A comparison of the efficacy, tolerability and safety of azithromycin and co-amoxiclav in the treatment of sinusitis in adults

WITHDRAWN: Antibiotics for acute maxillary sinusitis in adults

Currently, two separate Cochrane reviews, ‘Antibiotics for acute maxillary sinusitis in adults ’ and ‘Antibiotics for clinically diagnosed acute rhinosinusitis in adults ’ describe the effect of antibiotics for acute rhinosinusitis. Although both Cochrane reviews study the same condition, they look at different populations (patients in which the diagnosis was based on clinical signs and symptoms and patients in which the diagnosis was confirmed by imaging). Because of this, the conclusions are different in these Cochrane reviews. This was confusing for clinicians who needed to read both Cochrane reviews to know which conclusions are most applicable to their patients.
 
 This review is being withdrawn and will be incorporated into the updated publication of ‘Antibiotics for clinically diagnosed acute rhinosinusitis in adults ’. This ‘merged’ review will still maintain the relevant distinction between the two populations. However, information on the effectiveness of antibiotics for rhinosinusitis will be published in the ‘merged’ Cochrane review. We will omit the comparison between antibiotics (as published in this Cochrane review) because the choice for certain antibiotics and/or doses differs according to the local antibiotic resistance patterns and therefore this comparison is less relevant.

The editorial group responsible for this previously published document have withdrawn it from publication.

Antibiotics for acute maxillary sinusitis in adults

BACKGROUND

Sinusitis is one of the most common diagnoses among adults in ambulatory care, accounting for 15% to 21% of all adult outpatient antibiotic prescriptions. However, the role of antibiotics for sinusitis is controversial.

OBJECTIVES

To assess the effects of antibiotics in adults with acute maxillary sinusitis by comparing antibiotics with placebo, antibiotics from different classes and the side effects of different treatments.

SEARCH METHODS

We searched CENTRAL 2013, Issue 2, MEDLINE (1946 to March week 3, 2013), EMBASE (1974 to March 2013), SIGLE (OpenSIGLE, later OpenGrey (accessed 15 January 2013)), reference lists of the identified trials and systematic reviews of placebo-controlled studies. We also searched for ongoing trials via ClinicalTrials.gov and the WHO International Clinical Trials Registry Platform (ICTRP). We imposed no language or publication restrictions.

SELECTION CRITERIA

Randomised controlled trials (RCTs) comparing antibiotics with placebo or antibiotics from different classes for acute maxillary sinusitis in adults. We included trials with clinically diagnosed acute sinusitis, confirmed or not by imaging or bacterial culture.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened search results, extracted data and assessed trial quality. We calculated risk ratios (RRs) for differences between intervention and control groups in whether the treatment failed or not. All measures are presented with 95% confidence intervals (CIs). We conducted the meta-analyses using either the fixed-effect or random-effects model. In meta-analyses of the placebo-controlled studies, we combined data across antibiotic classes. Primary outcomes were clinical failure rates at 7 to 15 days and 16 to 60 days follow-up. We used GRADEpro to assess the quality of the evidence.

MAIN RESULTS

We included 63 studies in this updated review; nine placebo-controlled studies involving 1915 participants (seven of the studies clearly conducted in primary care settings) and 54 studies comparing different classes of antibiotics (10 different comparisons). Five studies at low risk of bias comparing penicillin or amoxicillin to placebo provided information on the main outcome: clinical failure rate at 7 to 15 days follow-up, defined as a lack of full recovery or improvement, for participants with symptoms lasting at least seven days. In these studies antibiotics decreased the risk of clinical failure (pooled RR of 0.66, 95% CI 0.47 to 0.94, 1084 participants randomised, 1058 evaluated, moderate quality evidence). However, the clinical benefit was small. Cure or improvement rates were high in both the placebo group (86%) and the antibiotic group (91%) in these five studies. When clinical failure was defined as a lack of full recovery (n = five studies), results were similar: antibiotics decreased the risk of failure (pooled RR of 0.73, 95% CI 0.63 to 0.85, high quality evidence) at 7 to 15 days follow-up.Adverse effects in seven of the nine placebo-controlled studies (comparing penicillin, amoxicillin, azithromycin or moxicillin to placebo) were more common in antibiotic than in placebo groups (median of difference between groups 10.5%, range 2% to 23%). However, drop-outs due to adverse effects were rare in both groups: 1.5% in antibiotic groups and 1% in control groups.In the 10 head-to-head comparisons, none of the antibiotic preparations were superior to another. However, amoxicillin-clavulanate had significantly more drop-outs due to adverse effects than cephalosporins and macrolides.

