Clinical implications of antibiotic resistance for management of acute otitis media

Streptococcus pneumoniae and chronic endobronchial infections in childhood

Streptococcus pneumoniae (pneumococcus) is the main cause of bacterial pneumonia worldwide and has been studied extensively in this context. However, its role in chronic endobronchial infections and accompanying lower airway neutrophilic infiltration has received little attention. Severe and recurrent pneumonia are risk factors for chronic suppurative lung disease (CSLD) and bronchiectasis; the latter causes considerable morbidity and, in some populations, premature death in children and adults. Protracted bacterial bronchitis (PBB) is another chronic endobronchial infection associated with substantial morbidity. In some children, PBB may progress to bronchiectasis. Although nontypeable Haemophilus influenzae is the main pathogen in PBB, CSLD and bronchiectasis, pneumococci are isolated commonly from the lower airways of children with these diagnoses. Here we review what is known currently about pneumococci in PBB, CSLD and bronchiectasis, including the importance of pneumococcal nasopharyngeal colonization and how persistence in the lower airways may contribute to the pathogenesis of these chronic pulmonary disorders. Antibiotic treatments, particularly long-term azithromycin therapy, are discussed together with antibiotic resistance and the impact of pneumococcal conjugate vaccines. Important areas requiring further investigation are identified, including immune responses associated with pneumococcal lower airway infection, alone and in combination with other respiratory pathogens, and microarray serotyping to improve detection of carriage and infection by multiple serotypes. Genome wide association studies of pneumococci from the upper and lower airways will help identify virulence and resistance determinants, including potential therapeutic targets and vaccine antigens to treat and prevent endobronchial infections. Much work is needed, but the benefits will be substantial.

Single-dose (30 mg/kg) azithromycin compared with 10-day amoxicillin/clavulanate for the treatment of uncomplicated acute otitis media: a double-blind, placebo-controlled, randomized clinical trial

BACKGROUND

The long half-life of azithromycin allows for single-dose oral therapy for acute otitis media (AOM).

OBJECTIVE

This study was designed to compare the efficacy and tolerability of single-dose azithromycin with 10-day, twice-daily amoxicillin/clavulanate for the treatment of new-onset, uncomplicated AOM in children.

METHODS

Children aged 6 months to 12 years with new-onset AOM were randomly assigned to receive either a single 30-mg/kg dose of azithromycin or standard-dose amoxicillin/clavulanate (45 mg/kg administered BID for 10 days) in a double-blind, double-placebo, multicenter clinical trial. The diagnosis of AOM was based on specific clinical signs and symptoms, and was confirmed by pneumatic otoscopy and acoustic reflectometry (level ≥3). Clinical response was assessed on days 12-16 and 28-32.

RESULTS

Mean (SD) age of children receiving azithromycin (n = 173) or amoxicillin/clavulanate (n = 173) was 2.7 (2.3) years and 3.4 (2.8) years, respectively, with 43% and 36% ≤2 years of age. Most (53.2%) of the children were boys, and most (51.2%) were white. Clinical success rates (intent-to-treat) for azithromycin and amoxicillin/clavulanate, respectively, were 87% and 88% (95% CI, -9.2 to 6.5) on day 12-16 and 75% and 75% (95% CI, -10.2 to 10.5) on day 28-32. The incidences of treatment-related adverse events for azithromycin and amoxicillin/clavulanate were 16.8% and 22.5%, respectively. Corresponding rates of diarrhea were 6.4% and 12.7%, respectively. Vomiting, which was generally mild, occurred in 7 children in each group. One azithromycin patient and 5 amoxicillin/clavulanate patients discontinued treatment because of adverse events. The compliance rate for azithromycin was significantly higher than that for amoxicillin/clavulanate (99% vs 83%; P<0.001).

CONCLUSIONS

In this trial comparing the efficacy of single-dose azithromycin (30 mg/kg) with twice-daily amoxicillin/clavulanate (45 mg/kg) for the treatment of new-onset, uncomplicated AOM, no differences were detected between the 2 regimens. Single-dose azithromycin was generally well tolerated and provides an alternative to conventional oral regimens for AOM.

