Comparison of 5-day, short-course gatifloxacin therapy with 7-day gatifloxacin therapy and 10-day clarithromycin therapy for acute exacerbation of chronic bronchitis

The potential of 4D's approach in curbing antimicrobial resistance among bacterial pathogens

INTRODUCTION

Antibiotics are life-saving drugs but irrational/inappropriate use leads to the emergence of antibiotic-resistant bacterial superbugs, making their treatment extremely challenging. Increasing antimicrobial resistance (AMR) among bacterial pathogens is becoming a serious public health concern globally. If ignorance persists, there would not be any antibiotics available to treat even a common bacterial infection in future.

AREA COVERED

This article intends to collate and discuss the potential of 4D's (right Drug, Dose, Duration, and De-escalation of therapy) approach to tackle the emerging problem of AMR. For this, we searched PubMed, Google Scholar, Medline, and clinicaltrials.gov databases primarily using keywords 'optimal antibiotic therapy,' 'antimicrobial resistance,' 'higher versus lower dose antibiotic treatment,' 'shorter versus longer duration antibiotic treatment,' 'de-escalation study', and 'antimicrobial stewardship measures' and based on the findings, form and expressed our opinion.

EXPERT OPINION

More efforts are needed for developing diagnostics for rapid, accurate, point-of-care, and cost-effective pathogen identification and antimicrobial susceptibility testing (AST) to facilitate rational use of antibiotics. Current dosing and duration of therapies also need to be redefined to maximize their impact. Furthermore, de-escalation approaches should be developed and encouraged in the clinic. This altogether will minimize selection pressure on the pathogens and reduce emergence of AMR.

2021 Guideline for the Management of COPD Exacerbations: Emergency Medicine Association of Turkey (EMAT) / Turkish Thoracic Society (TTS) Clinical Practice Guideline Task Force

Chronic obstructive pulmonary disease (COPD) is an important public health problem that manifests with exacerbations and causes serious mortality and morbidity in both developed and developing countries. COPD exacerbations usually present to emergency departments, where these patients are diagnosed and treated. Therefore, the Emergency Medicine Association of Turkey and the Turkish Thoracic Society jointly wanted to implement a guideline that evaluates the management of COPD exacerbations according to the current literature and provides evidence-based recommendations. In the management of COPD exacerbations, we aim to support the decision-making process of clinicians dealing with these patients in the emergency setting.

In vitro activity and pharmacodynamic/pharmacokinetic parameters of clarithromycin and azithromycin: why they matter in the treatment of respiratory tract infections

Clarithromycin and azithromycin are second-generation macrolides established and widely used for treating a range of upper and lower respiratory tract infections. Extensive clinical trials data indicate that these drugs are highly effective in these applications and broadly comparable in their clinical and microbiological effectiveness. However, consideration of pharmacokinetic, metabolic, and tissue-penetration data, including the significant antibacterial activity of the metabolite 14-hydroxy-clarithromycin, plus the findings of pharmacodynamic modeling, provide evidence that the long half-life and lower potency of azithromycin predispose this agent to select for resistant isolates. Comparison of the "mutant-prevention concentrations" of clarithromycin and azithromycin, and examination of large-scale epidemiological data from Canada, also support the view that these drugs differ materially in their propensity to promote resistance among bacterial strains implicated in common respiratory infections, and that clarithromycin may offer important advantages over azithromycin that should be considered when choosing a macrolide to treat these conditions.

Network meta-analysis of success rate and safety in antibiotic treatments of bronchitis

The purpose of this study was to compare the relative efficacy and safety of different antibiotic drugs and recommend superior regimens in the treatment of bronchitis. With respect to the antibiotic comparisons against quinolones in terms of intention-to-treat patients, we concluded that quinolones had advantages over placebo, β-lactams, sulfonamides, and double β-lactams. Concerning treatment methods for clinically evaluable patients, quinolones demonstrated better performance than β-lactams and sulfonamides. The secondary effects of macrolides, quinolones, and double β-lactams were significantly more adverse than β-lactams with odds ratios (ORs) of 1.5 (95% credible interval [CrI] =1.1–2.0), 1.7 (95% CrI =1.2–2.3), and 2.7 (95% CrI =1.8–4.1), respectively. Significant differences in the prevalence of diarrhea as a secondary effect were only identified among the comparisons of double β-lactams against β-lactams and macrolides (OR =5.0, 95% CrI =2.1–12.0; OR =3.0, 95% CrI =1.7–5.4, respectively). Quinolones can be recommended as the superior treatment for bronchitis, in accordance with our cluster analysis with surface under the cumulative ranking curve. The primary outcomes of network meta-analysis indicated that quinolones showed the best performance among the 8 treatments studied, although β-lactams showed the lowest risk of adverse side effects. Quinolones are recommended as the primary treatment option for bronchitis patients, having taking into account the success rates and safety profiles of the eight drugs studied here.

Comparison of Pathogen Eradication Rate and Safety of Anti-Bacterial Agents for Bronchitis: A Network Meta-Analysis

A large number of population in both developing and developed countries are affected by bronchitis, among all the factors, bacterial infection was considered as a critical cause of acute exacerbations of chronic bronchitis. Although several anti-bacterial agents were proved to have the effect of alleviating bronchitis, their relative efficacies and potential side effects remained not clear. We are keen to compare the pathogen eradication rate and safety of anti-bacterial agents for bronchitis. Relevant studies were searched in multiple sources and data were extracted from eligible studies. Then conventional meta-analysis and network meta-analysis (NMA) were conducted to determine the relative efficacy and safety of bronchitis medications. The efficacy of bronchitis medications was determined by using the outcome of pathogen eradication, including total pathogen eradication, pathogen eradication of Haemophilus influenzae, pathogen eradication of Moraxella catarrhalis, and pathogen eradication of Streptococcus pneumoniae. In addition, safety was assessed by using the outcome of adverse effects and diarrhoea. A 27 RCTs with 9,414 participants were included in the study. Among the medications, gatifloxacin and moxifloxacin exhibited better performance than clarithromycin with respect to pathogen eradication of H. influenzae (OR = 21.37, CI: 1.22-541.28; OR = 7.43, CI: 1.79-30.50). Clarithromycin, gemifloxacin, levofloxacin, moxifloxacin, and telithromycin appeared to be more preferable than amoxicillin + clavulanate and azithromycin with respect to diarrhoea (all OR <1). The surface under the cumulative ranking curve (SUCRA) results suggested that gemifloxacin and levofloxacin had a relatively high ranking in total pathogen eradication, whereas amoxicillin + clavulanate and azithromycin exhibited relatively lower ranking with respect to adverse effects and diarrhoea. Gemifloxacin and levofloxacin are more preferable than others for lowering respiratory tract inflammation and infections considering their balanced performance between pathogen eradication and adverse effects. J. Cell. Biochem. 118: 3171-3183, 2017. © 2017 Wiley Periodicals, Inc.

