Azithromycin administered for severe early-life respiratory syncytial virus (RSV) bronchiolitis did not prevent recurrent wheezing in affected children over the next 2-4 years, a randomized, single-center study found.
Antibiotics are frequently given to patients with RSV bronchiolitis, although this practice is not supported by American Academy of Pediatrics clinical guidelines. Many doctors will prescribe them anyway if they see redness in the ears or other signs of infection, lead author Avraham Beigelman, MD, a pediatric allergist and immunologist at Washington University in St. Louis, said in an interview.
The double-blind, placebo-controlled trial, presented at the 2022 meeting of the American Academy of Allergy, Asthma & Immunology in Phoenix, was simultaneouslyFeb. 27, 2022, in the New England Journal of Medicine–Evidence.
Since azithromycin has shown anti-inflammatory benefit in chronic lung diseases and is a mainstay of care in cystic fibrosis and had shown previous effects in RSV patients, this trial examined its potential for preventing future recurrent wheezing in infants hospitalized with RSV who are at risk for developing asthma later. About half of children admitted to the hospital for RSV will develop asthma by age 7, Dr. Beigelman said.
“We were very surprised that azithromycin didn’t help in this trial given our previous findings,” Dr. Beigelman said.
And while those given azithromycin versus those given a placebo showed no significant decrease in recurrent wheezing, there was a slight suggestion that treatment with antibiotics of any kind may increase the risk of later wheezing in infants hospitalized with the virus.
“The study was not designed to tease at the effects of different antibiotics or combinations of antibiotics, so we have to be very cautious about this trend,” Dr. Beigelman said. “There may be short-term effects and long-term effects. Certain antibiotics may affect the infant microbiome in other parts of the body, such as the gut, [in] a way that may predispose to asthma. But all these associations suggest that early-life antibiotics for viral infections are not good for you.”
He pointed to the longstanding question among clinicians whether it is the antibiotic that’s increasing the risk of the harm or the condition for which the antibiotic is prescribed. These exploratory data, however, suggest that antibiotics for RSV may be causing harm.
In pursuit of that hypothesis, his group has collected airway microbiome samples from these infants and plan to investigate whether bacteria colonizing the airway may interact with the antibiotics to increase wheezing. The researchers will analyze stool samples from the babies to see whether the gut microbiome may also play a role in wheezing and the subsequent risk of developing childhood asthma.
The trial prospectively enrolled 200 otherwise healthy babies aged 1-18 months who were hospitalized at St. Louis Children’s Hospital for acute RSV bronchiolitis. Although RSV is a very common pediatric virus, only bout 3% of babies will require hospitalization in order to receive oxygen, Dr. Beigelman said.
Babies were randomly assigned to receive placebo or oral azithromycin at 10 mg/kg daily for 7 days, followed by 5 mg/kg daily for 7 days. Randomization was stratified by recent open-label antibiotic use. The primary outcome was recurrent wheeze, defined as a third episode of post-RSV wheeze over the following 2-4 years.
The biologic activity of azithromycin was clear since nasal-wash interleukin at day 14 after randomization was lower in azithromycin-treated infants. But despite evidence of activity, the risk of post-RSV recurrent wheeze was similar in both arms: 47% in the azithromycin group versus 36% in the placebo group, for an adjusted hazard ratio of 1.45 (95% confidence interval, 0.92-2.29; P = .11).
Nor did azithromycin lower the risk of recurrent wheeze in babies already receiving other antibiotics at the time of enrollment (HR, 0.94; 95% CI, 0.43-2.07). As for antibiotic-naive participants receiving azithromycin, there was a slight signal of potential increased risk of developing recurrent wheezing (HR, 1.79; 95% CI, 1.03-3.1).
The bottom line? The findings support current clinical guidelines recommending against the use of antibiotics for RSV. “At the very least, azithromycin and antibiotics in general have no benefit in preventing recurrent wheeze, and there is a possibility they may be harmful,” Dr. Beigelman said.
This trial is funded by the National Heart, Lung, and Blood Institute. Dr. Beigelman reported relationships with AstraZeneca, Novartis, and Sanofi. Two study coauthors disclosed various ties to industry.