Otitis media today: a challenge for physicians and the community

Acute otitis media is one of the most common causes of medical consultation worldwide, and has a high economic impact. In this review, a clear definition between acute otitis media and otitis media with effusion is presented. The microbiology and characterization of the main bacterial isolates in acute otitis media and the susceptibility patterns are reviewed, and the latest concepts in antimicrobial treatment are discussed. The need for courses that improve the capability of primary care physicians to diagnose acute otitis media using pneumatic otoscopy, and for parental education is also discussed.

Microdialysis studies of the distribution of antibiotics into chinchilla middle ear fluid

For conditions such as acute otitis media, in which antibiotic penetration into middle ear fluid (MEF) may be slow or limited, antibiotic plasma levels may not reflect the concentrations at the site of infection that are relevant to clinical outcome. In such cases, a model is needed that will enable prediction of the time course of unbound, pharmacologically active antibiotic levels in MEF. We describe the use of microdialysis as a sampling tool for measurement of unbound antibiotic concentrations in the MEF of the awake, freely moving chinchilla. Results of studies of MEF penetration of the beta-lactam antibiotic, cefdinir, with use of this technique are also described. Preliminary results of studies of the penetration of antibiotics into MEF of the chinchilla appear consistent with clinical findings and suggest that the chinchilla microdialysis model may prove to be a useful tool for predicting antibiotic efficacy in patients.

The chinchilla microdialysis model for the study of antibiotic distribution to middle ear fluid

In cases of slow or limited penetration of an antibiotic to the site of infection such as in acute otitis media (the middle ear), plasma levels of the agent may not reflect the concentrations that are relevant in determining clinical outcome. There is a need for a model that allows prediction of the time-course of unbound, pharmacologically active drug levels in middle ear fluid (MEF). This article introduces microdialysis as a sampling tool to measure unbound antibiotic concentrations in the MEF of the chinchilla, and briefly summarizes the results of studies of MEF penetration of a cephalosporin, a macrolide, and a ketolide antibiotic using this technique. The general concurrence of preliminary results of the chinchilla studies with clinical findings suggests that the chinchilla microdialysis model may be useful in predicting efficacy in patients.

Rationale and design of the prevention of respiratory infections and management in children (PRIMAKid) study: a randomized controlled trial on the effectiveness and costs of combined influenza and pneumococcal vaccination in pre-school children with recurrent respiratory tract infections

Health and economic burden of recurrent respiratory tract infections (RTIs) in early childhood is considerable. A systematic review of licensed influenza and pneumococcal vaccines showed substantial efficacy in children, but the health-economic impact of such vaccines among pre-school children with recurrent RTIs is unknown. We therefore, designed a double-blind randomized controlled trial to determine the effectiveness and costs of a combined influenza and pneumococcal vaccination program among a primary care based cohort of children with recurrent episodes of RTI aged between 18 and 72 months. We will enroll 690 children over three consecutive years (2003--2005) who will be randomly allocated to receive vaccinations against influenza and pneumococcal disease, influenza alone or hepatitis B in a similar schedule. Follow up by parental diaries, tympanic temperature measurements, questionnaires and interviews is planned until May 2006. Primary outcome is number of febrile RTIs. Other outcomes include duration and severity of RTI episodes, medical consumption, safety and costs.

Community prescribing and resistant Streptococcus pneumoniae

We investigated the association between prescribing antimicrobial agents and antimicrobial resistance of Streptococcus pneumoniae among children with acute otitis media in southern Israel. During a 6-year period, all prescriptions of a sample of ≈20% of Jewish and Bedouin children <5 years of age were recorded and all pneumococcal isolates from middle ear fluid were collected. Although antimicrobial drug use was significantly higher in Bedouin children, the proportion of S. pneumoniae isolates with penicillin MIC ≥1.0 μg/mL was significantly higher in Jewish children. In both populations, antimicrobial prescriptions were markedly reduced over time, especially for penicillins and erythromycin. In contrast, azithromycin prescriptions increased from 1998 to 2001 with a parallel increase in macrolide and multidrug resistance. Penicillin resistance was associated with macrolide resistance. These findings strongly suggest that azithromycin affects increased antimicrobial resistance, including multidrug resistance, in S. pneumoniae.

Developing community-specific recommendations for first-line treatment of acute otitis media: is high-dose amoxicillin necessary?

OBJECTIVES

National recommendations are to use high-dose amoxicillin (80-90 mg/kg per day) to treat uncomplicated acute otitis media (AOM) in children who are at high risk for infection with nonsusceptible Streptococcus pneumoniae (NSSP). However, high-dose treatment may not be necessary if the local prevalence of NSSP is low. The objective of this study was to estimate the local prevalence of NSSP in children with acute upper respiratory illnesses and to develop community-specific recommendations for first-line empiric treatment of AOM.

