A recent study published in the Clinical Infectious Diseases journal highlight the complex impacts of administering azithromycin to women during labor. The randomized trial helps to understand the effects of intrapartum azithromycin on the prevalence of bacterial carriage and antibiotic resistance with significant implications for maternal and infant health.
The study included pregnant women who received either a 2g dose of azithromycin or a placebo during labor. The study analyzed the presence and antibiotic resistance of Escherichia coli (E. coli) and Klebsiella pneumoniae (K. pneumoniae) in various samples taken from both mothers and infants. These samples included rectal swabs (RS), nasopharyngeal swabs (NPS), breast milk, and recto-vaginal swabs (RVS). The bacteria were isolated using microbiological methods and their antibiotic susceptibility was tested with an E-test. The study used prevalence ratios (PR) with 95% confidence intervals (CIs) to compare outcomes between the two groups.

The key findings of this study were;
Reduction in Carriage: Infants whose mothers received azithromycin had a lower prevalence of E. coli in their rectal swabs at both six days (63.0% vs. 75.2%; PR 0.84, CI 0.75-0.95) and 28 days (52.7% vs. 70.4%; PR 0.75, CI 0.64-0.87) post-intervention.
Increase in Resistance: However, these infants showed a higher prevalence of azithromycin-resistant E. coli at both six days (13.4% vs. 3.6%; PR 3.75, CI 1.83-7.69) and 28 days (16.4% vs. 9.6%; PR 1.71, CI 1.05-2.79).
Increase in Carriage: The study found a higher prevalence of K. pneumoniae in the rectal swabs of infants in the azithromycin group at six days (49.6% vs. 37.2%; PR 1.33, CI 1.08-1.64) and 28 days (53.6% vs. 32.9%; PR 1.63, CI 1.31-2.03) post-intervention.
Increase in Resistance: There was also a notable rise in azithromycin-resistant K. pneumoniae at day 28 in the intervention group (7.3% vs. 2.1%; PR 3.49, CI 1.30-9.37).

The study found no significant differences in the other sample types (NPS, breast milk, RVS) regarding bacterial carriage and resistance. While intrapartum azithromycin effectively reduced the carriage of E. coli in infants, it also led to an increased carriage and resistance of K. pneumoniae and elevated azithromycin resistance in both bacteria. These results illuminate the need for a careful evaluation of the benefits and potential long-term impacts of using azithromycin during labor.
Source:
Getanda, P., Jagne, I., Bognini, J. D., Camara, B., Sanyang, B., Darboe, S., Sambou, E., Barry, M., Kassibo, K., Cham, A., Mendy, H., Singateh, B. K. J., Ndure, E., Rouamba, T., Bojang, A., Bottomley, C., Howden, B. P., D’Alessandro, U., … Tinto, H. (2024). Impact of Intrapartum Azithromycin on the Carriage and Antibiotic Resistance of Escherichia coli and Klebsiella pneumoniae in Mothers and their Newborns: a sub-study of a Randomized Double-Blind Trial Conducted in The Gambia and Burkina Faso. In Clinical Infectious Diseases. Oxford University Press (OUP). https://doi.org/10.1093/cid/ciae280