AUTHORS' CONCLUSIONS

There is moderate evidence that antibiotics provide a small benefit for clinical outcomes in immunocompetent primary care patients with uncomplicated acute sinusitis. However, about 80% of participants treated without antibiotics improved within two weeks. Clinicians need to weigh the small benefits of antibiotic treatment against the potential for adverse effects at both the individual and general population levels.

Macrolides: A Canadian Infectious Disease Society position paper

Since the introduction of erythromycin in 1965, no new compounds from the macrolide antimicrobial class were licensed in Canada until the 1990s. Clarithromycin and azithromycin, since their introduction, have become important agents for treating a number of common and uncommon infectious diseases. They have become prime agents in the treatment of respiratory tract infections, and have revolutionized the management of both genital chlamydial infections, by the use of single-dose therapy with azithromycin, and nontuberculous mycobacterial infections, by the use of clarithromycin. The improvement of clarithromycin and azithromycin over the gastrointestinal intolerability of erythromycin has led to supplanting the use of the latter for many primary care physicians. Unfortunately, the use of these agents has also increased the likelihood for misuse and has raised concerns about a resultant increase in the rates of macrolide resistance in many important pathogens, such as Streptococcus pneumoniae. This paper reviews the pharmacology and evidence for the current indications for use of these newer agents, and provides recommendations for appropriate use.

Antibiotics for acute maxillary sinusitis

BACKGROUND

Expert opinions vary on the appropriate role of antibiotics for sinusitis, one of the most commonly diagnosed conditions among adults in ambulatory care.

OBJECTIVES

We examined whether antibiotics are effective in treating acute sinusitis, and if so, which antibiotic classes are the most effective.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, 2007, Issue 3); MEDLINE (1950 to May 2007) and EMBASE (1974 to June 2007).

SELECTION CRITERIA

Randomized controlled trials (RCTs) comparing antibiotics with placebo or antibiotics from different classes for acute maxillary sinusitis in adults. We included trials with clinically diagnosed acute sinusitis, whether or not confirmed by radiography or bacterial culture.

DATA COLLECTION AND ANALYSIS

At least two review authors independently screened search results, extracted data and quality assessed trials. Risk ratios (RR) were calculated for differences in the intervention and control groups to see whether or not the treatment was a failure. In meta-analysing the placebo-controlled studies, the data across antibiotic classes were combined. Primary outcomes were the clinical failure rates at 7 to 15 days and 16 to 60 days follow up.

MAIN RESULTS

Fifty-seven studies were included in the review; six placebo-controlled studies and 51 studies comparing different classes of antibiotics. Five studies involving 631 participants provided data for comparison of antibiotics to placebo, when clinical failure was defined as a lack of cure or improvement at 7 to 15 days follow up. These studies found a slight statistical difference in favor of antibiotics, compared to placebo, with a pooled RR of 0.66 (95% confidence interval (CI) 0.44 to 0.98). However, the clinical significance of the result is equivocal, also considering that cure or improvement rate was high in both the placebo group (80%) and the antibiotic group (90%). Based on six studies, when clinical failure was defined as a lack of total cure, there was significant difference in favor of antibiotics compared to placebo with a pooled RR of 0.74 (95% CI 0.65 to 0.84) at 7 to 15 days follow up. None of the antibiotic preparations was superior to each other.

AUTHORS' CONCLUSIONS

Antibiotics have a small treatment effect in patients with uncomplicated acute sinusitis in a primary care setting with symptoms for more than seven days. However, 80% of participants treated without antibiotics improve within two weeks. Clinicians need to weigh the small benefits of antibiotic treatment against the potential for adverse effects at both the individual and general population level.

Staphylococcus aureus is a major pathogen in acute bacterial rhinosinusitis: a meta-analysis

BACKGROUND

Acute bacterial rhinosinusitis is a common health problem in the United States. Appropriate recommendations for the treatment of acute bacterial rhinosinusitis are based on the prevalence and expected antimicrobial susceptibilities of specific pathogens.

