Medication Summary
The FDA has approved more than a dozen antibiotics to treat otitis media (OM).
Some clinicians advocate administering corticosteroids in combination with a beta-lactam–stable antibiotic. Before prescribing such therapy, obtain a history of varicella, vaccination against varicella, and recent exposure to a patient with varicella to avoid the risk of disseminated varicella.
Studies of other adjunctive therapy for acute OM (AOM) and OME have shown that NSAIDs, decongestants, and antihistamines provide no obvious benefits.
Antimicrobial agents
Class Summary
These agents remove pathogenic bacteria from middle ear fluid.
Amoxicillin (Biomox, Amoxil, Trimox)
Mainly bactericidal. As with penicillins, inhibits third and final stage of bacterial cell wall synthesis by preferentially binding to specific PBPs located inside the bacterial cell wall.
PO semisynthetic aminopenicillin similar to ampicillin. Aminopenicillins are not stable in beta-lactamases of either gram-positive or gram-negative bacteria; more stable in gastric acid than penicillin and more bioavailable than PO ampicillin.
Amoxicillin is associated with a lower prevalence of diarrhea than is ampicillin administered PO because of the greater bioavailability of amoxicillin. Commonly used to treat infections (eg, OM, bronchitis, sinusitis, bacterial cystitis) caused by susceptible organisms. To increase efficacy against PRSP in OM or respiratory infections, higher dosing regimens have been recommended.
Amoxicillin and clavulanate (Augmentin)
As a beta-lactam antibiotic, amoxicillin is mainly bactericidal. Inhibits third and final stage of bacterial cell wall synthesis by preferentially binding to specific PBPs located inside the bacterial cell wall. As with all beta-lactam antibiotics, ability to interfere with PBP-mediated cell wall synthesis ultimately leads to cell lysis.
Clavulanic acid is a beta-lactamase inhibitor that possesses weak antibacterial activity and acts as a competitive "suicide" inhibitor of many plasmid-mediated and chromosome-mediated bacterial beta-lactamases.
Excellent choice for second-line therapy in AOM or initial therapy in OME. Drug combination treats bacteria resistant to beta-lactam antibiotics. Combination with clavulanic acid reestablishes amoxicillin's activity against beta-lactamase-producing bacteria. Excellent for treating infections due to beta-lactamase-producing H influenzae and penicillinase-producing anaerobes.
Commonly used to treat infections (eg, AOM, acute sinusitis, acute bacterial cystitis, uncomplicated gonorrhea, chancroid) caused by susceptible organisms.
For children >3 mo, base dosing protocol on amoxicillin content. Because of different amoxicillin/clavulanic acid ratios in 250-mg tab (250/125) vs 250-mg chewable tab (250/62.5), do not use 250-mg tab until child weighs >40 kg. Use the 7:1 formulation (ie, bid formulation) in higher doses to minimize GI tract effects.
Cefaclor (Ceclor)
Second-generation PO cephalosporin indicated for infections caused by susceptible gram-positive cocci and gram-negative rods. Has slightly improved activity against H influenzae compared to cephalexin. Although marketed after first-generation agents, causing some clinicians to consider it a second-generation agent, its spectrum more closely resembles first-generation cephalosporins. Clinically, used primarily to treat OM, sinusitis, and URIs caused by H influenzae that are resistant to ampicillin or amoxicillin.
Use higher doses for severe infections (eg, pneumonia, OM), less susceptible strains of pathogens, and in patients who are obese.
Cefprozil (Cefzil)
PO, semisynthetic, second-generation cephalosporin. Binds to one or more PBPs, which, in turn, inhibit cell wall synthesis and result in bactericidal activity. Possible second-line therapy for AOM or initial therapy for OME. Therapeutic uses include OM, soft tissue infections, and respiratory tract infections.
Cefuroxime (Ceftin)
Second-generation cephalosporin maintains the gram-positive activity of first-generation cephalosporins and adds activity against Proteus mirabilis, H influenzae, E coli, K pneumoniae, and M catarrhalis.
Common clinical uses include severe upper and lower respiratory tract infections, skin infections, OM, and surgical prophylaxis.
Condition of patient, severity of infection, and susceptibility of microorganism determine proper dose and route of administration. Susp is less bioavailable than tab. Bioavailability is enhanced when administered with food or infant formula.
Cefixime (Suprax)
Third-generation cephalosporin available in an PO formulation. As with ceftriaxone, has enhanced antibacterial activity and increased stability against many beta-lactamases. By binding to one or more PBPs, it arrests bacterial cell wall synthesis and inhibits bacterial growth.