Short-course fluoroquinolones in acute exacerbations of chronic bronchitis

It is estimated that 50-70% of acute exacerbations of chronic bronchitis (AECB) are caused by bacterial infections. Appropriate selection of antimicrobials may lead to better outcomes and reduced healthcare costs. Respiratory fluoroquinolones (moxifloxacin, levofloxacin and gemifloxacin) have a broad spectrum of activity against most AECB-causing pathogens and are used as first-line treatment in patients with comorbidity, severe airway obstruction or recurrent exacerbations. We review studies, identified through a MEDLINE search, that compared clinical efficacy and speed of recovery for short-course (≤ 5 days) fluoroquinolone therapy with commonly prescribed standard therapy (≥ 7 days). Among 177 studies reporting the use of fluoroquinolones for AECB treatment, 23 used a short-course regimen, shown to be at least as effective as standard therapy of 7 or more days duration. Furthermore, evidence suggests that short-course therapy offers faster resolution of symptoms, faster rate of recovery, fewer relapses, fewer and shorter hospitalizations, and longer time between recurrences.

Pharmacokinetics and pharmacodynamics of gatifloxacin in children with recurrent otitis media: application of sparse sampling in clinical development

Gatifloxacin is a 4th-generation fluoroquinolone previously under investigation for the treatment of otitis media in infants and children. These analyses were designed to evaluate the extent of drug exposure relative to adult populations and to examine the relationship between drug exposure and response to therapy in children with recurrent otitis media or early treatment failures of acute otitis media. The patient population included 187 patients from an open-label, multicenter, noncomparative study using gatifloxacin 10 mg/kg once daily. Gatifloxacin exposure was estimated using a single steady-state blood sample in conjunction with a pharmacostatistical model developed using a separate pediatric data set. Gatifloxacin exposure was equivalent to that in adults given 400 mg daily. Of the 41 patients who had Streptococcus pneumoniae from middle ear culture, there were only 3 bacteriologic failures; there was no relationship between plasma fu AUC(0-24):MIC ratio and outcome. In conclusion, population pharmacokinetic/pharmacodynamic methods allowed estimation of drug exposure using one sample per patient.

Three vs. 10 days of amoxycillin-clavulanic acid for type 1 acute exacerbations of chronic obstructive pulmonary disease: a randomised, double-blind study

The optimal duration of antibiotic treatment for acute exacerbations of chronic obstructive pulmonary disease (AECOPD) is unknown. This study compared the outcome of treatment for 3 vs. 10 days with amoxycillin-clavulanic acid of hospitalised patients with AECOPD who had improved substantially after initial therapy for 3 days. Between November 2000 and December 2003, 56 patients with AECOPD were enrolled in the study. Unfortunately, because of the low inclusion rate, the trial was discontinued prematurely. Patients were treated with oral or intravenous amoxycillin-clavulanic acid. Patients who showed improvement after 72 h were randomised to receive oral amoxycillin-clavulanic acid 625 mg or placebo, four times daily for 7 days. The primary outcome measure of the study was clinical cure after 3 weeks and 3 months. Of 46 patients included in the final analysis, 21 were in the 3-day treatment group and 25 were in the 10-day treatment group. After 3 weeks, 16 (76%) of 21 patients in the 3-day treatment group were cured, compared with 20 (80%) of 25 in the 10-day treatment group (difference -3.8%; 95% CI -28 to 20). After 3 months, 13 (62%) of 21 patients were cured, compared with 14 (56%) of 25 (difference 5.9%; 95% CI -23 to 34). Microbiological success, symptom recovery, the use of corticosteroids, the duration of oxygen therapy and the length of hospital stay were comparable for both treatment groups. It was concluded that 3-day treatment with amoxycillin-clavulanic acid can be a safe and effective alternative to the standard 10-day treatment for hospitalised patients with AECOPD who have improved after initial therapy for 3 days.

Role for 5-day, once-daily extended-release clarithromycin in acute bacterial exacerbation of chronic bronchitis

BACKGROUND

Clarithromycin is commonly dosed for 7 or more days in patients with acute bacterial exacerbation of chronic bronchitis (ABECB). Studies with other antibiotics have shown equivalent efficacy, reduced/similar frequency of adverse events, improved adherence and patient satisfaction, and lower treatment costs with a shorter treatment course.

PATIENTS AND METHODS

The study population was derived from two multicenter, randomized, double-blind (North America)/single-blind (France) comparative trials in which outpatients at least 35 years old with a presumptive diagnosis of obstructive ABECB were randomized to receive clarithromycin extended-release (ER) 1000 mg once daily for 5 days or a comparator agent--clarithromycin immediate-release (IR) 500 mg twice daily for 7 days (in North America) or telithromycin 800 mg once daily for 5 days (in France).

RESULTS

A total of 818 patients were randomized (411 to clarithromycin ER and 407 to a comparator agent). The clinical cure rate in clinically evaluable patients at the follow-up visit was 90% each for the clarithromycin ER group (318/353) and the comparator group (318/355). The patient bacteriological cure rate and the overall target pathogen eradication rate in clinically and bacteriologically evaluable patients were each 92% for the clarithromycin ER group (155/168 and 189/205, respectively) and 93% for the comparator group (147/158 and 183/197, respectively) at the follow-up visit. The study drugs were generally well tolerated, with < 2% of patients discontinuing their treatment prematurely due to a drug-related adverse event. The incidence of drug-related adverse events was 18% (73/411) in the clarithromycin ER group and 24% (97/407) in the comparator group. Clarithromycin ER-treated patients reported statistically significantly fewer episodes of abdominal pain than did patients treated with a comparator agent (0.2% vs. 1.7%, respectively; p = 0.037). This combined analysis is limited by differing blinding methods, comparator agents, and their duration of administration. Furthermore, many patients were excluded from the clinically and bacteriologically evaluable group due to lack of a pretreatment target pathogen.

