Antimicrobial resistance in commensal and pathogenic bacteria from resource-limited settings

Antimicrobial resistance (AMR) is a global health issue, particularly severe in resource-limited countries (RLCs) due to factors like limited healthcare access, poor sanitation, and unreliable water. These issues increase disease rates, especially in children. While high-income countries have programs to control AMR, many RLCs lack such actions. Commensal bacteria, though not targeted by antibiotics, develop resistance and serve as reservoirs for resistant strains and genes. This PhD research focused on the molecular epidemiology of antibiotic resistance in commensal and uropathogenic bacteria in the Bolivian Chaco. The study found a significant increase in CTX-M determinants (responsible of resistance to 3rd generation cephalosporins) in commensal E. coli among healthy children living in rural areas. Pandemic E. coli clones ST131 and ST1193 were widespread among these bacteria. Uropathogenic bacteria in hospitalized patients showed high resistance rates, with multidrug-resistant profiles and similar CTX-M enzyme prevalence. Also in this case we found a relevant prevalence of pandemic E. coli clones ST131 and ST1193. In community-acquired urinary tract infections (UTIs), E. coli exhibited high resistance, including first-line UTI’s antibiotic fosfomycin and last-resort antibiotic colistin. These findings highlight the need for a comprehensive approach to address AMR, recognizing it as a complex ecological challenge. Ongoing surveillance in settings with limited antibiotic exposure is essential to gain insights into the evolution of antibiotic resistance.