November 2000
Bacterial sinusitis is a commonly diagnosed condition. It is the fifth most common diagnosis for prescription of an antibiotic, with a recommended treatment duration of 10-14 days. This year, two advisory committees have published recommendations on the treatment of bacterial sinusitis in children and adults. This month's column will summarize these reports, with an emphasis on antibiotic therapy.
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The Sinus and Allergy Health Partnership is a joint creation of the American Academy of Otolaryngic Allergy, the American Academy of Otolaryngology-Head and Neck Surgery, and the American Rhinologic Society. Their recommendations, "Antimicrobial Treatment Guidelines for Acute Bacterial Rhinosinusitis" were published this year in Otolaryngology-Head and Neck Surgery.
The term acute bacterial rhinosinusitits (ABRS) is used throughout these recommendations, because sinusitis rarely occurs without concurrent rhinitis. Although a definition for a clinical diagnosis can be debated, the Sinus and Allergy Health Partnership guidelines state that a diagnosis of ABRS can be made in children with a viral upper respiratory tract infection that has not improved after 10 days or has worsened after five to seven days, along with some or all of the following symptoms: nasal drainage, nasal congestion, facial pain/pressure, postnasal drip, hyposomia/anosmia, fever, cough, fatigue, maxillary dental pain, or ear fullness/pressure. These guidelines for diagnosis may not apply to all patients, and thus, clinicians should use clinical judgement when following them.
The bacterial pathogens responsible for ABRS include Streptococcus pnuemoniae non-typeable Haemophilus influenzae and Moraxella catarrhalis with S. pneumoniae the primary pathogen. A major impetus for release of guidelines at this time is the increasing prevalence of antimicrobial resistance among these pathogens. Because S. pneumoniae is the most prevalent and most pathogenic bacterial cause of ABRS, increasing rates of resistance to penicillin (and amoxicillin) are important for clinicians to appreciate. The mechanisms of resistance to antibiotics among these pathogens differ, and these differences have important implications for antibiotic choice. Resistance to ß-lactam antibiotics, such as penicillin or amoxicillin, and cephalosporins, by S. pneumoniae is mediated by a change in the binding site (termed penicillin binding proteins, [PBPs]) of the antibiotic to the bacterium. Strains of S. pneumoniae that are nonsusceptible to penicillin can be intermediate or resistant in their nonsusceptibility. Activity of amoxicillin toward nonsusceptible strains can often be increased through increased dosages. Non-typeable H. influenzae and M. catarrhalis become resistant to ß-lactam antibiotics through production of inactivating enzymes (ß-lactamases).
Recent estimates of the prevalence of S. pneumoniae that are nonsusceptible to penicillin range from 25%-45%, while 32.5% and 43.2% of S. pneumoniae have been reported to be resistant to macrolides (e.g., clarithromycin [Biaxin, Abbott]) and trimethoprim-sulfmamethoxazole, respectively. Approximately 40% of non-typeable H. influenzae and essentially all (98%) of M. catarrhalis have been found to produce ß-lactamase enzymes in recent surveillance studies. Because rates of resistance vary throughout the country, it is important for clinicians to be familiar with resistance patterns in their communities.
The Sinus and Allergy Health Partnership recommendations were formulated from mathematic modeling using pathogen distribution, in vitro microbiologic efficacy and pharmacokinetic/pharmacodynamic principles (the relationship between drug concentration in the body with actions, or efficacy). Antibiotic recommendations are stratified according to mild or severe disease severity and recent (four to six weeks) antibiotic use. Recent antibiotic use has been found to be a major risk factor for carriage and infection with resistant organisms.
Antibiotics are ranked according to predicted efficacy based upon the above factors: >90% (amoxicillin-clavulanate, high-dose amoxicillin); 80%-90% (cefpodoxime proxetil [Vantin, Pharmacia & Upjohn], cefixime [based on non-typeable H. influenzae and M. catarrhalis coverage only, cefuroxime axetil (Ceftin, Glaxo Wellcome), clindamycin [based on S. pneumoniae coverage only], azithromycin [Zithromax, Pfizer], clarithromycin [Biaxin, Abbott], erythromycin, trimethoprim-sulfamethoxazole); 70%-80% (cefprozil [Cefzil, Bristol-Myers Squibb]); 60%-70% (cefaclor, lorcarbef). The spontaneous resolution rate of ABRS is 40%-50%. Antibiotic recommendations according to disease severity and recent antibiotic use are given in the table. Although not listed in the table, the Sinus and Allergy Health Partnership recommendations also list antibiotic choices for patients who fail initial therapy (defined as no improvement or worsening after 72 hours of therapy).
Also published this year are recommendations on the diagnosis and medical treatment of acute bacterial sinusitis from a clinical advisory committee. These recommendations, titled "Medical Management of Acute Bacterial Sinusitis," were published in the Annals of Otology, Rhinology, and Laryngology.
These antibiotic recommendations are presented as first-, second-, and third-line, and are incorporated into an algorithm. First-line antibiotics include amoxicillin and TMP-SMX. Second-line antibiotics, which can be used if the patient's symptoms do not resolve within three to five days or if symptoms return within two weeks, include cefprozil, cefuroxime axetil, cefpodoxime proxetil and amoxicillin-clavulanate. Macrolide antibiotics are recommended for patients allergic to penicillin.
While these recommendations and those of the Sinus and Allergy Health Partnership are generally similar, several differences do exist. TMP-SMX is recommended as a first-line antibiotic in the Clinical Advisory Committee recommendations, while it is recommended only for patients allergic to b-lactam antibiotics by the Sinus and Allergy Health Partnership. The Sinus and Allergy Health Partnership guidelines discuss in vitro susceptibility data from several studies indicating that relatively high rates of resistance exist toward TMP-SMX from the three major pathogens. The Clinical Advisory Committee second-line antibiotics includes cefprozil, while this antibiotic is generally not recommended by the Sinus and Allergy Health Partnership. While cefprozil maintains good activity towards S. pneumoniae its activity against non-typeable H. influenzae is substantially less than several other antibiotics, as determined in recent susceptibility studies.
The Clinical Advisory Committee recommendations also describe adjunctive treatments that can be used to decrease edema. Although evidence documenting their efficacy is limited, they may assist in decreasing symptoms. Measures such as saline nasal sprays, humidifiers, warm aerosols, steam and aromatic vapors can moisturize the nasal cavity. Topical decongestants can be used in older children to relieve obstruction. When used, a limit of three days should be applied, to prevent rebound congestion.
For more information:
- Sinus and Allergy Health Partnership. Antimicrobial treatment guidelines for acute bacterial rhinosinusitis. Otolaryngol Head Neck Surg. 2000;123:S1-32.
- Brook I, et al. Medical management of acute bacterial sinusitis, recommendations of a clinical advisory committee on pediatric and adult sinusitis. Ann Otol Rhinol Laryngol. 2000;109:2-20.
- Jacobs MR, et al. Susceptibilities of Streptococcus pneumoniae and Haemophilus influenzae to 10 oral antimicrobial agents based on pharmacodynamic parameters: 1997 US surveillance study. Antimicrob Agents Chemother. 1999;43:1901-8.
- Mason EO, et al. Streptococcus pneumoniae in the USA: in vitro susceptibility and pharmacodynamic analysis. J Antimicrob Chemother. 2000;45:623-31.
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