Treating Flu: Know when to prescribe antibiotics

It is a well-established fact that improper use of antibiotics does more harm than good. Clinicians should consider antibiotic treatment only if symptoms persist with no improvement for 10 or more days.

Antimicrobial therapy is recommended when patients exhibit complications. Patients are likely to have or are at higher risk of developing complications if they:

• Are systemically unwell
• Have symptoms and signs suggestive of serious illnesses (for example pneumonia, mastoiditis)
• Have pre-existing comorbidities such as lung, cardiac, renal, liver, and neuromuscular disease, and immunosuppression, or young children who were born premature
• Are older than 65 years and have type 1 or type 2 diabetes, history of congestive heart failure, are on steroids or have needed hospitalization in the previous year

Physicians are advised to consider antibiotic therapy in people with FeverPAIN score of 4 or 5, or Centor score of 3 or 4.

FeverPAIN criteria is as follows:

• Fever (during previous 24 hours)
• Purulence (pus on tonsils)
• Attend rapidly (within 3 days after onset of symptoms)
• Severely Inflamed tonsils
• No cough or coryza (inflammation of mucus membranes in the nose)

Each of the criteria scores 1 point (maximum score of 5). A higher score indicates more severe symptoms and likely a bacterial (streptococcal) cause. A score of 4 or 5 is thought to be associated with 62-65% likelihood of isolating streptococcus.

Centor criteria is as follows:

• Tonsillar exudate
• Tender anterior cervical lymphadenopathy or lymphadenitis
• History of fever (over 38°C)
• Absence of cough

Each of the Centor criteria scores 1 point (maximum score of 4). A score of 3 or 4 is thought to be associated with 32-56% likelihood of isolating streptococcus.

Which antibiotics to prescribe for initial empiric antimicrobial therapy?

• Amoxicillin therapy is advisable for LRTI. However, amoxicillin should be avoided if infectious mononucleosis is suspected. For patients who are allergic to penicillin, clarithromycin or azithromycin therapy may be used.
• Phenoxymethylpenicillin is advisable for sore throat. For patients who are allergic to penicillin, clarithromycin or Erythromycin therapy may be used.

When antibiotics are not indicated, physicians should reassure patients that antibiotics are not needed immediately as they are unlikely to make any difference to the symptoms and may on the other hand, cause side effects, such as, diarrhea vomiting and rash.

Author: Dr Reshma Ramracheya is a group leader at the University of Oxford with over 18 years of experience in teaching and medical research.

Reference:

• Hay AJ, McCauley JW. The WHO global influenza surveillance and response system (GISRS)—A future perspective. Influenza Other Respi Viruses. 2018;12:551–557. https://doi.org/10.1111/irv.12565.
• Hemila H., Chalker E., Douglas B. The Cochrane Library; 2010.
• Sabbaghi A, Miri SM, Keshavarz M, Zargar M, Ghaemi A. Inactivation methods for whole influenza vaccine production. Rev Med Virol. 2019 Jul 23:e2074. doi: 10.1002/rmv.2074.
• CDC, Centers for Disease Control and Prevention (https://www.cdc.gov/vaccines/pubs/pinkbook/flu.html)
• NICE, National Institute for Health and Care (https://www.nice.org.uk/guidance/conditions-and-diseases/infections/influenza)