Antibiotic-induced cardiac arrhythmias

Ruling out Legionella in community-acquired pneumonia

BACKGROUND

Assessing the likelihood for Legionella sp. in community-acquired pneumonia is important because of differences in treatment regimens. Currently used antigen tests and culture have limited sensitivity with important time delays, making empirical broad-spectrum coverage necessary. Therefore, a score with 6 variables recently has been proposed. We sought to validate these parameters in an independent cohort.

METHODS

We analyzed adult patients with community-acquired pneumonia from a large multinational database (Community Acquired Pneumonia Organization) who were treated between 2001 and 2012 with more than 4 of the 6 prespecified clinical variables available. Association and discrimination were assessed using logistic regression analysis and area under the curve (AUC).

RESULTS

Of 1939 included patients, the infectious cause was known in 594 (28.9%), including Streptococcus pneumoniae in 264 (13.6%) and Legionella sp. in 37 (1.9%). The proposed clinical predictors fever, cough, hyponatremia, lactate dehydrogenase, C-reactive protein, and platelet count were all associated or tended to be associated with Legionella cause. A logistic regression analysis including all these predictors showed excellent discrimination with an AUC of 0.91 (95% confidence interval, 0.87-0.94). The original dichotomized score showed good discrimination (AUC, 0.73; 95% confidence interval, 0.65-0.81) and a high negative predictive value of 99% for patients with less than 2 parameters present.

CONCLUSIONS

With the use of a large independent patient sample from an international database, this analysis validates previously proposed clinical variables to accurately rule out Legionella sp., which may help to optimize initial empiric therapy.

Erythromycin, QTc interval prolongation, and torsade de pointes: Case reports, major risk factors and illness severity

OBJECTIVES

Erythromycin is a macrolide antibiotic that is widely used for various infections of the upper respiratory tract, skin, and soft tissue. Similar to other macrolides (clarithromycin, azithromycin), erythromycin has been linked to QTc interval prolongation and torsade de pointes (TdP) arrhythmia. We sought to identify factors that link to erythromycin-induced/associated QTc interval prolongation and TdP.

METHODS AND RESULTS

In a critical evaluation of case reports, we found 29 cases: 22 women and 7 men (age range 18-95 years). With both oral and intravenous erythromycin administration, there was no significant relationship between dose and QTc interval duration in these cases. Notably, all patients had severe illness. Other risk factors included female sex, older age, presence of heart disease, concomitant administration of either other QTc prolonging drugs or agents that were substrates for or inhibitors of CYP3A4. Most patients had at least two risk factors.

CONCLUSIONS

On the basis of case report evaluation, we believe that major risk factors for erythromycin-associated TdP are female sex, heart disease and old age, particularly against a background of severe illness. Coadministration of erythromycin with other drugs that inhibit or are metabolized by CYP3A4 or with QTc prolonging drugs should be avoided in this setting.

Azithromycin and other macrolides for prevention of bronchopulmonary dysplasia: a systematic review and meta-analysis

BACKGROUND AND OBJECTIVE

Ureaplasma spp. infection has been associated with bronchopulmonary dysplasia (BPD) in preterm infants. Macrolides have been used for the treatment of Ureaplasma spp. infection, with an intention to prevent BPD. The objective of this meta-analysis is to evaluate the use of macrolides in the prevention of BPD in preterm infants.

METHODS

We searched MEDLINE, EMBASE, and Cochrane Central Register of Controlled Trials, abstracts of the major pediatric society meetings and bibliographies of retrieved articles. We included randomized controlled trials assessing the effects of macrolides therapy on BPD in preterm infants. A random/fixed-effect model was used to synthesize predefined outcomes.

RESULTS

Six studies involving 469 preterm infants were eligible for the analysis. Macrolides when used prophylactically (4 studies) did not show significant reduction in BPD (risk ratio, RR, 0.88, 95% confidence interval, CI, 0.75-1.03), death (RR 0.89, 95% CI 0.79-1.01) or in the composite outcome of BPD/death. Similarly, there was no significant reduction in BPD (RR 0.64, 95% CI 0.31-1.31) or the composite outcome of BPD/death (RR 0.41, 95% CI 0.05-3.13), when macrolides were used in Ureaplasma-positive infants. However, prophylactic azithromycin therapy (3 studies) was associated with significant reduction in BPD (RR 0.83, 95% CI 0.71-0.97; number needed to treat, NNT, 10) and composite outcome of BPD/death (RR 0.86, 95% CI 0.77-0.97; NNT 10).

CONCLUSION

This meta-analysis demonstrates prophylactic azithromycin therapy was associated with statistically significant reduction in BPD and the composite outcome of BPD/death in preterm infants. However, given the limited information on pharmacokinetics and potential harmful effects, further studies should be done before routine use of azithromycin in the neonatal population.