METHODS

We conducted a cross-sectional prevalence study in the offices of 7 community pediatricians in St Louis, Missouri. S pneumoniae was isolated from nasopharyngeal swabs collected from children who were younger than 7 years and had AOM, nonspecific upper respiratory infection, cough, acute sinusitis, or pharyngitis. Children were excluded from the study when they had received an antibiotic in the previous 4-week period. Parents and providers completed a brief questionnaire to assess risk factors for carriage of NSSP. On the basis of National Clinical Chemistry Laboratory Standards, isolates with a penicillin minimum inhibitory concentration > or =0.12 microg/mL were considered to be nonsusceptible to penicillin (NSSP), and isolates with a penicillin minimum inhibitory concentration >2 microg/mL were categorized as nonsusceptible to standard-dose amoxicillin (35-45 mg/kg per day; NSSP-A).

RESULTS

S pneumoniae was isolated from the nasopharynx of 85 (40%) of 212 study patients (95% confidence interval [CI]: 33%-47%); 41 (48%) of 85 isolates were NSSP (95% CI: 37%-59%), and 6 (7%) were NSSP-A (95% CI: 1.5%-13%). Among the 212 study patients, the prevalence of NSSP was 19% (95% CI: 14%-25%), and the prevalence of NSSP-A was 3% (95% CI: 0.6%-5%). Carriage of NSSP was increased in child care attendees compared with nonattendees (29% vs 14%; odds ratio: 2.6; 95% CI: 1.3-5.2).

CONCLUSIONS

In our community, although the prevalence of NSSP among isolates of S pneumoniae identified from the nasopharynx of symptomatic children is high (48%), the probability of NSSP-A infection among symptomatic children is <5%. Our data support a recommendation to treat most children who have uncomplicated AOM with standard-dose amoxicillin. Children who attend child care or have recently received an antibiotic may require treatment with high-dose amoxicillin. Other communities may benefit from a similar assessment of the prevalence of NSSP and NSSP-A.

Assessment of pediatric residents' otoscopic interpretive skills by videotaped examinations

BACKGROUND

Accurate diagnosis of otitis media is essential to facilitate appropriate management. Few residency programs assess formally their residents' competency in diagnosing middle ear disease.

OBJECTIVE

To evaluate the performance of pediatric residents' otoscopic interpretive skills by level of training, with a videotaped otoendoscopic examination (VOE).

METHODS

A VOE was used to assess and compare the performance of a cross-sectional sample of 141 residents with one another by level of training as well as with novice and expert groups. Total score, sensitivity, specificity, and kappa coefficients were calculated for each subject by comparing the subject's answers on the 50-ear test with the VOE's expert panel-derived answers, and averages were determined for each training level.

RESULTS

Each pediatric resident training group had moderate agreement (mean kappa coefficient range: .45-.56) with the VOE answers, compared with the novice group (mean kappa: .31, fair) and expert group (mean kappa: .80, substantial). Twenty-eight residents (20%) had fair or less agreement (kappa<.41) with the VOE answers. The mean total scores of all pediatric resident training levels were significantly (P<.05) lower than the expert group and significantly (P<.05) higher than the novice group (with exception of the early postgraduate year-1 group). Subjects with more training had higher kappa levels (r=.33,<.001, Spearman) when results were compared among novice, residents, and experts.

CONCLUSIONS

We found the VOE to be a feasible and reliable instrument to accurately distinguish novice, resident, and expert level skills in the determination of middle ear effusion status.

Epidemiología e impacto de la otitis media aguda en la Comunidad Valenciana

OBJECTIVE

To assess the burden (incidence, treatment and complications) of acute otitis media (AOM) and otitis media with effusion (OME) in children younger than 5 years of age from Valencia, Spain.

SUBJECT AND METHODS

We performed a retrospective cohort study of 1,399 children followed-up for the first 5 years of life. Seventeen pediatricians reviewed the medical records of their patients born in 1995 and 1996 and followed-up from birth until the age of 5 years. For each child, the number of otitis episodes, treatment, complications, and surgical interventions was obtained.