METHODS

A meta-analysis was performed on the English language literature from the period 1990-2006, including prospective studies of antibiotic therapy for acute bacterial rhinosinusitis for which sinus cultures were required in the form of either maxillary sinus taps or middle meatal cultures. Weighted mean culture rates for Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, and Staphylococcus aureus were abstracted from the included articles and compared according to culture technique.

RESULTS

Culture rates (i.e., the percentage of patients with positive culture results) were 32.7% for S. pneumoniae, 31.6% for H. influenzae, 10.1% for S. aureus, and 8.8% for M. catarrhalis. No statistically significant difference was seen between the culture rates for S. aureus and M. catarrhalis. Analysis of the effect of culture technique on the culture rates revealed no statistically significant difference.

CONCLUSIONS

The prevalence of S. aureus among sinus cultures warrants its reconsideration as a major pathogen in acute bacterial rhinosinusitis. As a result, increasing trends of drug-resistant strains may complicate antibiotic recommendations.

Oral beta-lactams in the treatment of acute bacterial rhinosinusitis

Acute bacterial rhinosinusitis (ABRS) is a well-known complication of viral upper respiratory tract infection and is associated with a significant socioeconomic burden. Difficulties in diagnosis, a substantial spontaneous resolution rate, and growing concerns regarding antimicrobial resistance make the proper management of ABRS quite challenging. Treatment guidelines have been developed, taking into account the major bacterial pathogens, rates of antimicrobial resistance, spontaneous resolution rates, and pharmacokinetic and pharmacodynamic considerations. Optimal choices for initial treatment of ABRS in patients without prior antibacterial exposure include the oral beta-lactam agents amoxicillin/clavulanate, cefdinir, cefpodoxime, and cefuroxime. Clinicians are encouraged to consider the local pathogen distribution and rates of antibacterial resistance in selecting therapy for ABRS.

The use of macrolides in treatment of upper respiratory tract infections

Antimicrobial resistance is a growing problem among upper respiratory tract pathogens. Resistance to beta-lactam drugs among Streptococcus pneumoniae, Haemophilus influenzae, and Streptococcus pyogenes is increasing. As safe and well-tolerated antibiotics, macrolides play a key role in the treatment of community-acquired upper respiratory tract infections (RTIs). Their broad spectrum of activity against gram-positive cocci, such as S. pneumoniae and S. pyogenes, atypical pathogens, H. influenzae (azithromycin and clarithromycin), and Moraxella catarrhalis, has led to the widespread use of macrolides for empiric treatment of upper RTIs and as alternatives for patients allergic to beta-lactams. Macrolide resistance is increasing among pneumococci and recently among S. pyogenes, and is associated with increasing use of the newer macrolides, such as azithromycin. Ribosomal target modification mediated by erm(A) and erm(B) genes and active efflux due to mef(A) and mef(E) are the principal mechanisms of resistance in both S. pneumoniae and S. pyogenes. Recently, ribosomal protein and RNA mutations have been found to be responsible for acquired resistance to macrolides in S. pneumoniae, S. pyogenes, and H. influenzae. Although macrolides are only weakly active against macrolide-resistant streptococci species, producing an efflux pump (mef), and are inactive against pathogens with ribosomal target modification (erm), treatment failures are uncommon. Therefore, macrolide therapy, for now, remains a good alternative for treatment of upper RTIs; however, continuous monitoring of the local resistance patterns is essential.

Efficacy/safety of amoxicillin/clavulanate in adults with bacterial rhinosinusitis

PURPOSE

Acute bacterial rhinosinusitis (ABRS) is a common and uncomfortable condition, frequently caused by Streptococcus pneumoniae or Haemophilus influenzae. Antibacterial resistance among these and other common respiratory pathogens is now widespread and of concern. Pharmacokinetically enhanced amoxicillin/clavulanate 2000/125 mg was developed to be effective against the common respiratory pathogens, including many resistant strains.

MATERIALS AND METHODS

This open-label, noncomparative study assessed the bacteriologic and clinical efficacy of amoxicillin/clavulanate 2000/125 mg in adult patients with ABRS. Requirements for study entry included a clinical diagnosis of ABRS supported by radiologic findings. In addition, sinus puncture for bacteriologic assessment was required at study entry.