CONCLUSION

A once daily, 5-day clarithromycin ER regimen appears to be a suitable choice for treating patients with ABECB.

Antibiothérapie des exacerbations de bronchopneumopathie chronique obstructive : analyse critique des essais cliniques

OBJECTIVE

The authors had for aim to assess the role of antibiotics in acute exacerbations of chronic obstructive pulmonary disease (COPD).

METHODS

Comparative antibiotic trials were collected through systematic search on Medline data base--well-designed studies were selected.

RESULTS

Eight equivalence studies were selected. No clear difference between antibiotics was demonstrated. The shortest treatment was as effective as the longest.

CONCLUSION

No antibiotic has demonstrated its superiority. A new generation of antibiotic comparative trials for exacerbation of COPD is clearly needed.

Macrolide immunomodulatory effects and symptom resolution in acute exacerbation of chronic bronchitis and acute maxillary sinusitis: a focus on clarithromycin

Bacterial respiratory tract infections are common in the primary care setting and patients often seek the assistance of a healthcare professional in order to achieve resolution of their symptoms. Antibiotic agents that offer rapid symptom relief, in addition to excellent bacteriological and clinical cure, are highly desired. Macrolides have proven to be highly effective in treating acute bacterial exacerbations of chronic bronchitis and acute maxillary sinusitis. In addition, immunomodulatory effects that may contribute to symptom resolution have been reported. This article reviews current literature on symptom resolution in acute bacterial exacerbations of chronic bronchitis and acute maxillary sinusitis, with a focus on clarithromycin, and explores the potential mechanisms that may contribute to this action.

Should patients with acute exacerbation of chronic bronchitis be treated with antibiotics? Advantages of the use of fluoroquinolones

The pathological changes in chronic bronchitis (CB) produce airflow obstruction, reduce the effectiveness of the mucocilliary drainage system and lead to bacterial colonisation of bronchial secretion. The presence of bacteria induces an inflammatory response mediated by leukocytes. There is a direct relationship between the degree of impairment of the mucocilliary drainage system, the density of bacteria in mucus and the number of leukocytes in the sputum. Purulent sputum is a good marker of a high bacterial load. Eventually, if the number of leukocytes is high, their normal activity could decrease the effectiveness of the drainage system, increase the bronchial obstruction and probably damage the lung parenchyma. Whenever the density of bacteria in the bronchial lumen is >or=10(6) CFU/mL, there is a high probability that the degree of inflammatory response will lead to a vicious cycle which in turn tends to sustain the process. This situation can arise during the clinical course of any acute exacerbation of CB, independently of its aetiology, provided the episode is sufficiently severe and/or prolonged. Fluoroquinolones of the third and fourth generation are bactericidal against most microorganisms usually related to acute exacerbations of CB. Their diffusion to bronchial mucus is adequate. When used in short (5-day) treatment they reduce the bacterial load in a higher proportion than is achieved by beta-lactam or macrolide antibiotics given orally. Although the clinical cure rate is similar to that obtained with other antibiotics, the time between exacerbations could be increased.

Acute exacerbation of chronic bronchitis: Need for an evidence-based approach

Acute exacerbations of chronic bronchitis (AECB) can be classified into three levels according to severity: (1) home treatment sufficient; (2) hospitalisation required; (3) hospitalisation in the presence of respiratory failure. This evidence-based classification is useful in ranking the clinical relevance of the episode and its outcome, and makes it possible to define the clinical history, clinical evaluation and diagnostic procedures of an exacerbation. Treatment guidelines vary according to severity, but they are essentially based on appropriate bronchodilator therapy (beta(2) agonists and/or anticholinergics, corticosteroids and antibiotics selected according to the local bacterial resistance pattern). It is important that cases requiring management in an intermediate/special respiratory care unit or intensive care unit (ICU) be identified. This is the stage where oxygen therapy and ventilatory support become particularly important. As first choice, they should be non-invasive, saving intubation and invasive ventilatory support for most severe cases characterised by severe acidemia and hypercapnia. We identify the optimal criteria for hospital discharge and follow-up of patients with AECB. In view of the chronic nature of the underlying disease, a correct follow-up is essential to avoid frequent and repeated relapses.

Glucose Homeostasis Abnormalities Associated with Use of Gatifloxacin

BACKGROUND

More than 20 published case reports have described an association between the use of gatifloxacin and hypoglycemia or hyperglycemia. We compare the rates of glucose homeostasis abnormality (GHA) adverse event reports (AERs) associated with the use of gatifloxacin and comparator quinolones.

METHODS

We obtained spontaneous AERs associated with the use of ciprofloxacin, gatifloxacin, levofloxacin, and moxifloxacin from the US Food and Drug Administration that were reported between November 1997 and September 2003. We removed duplicate and foreign cases. We used specific coding terms to identify GHA AERs. We calculated GHA AER rates, using either the total number of AERs or estimated retail prescriptions as denominators.

RESULTS

The use of ciprofloxacin, gatifloxacin, levofloxacin, and moxifloxacin was associated with 10,025 unique AERs in the United States, including 568 GHA AERs, 25 of which had fatality. Use of gatifloxacin was associated with 453 GHA AERs (80%) and 17 GHA AERs with fatality (68%). GHA AERs comprised 24% of all AERs associated with gatifloxacin, compared with ciprofloxacin (1.3%), levofloxacin (1.6%), and moxifloxacin (1.3%) (P<.0001 for each comparison). Use of gatifloxacin was associated with 477 GHA AERs per 10(7) retail prescriptions, compared with ciprofloxacin (4 GHA AERs), levofloxacin (11 GHA AERs), and moxifloxacin (39 GHA AERs) (P<.0001 for each comparison). Patients with GHA AERs were older and more likely to be receiving concomitant treatment for diabetes. Limitations of the study include the use of spontaneous adverse event reporting, which is incomplete and potentially biased. This analysis cannot be used alone to demonstrate causality.

CONCLUSIONS

Use of gatifloxacin is associated with a much higher rate of GHA AERs than are comparator quinolones. This analysis is consistent with the results of in vitro analyses, animal studies, human volunteer studies, case reports, and a large randomized trial. Alternatives to gatifloxacin should be used in patients with diabetes.

