2025/04/25 by Troy Grennan, Mark Hull · 1 voice
Biochemistry, Genetics and Molecular Biology · Medicine · #Antimicrobial Resistance in Staphylococcus #Bacterial Identification and Susceptibility Testing #Drug-Induced Adverse Reactions
paper · doi:10.1093/cid/ciaf220
openalex publication_date 2025/04/25 · openalex created_date 2025/10/10 · openalex updated_date 2026/06/25
To the Editor—We thank Manoharan-Basil and colleagues for their comments [1] on our recently published trial of doxycycline preexposure prophylaxis (doxyPrEP) for sexually transmitted infections (STIs) [2]. Quite justifiably, we share their concerns about antimicrobial resistance (AMR). This is a key evaluation parameter for studies in this field, including doxycycline postexposure prophylaxis (doxyPEP) trials [3–5]. In their letter, they assert that our article concludes that “the risk of doxyPrEP selecting for antimicrobial resistance is low.” This was not our conclusion, and we are pleased to be given an opportunity to clarify our position. Manoharan-Basil and colleagues [1] suggest that we base our assessment on 2 claims: (1) that there was no significant increase in Staphylococcus aureus resistance in our study's immediate arm and, (2) that there is no association between doxycycline and β-lactam resistance in S. aureus. In response we would reiterate, as they rightly point out, that our analysis showed no statistically significant difference in doxycycline-resistant S. aureus between study arms. In addition, despite these nonsignificant findings, we clearly state in our Discussion that “S. aureus from nasal samples showed a potential increase in doxycycline resistance over time”—acknowledging possible longitudinal changes within our trial's immediate doxyPrEP arm. Second, Manoharan-Basil and colleagues reanalyzed our S. aureus AMR data using slightly different parameters (ie, on vs off doxyPrEP) and did find a significant difference (P = .002). It is not surprising that different analytic methods may yield slightly different results, particularly with a low sample size. Regardless of this, we highlight in our article that doxycycline resistance may emerge during doxyPrEP.