## 5 Bridging Concept and Practice in the Implementation of National Surveillance Studies
Combining these methodologies in a multipronged approach, where culture-based methods validate molecular findings, may be one potential framework for surveillance. The variability in antibiotic prescribing practices [77; 78] means that regional and/or national surveillance programs should prioritize the inclusion of diverse clinical isolates from symptomatic and asymptomatic infections as well as from both urogenital and extra-genital sites. This is especially important in regions with high azithromycin or tetracycline consumption, where selective pressure may drive the emergence of resistance mechanisms that have yet to be fully characterized [68; 72]. Additionally, in the future, periodic reassessment of treatment guidelines may be more readily informed by MICs and MCCs rather than by historical efficacy alone. Figure 1: A simplified diagram of the proposed surveillance algorithm to monitor _Chlamydia trachomatis_ (_C. trachomatis_) antimicrobial susceptibility trends. Collaboration among microbiology laboratories, public health agencies, and clinical practitioners is essential for establishing a sustainable and effective surveillance network for _C. trachomatis_ antimicrobial susceptibility [79]. Considering all the challenges associated with _C. trachomatis_ culture-based AST, which is not routinely performed in clinical microbiology laboratories, there is a need to include institutes for public health and national/regional reference laboratories (as is the case in infectious disease surveillance in general) and adequately fund them [80]. They should also take the lead in ensuring diagnostic stewardship and data quality across different geographic regions and healthcare systems [81]. Public health agencies should also be tasked with facilitating coordination between laboratories, providing logistical support, funding, and policy guidance to integrate sensitivity profiles into broader STI surveillance and control programs. Equally significant is the involvement of clinical practitioners who manage chlamdial infections on the front lines. They should be included in surveillance efforts by contributing clinical data and recognizing potential treatment failures but also advocating for confirmatory testing in cases of persistent infections [82]. Training programs for healthcare providers, which are already part of continuing medical education to increase screening yields [83], should additionally emphasize the importance of monitoring treatment efficacy and implementing follow-up testing in high-risk populations. Additionally, collaborations with primary care providers and sexual health services (primarily STI clinics) are indispensable if we aim for the surveillance data to reflect real-world treatment outcomes. To achieve consistency and reproducibility across different settings, standardized protocols for _C. trachomatis_ AST must be developed and widely adopted, which is still something the medical community needs to work on. These should encompass not only traditional cell culture-based approaches but also molecular assays that detect resistance-associated mutations in key genes such as _235 rRNA_ (for macrolides), _ompB/porB_ and _tetM_ (for tetracyclines), _gyrA/parC_ (for fluoroquinolones), and efflux pump-related genes (Table 1). The establishment of international reference panels for AST, including wild-type and resistant _C. trachomatis_ strains, would allow laboratories to calibrate their methods and interpret results with greater reliability. A good step forward would be the definition epidemiological cut-off values (ECOFFs) and clinical breakpoints for _C. trachomatis_ to establish resistance [84], as this is the way to differentiate natural MIC variability from true resistance. Beyond traditional AST, genomic surveillance initiatives should be incorporated into routine clinical and epidemiological investigations to enable the early detection of resistance-associated mutations and their potential transmission dynamics.