Efficacité et tolérance de la clarithromycine, forme à libération modifiée en traitement court de cinq jours dans les exacerbations aiguës de bronchite chronique, comparativement à la télithromycine

BACKGROUND

The extended-release formulation of clarithromycin (CLA-ER) allows using this macrolide as a single daily dose. The purpose of this study was to evaluate the efficacy and safety of the CLA-ER formulation (500 mgx2) vs telithromycin (TELI) (400 mgx2) as a short course 5-day treatment, once a day, in patients with AECB.

METHOD

This randomized double-blind study was conducted in patients with AECB without severe airflow limitation (FEV1>35%), with sputum purulence (mandatory criterion), and with either increased sputum volume or increased dyspnea, or both (Anthonisen criteria I or II).

RESULTS

Three hundred sixty-two patients were assessed (62.6 years of age+/-12.9, men: 58.8%) positive culture on inclusion for 53.8%, with Haemophilus influenzae (N=57), Moraxella catarrhalis (N=42), and Streptococcus pneumoniae (N=41). In the per protocol population, the clinical success rate at day 8 was 97% (161/166) vs 97% (146/151), 97.5% CI=[-4.12 -4.71], the clinical cure rate at day 30 was 78% (129/166) versus 77% (116/151), P=0.85, and mean time without recurrence was 62 days versus 61 days (P=0.51), in CLA-ER and TELI groups, respectively. Fourteen patients in the CLA-ER group (8.2%) and 20 patients in the TELI group (12.4%) experienced at least one treatment-related adverse event (P=0.21), upon which gastrointestinal events were the most commonly reported treatment-related ones.

CONCLUSION

CLA-ER (1000 mg once a day) for 5 days is at least as effective as telithromycin in the treatment of AECB without severe airflow limitation and is well tolerated.

Gatifloxacin: a review of its use in the treatment of bacterial infections in the US

Gatifloxacin (Tequin) is an 8-methoxy fluoroquinolone approved in the US for use in the treatment of community-acquired pneumonia (CAP), acute exacerbations of chronic bronchitis (AECB), acute sinusitis, uncomplicated and complicated urinary tract infections (UTIs), pyelonephritis, gonorrhoea and uncomplicated skin and skin structure infections. Gatifloxacin has a broad spectrum of antibacterial activity in vitro and good clinical and bacteriological efficacy in patients with indicated infections following once-daily administration by the intravenous or oral routes. It is generally well tolerated; the most common adverse events are associated with the gastrointestinal tract and CNS. Recent approvals for the use of gatifloxacin in the treatment of CAP due to multidrug-resistant Streptococcus pneumoniae (MDRSP) and in uncomplicated skin and skin structure infections extend the role of this drug in the treatment of bacterial infections in the US.

Clinical efficacy of newer agents in short-duration therapy for community-acquired pneumonia

Streptococcus pneumoniae, the most important respiratory tract pathogen implicated in community-acquired pneumonia (CAP), is becoming increasingly resistant in vitro to the beta -lactams and macrolides, and fluoroquinolone resistance has been detected. A growing body of evidence suggests that prolonged antimicrobial use may contribute directly and indirectly to increased antimicrobial resistance among common respiratory pathogens. Long-term exposure to antimicrobial agents, especially less-potent agents, directly increases selection pressure for resistance. Indirectly, poor patient compliance, multiple daily dosing, and the increased risk of adverse events further complicate the resistance issue and diminish the efficacy of long-term antimicrobial use. Controlled clinical trials addressing the appropriate duration of therapy for CAP are lacking. However, available data suggest that with appropriate antibiotic selection, based on appropriate spectrum, potency, and pharmacokinetic/pharmacodynamic profile, lower respiratory tract infections in outpatients can be successfully treated in <7 days rather than the 7-14 days currently recommended.

Efficacy and safety of pharmacokinetically enhanced amoxicillin-clavulanate at 2,000/125 milligrams twice daily for 5 days versus amoxicillin-clavulanate at 875/125 milligrams twice daily for 7 days in the treatment of acute exacerbations of chronic bronchitis

This randomized, controlled trial was designed to show that a short, 5-day course of pharmacokinetically enhanced amoxicillin-clavulanate at 2,000/125 mg (Augmentin XR) is as effective clinically as a longer, 7-day course of conventional amoxicillin-clavulanate at 875/125 mg (both given twice daily) in the treatment of acute exacerbations of chronic bronchitis (AECB). Amoxicillin-clavulanate at 2,000/125 mg was designed to extend the therapeutic levels of amoxicillin in serum over the 12-h dosing interval, compared with conventional formulations, to eradicate bacterial strains for which amoxicillin MICs were < or =4 microg/ml while retaining efficacy against beta-lactamase-producing pathogens. A total of 893 patients were randomized and received study medication (amoxicillin-clavulanate at 2,000/125 mg for 443 patients and 875/125 mg for 450 patients). Overall, 141 patients receiving amoxicillin-clavulanate at 2,000/125 mg and 135 receiving the comparator formulation had at least one pathogen identified at screening. Amoxicillin-clavulanate at 2,000/125 mg was as effective clinically in the per-protocol (PP) population at the test of cure (days 14 to 21, primary efficacy endpoint) as amoxicillin-clavulanate at 875/125 mg (clinical success rates of 93.0 and 91.2%, respectively; treatment difference, 1.8; 95% confidence interval [CI], -2.2, 5.7). Bacteriological success in the bacteriology PP population was high for both formulations (amoxicillin-clavulanate at 2,000/125 mg, 76.7%; amoxicillin-clavulanate at 875/125 mg, 73.0%; treatment difference, 3.8; 95% CI, -7.5, 15.0). Both therapies were well tolerated, with a similar incidence of adverse events. Fewer than 5% of patients in each group withdrew from the study due to adverse events. The shorter, 5-day course of amoxicillin-clavulanate at 2,000/125 mg was shown to be as effective clinically as a longer, 7-day course of amoxicillin-clavulanate at 875/125 mg, with high bacteriological efficacy and no difference in tolerability.

