eMedicine Specialties > Otolaryngology and Facial Plastic Surgery > Middle Ear & Mastoid

Middle Ear, Chronic Suppurative Otitis, Medical Treatment: Treatment & Medication

Author: David Parry, MD, Staff Physician, Department of Otolaryngology-Head and Neck Surgery, ENT Associates of Children's Hospital, Boston
Coauthor(s): Peter S Roland, MD, Professor, Department of Neurological Surgery, Professor and Chairman, Department of Otolaryngology-Head and Neck Surgery, Director of Clinical Center for Auditory, Vestibular and Facial Nerve Disorders, Chief of Pediatric Otology, University of Texas Southwestern Medical Center; Adjunct Professor of Communicative Disorders, University of Texas School of Human Development
Contributor Information and Disclosures

Updated: Jul 7, 2009

Treatment

Medical Care

Antibiotic drops

The antibiotic should have an appropriate spectrum of activity that includes gram-negative organisms, especially pseudomonads, and gram-positive organisms, especially S aureus. The antibiotics that meet this initial criterion are the aminoglycosides and the fluoroquinolones. Topical antibiotic drops containing aminoglycosides have been marketed and used for more than 20 years.

Most drops marketed specifically for otologic use contain neomycin combined with a cationic detergent (polymyxin B). Neomycin has remained fairly effective over the last 2 decades for gram-positive organisms but has lost almost all of its effectiveness for gram-negative organisms. Dohar's recent studies indicate fewer than 20% of gram-negative organisms remain sensitive to neomycin; however, polymyxin B has remained effective for gram-negative bacteria. The combination consequently remains reasonably effective from an antimicrobial point of view.

Gentamicin- and tobramycin-containing ophthalmic drops have been widely used off-label for the treatment of otologic infections. A fixed-ration combination of tobramycin and dexamethasone (TobraDex) has been especially popular within the United States, while gentamicin-containing drops have been more popular in Canada and Europe.

All aminoglycosides have significant potential toxicity. Some are more vestibular toxic than cochlear toxic and, therefore, are more likely to produce vestibular dysfunction than hearing loss. For other aminoglycosides, the opposite is true. Studies designed to detect hearing loss from use of ototopical aminoglycosides demonstrate that such incidence is, at worst, low. Recent information, however, suggests that the potential for vestibular toxicity may be much higher, especially if preparations containing gentamicin are used.

Otic drops differ in pH. Drops designed for otic use are often buffered slightly to an acidic pH because the normal environment of the external auditory canal is acidic. Such drops can be extremely painful if they penetrate into the middle ear, especially if the middle ear mucosa is normal. The normal pH of the middle ear is neutral.

Most ototopic antibiotic steroid combinations are at least somewhat acidic because it is almost impossible to keep either quinolones or aminoglycosides in solution at a neutral or basic pH. The acidity of polymyxin, neomycin, and hydrocortisone varies from as low as 3.5 to 4.5. Ciprofloxacin and hydrocortisone combinations have a pH of 4.5-5.0, as do tobramycin and dexamethasone combinations.

While low pH is an advantage when treating infections in the external auditory canal, the advantage is lost in the middle ear. Within the middle ear space, the potential for low pH solutions to cause pain or to irritate mucosa can render them disadvantageous.

Ototopical preparations vary in viscosity. Preparations containing an antibiotic are usually solutions and have relatively low viscosities approaching that of water (1.0 cP). Preparations containing a steroid are often of considerably higher viscosity, ranging from 2-8 cP. Polyviscous solutions may effectively coat and remain in contact with tissues for longer periods, although they are less likely to move through or around small spaces (eg, tympanostomy tubes, granulation tissue, polyps) than are preparations of lower viscosity.

Some controversy surrounds the development of bacterial resistance due to ototopical treatment. Recent studies have not identified any increase in bacterial resistance through ototopical antibiotic administration. Specifically, the concentration in quinolone ototopical drops overwhelms the most resistant pseudomonal and staphylococcal strains. Failure of topical antibiotic delivery to the pathogenic organisms should be considered a cause of persistent infections.

Roland et al demonstrated that the anti-inflammatory effect of steroids is an important advantage when significant amounts of granulation tissue are present. Ototopicals with steroids were superior to steroid-free ototopicals in reducing granulation tissue at days 11 and 18 of treatment. The steroid-containing drops should be considered in chronic suppurative otitis media with granulation tissue.

Aural toilet

Aural toilet is a critical process in the treatment of CSOM. The external auditory canal and tissues lateral to the infected middle ear are often covered with mucoid exudate or desquamated epithelium. Topically applied preparations cannot penetrate affected tissues until these interposing materials are removed.

