Azithromycin Linked to Belly Blockage in Infants
Published: Sep 10, 2014
By Ed Susman , Contributing Writer, MedPage Today

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Note that this study was published as an abstract and presented at a conference. These data and conclusions should be considered to be preliminary until published in a peer-reviewed journal.

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WASHINGTON — Infants who received azithromycin (Zithromax) in the early days of life were at an increased risk for developing infantile hypertrophic pyloric stenosis (IHPS), researchers reported here.

In a retrospective analysis, among 163 infants given azithromycin in the first 14 days of life, about 2% developed IHPS for an odds ratio of 7.52 (95% CI 2.39-23.70,P<0.001), said Matthew Eberly, MD, from the Uniformed Services University of the Health Sciences in Bethesda, Maryland, and colleagues.

The link was strongest if exposure to the antibiotic occurred in the first 2 weeks of life, and persisted to a lesser degree in kids between 2 and 6 weeks of age (two- to threefold increase in the odds), Eberly’s group reported in a poster presentation at the Interscience Conference on Antimicrobial Agents and Chemotherapy.

“Practitioners must carefully weigh the risks and benefits when prescribing azithromycin [in young infants],” Eberly advised. “These infants should be monitored for signs and symptoms of [IHPS] for 6 weeks following treatment with azithromycin.”

Previous reports have found ties between the oral administration of erythromycin — often given for the treatment of chlamydia pneumoniae infections and chlamydial conjunctivitis — in the first few weeks of an infant’s life and an increased risk for developing IHPS, they pointed out.

Healthcare providers have used azithromycin, generally as a prophylaxis against pertussis, but the risk associated with this antibiotic remains unknown.

Eberly and colleagues evaluated the associated risk of exposure to oral azithromycin in the first 90 days of life and subsequent development of IHPS.

They reviewed cases in the Tricare Management Activity military health system database from 2011-2012.. From 1.07 million infant records, they identified 2,466 cases of IHPS for an incidence of 2.29 per 1,000.

Of the 820 infants who were ages 15-42 days at the time of exposure to azithromycin, five developed IHPS (OR 2.69, 95% CI 1.11-6.50, P=0.028).

But none of the 4,590 infants who were received azithromycin at ages 43-90 days developed IHPS, they reported.

In comparison, among 312 infants exposed to erythromycin in the first 14 days of life, 2.88% developed IHPS (OR 11.75, 95% CI 6.02-22.94, P<0.001). Older children also developed the disease: OR 3.60 (95% CI 1.49-8.72 P=0.004) for infants ages 15-42 days and OR 1.40 (95% CI 0.52-3.74, P=0.50) for infants ages 43-90 days.

Among the children who developed IHPS, the median age at diagnosis was 49 days for those who received azithromycin and 34 days if they were given erythromycin.

The median time to development of IHPS serious enough to require pyloromyotomy was 29.5 days for children treated with azithromycin and 13 days for infants treated with erythromycin, the authors stated.

The surgery to correct the condition takes about 2 hours to complete, Eberly explained toMedPage Today, adding that a couple of days of hospitalization is generally required post procedure.

The study results were not surprising given that azithromycin and erythromycin are both macrolides. “Both drugs have similar action on the stomach so it is reasonable to think we would get these kinds of results,” Eberly said.