RESULTS

There were 2,961 episodes of AOM in the first 5 years of life (2.23 cases/child). Four hundred seventy-six cases (16.1 %) occurred before 1 year of age and 1,346 between the first and second year of life (45.5 %). By the third year of life, 59.8 % had had at least one episode. In most children (80.9 %), diagnosis was made in primary care and required a median of 1.81 visits/episode for follow-up. A total of 94.5 % were treated with antibiotics (amoxicillin-clavulanate 38.8 %, cefuroxime 14.3 %, clarithromycin 8.2 % and amoxicillin 5.9 %) and 8.5 % required a change of antibiotic therapy. Two hundred seventeen children (15.2 %) had at least one episode of OME. Twenty-six patients (1.8 %, 95 % CI: 1.2-2.7 %) required insertion of ventilation tubes. Twenty-four patients (1.7 %) had secondary hypoacusis. There was one case of meningitis and two cases of chronic otorrhea. No cases of mastoiditis were recorded.

CONCLUSIONS

The incidence of AOM in Valencia is 40,014 episodes/100,000 children younger than 5 years/year (95 % CI: 39,700-40,300). It represents a significant burden due to the large number of visits, antibiotic use, associated surgical procedures and need for auditory rehabilitation.

Etiology of acute otitis media in childhood and evaluation of two different protocols of antibiotic therapy: 10 days cefaclor vs. 3 days azitromycin

BACKGROUND

Acute otitis media (AOM) is a common childhood infection that is frequently treated by antibiotics. There are no prospective and comprehensive trials evaluating childhood AOM for etiologic pathogens and resistance pattern in Turkey. The aims of the study were to determine the bacterial etiologies and resistance patterns, and identify the efficacy and the relapse rates of 3 days of azitromycin and 10 days of cefaclor therapy in AOM.

METHODS

This prospective, randomized, single-blind, open study was carried out in 78 cases of AOM. Mean age was 30.7+/-27 months. Tympanocentesis and aspiration of middle ear fluid (MEF) were used to obtain purulent material from the middle ear. Group 1 consisted of the cases (n=41) on azitromycin therapy and Group 2 (n=37) on cefaclor. Dosage of azitromycin was 10 mg/kg per day for 3 days and cefaclor 40 mg/kg per day for 10 days. The patients were evaluated on days 3-5 (second visit), day 10 (third visit), and day 30 (fourth visit) during follow-up.

RESULTS

A total of 50 species were isolated from 44 of 78 cases from which materials were obtained (44/78; 56.4%). Most frequently isolated microorganism was Streptococcus pneumoniae (n=18; 36%), followed by Haemophilus influenzae (n=11; 22%), S. aureus (n=9; 18%), Moraxella catarrhalis (n=4; 8%), and group A beta-hemolytic streptococcus (GAS, n=4; 8%). Enterococcus faecalis was isolated from three cases and H. parainfluenzae from one. Penicillin and amoxicillin resistances of bacteria were found to be 40 and 36%, respectively. The frequency of penicillin and amoxicillin resistance in </=24-month age group was 59 and 66.6%, respectively. The patients did not demonstrate significant differences in terms of cure rate on the third to fifth day (Group 1: 32.5%; Group 2: 36.4%), 10th day (Group 1: 76.9%; Group 2: 84.8%), and on 30th day (Group 1: 91.3%; Group 2: 81.8%). There were no significant differences with respect to side effects, relapse, and re-infection rate between the two groups.

CONCLUSION

In more than half of the AOM cases, bacteria were isolated from MEF and most frequently isolated organisms were S. pneumoniae, H. influenzae, and S. aureus. Three-day azitromycin therapy was as effective as 10-day cefaclor therapy.

Influenza virus vaccines in children and their impact on the incidence of otitis media

Otitis media has been identified as the most frequent reason for outpatient antibiotic therapy. Several studies have linked viral respiratory infections with bacterial otitis media. In light of rising concerns about antibiotic resistance, the possibility of reducing the incidence of otitis media through vaccination against respiratory viruses has received increasing attention. This article reviews inactivated and live attenuated influenza virus vaccines and their possible impact on the incidence of otitis media. Inactivated and live attenuated influenza virus vaccines are safe and immunogenic in children older than 6 months and are linked to a decrease in the incidence of otitis media. Influenza vaccination of infants younger than 6 months has resulted in less predictable immunogenicity and deserves further investigation.