RESULTS

Overall, bacteriologic success (eradication or clinical evidence of eradication) at the follow-up visit (days 17-28) was achieved in 87.8% (722/822) of patients with 1 or more pathogen isolated at screening, in 93.2% (246/264) of patients with S pneumoniae, in 96.7% (29/30) of those with penicillin-resistant S pneumoniae (penicillin minimum inhibitory concentrations >or=2 microg/mL), and in 88.7% (110/124) of patients with beta-lactamase-positive pathogens. Bacteriologic success was achieved against 6 of 7 S pneumoniae isolates with amoxicillin/clavulanic acid minimum inhibitory concentrations of 4/2 microg/mL or higher.

CONCLUSIONS

Amoxicillin/clavulanate 2000/125 mg was generally well tolerated. This new amoxicillin/clavulanate formulation provides a suitable option for empiric therapy for ABRS in adults.

Current concepts in therapy of chronic rhinosinusitis and nasal polyposis

The exact pathophysiological mechanisms leading to chronic rhinosinusitis (CRS) still to a large extent remain obscure. However, recently there has been some progress in elucidating the etiology of nasal polyposis, especially regarding tissue eosinophilia as well as the role of aspirin intolerance and eicosanoid mediators. Endonasal sinus surgery has evolved to be the treatment of choice in CRS and nasal polyposis in all cases where conservative treatment has failed or resulted in only a partial or temporary relief. Today, state of the art in surgical technique includes the ability to combine microscopic and endoscopic procedures. Regardless of technical advances like powered instrumentation or computer-aided surgery, in a modern protocol, surgical therapy can offer only one option within a complex and individually tailored therapeutical concept. This review discusses current concepts and new developments in the diagnosis and treatment of CRS and nasal polyposis.

Value of short-course antimicrobial therapy in acute bacterial rhinosinusitis

Traditional approaches to antimicrobial management of acute bacterial rhinosinusitis (ABRS) focus on courses of therapy of at least 10 days duration. The rationale for this length of therapy originated from studies in tonsillopharyngitis. Short-course antibiotic therapy for ABRS with 3-5 days of azithromycin has proved equally effective. Potential added benefits of short-course therapy include improved compliance, fewer adverse events as well as reduced risk of treatment failure, bacterial resistance and cost. Single-dose therapy is now possible with a novel microsphere formulation of azithromycin, which permits administration of a higher 2.0 g oral dose. This has proved as effective and well tolerated as 10 days levofioxacin 500 mg/day in patients with uncomplicated ABRS. High single-dose therapy has the potential to maximize adherence to prescribed therapy and thus to help in the battle to control rising antibiotic resistance among respiratory pathogens.

Efficacy and safety of a novel, single-dose azithromycin microsphere formulation versus 10 days of levofloxacin for the treatment of acute bacterial sinusitis in adults

OBJECTIVE

To compare the efficacy and safety of a single 2.0-g dose of a novel azithromycin microsphere formulation with that of 10 days of levofloxacin, 500 mg/d, when used to treat adults with uncomplicated acute bacterial maxillary sinusitis (ABS).

STUDY DESIGN AND SETTING

An international, multicenter, randomized, double-blind, double-dummy trial. Eligible outpatients > or =18 years of age with clinical and radiographic evidence of ABS underwent maxillary sinus aspiration before randomization. Primary endpoint was clinical efficacy at the test-of-cure visit (day 17-24).

RESULTS

Clinical success rates were 94.5% (242/256) in azithromycin-microspheres-treated patients and 92.8% (233/251) in the levofloxacin group. In patients with documented Streptococcus pneumoniae, Haemophilus influenzae, or Moraxella catarrhalis, clinical cure rates were 97.3% (36/37), 96.3% (26/27), and 100% (8/8), respectively, for the azithromycin group and 92.3% (36/39), 100% (30/30), and 90.9% (10/11), respectively, for the levofloxacin group.

CONCLUSIONS

Single-dose azithromycin microspheres provided clinical and bacteriologic efficacy and safety comparable to 10 days of levofloxacin.

