Treatment Guideline Chart
Acute bacterial rhinosinusitis is the mucosal inflammation of the nose and paranasal sinuses caused by bacteria lasting ≥10 days for up to 4 weeks with no clinical improvement, severe signs or symptoms (eg high fever [39°C], purulent nasal discharge, facial pain) of ≥3-4 consecutive days, and worsening of symptoms within 10 days after initial improvement.
It is often preceded by a viral upper respiratory tract infection, rhinitis or other conditions that impair local or systemic immune function (eg nonallergic rhinitis, dental infection, mechanical obstruction of the nose, cystic fibrosis, ciliary dysfunction, immunodeficiency that impair the sinus drainage).
Signs and symptoms are nonspecific and typically difficult to differentiate from viral upper respiratory tract infection.
There is fever with nasal obstruction/congestion or anterior and/or posterior purulent drainage, with or without facial pressure/pain/fullness and reduction/loss of smell.
Streptococcus pneumoniae and unencapsulated strains of Haemophilus influenzae cause half of acute rhinosinusitis cases.

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Principles of Therapy

General Antibiotic Therapy Principles

  • Empiric therapy should be started as soon as ABRS is diagnosed
    • Therapy should be based on cost, safety, likely pathogen, local resistance patterns and recent antibiotic use
  • Antibiotic therapy should be started in patients with the following presentations:
    • Severe ABRS: Patient with >3 consecutive days of fever (≥39°C) with purulent nasal discharge or facial pain
    • Worsening ABRS: Presence of increased nasal discharge, headache or new fever after a typical viral URTI of 5-6 days that was initially improving
    • Persistent ABRS: ≥10 days symptoms (nasal discharge of any quality, cough) without signs of improvement
    • Severe, worsening or persistent ABRS with accompanying acute otitis media, pharyngitis, adenitis or pneumonia, or if suspected to have orbital or intracranial involvement
    • Uncomplicated severe, worsening or persistent ABRS without concomitant disease
  • Initial antibiotic prescribed should be the most narrow-spectrum agent that is active against the likely pathogens: S pneumoniae, H influenzae, M catarrhalis
    • Consider the local prevalence of resistance among each of the likely bacterial species
  • Initial empiric therapy coverage for S aureus or methicillin-resistant S aureus is not recommended
  • Factors that predispose patients to antibiotic-resistant bacteria need to be considered (eg antibiotic usage within the past month, hospitalization in the past 5 days, age <2 or >65 years, exposure to daycare, comorbid conditions, impaired immune response, severe infection, living in areas with high rates of resistance)

Goals of Antibiotic Therapy

  • Eradicate bacterial infection from the sinuses
  • Hasten resolution of symptoms
  • Prevent complications
  • Decrease the development of chronic disease


Mild Disease and No Antibiotics within the Last 4-6 Weeks

  • In patients who have not responded to symptomatic therapy alone or those whose symptoms have worsened

Amoxicillin (Usual or High Dose)

  • Amoxicillin continues to be the agent of choice for ABRS due to its safety, efficacy, low cost and narrow microbiologic spectrum when still effective in the locality
    • Should be taken for 5-10 days
  • In areas with high incidence of resistant S pneumoniae, high-dose Amoxicillin should be considered
  • Generally considered the most active of all oral beta-lactams against streptococci and only S pneumoniae that is highly resistant to Penicillin will not respond to conventional doses of Amoxicillin
    • Activity against beta-lactamase-negative strains of H influenzae is fair to good but it is ineffective against beta-lactamase-producing strains

Amoxicillin/Clavulanic Acid with or without High-Dose Amoxicillin

  • Recommended as initial empiric therapy for ABRS rather than Amoxicillin alone
  • Recommended in patients with moderate to severe disease who have failed high-dose Amoxicillin or if beta-lactamase-producing strains of H influenzae, M catarrhalis or oral anaerobes are suspected
  • Amoxicillin may be added to Amoxicillin/clavulanic acid to overcome drug resistance of S pneumoniae and should be considered in areas with high incidence of resistant S pneumoniae

Cephalosporins (Second and Third Generation)

  • Eg Cefaclor, Cefdinir, Cefixime, Cefuroxime, Cefpodoxime, Ceftriaxone
  • Alternative agents that may be considered for patients with ABRS who have non-type 1 allergy to Penicillin
    • Because of variable resistance to S pneumoniae, it is not recommended for single-agent empiric therapy
    • Local resistance patterns and antimicrobial spectrum of the cephalosporins to S pneumoniae, H influenzae and M catarrhalis will need to be considered prior to choosing an agent
  • Cefaclor has poor overall efficacy against bacterial respiratory tract pathogens
  • Cefixime has potent activity against H influenzae
  • Cefpodoxime is the preferred agent for patients with treatment failure on high-dose Amoxicillin or Amoxicillin/clavulanic acid
    • Has similar activity with Cefuroxime and Cefdinir against S pneumoniae but greater efficacy against H influenzae
  • Cefuroxime has good efficacy against S pneumoniae but less active than Cefpodoxime against H influenzae
  • Intravenous/intramuscular Ceftriaxone (50 mg/kg single dose) may be considered for patients intolerant to oral medications and highly unlikely to adhere to prescribed medications


