After applying exclusion criteria, the study included 14 patients that were exposed to azithromycin in the 30 days before diagnosis with gonorrhea, 97 patients exposed between 31 and 60 days before diagnosis, and 212 patients were unexposed to the drug. The majority of patients were of Dutch descent and 73% of the 395 patients included in the study were men who have sex with men (MSM). After adjusting for age, ethnicity, year of infection, and anatomical site, the authors found a significant correlation between exposure and azithromycin MIC. Professor de Vries and his colleagues determined that patients exposed to azithromycin in the 30-day group had azithromycin MICs that were 2.7 times higher than the unexposed group. However, in the group exposed between 31 and 60 days prior to diagnosis, there was no significant association compared to the unexposed group.
In addition to MIC assays, the authors performed whole genome sequencing (WGS) to compare exposed and unexposed isolates in an effort to evaluate molecule resistance markers. The results indicated there were no shared molecular markers based on exposure to azithromycin. However, mutations in the gene mtrR were more common in isolates from patients exposed to azithromycin.
Overall, Professor de Vries and his colleagues demonstrated a significant correlation between higher azithromycin MICs and exposure to the azithromycin, suggesting that frequent use of the drug in high-risk patients can result in antibiotic resistance.
Samar Mahmoud graduated from Drew University in 2011 with a BA in Biochemistry and Molecular Biology. After two years of working in industry as a Quality Control Technician for a blood bank, she went back to school and graduated from Montclair State University in 2016 with an MS in Pharmaceutical Biochemistry. She is currently pursuing her PhD in Molecular and Cellular Biology at the University of Massachusetts at Amherst.
To stay informed on the latest in infectious disease news and developments, please sign up for our weekly newsletter.