Guide to selection of fluoroquinolones in patients with lower respiratory tract infections

Newer fluoroquinolones such as levofloxacin, moxifloxacin, gatifloxacin and gemifloxacin have several attributes that make them excellent choices for the therapy of lower respiratory tract infections. In particular, they have excellent intrinsic activity against Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis and the atypical respiratory pathogens. Fluoroquinolones may be used as monotherapy to treat high-risk patients with acute exacerbation of chronic bronchitis, and for patients with community-acquired pneumonia requiring hospitalisation, but not admission to intensive care. Overall, the newer fluoroquinolones often achieve clinical cure rates in > or =90% of these patients. However, rates may be lower in hospital-acquired pneumonia, and this infection should be treated on the basis of anticipated organisms and evaluation of risk factors for specific pathogens such as Pseudomonas aeruginosa. In this setting, an antipseudomonal fluoroquinolone may be used in combination with an antipseudomonalbeta-lactam. Concerns are now being raised about the widespread use, and possibly misuse, of fluoroquinolones and the emergence of resistance among S. pneumoniae, Enterobacteriaceae and P. aeruginosa. A number of pharmacokinetic parameters such as the peak concentration of the antibacterial after a dose (C(max)), and the 24-hour area under the concentration-time curve (AUC24) and their relationship to pharmacodynamic parameters such as the minimum inhibitory and the mutant prevention concentrations (MIC and MPC, respectively) have been proposed to predict the effect of fluoroquinolones on bacterial killing and the emergence of resistance. Higher C(max)/MIC or AUC24/MIC and C(max)/MPC or AUC24/MPC ratios, either as a result of dose administration or the susceptibility of the organism, may lead to a better clinical outcome and decrease the emergence of resistance, respectively. Pharmacokinetic profiles that are optimised to target low-level resistant minor subpopulations of bacteria that often exist in infections may help preserve fluoroquinolones as a class. To this end, optimising the AUC24/MPC or C(max)/MPC ratios is important, particularly against S. pneumoniae, in the setting of lower respiratory tract infections. Agents such as moxifloxacin and gemifloxacin with high ratios against this organism are preferred, and agents such as ciprofloxacin with low ratios should be avoided. For agents such as levofloxacin and gatifloxacin, with intermediate ratios against S. pneumoniae, it may be worthwhile considering alternative dose administration strategies, such as using higher dosages, to eradicate low-level resistant variants. This must, of course, be balanced against the potential of toxicity. Innovative approaches to the use of fluoroquinolones are worth testing in further in vitro experiments as well as in clinical trials.

Role of antimicrobial agents in the management of exacerbations of COPD

Acute exacerbations of chronic obstructive pulmonary disease (AECOPD) are a common occurrence and characterize the natural history of the disease. Over the past decade, new knowledge has substantially enhanced our understanding of the pathogenesis, outcome and natural history of AECOPD. The exacerbations not only greatly reduce the quality of life of these patients, but also result in hospitalization, respiratory failure, and death. The exacerbations are the major cost drivers in consumption of healthcare resources by COPD patients. Although bacterial infections are the most common etiologic agents, the role of viruses in COPD exacerbations is being increasingly recognized. The efficacy of antimicrobial therapy in acute exacerbations has established a causative role for bacterial infections. Recent molecular typing of sputum isolates further supports the role of bacteria in AECOPD. Isolation of a new strain of Haemophilus influenzae, Moraxella catarrhalis, or Streptococcus pneumoniae was associated with a considerable risk of an exacerbation. Lower airway bacterial colonization in stable patients with COPD instigates airway inflammation, which leads to a protracted self-perpetuating vicious circle of progressive lung damage and disease progression. A significant proportion of patients treated for COPD exacerbation demonstrate incomplete recovery, and frequent exacerbations contribute to decline in lung function. The predictors of poor outcome include advanced age, significant impairment of lung function, poor performance status, comorbid conditions and history of previous frequent exacerbations requiring antibacterials or systemic corticosteroids. These high-risk patients, who are likely to harbor organisms resistant to commonly used antimicrobials, should be identified and treated with antimicrobials with a low potential for failure. An aggressive management approach in complicated exacerbations may reduce costs by reducing healthcare utilization and hospitalization.

In vivo pharmacodynamic efficacy of gatifloxacin against Streptococcus pneumoniae in an experimental model of pneumonia: impact of the low levels of fluoroquinolone resistance on the enrichment of resistant mutants

OBJECTIVES

To investigate the impact of low levels of fluoroquinolone resistance on the emergence of resistant mutants, we examined the mutant selection window (MSW) hypothesis in experimental pneumonia in rabbits infected with pneumococci with various susceptibility levels to fluoroquinolones and treated with gatifloxacin using a human-like regimen (equivalent to 400 mg once daily). The MSW corresponds to the range of concentrations between the minimal inhibitory concentration (MIC) and the mutant prevention concentration (MPC), which is the antibiotic concentration that prevents selection of resistant mutants.

MATERIALS AND METHODS

Five pneumococcal strains were tested and were defined as follows [MIC of ciprofloxacin (mg/L)/MIC of gatifloxacin (mg/L)/MPC of gatifloxacin (mg/L)/involved quinolone resistance mechanisms]: strain 16089=0.5/0.25/0.25/wild-type; strain MS1A=2/0.5/1/efflux; strain MS2A=8/1/8/parC S79F; strain MR3B4=10/1/8/parC S79T; strain Gyr-1207=6/4/4/gyrA S81F.

RESULTS

A 48 h human-like treatment with gatifloxacin was significantly bactericidal on pneumonia induced by strain 16089 ( > 6 log(10) killing) as well as the efflux derivative strain MS1A ( > 5 log(10) killing). However, a small number of parC-gyrA mutants were recovered in 26% of the animals infected with this efflux strain. As expected, no decrease in viable bacteria counts was observed when pneumonia was induced by the gyrA resistant strain. In contrast, because of the enrichment of highly resistant mutants in 100% of the animals, no significant bacterial reduction was observed after treatment of pneumonia induced by the two susceptible parC mutated strains. A classification and regression tree (CART) analysis identified T(MSW) (percentage of the time during which gatifloxacin serum concentrations are inside the MSW) and AUC(MSW) (area under curve between MIC and MPC values) as the best parameters associated with the enrichment of resistant pneumococci.

CONCLUSIONS

This study shows that the acquisition of a low level of fluoroquinolone resistance (especially a parC mutation and to a lesser extent an efflux mechanism) is associated with a clearly lower potential for preventing resistance development. These data support the concept that resistant mutants are selectively enriched when antibiotic concentrations fall inside the mutant selection window and suggest that in vivo dynamic models have to be used to predict the relative abilities of quinolones to prevent mutant selection.