SIGNIFICANCE

A novel microsphere formulation of azithromycin given as a single dose was safe and effective for the treatment of ABS.

The use of macrolides in treatment of upper respiratory tract infections

Antimicrobial resistance is a growing problem among upper respiratory tract pathogens. Resistance to beta-lactam drugs among Streptococcus pneumoniae, Haemophilus influenzae, and Streptococcus pyogenes is increasing. As safe and well-tolerated antibiotics, macrolides play a key role in the treatment of community-acquired upper respiratory tract infections (RTIs). Their broad spectrum of activity against gram-positive cocci, such as S. pneumoniae and S. pyogenes, atypical pathogens, H. influenzae (azithromycin and clarithromycin), and Moraxella catarrhalis, has led to the widespread use of macrolides for empiric treatment of upper RTIs and as alternatives for patients allergic to b-lactams. Macrolide resistance is increasing among pneumococci and recently among S. pyogenes, and is associated with increasing use of the newer macrolides, such as azithromycin. Ribosomal target modification mediated by erm(A) and erm(B) genes and active efflux due to mef(A) and mef(E) are the principal mechanisms of resistance in S. pneumoniae and S. pyogenes. Recently, ribosomal protein and RNA mutations have been found responsible for acquired resistance to macrolides in S. pneumoniae, S. pyogenes, and H. influenzae. Although macrolides are only weakly active against macrolide-resistant streptococci species producing an efflux pump (mef) and are inactive against pathogens with ribosomal target modification (erm), treatment failures are uncommon. Therefore, macrolide therapy, for now, remains a good alternative for treatment of upper RTIs; however, continuous monitoring of the local resistance patterns is essential.

Macrolides and ketolides: azithromycin, clarithromycin, telithromycin

The advanced macrolides, azithromycin and clarithromycin, and the ketolide telithromycin are structural analogues of erythromycin. They have several distinct advantages when compared with erythromycin including enhanced spectrum of activity, more favorable pharmacokinetics and pharmacodynamics, once daily administration, and improved tolerability. This article reviews the pharmacokinetics, antimicrobial activity, clinical use, and adverse effects of these antimicrobial agents.

Azithromycin and dentistry - a useful agent?

OBJECTIVES

Azithromycin has recently replaced clindamycin oral suspension for prop hylaxis of infective endocarditis (IE) in children. It is also currently recommended by the American Heart Association as an alternative to penicillin, along with clindamycin for prophylaxis of infective endocarditis in adults. The objectives of this paper were to firstly, review the current literature on the efficacy of azithromycin as a suitable prophylactic agent in the prevention of infective endocarditis; and secondly, to review its pharmacological properties as a suitable therapeutic agent in the management of odontogenic infections.

DESIGN

A review of the literature.

CONCLUSIONS

The available evidence from animal models on infective endocarditis supports the efficacy of this drug as a prophylactic agent against oral streptococci. The pharmacological properties of this agent would make it a very promising therapeutic adjunct in the management of odontogenic infections. At present there are only a small number of studies available with valuable data on the efficacy of this relatively new drug. Further investigations comparing this compound with other commonly used adjuncts would be of great benefit.

Randomized double-blind study comparing 3- and 6-day regimens of azithromycin with a 10-day amoxicillin-clavulanate regimen for treatment of acute bacterial sinusitis

A randomized, double-blind, multicenter study of adults with acute bacterial sinusitis (ABS) compared the efficacy and safety of two azithromycin (AZM) regimens, 500 mg/day once daily for 3 days (AZM-3) or 6 days (AZM-6) to the efficacy and safety of an amoxicillin-clavulanate (AMC) regimen of 500-125 mg three times daily for 10 days. A total of 936 subjects with clinically and radiologically documented ABS were treated (AZM-3, 312; AZM-6, 311; AMC, 313). Clinical success rates were equivalent among per-protocol subjects at the end of therapy (AZM-3, 88.8%; AZM-6, 89.3%; AMC, 84.9%) and at the end of the study (AZM-3, 71.7%; AZM-6, 73.4%; AMC, 71.3%). Subjects treated with AMC reported a higher incidence of treatment-related adverse events (AE) (51.1%) than AZM-3 (31.1%, P < 0.001) or AZM-6 (37.6%, P < 0.001). More AMC subjects discontinued the study (n = 28) than AZM-3 (n = 7) and AZM-6 (n = 11) subjects. Diarrhea was the most frequent treatment-related AE. AZM-3 and AZM-6 were each equivalent in efficacy and better tolerated than AMC for ABS.

