Community-level Monitoring of Antimicrobial Resistance following Mass Administration of Azithromycin to Reduce Child Mortality in Côte d'Ivoire: Results from Two Rounds of Surveillance.

BACKGROUND

Mass Drug Administration (MDA) of azithromycin for the elimination of trachoma and, more recently, for the reduction of child mortality, are public health strategies shown, with mixed results, to contribute to the development of azithromycin resistance in treated communities. The objective of this study was to monitor bacterial resistance to azithromycin among children targeted by bi-annual MDA-azithromycin campaigns to improve child survival in eight high-mortality regions of Côte d'Ivoire.

METHODS

Two rounds of cross-sectional surveys were carried out in targeted health districts using a 2-stage cluster sampling to select representative samples of children aged 1-11 months at the time of the most recent MDA. Parents/primary caregivers were interviewed about the child's overall health and exposure to MDA, azithromycin, and other antibiotics. Nasopharyngeal swabs were collected to estimate the carriage of Streptococcus pneumoniae and the prevalence of macrolide-resistant S. pneumoniae using erythromycin as a proxy for azithromycin. Phenotypic and genotypic determinants of macrolide resistance were tested in a subsample of resistant bacteria using duplex PCR.

RESULTS

A total of 606 and 692 eligible children in 2022 and 2023, respectively, were included in the analyses. Prevalence of S. pneumoniae carriage was 28.8% (95%CI:22.4, 35.3) in 2022 and 30.8% (95%CI:25.0, 36.7) in 2023 (p=0.6506). There was no statistically significant difference in the prevalence of erythromycin-resistant S. pneumoniae between the two surveys (32.8% (95%CI:25.3, 40.2) versus 26.2% (95%CI:19.8, 32.6); p=0.0537). The majority of macrolide resistance phenotypes in both surveys were predominantly constitutive macrolide-lincosamide-streptogramin B (MLSb), carried by erm(B)-type genes.

CONCLUSIONS

Community-level bacterial resistance to azithromycin in our samples of S. pneumoniae did not increase significantly between the two surveys. As countries weigh the benefits and costs to implement MDA azithromycin, more is needed to interpret the relevancy and clinical impact of observed antimicrobial resistance.