Clarithromycin in 2003: sustained efficacy and safety in an era of rising antibiotic resistance

Data from surveillance studies show increasing prevalence of respiratory pathogens resistant to commonly used antibiotics. Thus, a Medline search was conducted to identify studies of clarithromycin, especially those addressing macrolide resistance. Changing trends of in vitro susceptibility have not affected clinical efficacy with clarithromycin. Over the last 12 years, clarithromycin study results have shown consistent rates of clinical cure and bacteriological eradication, which are similar to those observed with comparator agents. The incidence of clarithromycin treatment failure in patients infected with Streptococcus pneumoniae is substantially less than that predicted by macrolide resistance rates from surveillance programmes. In summary, despite widespread use since its introduction, clarithromycin remains active both in vitro and in vivo against clinically relevant respiratory tract pathogens.

Short-course antimicrobial therapy of respiratory tract infections

Accumulating evidence suggests that short-course (</=5 days, </=3 days for azithromycin) antimicrobial therapy may be at least as effective as and, in some cases, may be more effective than traditional longer (10- to 14-day) therapies. In group A beta-haemolytic streptococcal tonsillopharyngitis, short-course therapy with 6 days of amoxicillin, 4-5 days of a variety of cephalosporins and 5 days of clarithromycin modified-release and telithromycin are all reasonable alternatives to traditional 10-day penicillin therapy. Short-course (i.e. 3-day) azithromycin therapy is not recommended because of suboptimal clinical and bacteriological results compared with penicillin therapy, unless the dosage is doubled from 10 to 20 mg/kg/day for all 3 days. In uncomplicated acute suppurative otitis media, single-dose intramuscular ceftriaxone or 3- to 5-day short-course oral antimicrobial therapy should be effective in the majority (>/=80%) of patients. However, more research is clearly needed in the subpopulations of children <2 years of age and in those with unresponsive/recurrent disease, since short-course therapy may not be successful in the majority of these patients. In sinusitis, most short-course therapy data have involved maxillary disease in adult patients. Regimens have included 3 days of azithromycin or cotrimoxazole (trimethoprim/sulfamethoxazole) or 5 days of cefpodoxime, telithromycin, gatifloxacin, gemifloxacin or amoxicillin/clavulanic acid. Preliminary results are encouraging but more study is clearly needed, especially in the paediatric population. In acute bacterial exacerbations of chronic bronchitis, short-course therapy with a variety of cephalosporins, second-generation fluoroquinolones and advanced generation macrolides/azalides/ketolides are all reasonable alternatives to traditional 7- to 14-day therapies. Cost containment in antimicrobial therapy should involve consideration of short-course therapy in the management of the most common types of respiratory tract infections.

Short-course therapy of acute bacterial exacerbation of chronic bronchitis: a double-blind, randomized, multicenter comparison of extended-release versus immediate-release clarithromycin

OBJECTIVE

The objective of this study was to compare the efficacy and safety of two clarithromycin formulations given for 5 days to patients with acute bacterial exacerbation of chronic bronchitis (ABECB).

PATIENTS AND METHODS

This was a double-blind, randomized, multicenter study of ambulatory patients between 40 and 75 years of age with a medical history of chronic bronchitis, chronic obstructive pulmonary disease and a presumptive diagnosis of ABECB who met Anthonisen Type 1 criteria (increased dyspnea, increased sputum volume and increased sputum purulence). Eligible patients received a 5-day course of clarithromycin extended-release (ER) 500 mg once daily or clarithromycin immediate-release (IR) 250 mg twice daily. Clinical cure, bacteriological cure and pathogen eradication rates were determined at the end of therapy and at a follow-up visit.

RESULTS

Clinical cure rates were similar at the test-of-cure visit for evaluable patients in the clarithromycin ER group (97%, 298/307) and clarithromycin IR group (98%, 300/307) (95% CI (-3.2, 1.9)). The bacteriological cure rate was 89% and the pathogen eradication rate was 90% in both treatment groups. Resolution or improvement in cough, sputum production, sputum volume and sputum appearance was observed in > 90% of evaluable patients in each treatment group. The incidence of study drug-related adverse events was 6.6% (23/351) in the clarithromycin ER group and 5.4% (19/352) in the clarithromycin IR group. The most frequently occurring study drug-related adverse events were abdominal pain, diarrhea and taste perversion.

CONCLUSION

Clarithromycin ER 500 mg once daily for 5 days is equivalent to clarithromycin IR 250 mg twice daily for 5 days in treating adults with ABECB. Both regimens were effective in resolving clinical signs and symptoms of ABECB and eradicating the target pathogens, and were well tolerated.

Fluoroquinolones for the treatment of outpatient community-acquired pneumonia

The increasing prevalence of beta-lactam and macrolide resistance in bacteria that cause respiratory infections has underscored the need for effective antimicrobial agents. The broad spectrum, excellent oral bioavailability, and once-daily dosing of fluoroquinolones contributed to the introduction of several new agents in the past decade. This class is among the world's most used antimicrobial therapies in community and hospital settings. Fluoroquinolones are generally well tolerated, but safety profiles differ widely among agents. Knowledge of in vitro activity, local microbiologic susceptibility and resistance patterns, adverse effects, and potential drug interactions should influence the selection of the best agent for individual patients. This overview of the fluoroquinolones directs particular attention to use in community-acquired pneumonia and safety.

Evaluation and cost assessment of fluoroquinolones in community-acquired respiratory infections

Several new fluoroquinolones have been marketed since the late 1990s. Fluoroquinolones are an effective treatment for most community-acquired respiratory tract infections, including acute sinusitis, acute exacerbations of chronic bronchitis and community-acquired pneumonia. However, other antibiotics, including beta-lactams, macrolides, tetracyclines and trimethoprim-sulfamethoxazole, are also effective against these respiratory infections. From a managed care perspective, it is the subtle differences between the drugs in the eradication of bacterial pathogens, adverse effects, dose regimens, compliance issues, bacterial resistance and cost that determine the best choice for the management of pneumonia, sinusitis or exacerbations of chronic bronchitis. The potential for bacterial resistance is perhaps the only significant barrier to extensive fluoroquinolone use in community-acquired respiratory tract infections. Cost-effectiveness must be balanced with quality care, both from an individual perspective and that of the greater society.