Macrolide-resistant Streptococcus pneumoniae in Canada during 1998-1999: prevalence of mef(A) and erm(B) and susceptibilities to ketolides

In this study (1998-1999), we collected 215 macrolide-resistant Streptococcus pneumoniae isolates from an ongoing Canadian Respiratory Organism Surveillance Study involving 23 centers representing all regions of Canada. The prevalence of erythromycin-resistant S. pneumoniae was 8% (215 of 2,688). Of the 215 isolates, 48.8% (105 of 215) were PCR positive for mef(A) and 46.5% (100 of 215) were PCR positive for erm(B). The ketolides telithromycin and ABT-773 demonstrated excellent activity against both mef(A) (MIC for 90% of strains [MIC(90)], 0.06 and 0.03 microg/ml, respectively) and erm(B) (MIC(90), 0.06 and 0.03 microg/ml, respectively) strains of S. pneumoniae.

Short-term penicillin-V prophylaxis did not prevent acute otitis media in infants

OBJECTIVE

To determine whether prophylactic, short-term penicillin V treatment during upper respiratory tract infections can prevent the occurrence of recurrent acute otitis media in young children.

METHODS

Seventy children were studied in a prospective, double-blind, placebo-controlled study. All children had suffered their first episode of acute otitis media before the age of 6 months. After inclusion in the study group, administration of penicillin V or placebo was initiated by the parents at subsequent upper respiratory tract infections. The children were examined by otomicroscopy within 3 days after treatment was initiated. The children were scheduled for a total follow-up period of 12 months, including bimonthly visits for check-up irrespective of treatment periods.

RESULTS

There were 304 treated episodes of upper respiratory tract infection. There was no significant difference in the number of acute otitis episodes between groups.

CONCLUSION

Initiation of penicillin V prophylaxis at upper respiratory tract infection in small children did not prevent recurrent acute otitis media in this study.

treatment and prevention of otitis media

OBJECTIVE

To review and summarize recent advances in the treatment and prevention of otitis media (OM).

DATA SOURCES

A MEDLINE search (1996-March 2000) was performed to identify relevant primary and review articles. References from these articles were also reviewed if deemed important.

STUDY SELECTION AND DATA EXTRACTION

English-language primary and review articles focusing on the treatment and prevention of acute otitis media (AOM) were included. Studies focusing exclusively on OM with effusion or serous OM and chronic suppurative OM were excluded. Information regarding prevention and drug therapy was reviewed, with an emphasis placed on advances made in the last two years.

DATA SYNTHESIS

Recently, an expert panel of the Centers for Disease Control and Prevention recommended use of only three of 16 systemic antibiotics approved by the Food and Drug Administration for treatment of AOM: amoxicillin, cefuroxime axetil, and ceftriaxone. Controversy exists over the importance of key selection factors used by the expert panel in determining which antibiotics to recommend in a two-step treatment algorithm, that is, in vitro data, pharmacodynamic profiles, and necessity for coverage of drug-resistant Streptococcus pneumoniae at all steps of empiric treatment. Additional antibiotic and patient selection factors useful for individualizing therapy include clinical efficacy, adverse effects, frequency and duration of administration, taste, cost, comorbid infections, and ramifications should bacterial resistance develop to the chosen antibiotic. Presumed or past patient/caregiver adherence (especially when antibiotic failure has occurred) is also paramount in selecting antibiotic therapy. A three-step treatment algorithm for refractory AOM that employs amoxicillin, trimethoprim/sulfamethoxazole (TMP/SMX), or high-dose amoxicillin/clavulanate (depending on the prior dose of and adherence to amoxicillin therapy), and ceftriaxone or tympanocentesis at steps 1, 2, and 3, respectively, appears rational and cost-effective. The recent upsurge in antimicrobial resistance is highlighted, and recommendations are presented for the treatment of AOM and prevention of recurrent otitis media (rAOM).