  • Depending on the sensitivity pattern of local isolates, Co-trimoxazole may be considered an alternative for patients with type 1 allergy to Penicillin
    • Not advised for empiric therapy due to increased rates of resistance to both S pneumoniae and H influenzae


  • Alternative agent to Amoxicillin or Amoxicillin/clavulanic acid in initial empiric therapy or to those who have type 1 allergy to Penicillin
  • Doxycycline has activity against Penicillin-susceptible pneumococci and M catarrhalis, but limited coverage for H influenzae
    • The probability of non-susceptibility to Doxycycline tends to rise in pneumococcal strains that have any level of Penicillin resistance


  • These agents may be considered alternatives in patients who have type 1 allergy to Penicillin
  • All macrolides have good activity against macrolide-susceptible pneumococci but are not recommended for empiric therapy because of increasing prevalence of macrolide-resistant S pneumoniae
  • Azithromycin and Clarithromycin are relatively weak against penicillin-resistant H influenzae and S pneumoniae

Moderate-Severe Disease or Antibiotics Received within the Last 4-6 Weeks

  • Patients who failed first-line therapy may be considered with this group of patients

Amoxicillin/Clavulanic Acid with High-Dose Amoxicillin

  • Considered first-line agent by many authorities for patients who have failed Amoxicillin or in those with risk for resistant organisms
  • Therapy should be initiated using higher doses of Amoxicillin (add Amoxicillin therapy to Amoxicillin/clavulanic acid); this will increase the coverage of S pneumoniae


  • Five-day therapy may be considered in those at risk for resistant organisms or in those who have failed first-line therapy

Respiratory Quinolones

  • Eg Levofloxacin, Moxifloxacin
  • Provide excellent coverage for all the likely pathogens, especially S pneumoniae and H influenzae
  • Because of the potential for increased resistance and toxicity, these agents should be reserved for adults with type 1 allergy to Penicillin and risk factors for resistant organisms, moderate disease, or in those who have failed recent antibiotic coverage

Combination Therapy

  • Eg Cefixime + high-dose Amoxicillin or Clindamycin or Rifampicin + high-dose Amoxicillin or Clindamycin
  • Combination therapy that has adequate Gram-positive and negative coverage may be considered in patients with risk of resistant organisms, moderate disease or have failed first-line therapy
  • At this time, there is no clinical evidence supporting the use or safety of combination therapy but it is recommended based on in vitro spectrum activity
  • Rifampicin + Clindamycin
    • Rifampicin should not be used as monotherapy or for longer than 10-14 days because resistance develops rapidly to this agent
  • Clindamycin/Linezolid + Cefixime
    • Recommended for patients with severe type 1 Penicillin hypersensitivity with moderate-severe sinusitis

Duration of Antibiotic Therapy

  • The appropriate duration of antibiotic therapy is not well defined
  • Most patients with ABRS that have been treated with the appropriate antibiotic agent will show clinical improvement within 48-72 hours
  • If ABRS is worse within 72 hours after initiating treatment:
    • If initially advised further observation, may start Amoxicillin with or without Clavulanate therapy
    • If initially prescribed with Amoxicillin, may increase dose and may add Clavulanate
    • If initially prescribed with high-dose Amoxicillin-Clavulanate, may shift to Clindamycin + Cefixime or Linezolid + Cefixime or Levofloxacin
  • No clinical improvement seen after 72 hours:
    • If initially advised further observation, may start antibiotic therapy
    • If initially prescribed with Amoxicillin, may initiate high-dose Amoxicillin/clavulanate therapy
    • If initially prescribed with high-dose Amoxicillin-Clavulanate, may continue giving high-dose Amoxicillin-Clavulanate or may shift to Clindamycin + Cefixime or Linezolid + Cefixime or Levofloxacin
  • In patients without severe ABRS and comorbidities, they may benefit from short-course treatment which leads to better compliance, fewer adverse effects, lower resistance rates and lower costs of medications
  • Short-course treatment with appropriate oral antibiotic treatment is given in 7 days
    • May be extended to 14 days if symptoms fail to resolve
  • The duration of antibiotic therapy in patients with moderate to severe ABRS is 7 to 14 days
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