Commonly used to treat OM, respiratory tract infections, and URIs caused by susceptible organisms.
When treating OM, susp is preferred due to higher serum concentrations achieved with this dosage form compared with tabs.
Ceftriaxone (Rocephin)
Third-generation cephalosporin with broad-spectrum gram-negative activity; lower efficacy against gram-positive organisms; higher efficacy against resistant organisms. Arrests bacterial growth by binding to one or more PBPs. Has longest half-life of all cephalosporins, allowing once-daily dosing and making it a useful antibiotic for outpatient therapy.
In Dec 1997, the FDA approved IM ceftriaxone to treat bacterial AOM caused by H influenzae (beta-lactamase negative), H influenzae (beta-lactamase positive), M catarrhalis (including beta-lactamase producing strains), and S pneumoniae. Approval was based on the following data in children aged 5 months to 5 years: A prospective, randomized, double-blind, clinical trial compared the effectiveness of a 50 mg/kg single dose of IM ceftriaxone (n=116) with a 10-d course of PO amoxicillin (n=117). The authors concluded that a single IM injection of ceftriaxone is as effective as PO amoxicillin to treat uncomplicated OM in children.
The CDC's DRSP therapeutic working group suggests this dose for 3 consecutive days in cases of suspected resistant bacteria.
Cefpodoxime (Vantin)
Cefpodoxime proxetil is an PO prodrug for the extended-spectrum, semisynthetic, cephalosporin antibiotic cefpodoxime. Spectrum is similar to third-generation cephalosporins and primarily has gram-negative coverage but also covers some gram-positive organisms. Highly stable in the presence of beta-lactamase enzymes; as a result, many organisms resistant to penicillins and some cephalosporins (due to beta-lactamases) may be susceptible to cefpodoxime.
Indicated for treatment of upper and lower respiratory tract infections, UTIs, STDs, and skin and skin structure infections. Has long half-life, allowing twice-daily administration. Approved by the FDA in 1984.
Cefdinir
Cefdinir is a third-generation cephalosporin. It inhibits mucopeptide synthesis in the bacterial cell wall and is typically bactericidal, depending on organism susceptibility, dose, and serum or tissue concentrations. It is indicated for acute bacterial otitis media caused by H influenzae (including beta-lactamase-producing strains), S pneumoniae (penicillin-susceptible strains only), or M catarrhalis (including beta-lactamase-producing strains) in children aged 6 months or older. The typical dosage is 14 mg/kg/day PO once daily or divided q12h.
Clarithromycin (Biaxin)
PO macrolide antibiotic similar to erythromycin and azithromycin. Commonly used in infections of the respiratory tract, STDs, OM, and infections in patients with AIDS. As with other macrolides, binds to 50S subunit of the 70S ribosome, thereby blocking RNA-mediated bacterial protein synthesis. Can be bacteriostatic or bactericidal in action, depending on concentration and the particular organism and its inoculum. Also penetrates phagocytes and macrophages efficiently, and, as a result, is effective against a wide variety of organisms in respiratory infections.
Generally active against organisms that are usually susceptible to erythromycin, including most staphylococcal and streptococcal strains. In addition, clarithromycin is active against M catarrhalis, Mycoplasma pneumoniae, Legionella species, and Chlamydia pneumoniae. Beta-lactamase production should have no effect on activity. Most strains of methicillin-resistant and oxacillin-resistant staphylococci are resistant to clarithromycin.
Originally approved by the FDA in Oct 1991.
Azithromycin (Zithromax)
Semisynthetic antibiotic belonging to the macrolide subgroup of azalides. Similar in structure to erythromycin. Inhibits protein synthesis in bacterial cells by binding to the 50S subunit of bacterial ribosomes. Action is generally bacteriostatic but can be bactericidal in high concentrations or against susceptible organisms.
Although significantly more expensive, it can be administered as a once-daily dose and produces less GI tract intolerance than erythromycin. Apparent advantage over erythromycin is that it reaches higher intracellular concentrations, thus increasing efficacy and duration of action. These advantages are demonstrated in studies that show that single doses are effective for the treatment of STDs caused by chlamydial and gonorrheal organisms.
Approved by FDA in Nov 1991. PO susp was introduced in Apr 1995. In late 1995, was approved for treatment of pediatric OM and pharyngitis and, in mid 1996, was approved for MAC prophylaxis in patients with advanced HIV disease.
IV form is also available for initial treatment of community-acquired pneumonia and pelvic inflammatory disease.