CONCLUSIONS

Amoxicillin remains the antibiotic of choice for initial empiric treatment of AOM, although the traditional dosage should be increased in patients at risk for drug-resistant S. pneumoniae. In cases refractory to high-dose amoxicillin, TMP/SMX should be prescribed if adherence to prior therapy seemed good or complete, or high-dose amoxicillin/clavulanate if adherence was incomplete or questionable. Ceftriaxone should be reserved as third-line treatment. The increasing prevalence of drug-resistant S. pneumoniae emphasizes the importance of alternative medical approaches for the prevention of OM, as well as judicious antibiotic use in established cases. Removal of modifiable risk factors should be first-line therapy for prevention of rAOM. We support the use of conjugate pneumococcal vaccine per guidelines for prevention of rAOM from the Advisory Committee on Immunization Practice of the Centers for Disease Control and Prevention, with consideration given to influenza vaccine for cases of rAOM that historically worsen during the flu season. Sulfisoxazole prophylaxis should be reserved for children who are immunocompromised, have concurrent disease states exacerbated by AOM, or meet the criteria of rAOM despite conjugate pneumococcal and influenza vaccination. Therapy should be intermittent, beginning at the first sign of an upper respiratory infection, and should continue for 10 days. The invasive nature and risks of anesthesia relegate myringotomy, tympanostomy tubes, and adenoidectomy to last-line therapies for rAOM.

Noninvasive fluorescent identification of bacteria causing acute otitis media in a chinchilla model

OBJECTIVES

To evaluate a noninvasive method of bacterial identification via fluorescence spectroscopy in the setting of acute otitis media in a chinchilla model.

STUDY DESIGN

Prospective.

METHODS

For each chinchilla, transbullar inoculation with Streptococcus pneumoniae, Haemophilus influenzae, or Staphylococcus aureus was performed bilaterally and clinical infection was determined by otoscopy. An optical fiber coupled to a spectrofluorometer allowed for the delivery of an excitation wavelength to the inflamed tympanic membrane and the acquisition of the resulting emission signal. Sequential emission spectra obtained over a range of excitation wavelengths were assembled by a computer algorithm, and a single, three-dimensional plot was created for each test ear. Similarly, plots from the healthy external auditory canal (EAC) were also recorded. Twelve animals were used to establish a library of four reference plots representing the three bacteria and the EAC. Of the 24 ears available for study, 10 were excluded from analysis because of lack of clinical infection or presence of tympanic membrane perforation with purulent drainage. From four additional animals, four samples from ears infected with the above bacteria and three samples of the EAC served as unknowns. The unknown plots were analyzed by an investigator blinded to their identity.

RESULTS

Using a multiple correlation of the unknown to the reference plots, seven of seven samples were correctly identified.

CONCLUSIONS

We were able to establish a prototype method for the noninvasive identification of a limited library of pathogens in a chinchilla model of acute otitis media.

Clinical significance of resistant organisms in otitis media

BACKGROUND

Otitis media is an important health care problem of childhood. The bacteriology of otitis media comprises three main pathogens: Streptococcus pneumoniae, nontypable Haemophilus influenzae and Moraxella catarrhalis. Although the prevalence of resistant strains varies geographically and temporally, antimicrobial resistance is widespread and increasing.

RESISTANCE TO ANTIBIOTIC DRUGS

Among the risk factors for development of resistance in otitis media are antimicrobial use, young age, day-care attendance and prior hospitalization. The increasing rate of resistance to antibiotic drugs is associated with a decreased rate of successful eradication of pathogens from middle ear fluid, which is associated with clinical failure. A bacteriologic cure rate of 80 to 85% is observed for S. pneumoniae and nontypable H. influenzae when serum concentrations exceed the MIC for 40 to 50% of dosing interval. Comparative trials indicate that some of the beta-lactams can achieve bacteriologic eradication in acute otitis media, although major differences in outcome exist among agents based on pathogen, beta-lactamase status and MIC values.

ANTIBIOTIC CHOICE

Overall the choice of antibiotics for treatment of otitis media should take into consideration their in vitro activity against the locally prevalent organisms, especially resistant organisms, and results obtained from studies in which bacteriologic outcome was used as the endpoint.

Update on acute otitis media

The increase in drug-resistant Streptococcus pneumoniae has led to concerns about antibiotic resistance. Otitis media is the leading indication for antibiotic use in the United States. Evidence suggests that antibiotics do provide benefit to children with documented acute otitis media, and that carefully selected children may respond to shorter courses of antibiotics. Despite the increase in resistance, amoxicillin remains the drug of choice for acute otitis media even in areas with high levels of resistance. Pneumococcal conjugate vaccine and live attenuated influenza vaccine, which may be licensed in the future, will both have an impact on acute otitis media. During the next few years, these vaccines, along with more stringent diagnostic criteria, and more judicious use of antibiotics, may all contribute towards reducing the incidence of acute otitis media, the number of antibiotic prescriptions given and the adverse impact of antimicrobial resistance.

