Predictive utility of prior positive urine culture of extended- spectrum β -lactamase producing strains.

Rising incidence of extended- spectrum beta-lactamase (ESBL) induced urinary tract infections (UTIs) is an increasing concern worldwide. Thus, it is of paramount importance to investigate novel approaches that can facilitate the identification and guide empiric antibiotic therapy in such episodes. The study aimed to evaluate the usability of antecedent ESBL-positive urine culture to predict the pathogenic identity of future ones. Moreover, the study evaluated the accuracy of selected empiric therapy in index episodes. This was a retrospective study that included 693 cases with paired UTI episodes, linked to two separate hospital admissions within 12 month-period, and a conditional previous ESBL positive episode. Pertinent information was obtained by reviewing patients' medical records and computerized laboratory results. Multivariate analysis showed that shorter interval between index and previous episodes was significantly associated with increased chance of ESBL-positive results in current culture (OR = 0.912, 95CI% = 0.863-0.963, p = 0.001). Additionally, cases with ESBL-positive results in current culture were more likely to have underlying urological/surgical condition (OR = 1.416, 95CI% = 1.018-1.969, p = 0.039). Investigations of the accuracy of current empirical therapy revealed that male patients were less accurately treated compared to female patients (OR = 0.528, 95CI% = 0.289-0.963, p = 0.037). Furthermore, surgical patients were treated less accurately compared to those treated in internal ward (OR = 0.451, 95CI% = 0.234-0.870, p = 0.018). Selecting an agent concordant with previous microbiologic data significantly increased the accuracy of ESBL-UTIs therapy (p<0.001). A quick survey of the previous ESBL urine culture results can guide practitioners in the selection of empiric therapy for the pending current culture and thus improve treatment accuracy.