Trimethoprim/sulfamethoxazole (Bactrim DS, Septra DS)
Also known as co-trimoxazole. Combination product of TMP and SMZ in a fixed 1:5 ratio. Ratio produces serum concentrations of 1:20, which optimize antibacterial activity against some organisms. Both TMP and SMZ are synthetic folate antagonists that are effective antimicrobials as individual agents. TMP is usually bactericidal and acts by inhibiting sequential enzymes of the folic acid–synthesis pathway. SMZ is a structural analog of PABA and competitively inhibits formation of dihydrofolic acid from PABA. TMP binds to and reversibly inhibits the enzyme dihydrofolate reductase, which prevents formation of THF from dihydrofolic acid.
THF is a metabolically active form of folic acid. Without THF, bacteria cannot synthesize thymidine, which leads to interference with bacterial nucleic acid and protein formation.
Combination of TMP with SMZ is synergistic against some bacteria. Usually active against Staphylococcus epidermidis, S aureus, S pneumoniae, Streptococcus viridans, most Enterobacteriaceae, Salmonella and Shigella species, H influenzae, M catarrhalis, and Stenotrophomonas maltophilia.Enterococcus species, Neisseria gonorrhoeae, P aeruginosa, and anaerobes are usually resistant or less susceptible. Also effective against Pneumocystis carinii, Listeria monocytogenes, many Nocardia species, Yersinia enterocolitica, and Legionella pneumophila.
Initially used in the treatment of UTIs but has since proved to be a versatile agent and is now widely used in the prevention and treatment of P carinii pneumonia. Approved by FDA in 1973.
Erythromycin (E-Mycin, Eryc, Ery-Tab, Erythrocin)
Macrolide antibiotic produced by Streptomyces erythraeus; first of several macrolide antibiotics now on the market.
Inhibits bacterial growth, possibly by blocking dissociation of peptidyl tRNA from ribosomes, causing RNA-dependent protein synthesis to arrest. For treatment of staphylococcal and streptococcal infections. Effective against wide range of microorganisms and, as with other antibiotics that inhibit protein synthesis, is mainly bacteriostatic.
Activity against gram-positive organisms is usually greater than against gram-negative organisms because of superior penetration into gram-positive organisms.
Gram-positive organisms susceptible to erythromycin include S aureus, Streptococcus agalactiae, Streptococcus pyogenes, S pneumoniae, S viridans, and Corynebacterium diphtheriae. Gram-negative coverage is limited. In general, should not be used against H influenzae, although, in some cases, organism may be susceptible. Although erythromycin is active against many microbes, its clinical applications are relatively few.
In children, age, weight, and severity of infection determine proper dosage. When bid dosing is desired, half of the total daily dose may be taken q12h. For more severe infections, double the dose.
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Diagram of the normal tympanic membrane anatomy.
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Healthy tympanic membrane.
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Acute otitis media with purulent effusion behind a bulging tympanic membrane.
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Chronic otitis media with a retraction pocket of the pars flaccida.
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Cholesteatoma of the pars flaccida.
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Central/pars tensa tympanic membrane perforation with a healthy middle ear membrane.
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Central/pars tensa tympanic membrane perforation with a tympanostomy tube in place.
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Various tympanostomy tube styles and sizes.
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Initial presentation of a young girl with chronic right ear pain and multiple untreated middle ear infections.
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Acute coalescent mastoiditis with a Bezold abscess in a young girl who presented with chronic right ear pain and multiple untreated middle ear infections.
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A young girl who presented with chronic right ear pain and multiple untreated middle ear infections on the operating table for mastoidectomy and drainage of Bezold abscess.
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Aspirating pus from the Bezold abscess for Gram staining, culturing, and sensitivity testing in a young girl who presented with chronic right ear pain and multiple untreated middle ear infections.
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Surgical incision to aspirate pus in a young girl who presented with chronic right ear pain and multiple untreated middle ear infections.
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Freer elevator demonstrating extension of an abscess cavity from the mastoid into the neck in a young girl who presented with chronic right ear pain and multiple untreated middle ear infections.
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Incision is closed and a drain is placed in the abscess cavity in a young girl who presented with chronic right ear pain and multiple untreated middle ear infections.
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Postoperative bandage in a young girl who presented with chronic right ear pain and multiple untreated middle ear infections.
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The wound now appears clean and dry on postoperative day 4. This young girl initially presented with chronic right ear pain and multiple untreated middle ear infections.
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Postoperative day 4: Mom is smiling. This young girl initially presented with chronic right ear pain and multiple untreated middle ear infections.