Oral fluoroquinolones in the treatment of pneumonia, bronchitis and sinusitis

BACKGROUND

Despite a relatively large number of clinical studies comparing oral fluoroquinolones to one antibiotic class comparator, there is limited information on the relative efficacy of different fluoroquinolones.

OBJECTIVE

To examine the efficacy and tolerability of oral fluoroquinolones in the treatment of mild to moderate community-acquired pneumonia, acute exacerbations of chronic bronchitis and sinusitis.

METHODS

A systematic review was undertaken with a MEDLINE search for antibiotics and indications. Included studies met the following criteria: original study; random allocation to treatment groups; treatment with one of the following oral antibiotics - moxifloxacin, levofloxacin, ciprofloxacin, gatifloxacin; controlled by either placebo or an active comparator medication; double-blind, single-blind or open treatment; men and women (18 years of age and older); diagnosis of one of the three indications; and treatment duration of at least three days. Outcome measures included efficacy and safety. Comparative and single arm meta-analyses were conducted. Statistical differences in antibiotic success rates were evaluated. Pooled point estimates and 95% CIs for the comparative statistics (z-scores, P-values) and the single-arm analysis were examined to evaluate equivalence.

RESULTS

The results of the comparative and single meta-analyses revealed no major differences between the new fluoroquinolones. This is not surprising because the clinical studies were designed to show equivalence versus their comparators. Few comparative evaluations were conducted due to a paucity of studies. In relation to other competitors, small differences were seen.

CONCLUSIONS

Results indicate that, in general, fluoroquinolones had similar efficacy, overall safety and dropout rates.

Antibiotics in the treatment of acute exacerbations of chronic bronchitis

The benefit of antimicrobial therapy for patients with an acute exacerbation of chronic bronchitis (AECB) remains controversial for two main reasons. First, the distal airways of patients with chronic bronchitis are persistently colonised, even during clinically stable periods, with the same bacteria that have been associated with AECB. Second, bacterial infection is only one of several causes of AECB. These factors have led to conflicting analyses on the role of bacterial agents and the response to antimicrobial therapy of patients with AECB. An episode of AECB is said to be present when a patient with chronic obstructive pulmonary disease (COPD) experiences some combination of increased dyspnoea, increased sputum volume, increased sputum purulence and worsening lung function. While the average COPD patient experiences 2 - 4 episodes of AECB per year, some patients, particularly those with more severe airway obstruction, are more susceptible to these attacks than others. Bacterial agents appear to be particularly associated with AECB in patients with low lung function and those with frequent episodes accompanied by purulent sputum. Non-typeable Haemophilus influenzae, Streptococcus pneumoniae and Moraxella catarrhalis account for up to 50% of episodes of AECB. Gram-negative bacilli are more likely to occur in patients with more severe lung disease. Antibiotics have been used to ameliorate AECB, to prevent AECB and to prevent the long-term loss of lung function that characterises COPD. Numerous prevention trials have been conducted with fairly consistent results; antibiotics do not lessen the number of episodes of AECB but do reduce the number of days lost from work. Most antibiotic trials have studied the impact of treatment on episodes of AECB and results have been inconsistent, largely due to patient selection and end point definition. In patients with severe airway obstruction, especially in the presence of purulent sputum, antibiotic therapy significantly shortens the duration of symptoms and can be cost-effective. Over the past 50 years, virtually all classes of antimicrobial agents have been studied in AECB. Important considerations include penetration into respiratory secretions, spectrum of activity and antimicrobial resistance. These factors limit the usefulness of drugs such as amoxicillin, erythromycin and trimethoprim-sulfamethoxazole. Extended-spectrum oral cephalosporins, newer macrolides and doxycycline have demonstrated efficacy in clinical trials. Amoxicillin-clavulanate and flouoroquinolones should generally be reserved for patients with more severe disease. A number of investigational agents, including ketolides and newer quinolones, hold promise for treatment of AECB.

Clinical outcomes of ambulatory acute exacerbations of chronic bronchitis with older versus newer antimicrobials

OBJECTIVE

To determine whether the cure rate was similar between traditional and newer antibiotics in the treatment of acute exacerbations of chronic bronchitis (AECB), to determine whether antibiotic selection during the first AECB of the season influences the frequency of subsequent AECB, and to identify variables associated with poor short- and long-term treatment outcome.

METHODS

A retrospective analysis of subjects seen for management of their first seasonal AECB was conducted. Subjects were stratified into traditional therapies (n = 95) or newer therapies (n = 101) by antibiotic prescription.

RESULTS

There was no difference in initial cure rates between older versus newer antibiotics (93% vs. 95%; p = 0.48). There was no difference in the number of subjects that remained AECB-free for 6 months after initial treatment with older versus newer antibiotic regimens (34% vs. 28%; p = 0.37). Oxygen initiation or increased dose (OR 10.9; 95% CI 1.4 to 84.2; p = 0.02) was the only variable independently associated with lack of AECB resolution. Nonsmoking status trended toward an association with remaining AECB-free at 180 days (OR 0.39; 95% CI 0.15 to 1.01; p = 0.053).

CONCLUSIONS

The use of older versus newer antibiotics did not independently predict short-term outcome or future AECB.

Efficacy and tolerability of gatifloxacin in community treatment of acute exacerbations of chronic bronchitis

BACKGROUND

Recognizing acute exacerbations of chronic bronchitis (AECB) and selecting appropriate antibiotic treatment for patients who would benefit most is a challenge for community-based physicians.

OBJECTIVE

The Tequin Clinical Experience Study, an open-label, noncomparative, postmarketing trial, assessed the efficacy and tolerability of gatifloxacin, an 8-methoxy fluoroquinolone, in the treatment of AECB in the community-practice setting.

METHODS

Consecutive patients with respiratory tract infections in community-based settings were eligible for participation. Treated patients (N = 2512) included 1107 men (44.1%) and 1405 women (55.9%) aged > or =18 years with a clinical diagnosis of chronic bronchitis. All participants received oral gatifloxacin 400 mg once daily for 7 to 10 days. Clinical response was determined via telephone contact conducted by the investigator or study coordinator using case-report forms or during an office visit after the last dose. The investigator or coordinator collected expectorated or induced sputum specimens that were then smeared on a microscope slide, stored in a tube, and transported to a central reference laboratory for Gram-staining and culture. Of 1388 pretreatment sputum specimens submitted, pathogens were isolated from 424.

