Objective To estimate the excess costs of urinary tract infection associated with catheter use and clinical interventions that influence costs the most. Methods A study of cohorts paired by the time of occurrence of the nosocomial event was carried out. Those exposed were patients with urinary tract infection associated with catheters and those unexposed were patients without nosocomial infection, admitted with a similar diagnosis. In both cohorts the direct costs of hospital care were evaluated. Results Excess total cost of care for a urinary tract infection associated with catheter was 2 460 168 (Colombian pesos in 2009). The highest percentage (71.8 %) was attributed to the days of hospitalization in the general ward; daily valuations contributed 19.1%, followed by antibiotics (6%), blood cultures (5 %), arterial blood gases (2 %). The remaining cost categories contributed less than 1 % each. Discussion This study tried to get closer to the actual cost, using variables such as ultrasound, arterial blood gases and others unused in previous studies in addition to the common variables such as length of hospital stay, and consumption of antibiotics. To our knowledge this is the first study of micro costs of nosocomial infections that has been done in the country, using a cohort as a design. Conclusion It was found that urinary tract infection associated with catheter use had a direct excess of costs of 2 460 168 Colombian pesos (US$ 1 329 dollars in 2009) It was found that urinary tract infection associated with catheter had a direct excess of costs of 2 460 168 Colombian pesos (US$ 1 329 dollars in 2009).