Antibiotics for acute maxillary sinusitis

BACKGROUND

For adults seeking care in ambulatory medical practices, sinusitis is the most common diagnosis treated with antibiotics.

OBJECTIVES

We examined whether antibiotics are indicated for acute sinusitis, and if so, which antibiotic classes are most effective.

SEARCH STRATEGY

Relevant studies were identified from searches of MEDLINE and EMBASE in December 2001, contacts with pharmaceutical companies and bibliographies of included studies.

SELECTION CRITERIA

Randomized trials were eligible that compared antibiotic to control or antibiotics from different classes, for acute maxillary sinusitis. Additional criteria for inclusion were diagnostic confirmation by radiograph or sinus aspiration, outcomes that included clinical cure or improvement, and a sample size of 30 or more adults. Of 2058 potentially relevant studies, two or more reviewers identified 49 studies meeting selection criteria.

DATA COLLECTION AND ANALYSIS

Data were extracted independently by two persons and synthesized descriptively. Some data were analyzed quantitatively using a random effects model. Primary outcomes were: a) clinical cure, and b) clinical cure or improvement. Secondary outcomes were radiographic improvement, relapse rates, and dropouts due to adverse effects.

MAIN RESULTS

Forty-nine trials, involving 13,660 participants, evaluated antibiotic treatment for acute maxillary sinusitis. Major comparisons were antibiotic versus control (n of 5); newer, non-penicillin antibiotic versus penicillin class (n of 10); and amoxicillin-clavulanate versus other extended spectrum antibiotics (n of 17), where n is the number of trials. Most trials were conducted in otolaryngology settings. Only 8 trials described adequate allocation and concealment procedures; 20 were double-blind. Compared to control, penicillin improved clinical cures [relative risk (RR) 1.72; 95% CI 1.00 to 2.96]. Treatment with amoxicillin did not significantly improve cure rates (RR 2.06; 95% CI 0.65 to 6.53) but there was significant variability between studies. Radiographic outcomes were improved by antibiotic treatment. Comparisons between classes of antibiotics showed no significant differences: newer non-penicillins versus penicillins (RR for cure 1.07; 95% CI 0.99 to 1.17); newer non-penicillins versus amoxicillin-clavulanate (RR for cure 1.03; 95% CI 0.96 to 1.11). Compared to amoxicillin-clavulanate, dropouts due to adverse effects were significantly lower for cephalosporin antibiotics (RR 0.47; 95% CI 0.30 to 0.73). Relapse rates within one month of successful therapy were 7.7%.

REVIEWER'S CONCLUSIONS

For acute maxillary sinusitis confirmed radiographically or by aspiration, current evidence is limited but supports the use of penicillin or amoxicillin for 7 to 14 days. Clinicians should weigh the moderate benefits of antibiotic treatment against the potential for adverse effects.