Traditionally, in otolaryngology, aural toilet has been achieved using the microscope and microinstruments to mechanically remove such materials. For best results, aural toilet should be performed 2-3 times per day just before the administration of topical antimicrobial agents.

Aural irrigation is an effective alternative that is often less burdensome for patients and physicians. A solution of 50% peroxide and 50% sterile water is generally painless and effective. Thirty to 40 mL of this solution can be irrigated through the external auditory canal, using a small syringe or bulb-type aspirator. The irrigant solution can be allowed to drain out for 5-10 minutes prior to instilling the ototopical antimicrobial.

Granulation tissue

Granulation tissue often fills the middle ear and medial portions of the external auditory canal. Granulation tissue can prevent topically applied antimicrobial agents from penetrating to the site of infection. The use of topical antimicrobial drops is the first step in controlling granulation.

These drops help reduce granulation tissue by eliminating infection and by removing the inciting irritating inflammation. As previously discussed, most physicians believe that topical steroids are important and hasten the resolution of middle ear granulation, thus improving penetration of topically delivered antimicrobial agents.

Cautery is often used to reduce the amount of granulation tissue and to control its formation. Microbipolar cautery can be used in the office, but chemical cautery is used more commonly. Silver nitrate can conveniently be applied in the form of silver nitrate sticks. Caution must be exercised, as the depth of the chemical burn induced by the application of chemical agents, including silver nitrate, is uncontrolled. Excision of granulation tissue can be accomplished in the office with the use of a microscope and microinstruments. Silver nitrate is often used to control bleeding and to enhance the efficacy of granulation tissue removal.

An important part (perhaps the most important part) of tympanomastoidectomy for the treatment of CSOM consists of removing and controlling granulation tissue within the middle ear, mastoid, and mastoid antrum.

Treatment failures

Failures of topical antimicrobial therapy are almost always failures of delivery. Specifically, failure of delivery describes the inability of an appropriate, topical antibiotic to reach the specific site of infection within the middle ear. Various elements may obstruct the delivery of the medication including infectious debris, granulation tissue, cholesteatoma, neoplasia, cerumen, and others. When topical therapy fails, the patient needs a thorough evaluation for anatomic obstruction including microscopic examination and radiologic studies as needed. Additionally, a clear understanding of the very high concentration of the antibiotic within topical preparations must be kept in mind.

The minimal inhibitory concentrations (MICs) for S aureus, S pneumoniae, and the other organisms that commonly cause CSOM are generally 1-2 mcg/mL. Generally, intravenously administered aminoglycosides and any pseudomonal cephalosporins can slightly exceed these levels.

Orally administered fluoroquinolones also slightly exceed the MICs of most of the relevant organisms. (Oral administration achieves blood levels as high as those achieved with parenteral administration.) Concentrations of medicines in the middle ear fluid rarely exceed 4-6 mcg/mL. In contrast, a 0.3% topical antibiotic solution contains 3000 mcg/mL, a concentration 100-1000 times that which can be achieved using systemic administration. Moreover, this concentration greatly exceeds the MIC for any relevant organism. These high concentrations have the following important implications:

• Topical therapy does not fail because the organism is resistant. Even supposedly resistant organisms succumb to these very high concentrations. For instance, even an extraordinarily resistant strain of S aureus with an MIC of 256 mcg/mL cannot survive in an environment in which the concentration of antibiotic is 3000 mcg/mL.
• The emergence of resistance to topical therapy is extremely uncommon. The rapid kill rates and high concentrations of topically administrated drops do not permit even mutant strains with higher MICs to survive.
• Sensitivity reports from the clinical laboratory are irrelevant. Sensitivity testing in the clinical laboratory is designed for the tissue concentrations achievable by systemic administration. Consequently, a pseudomonad with an MIC of 48 mcg/mL is likely to be reported as resistant by the clinical laboratory.

Consequently, when topical therapy for CSOM fails, it is almost never because of an antimicrobial resistance of the organisms involved. Therefore, culture and sensitivity are of little benefit as long as therapy is topical.

Because of the high concentrations of antimicrobial agents, topical therapy is more likely to be effective than systemic therapy. Studies comparing systemic administration to topical administration show that topical cure rates nearly double systemic rates.

Systemic therapy

Systemic therapy should be reserved for cases of CSOM that fail to respond to topical therapy. Topical therapy presumably fails because antibiotics cannot reach infected tissues. Systemic therapy is expected to succeed in penetration of the tissues.

