‘Reassuring’: No long-term resistance in S. pneumonia after mass antibiotic dosing
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There was a short-term increase in selection for resistance in Streptococcus pneumoniae among children who received azithromycin during a mass administration of the antibiotic, but no evidence of long-term resistance, a study found.
Past studies have shown that mass administration of broad-spectrum antibiotics like azithromycin can reduce child mortality in sub-Saharan Africa, although perhaps not without a risk for antibiotic resistance.
Catherine E. Oldenburg, ScD, MPH, an infectious disease epidemiologist and associate professor at the University of California, San Francisco, and co-author of the new study published recently in The Pediatric Infectious Disease Journal, said they conducted the investigation to understand the implications that mass distribution of azithromycin may have against pneumococcus at an “individual child level.”
She called pneumococcus “an important organism that can cause an invasive disease that causes pneumonia in children who are getting azithromycin.”
“Azithromycin has been shown in trials in three countries in Africa to be effective at reducing childhood mortality when distributed biannually to all children under the age of 5 in a given community,” Oldenburg said. “One of the outstanding questions in this line of research has been: What are the mechanisms of azithromycin for preventing childhood mortality? And what are the consequences? The big one is ... What are the implications in terms of antimicrobial resistance?”
Oldenburg and colleagues conducted a randomized controlled trial in Nouna Town, Burkina Faso, that randomly assigned 450 children aged 3 to 59 months to a single oral dose of azithromycin (n = 230) or a matching placebo (n = 220). The prevalence of pneumococcal carriage at baseline was 44% among participants.
Study participants were seen at 2 weeks and 6 months, allowing the researchers to examine short- and long-term effects on antimicrobial resistance.
At the short-term review, pneumococcal carriage was significantly lower in the group that had received azithromycin at 27% vs. 41% in the control group, but the former group had a higher prevalence of resistance to erythromycin (55% vs. 13%), oxacillin (73% vs. 43%) and clindamycin (33% vs. 9%).
At the 6-month long-term review, there was no significant difference in pneumococcal carriage between children receiving the azithromycin (44% vs. 51%; P = 0.92) and the prevalence of resistance was the same, returning approximately to baseline in the treatment arm.
The results, Oldenburg said, were not surprising but rather “reassuring.”
“The reassuring part was that at 6 months, there was no difference between arms, and so that suggests that although you see sort of the short-term selection, things normalize over time,” Oldenburg said.
Oldenburg added that she and her fellow researchers are continuing to examine the effects.
“We have a couple of studies that are ongoing, that are looking at different leads in how azithromycin should be used for prevention of childhood mortality,” Oldenburg said. “So, we have a number of studies in the pipeline now that are looking at different uses for azithromycin for childhood mortality, including using different targeting strategies and comparing mass azithromycin distributions.”
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