MOLECULAR EPIDEMIOLOGY OF EMERGING ANTIBIOTIC RESISTANCE MECHANISMS IN COMMENSAL AND PATHOGENIC BACTERIA IN LATIN AMERICA

Bacterial resistance to antibiotics is a major public health problem, and the increasing spread of multi-resistant isolates represents an alarming challenge due to the limited treatment options for infections caused by these pathogens. This phenomenon is an important concern in low resource countries like those of Latin America, where the combination of factors such as inefficient health systems, poor sanitation and uncontrolled use of antimicrobials provide conditions to develop and maintain resistant strains in the hospital settings, at the community level and in the environment. In this work, was analysed the molecular epidemiology of emerging antibiotic resistance mechanisms in commensal and pathogenic bacteria from Latin America. In particular, the study on the antimicrobial susceptibility of clinical isolates from urinary tract infections in Bolivia allowed to gather insight into the mechanisms of dissemination of emerging resistance determinants of clinical significance (such as CTX-M, RmtB, FOSA3), emphasizing the role of high-risk clones in the dissemination of antimicrobial resistance determinants. The same burning phenomenon can be observed in Argentina, where the dissemination of successful clones, responsible for the diffusion of CTX-M and AAC(6’)-Ib-cr determinants in clinical settings, has partially contributed to the change of ESBL epidemiology in this country. Furthermore the finding of the F33:A-:B- epidemic plasmid (widely disseminated among animals in China) in clinical isolates in Bolivia confirm the role of animals as reservoir of multiresistance bacteria. The routes of spreading of such plasmids are unclear and would deserve further investigation, even though the increasing frequency of international travel and the intensive intercontinental commerce could be an easy way for the circulation of resistant strains. Similarly to pathogenic bacteria, commensals are exposed to the selective pressure of antimicrobial drugs. This exposure may have long-term effects on commensal microbiota, which may evolve in an important reservoir of antibiotic resistant strains potentially transferable to pathogens. Therefore, commensal bacteria are considered indicator in predicting the dissemination of resistance among pathogens. Indeed, surveillance is considered crucial for the implementation of intervention strategies aimed at preserving the efficacy of antimicrobial chemotherapy. Surveillance studies performed on commensal bacteria in healthy children from urban areas of Bolivia and Peru provided new information regarding the dynamics of emergence and dissemination of clinically relevant resistance phenotypes, included those associated to CTX-M and Qnr determinants. To investigate the correlation between resistance rates observed in the microbiota of healthy individuals and in the pathogens circulating in the same setting, we have started collaborating with two hospitals that have recently implemented microbiological diagnosis for UTIs (urinary tract infections) and SSTIs (skin and soft-tissues infections). In this regard, first data concerning the comparison between S. aureus from colonization and infection revealed the circulation of the same clones among carriers and patients. These findings underscore that surveillance of antimicrobial resistance on commensal microbiota can be useful to guide empiric management of infections, especially in settings where microbiological diagnosis is not available. In conclusion, the problem of antimicrobial resistance in Latin America, although a regional challenge, deserves international efforts. Multidisciplinary and collaborative efforts should be made to tackle antibiotic resistance and to achieve “One Health” that is a global health for people, animals and the environment. Investments in education, public health and sanitation, development of guidelines for strategic antibiotic use, attempts to facilitate the access to rapid diagnostic tools, implementation of effective and internationally connected resistance surveillance programs and strict control and transparency in the antimicrobial supply chain are some examples of measures that could help to decelerate de advance of the antimicrobial resistance in low resource countries.