Antimicrobial therapy of acute otitis media: review of treatment recommendations

OBJECTIVE

This paper reviews 3 previously published articles that provided recommendations for antimicrobial therapy of acute otitis media (AOM) and combines them to provide revised recommendations.

BACKGROUND

AOM is one of the most common pediatric infections requiring a prescription for an antimicrobial agent. The optimal approach to treatment of AOM requires early, efficacious, and practical therapy. Several experts and organizations have developed recommendations for the management of AOM, but the number of these may overwhelm the busy primary care practitioner. A MEDLINE search of the pediatric and infectious disease literature on AOM treatment recommendations was used to select 3 representative, previously published articles for this review. When selecting an agent, physicians should consider in vitro activity, particularly against drug-resistant Streptococcus pneumoniae; pharmacokinetics; adverse events; palatability of the suspension; and cost. In addition, physicians' clinical experience is an important determinant.

CONCLUSIONS

Amoxicillin is recommended as the first-line agent to treat uncomplicated AOM. For clinical treatment failures after 3 days of amoxicillin, recommended antimicrobial agents include oral amoxicillin/clavulanate, cefuroxime axetil, cefprozil, cefpodoxime proxetil, and intramuscular (i.m.) ceftriaxone. I.m. ceftriaxone should be reserved for severe cases or patients in whom noncompliance is expected. Tympanocentesis for identification of pathogens and susceptibility to antimicrobial agents is recommended for selection of third-line agents.

Of bugs and drugs. A guide through the labyrinth of antimicrobial therapy for respiratory tract infections

Choosing appropriate antimicrobial therapy is no longer a simple process. Even for the common problems of respiratory tract disease in children and adults, selection is complicated by both increasing microbial resistance and the daunting number of extended-spectrum antibiotics now on the market. In this article, Drs Singh and Arrieta look at the problem from all aspects and give their specific recommendations.

In vitro activity and pharmacodynamics of oral beta-lactam antibiotics against Streptococcus pneumoniae from southeast Missouri

STUDY OBJECTIVES

To determine the frequency of reduced susceptibility to penicillin, and to compare the in vitro activity and pharmacodynamics of oral beta-lactam antibiotics against clinical isolates of Streptococcus pneumoniae from southeast Missouri.

SETTING

Cape Girardeau, Missouri (population 35,500). Interventions. Minimum inhibitory concentrations (MICs) were determined for penicillin, amoxicillin, amoxicillin-clavulanic acid, cefprozil, cefuroxime, cefpodoxime, cefaclor, and loracarbef by E test for 108 isolates of S. pneumoniae. The MIC50, MIC90, and percentage susceptibility were calculated for each agent. Pharmacokinetic variables were obtained from the literature, and serum concentration-time profiles were simulated for a 25-kg child taking pediatric dosages commonly administered to treat otitis media. The average time above MIC (T > MIC) was calculated as percentage of the dosing interval using free concentrations and the MIC for each individual isolate. Analysis of variance (Scheffe post hoc test) was used to determine differences among agents for in vitro activity and T > MIC (level of significance, p<0.05).

MEASUREMENTS AND MAIN RESULTS

The frequency of penicillin-nonsusceptible S. pneumoniae was 28.7% (31/108). For 25 penicillin-intermediate isolates, amoxicillin and amoxicillin-clavulanic acid were significantly more active than cefprozil, cefaclor, and loracarbef. The T > MIC for amoxicillin and amoxicillin-clavulanic acid, simulated at 13.3 mg/kg every 8 hours, was significantly longer than that for all other beta-lactams.

CONCLUSION

Amoxicillin and amoxicillin-clavulanic acid have superior in vitro activity and longer T > MIC for penicillin-intermediate isolates than the other oral beta-lactams.

Current Concepts of Therapy for Otitis Media

The therapy for acute otitis media is currently a topic in evolution. What was once a straightforward approach of matching middle ear pathogens to appropriate antibiotics has become a complex calculus that attempts to balance multiple terms such as spontaneous cure, emergence of resistance, pharmacokinetics-dynamics, antibiotic therapeutic efficacy, suppurative complications, and cost. This review highlights new developments in our understanding of this complex interaction of the issues surrounding a physician's decision to begin antibiotic therapy for acute otitis media.