If a focus of infection in the mastoid cannot be reached by topical drops, there is a reasonable chance that systemically administered antibiotics can penetrate into these areas in sufficient concentrations to control or eliminate infection, though concentrations are lower. Ototopical therapy is generally continued once systemic therapy is begun. Indeed, since systemic therapy frequently involves hospitalization for intravenous administration of drugs, aural toilet can frequently be intensified. The ability to perform reliable aural toilet may be as important as the systemic antimicrobial therapy in eliminating the disease for some patients.

Prior to instituting systemic therapy, a culture should be obtained for sensitivity. Sensitivity testing is important when systemic therapy is being considered. The antibiotics should be selected on the basis of the resulting sensitivity profile. The narrowest spectrum antibiotic with the fewest adverse effects and complications should be used.

All the aminoglycosides are potentially useful, although tobramycin has been shown to be more effective against pseudomonads than gentamicin. Dohar et al have shown that piperacillin is probably the most effective antibiotic. Ceftazidime remains a useful choice for many patients.

Systemic therapy should be continued for 3-4 weeks. Most individuals experience cessation of otorrhea in shorter periods. Antimicrobial therapy should probably be continued at least 3-4 days after cessation of otorrhea.

Potentially, the fluoroquinolones are the most useful class of oral antibiotics for treating CSOM. Oral therapy achieves serum concentrations as high as parenteral therapy, obviating the need for intravenous delivery.

Ciprofloxacin remains the most effective of the quinolones for pseudomonads. Some of the late-generation "respiratory quinolones" appear to be more efficacious for S aureus. Fluoroquinolones are not approved for use in children because they elicit joint injury in juvenile experimental animals. Nevertheless, a large database of children with cystic fibrosis who have been treated with systemic fluoroquinolones at relatively high doses for prolonged periods demonstrates that the risk of joint injury appears to be absent or very low. No cases of permanent joint injury have been reported.

A few children of the many thousands treated have developed pain that remitted with cessation of therapy. Given the real potential toxicity of intravenously administered antibiotics—especially the aminoglycosides—serious consideration should be given to the use of oral fluoroquinolones when treating children with CSOM unresponsive to topical therapy. The risk of injury, adverse reaction, or significant adverse effects appears to be lower overall with systemic quinolones than with many of the other antibiotics normally used to treat gram-negative infections. Most parents are agreeable to the off-label use of oral fluoroquinolones if they understand the relative risks and potential benefits offered by this class of drugs in comparison to the variable alternatives.

Surgery should be considered if CSOM fails to respond to a combination of topical and systemic therapy. A tympanomastoidectomy can eliminate infection and stop otorrhea in 80% of patients.

Surgical Care

Patients with CSOM that is unresponsive to topical and/or systemic medical therapy with appropriate aural toilet and control of granulation tissue require surgery. Please see Middle Ear, Chronic Suppurative Otitis, Surgical Treatment.

Consultations

Neurosurgeons should be consulted as indicated in Complications.

Activity

Swimming is contraindicated during treatment for CSOM.

Medication

An expert panel of the American Academy of Otolaryngology-Head and Neck Surgery recently convened to provide guidelines for the use of antibiotics in CSOM. The panel concluded that topical antibiotics alone constitute first-line treatment for most patients, barring systemic infection. If systemic infection is present, oral or, if necessary, parenteral antibiotics are warranted.

Please see Medical Care for a complete discussion of alternatives.

Antibiotics

Topical and systemic antibiotics are used in the treatment of chronic suppurative otitis media. Fluoroquinolone otic preparations, with or without a corticosteroid, are excellent options for topical treatment. Aminoglycoside otics may also be used, but monitoring of vestibular or cochlear toxicity is necessary. Representative examples of each class are listed below.

Ciprofloxacin (Cipro HC Otic suspension), Ciprofloxacin/dexamethasone combination (Ciprodex)

Ototopical fluoroquinolone containing hydrocortisone. This class of antimicrobial has a broad spectrum of activity. Additionally, fluoroquinolones do not cause vestibular or cochlear toxicity recognized with aminoglycosides.

Tobramycin (Tobrex, TobraDex)

Ototopical aminoglycoside with or without corticosteroid. Has a long, successful history in the treatment of chronic suppurative otitis media and is widely used today. Risk of vestibular or cochlear toxicity with prolonged use or use on the noninflamed middle ear exists; consider this when choosing to treat chronic suppurative otitis media with this class of medication.

Piperacillin (Pipracil)

Inhibits biosynthesis of cell wall mucopeptides and stage of active multiplication. Has antipseudomonal activity.

Ceftazidime (Fortaz, Ceptaz, Tazidime, Tazicef)

Studies show this to be an effective IV antibiotic for systemic treatment of chronic suppurative otitis media. Penetrates the middle ear mucosa effectively and does not cause vestibular or cochlear toxicity.

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