Search

A 6-month clinical trial of azithromycin (AZM) in American cystic fibrosis (CF) patients with chronic Pseudomonas aeruginosa infection showed clinical improvement without significant reduction in bacterial density. Sub-inhibitory AZM has been hypothesized to affect P. aeruginosa virulence, partly contributing to the mechanism of action of AZM. To correlate bacterial phenotypes of P. aeruginosa isolates with clinical response to AZM in CF patients. Pre-treatment P. aeruginosa isolates from subjects randomized to AZM in the US trial were characterized for bacterial phenotypes: AZM minimal inhibitory concentration (MIC), mucoidy, and baseline and AZM effects on twitching and swimming motility, and production of pyocyanin, protease and phospholipase C (PLC). Initial analyses of a subset of subjects identified phenotypes most strongly associated with FEV(1) response and pulmonary exacerbation. These phenotypes were subsequently characterized and tested in isolates from subjects of the complete AZM cohort. Exploratory analyses of the initial subset suggested that the MIC and in vitro change in PLC and swimming motility with AZM were the strongest candidates among the bacterial phenotypes. When tested, only the change in PLC was significantly correlated with the change in FEV(1) (P=0.05), and occurrence and time to pulmonary exacerbation (both P=0.02). In the complete cohort, change in PLC continued to show significant correlation with FEV(1) response (P=0.006), but not exacerbation. The in vitro effect of AZM on PLC correlates with FEV(1) response to AZM. This suggests that AZM anti-virulence effects may be predictive of clinical response and play a role in the mechanism of action of AZM in CF patients., ((c) 2007 Wiley-Liss, Inc.)

The article discusses a study which investigated the link between azithromycin treatment and an improvement in lung function and a reduction in pulmonary exacerbations in pediatric cystic fibrosis (CF) patients uninfected with Pseudomonas aeruginosa. The researchers conducted a multicenter, randomized, double-blind placebo-controlled trial in the U.S. and Canada involving 260 participants. It was found that there was no link between treatment with the drug for 24 weeks and improved pulmonary function.

Context: Treatment strategies for cystic fibrosis (CF) lung disease include antibiotics, mucolytics, and anti-inflammatory therapies. Increasing evidence suggests that macrolide antibiotics might be beneficial in patients with CF. Objective: To determine if an association between azithromycin use and pulmonary function exists in patients with CF. Design and Setting: A multicenter, randomized, double-blind, placebo-controlled trial conducted from December 15, 2000, to May 2, 2002, at 23 CF care centers in the United States. Participants: Of the 251 screened participants with a diagnosis of CF, 185 (74%) were randomized. Eligibility criteria included age 6 years or older, infection with Pseudomonas aeruginosa for 1 or more years, and a forced expiratory volume in 1 second (FEV[sub 1]) of 30% or more. Participants were stratified by FEV[sub 1] (≥60% predicted vs <60% predicted), weight of less than 40 kg vs 40 kg or more, and CF center. Intervention: The active group (n = 87) received 250 mg (weight <40 kg) or 500 mg (weight ≥40 kg) of oral azithromycin 3 days a week for 168 days; placebo group (n = 98) received identically packaged tablets. Main Outcome Measures: Change in FEV[sub 1] from day 0 to completion of therapy at day 168 and determination of safety. Secondary outcomes included pulmonary exacerbations and weight gain. Results: The azithromycin group had a mean 0.097-L (SD, 0.26) increase in FEV[sub 1] at day 168 compared with 0.003 L (SD, 0.23) in the placebo group (mean difference, 0.094 L; 95% confidence interval [CI], 0.023-0.165; P = .009). Nausea occurred in 17% more participatns in the azithromycin group (P = .01), diarrhea in 15% more (P = .009), and wheezing in 13% more (P = .007). Participants in the azithromycin group had less risk of experiencing an exacerbation than participants in the placebo group (hazard ratio, 0.65; 95% CI, 0.44-0.95; P = .03) and weighed at the end of the study an average 0.7 kg more than participants receiv... [ABSTRACT FROM AUTHOR]

Abstract: Background: Current definitions of pulmonary exacerbation (PE) in cystic fibrosis are based on studies in participants with significant lung disease and may not reflect the spectrum of findings observed in younger patients with early lung disease. Methods: We used data from a recent trial assessing the efficacy of azithromycin in children to study signs and symptoms associated with PEs and related changes in lung function and weight. Results: While increased cough was present in all PEs, acute weight loss and reduction in oxygen saturation were not observed. Changes in lung function did not differ between subjects who did experience a PE and those who were exacerbation-free. Conclusions: Cough was the predominant symptom in CF patients with early lung disease experiencing a PE. There was no significant difference in mean 6-month change in lung function or weight among subjects with one or more exacerbations and those without an exacerbation. [Copyright &y& Elsevier]