Review of macrolides and ketolides: focus on respiratory tract infections

The first macrolide, erythromycin A, demonstrated broad-spectrum antimicrobial activity and was used primarily for respiratory and skin and soft tissue infections. Newer 14-, 15- and 16-membered ring macrolides such as clarithromycin and the azalide, azithromycin, have been developed to address the limitations of erythromycin. The main structural component of the macrolides is a large lactone ring that varies in size from 12 to 16 atoms. A new group of 14-membered macrolides known as the ketolides have recently been developed which have a 3-keto in place of the L-cladinose moiety. Macrolides reversibly bind to the 23S rRNA and thus, inhibit protein synthesis by blocking elongation. The ketolides have also been reported to bind to 23S rRNA and their mechanism of action is similar to that of macrolides. Macrolide resistance mechanisms include target site alteration, alteration in antibiotic transport and modification of the antibiotic. The macrolides and ketolides exhibit good activity against gram-positive aerobes and some gram-negative aerobes. Ketolides have excellent activity versus macrolide-resistant Streptococcus spp. Including mefA and ermB producing Streptococcus pneumoniae. The newer macrolides, such as azithromycin and clarithromycin, and the ketolides exhibit greater activity against Haemophilus influenzae than erythromycin. The bioavailability of macrolides ranges from 25 to 85%, with corresponding serum concentrations ranging from 0.4 to 12 mg/L and area under the concentration-time curves from 3 to 115 mg/L x h. Half-lives range from short for erythromycin to medium for clarithromycin, roxithromycin and ketolides, to very long for dirithromycin and azithromycin. All of these agents display large volumes of distribution with excellent uptake into respiratory tissues and fluids relative to serum. The majority of the agents are hepatically metabolised and excretion in the urine is limited, with the exception of clarithromycin. Clinical trials involving the macrolides are available for various respiratory infections. In general, macrolides are the preferred treatment for community-acquired pneumonia and alternative treatment for other respiratory infections. These agents are frequently used in patients with penicillin allergies. The macrolides are well-tolerated agents. Macrolides are divided into 3 groups for likely occurrence of drug-drug interactions: group 1 (e.g. erythromycin) are frequently involved, group 2 (e.g. clarithromycin, roxithromycin) are less commonly involved, whereas drug interactions have not been described for group 3 (e.g. azithromycin, dirithromycin). Few pharmacoeconomic studies involving macrolides are presently available. The ketolides are being developed in an attempt to address the increasingly prevalent problems of macrolide-resistant and multiresistant organisms.

The Microbiology and Management of Acute and Chronic Rhinosinusitis

Although most cases of rhinosinusitis are benign, the disruption of quality of life due to disease symptoms leads patients to seek early medical care. Ongoing debates dispute the definition, bacteriology, and medical management of chronic sinusitis, while the criteria for acute sinusitis are relatively well established. Chronic rhinosinusitis remains poorly categorized, and authors differ in opinions of symptoms, time course, and bacteriology of the infections, as well as proper medical management. Recent studies from the Mayo Clinic even question the idea that chronic sinusitis is a bacterial disease and document the presence of fungal pathogens that are responsible for the inflammatory reaction and mucosal response. In general, medical management is based on physiologic principles of re-establishing natural mucociliary function and restoring proper aeration of the paranasal sinuses after an inflammatory insult. Injudicious use and indiscriminate overprescription of antibiotics has fostered the rapid development of penicillin-resistant organisms over the past two decades. Drug-resistant Streptococcus pneumonia and b-lactamase-producing Haemophilus influenzae and Moraxella catarrhalis are becoming the norm, forcing the need to consider alternatives in antibacterial management. Appropriate medical management of this common problem requires a systematic approach and consideration of adjunctive therapy. This article examines the current bacteriology of these common infections and reviews the management of acute and chronic infections.

The newer macrolides: azithromycin and clarithromycin

Azithromycin and clarithromycin are two relatively new macrolide antimicrobial agents. Although azithromycin and clarithromycin are structural analogues of erythromycin, they offer distinct advantages in comparison. This article reviews the pharmacokinetics, antimicrobial activity, clinical use, and adverse affects of these antimicrobial agents.

Efficacy and safety of oral levofloxacin compared with clarithromycin in the treatment of acute sinusitis in adults: a multicentre, double-blind, randomized study. The Canadian Sinusitis Study Group

Adult patients with acute sinusitis (n = 236) were randomized in a double-blind study to levofloxacin 500 mg orally once daily (n = 119) or clarithromycin 500 mg orally twice daily (n = 117) for 10-14 days. Between 2 and 5 days after therapy participants were evaluated as cured (no symptoms), improved (symptoms improved, no further therapy required), or failed (further therapy required). Clinical response rates (cured plus improved) for clinically evaluable patients were 93.9% for levofloxacin (n = 98) and 93.5% for clarithromycin (n = 93). The proportion of patients evaluated as cured was higher in the levofloxacin (40.8%) than in the clarithromycin arm (29.0%) and individual symptoms showed higher rates of resolution. Of patients receiving levofloxacin and clarithromycin, 22.5% and 39.3%, respectively, experienced adverse events related or possibly related to the study therapy. This study showed that, in the treatment of acute sinusitis, daily levofloxacin therapy is as effective as twice-daily clarithromycin therapy with more complete clearing of symptoms and a more tolerable side-effect profile.