test results obtained from RIDTs that detect influenza viral antigens do not exclude influenza virus infection in patients with signs and symptoms of influenza. A negative test result could be a false-negative result and should not preclude further diagnostic testing, such as a polymerase chain reaction (PCR), and starting empiric antiviral treatment.2
Antiviral medications, known as neuraminidase inhibitors, may be started as soon as a diagnosis is made. These medicines may also be given prophylactically if the patient is not vaccinated and is at risk for complications of influenza. Antiviral treatment should begin as soon as possible after illness onset, ideally within 48 hours of the onset of signs and symptoms, and continue for 5 days.8
The goals of influenza treatment are to treat signs and symptoms, provide supportive therapy, and prevent further complications. Fever, pain, and congestion may be treated with over-the-counter medications.
Infants 6 months old or older, children, and adults, including those who are pregnant, should get a yearly influenza vaccination.7 A influenza vaccination can be performed through an intramuscular injection or as a nasal spray. Infants younger than 6 months old and those who have life-threatening allergies to the ingredients in the vaccination or who have a history of Guillain-Barré syndrome should not get the influenza vaccination.8 Those with a history of egg allergy, regardless of severity, may receive any of the recommended age-appropriate influenza vaccines.8 Patients should receive their annual influenza vaccination by the end of October. Upward of 79,000 patients died in the United States from influenza-related complications, per the CDC mortality math model.6
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Rationale: During auscultation of lung sounds, a patient with influenza may have clear lungs; rales or rhonchi are suggestive of viral or secondary bacterial pneumonia.8
Rationale: By having the swab and the culture tube ready, the swab can be grasped easily without danger of contamination.
Rationale: The swab should remain sterile until it reaches the area to be cultured. Rotating the swab ensures that it touches all surfaces where exudate is present.
Rationale: Avoiding contact with the sides of the nose prevents contaminating the swab with resident bacteria.
Rationale: Mixing the swab tip with the culture medium helps ensure live bacteria for testing.
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