BackgroundAcute exacerbations of chronic obstructive pulmonary disease (AECOPDs) can lead to high frequencies and rates of hospitalization and mortality. Macrolides are a class of antibiotics that possess both antimicrobial and anti-inflammatory properties. Since the occurrence of AECOPDs is associated with aggravation of airway inflammation and bacterial infections, prophylactic macrolide treatment may be an effective approach towards the prevention of AECOPDs.MethodsWe systemically searched the PubMed, Embase and Cochrane Library databases to identify randomized controlled trials (RCTs) that evaluated the effect of prophylactic macrolide therapy on the prevention of AECOPDs. The primary outcomes were the total number of patients with one or more exacerbations as well as the rate of exacerbations per patient per year.ResultsNine RCTs comprising 1666 patients met the inclusion criteria. Pooled evidence showed macrolides could reduce the frequency of exacerbations in patients with COPD by both unweighted (RR = 0.70; 95% CI: 0.56–0.87; P < 0.01) and weighted approaches (RR = 0.58, 95% CI: 0.43–0.78, P < 0.01). Subgroup analysis showed only 6–12 months of erythromycin or azithromycin therapy could be effective. Moreover, among studies with 6–12 months of azithromycin therapy, both the daily dosing regimen and the intermittent regimen significantly reduced exacerbation rates. The overall number of hospitalizations and the all-cause rate of death were not significantly different between the treatment and control groups. A tendency for more adverse events was found in the treatment groups (OR = 1.55, 95%CI: 1.003–2.39, P = 0.049).ConclusionsOur results suggest 6-12 months erythromycin or azithromycin therapy could effectively reduce the frequency of exacerbations in patients with COPD. However, Long-term treatment may bring increased adverse events and the emergence of macrolide-resistance. A recommendation for the prophylactic use of macrolide therapy should weigh both the advantages and disadvantages.

Carbapenem-resistant Enterobacteriaceae (CRE) infections are prevalent worldwide; they have few effective treatments and this jeopardizes public health. Clinicians often use tigecycline to combat CRE, but its clinical efficacy remains controversial. Therefore, to compare the efficacy and safety of tigecycline in treating CRE infections compared with that of other antimicrobial agents, and to evaluate whether combination therapy and high-dose regimens are beneficial, we performed a systematic review and meta-analysis.PubMed and Embase were searched for controlled trials or cohort studies reporting the efficacy and/or safety of tigecycline-based regimens to treat CRE infections. Statistical analyses were performed using the Comprehensive Meta-Analysis V2.2. All meta-analyses were performed based on fixed- or random-effects model, and the I2 method was used to assess heterogeneity.Twenty-one controlled studies and 5 single-arm studies were included in this systematic review. With regard to the controlled studies, the tigecycline groups did not differ significantly from the control groups in terms of overall mortality (Odds ratio (OR) = 0.96 [95% confidence interval (CI) = 0.75–1.22; P = 0.73]), clinical response rate (OR = 0.58 [95% CI = 0.31–1.09; P = 0.09]), or microbiological response rate (OR = 0.46 [95% CI = 0.15–1.44; P = 0.18]). Subgroup analyses showed that 30-day mortality was significantly lower in patients who received tigecycline combination therapy than in those who received monotherapy (OR = 1.83 [95% CI = 1.07–3.12; P = 0.03]) and other antibiotic regimens (OR = 0.59 [95% CI = 0.39–0.88; P = 0.01]), respectively. In addition, high-dose tigecycline regimens differed significantly from standard dose schedules in terms of ICU mortality (OR = 12.48 [95% CI = 2.06–75.43; P = 0.006]). The results of the 5 single-arm studies corroborated the findings of the controlled studies.Our results indicated that the efficacy of tigecycline in treating CRE infections is similar to that of other antibiotics. Tigecycline combination therapy and high-dose regimens may be more effective than monotherapy and standard-dose regimens, respectively. Nonetheless, considering that the current available evidence is limited, well-designed randomized controlled trials are urgently needed to clarify the comparative efficacy of tigecycline in treating CRE infections.