RESULTS

The most frequently detected pathogens were Haemophilus influenzae, Moraxella catarrhalis, and Streptococcus pneumoniae. All H. influenzae and 99% of S. pneumoniae isolates tested were susceptible to gatifloxacin. Of the 2267 patients with a determinable clinical response, 2084 (91.9% [95% CI, 90.8%-93.0%]) were cured (all acute symptoms improved or returned to baseline level, no new symptoms present, no additional antibiotic required). The 95.8% cure rate in 166 patients with H. influenzae included 100% of those with beta-lactamase-positive strains. Overall, 89.2% of 111 patients with M. catarrhalis were cured; rates were similar regardless of beta-lactamase production. The clinical cure rate in 74 patients with S. pneumoniae was 98.6% and was independent of the degree of penicillin resistance (minimum inhibitory concentration > or =2.0 microg/ mL). All 6 patients infected with S. pneumoniae fully resistant to penicillin were cured. Gatifloxacin was generally well tolerated, and the majority of adverse events were mild to moderate; only 11 drug-related adverse events in 10 patients (0.4%) were serious. Drug-related nausea (3.0%), dizziness (1.5%), diarrhea (1.2%), and vomiting (0.9%) were the most common adverse events.

CONCLUSIONS

The high clinical cure rate and favorable tolerability support gatifloxacin as a rational choice for the treatment of AECB in patients such as those in this community-based study.

Gatifloxacin: a review of its use in the management of bacterial infections

Gatifloxacin is an 8-methoxy fluoroquinolone antibacterial agent. The drug has a broader spectrum of antibacterial activity than the older fluoroquinolones (e.g. ciprofloxacin) and shows good activity against many Gram-positive and Gram-negative pathogens, atypical organisms and some anaerobes. Notably, gatifloxacin is highly active against both penicillin-susceptible and -resistant strains of Streptococcus pneumoniae, a common causative pathogen in community-acquired pneumonia (CAP), acute sinusitis and acute bacterial exacerbations of bronchitis. Gatifloxacin is absorbed well from the gastrointestinal tract (oral bioavailability is almost 100%). Therefore, patients can be switched from intravenous to oral therapy without an adjustment in dosage. High concentrations of gatifloxacin are achieved in plasma and target tissues/fluids. Gatifloxacin has a long plasma elimination half-life, thus allowing once-daily administration. Few clinically significant interactions between gatifloxacin and other drugs have been reported. In patients with CAP, clinical response rates in recipients of intravenous/oral gatifloxacin 400 mg/day ranged from 86.8 to 98.0% and rates of bacterial eradication ranged from 83.1 to 100% (up to 28 days post-treatment). Gatifloxacin showed efficacy similar to that of amoxicillin/clavulanic acid, ceftriaxone (with or without erythromycin) with or without stepdown to clarithromycin, levofloxacin or clarithromycin. Gatifloxacin was as effective as clarithromycin or amoxicillin/clavulanic acid, and was significantly more effective (in terms of clinical response; p < 0.035) than 7 to 10 days' treatment with cefuroxime axetil in the treatment of acute exacerbations of chronic bronchitis. In acute sinusitis, gatifloxacin showed clinical efficacy similar to that of clarithromycin, trovafloxacin or amoxicillin/clavulanic acid. Genitourinary infections were also successfully treated with gatifloxacin. Gatifloxacin is generally well tolerated. Its tolerability profile was broadly similar to those of comparator agents in comparative trials. The most common adverse events are gastrointestinal symptoms (oral formulation) and injection site reactions.

CONCLUSIONS

Gatifloxacin has an extended spectrum of antibacterial activity and provides better coverage of Gram-positive organisms (e.g. S. pneumoniae) than some older fluoroquinolones. The drug has favourable pharmacokinetic properties, is administered once daily and is at least as well tolerated as other fluoroquinolones. Gatifloxacin is a useful addition to the fluoroquinolones currently available for use in the clinical setting and has an important role in the management of adult patients with various bacterial infections. As with other fluoroquinolones, careful control of gatifloxacin usage in the community is important in order to prevent the emergence of bacterial resistance and thus preserve the clinical value of this agent.

Community-acquired lower respiratory tract infections: etiology and treatment

The current therapy for community-acquired lower respiratory tract infections is often empiric, usually involving administration of a beta-lactam or macrolide. However, the increasing prevalence of antibiotic resistance in frequently isolated respiratory tract pathogens has complicated the antimicrobial selection process. This review will discuss the incidence of various respiratory pathogens, as well as update the clinician on the various antimicrobial alternatives available, with particular emphasis on the role of the newer fluoroquinolones in the treatment of acute exacerbations of chronic bronchitis and community-acquired pneumonia.

Selection of clinical, patient-reported, and economic end points in acute exacerbation of chronic bronchitis

BACKGROUND

Acute exacerbation of chronic bronchitis (AECB) places tremendous burden on patients, providers, employers, and health care systems.

OBJECTIVE

The purpose of this paper is to (1) review the clinical, patient-reported, and economic measures used to evaluate disease burden and treatment effectiveness in AECB in clinical trials and (2) propose a guide for selecting study end points in AECB that will help capture all the relevant disease outcomes.

METHODS

Two literature searches of the PubMed database were conducted to identify studies of clinical trials in bronchitis and evaluate the clinical, patient-reported, and economic end points used in these studies.

RESULTS

Previous studies have focused primarily on clinician-assessed outcomes, which do not capture the full impact of AECB on patients' lives. Reporting mechanisms for most end points have been inconsistent, limiting the ability to compare information or interpret differences. Previous studies have given limited attention to patient-reported outcomes and the economic implications of AECB. Patient-reported outcomes such as speed of symptom relief and work productivity are important parameters for assessing treatment effectiveness and provide practical information for treatment evaluation.

CONCLUSIONS

Additional research is needed to develop, examine, and validate patient-reported outcomes and the indirect costs of AECB. Measuring the relevant clinical, economic, and patient-reported outcomes in AECB patients using standardized methods may lead to a clearer understanding of the disease burden and the role, effectiveness, and cost-effectiveness of antibiotic treatment.