A new study published in The Lancet, Infectious Diseases, has found that mass treatment with azithromycin (AZM), a common antibiotic, can lead to increased drug resistance in harmful bacteria.
Researchers from the Malawi Liverpool Wellcome Programme, the University of Liverpool, the London School of Hygiene & Tropical Medicine, the Wellcome Sanger Institute and Yale University have discovered that mass use of the antibiotic can boost antimicrobial resistance (AMR) in bacterial strains known to cause pneumonia and meningitis.
The researchers found that in areas that had received antibiotics en masse, resistance to AZM and similar antibiotics rose from 21.7% to 32.1% three and a half years after treatment concluded, and that this resistance also spread to children born in these communities subsequently.
However, resistance also increased in areas that had received a placebo, from 21% to 30.9% three and a half years post-treatment, suggesting that AMR appeared to be spreading across communities.
Additionally, S. pneumoniae strains were identified that had acquired resistance to multiple other antibiotics, including the frontline antibiotic penicillin, which is in widespread use.
This has raised concerns, as the consistent use of AZM and other common antibiotics has the potential to trigger the evolution and spread of strains with AMR.
To assess how this could impact countries using mass antibiotic adminstration to manage childhood mortality, the authors of the study are calling for long-term genomic surveillance, which could be used to monitor trends in antibiotic resistance.
By following through on this, they could accurately perform a benefit/risk assessment of mass antibiotic adminstration and the potential of AMR, allowing healthcare services to make interventions if necessary.
"Our findings highlight the potential trade-offs between mass antibiotic administration to improve childhood survival and increased AMR that makes common infections more difficult to treat. It is important to get the balance right," stated Dr Akuzike Kalizang’oma, lead researcher on the study from UCL Division of Infection & Immunity and the Malawi Liverpool Wellcome Programme.
“In high mortality regions where this type of programme is being rolled out, mortality surveillance to assess the benefits of intervention is needed, so that the risks of AMR can be appropriately weighed against the benefits of MDA. Careful monitoring using robust genomic approaches to monitor the impact of MDA, and guide the appropriate course of action to prevent resistant strains from rapidly spreading in the community is also essential."
According to Professor Robert Heyderman, senior author of the study from UCL Division of Infection & Immunity, it has long been believed that resistance to macrolide antibiotics such as AZM goes away once you stop using them.
"We've now shown that pneumococcal AZM resistance persists and spreads to children not exposed to the antibiotic, and the emergence of pneumococcal AZM resistance is frequently associted with resistance to other important antibiotics."
“Without timely detection of resistant strains and intervention, these trends may become difficult to reverse.”
The authors stress that AZM MDA programmes remain an important tool for improving child survival in populations where mortality is unacceptably high.
However, the findings of the study raise questions about the long-term impact of MDA on public health. Without timely detection and intervention, they say these trends have the potential to make common serious infections much more difficult to treat, potentially reversing the benefits of the MDA programme.