The main mechanisms of antimicrobial resistance are described using the Vitek 2 system in uropathogens isolated in older adults from a private clinic in Lima. Descriptive study conducted between January 2014 and October 2016. Escherichia coli, Klebsiella pneumoniae, and Proteus mirabilis obtained a sensitivity greater than 80% against piperacillin/ tazobactam, amikacin, and carbapenems. Moreover, 83.6% of Escherichia coli were nitrofurantoin-sensitive strains. A 41.7% of Escherichia coli, 50.9% of Klebsiella pneumoniae, and 50% of Proteus mirabilis were producers of extended spectrum beta-lactamases (ESBL). Similarly, 60% of Pseudomonas aeruginosa were producers of carbapenemases. Active site modification (PBP) and enzymatic inactivation by penicillinases occurred in 7.8% of Enterococcus faecalis. Resistance to aminoglycosides was presented in Escherichia coli (27.1%), Klebsiella pneumoniae (46.7%), and Proteus mirabilis (84.6%) for the production of modifier enzymes. There is an increase in bacterial resistance in relation to age. Enzymatic inactivation of beta-lactam antibiotics and aminoglycosides is the most common resistance mechanism.