One course of antibiotics could expand the gut resistome in children, according to the results of a randomized clinical trial published in Clinical Infectious Diseases. Researchers suggested that azithromycin may cause more drastic changes to the gut microbiota compared with antibiotics in other classes.
Study author Catherine E. Oldenburg, PhD, an infectious disease epidemiologist at the Francis I. Proctor Foundation for Research in Ophthalmology at the University of California, San Francisco, and colleagues enrolled households with at least two children aged 6 to 59 months in two rural communities in Burkina Faso.
In July 2017, 124 children were randomly assigned to receive amoxicillin (25 mg/kg daily in two doses for 5 days), azithromycin (10 mg/kg on day 1 and 5 mg/kg once daily for 4 days), cotrimoxazole (240 mg once daily for 5 days) or placebo (powdered milk and sugar in bottled water for 5 days). The researchers collected rectal samples (n = 120) 5 days after the last antibiotic treatment.
Children who received placebo commonly showed resistance to beta-lactams (73.3%), but this finding was not significantly different compared with other groups. Those who received placebo demonstrated the least resistance to sulfonamide (3.3%).
Oldenburg and colleagues observed that children who received azithromycin were more than twice as likely to have genetic resistance determinants to macrolides (RR = 2.61; 95% CI, 1.55-4.42) compared with placebo. All children who received antibiotics had greater resistance determinants to sulfonamides compared with placebo as well.
Although trimethoprim resistance was not different among children receiving azithromycin or amoxicillin, those who received cotrimoxazole had three times greater genetic resistance determinants compared with placebo (RR = 3.29; 95% CI, 1.08-9.95).
“The presence of resistance genes does not necessarily mean there is functional resistance,” Oldenburg told Infectious Diseases in Children. “While these results suggest that a single course of antibiotics could lead to increased selection for resistance genes, whether this eventually translates to infections that are more difficult to treat is unknown. However, physicians should be aware of potential unintended consequences of unnecessary antibiotic prescription, including the potential for inducing an increase in resistant infections.” – by Katherine Bortz
Disclosures: The authors report no relevant financial disclosures.