Stepwise model to differentiate pathogenic from non-pathogenic organisms in urinary isolates: Effectiveness, safety, and feasibility prospective study.

BACKGROUND

Clinical decision-making in urinary tract infections depends heavily on accurately distinguishing between pathogenic and non-pathogenic organisms. The interpretation of urine culture results is influenced by proper sample collection, the patient's clinical context, and organism-specific characteristics. However, there is currently no definitive method to determine whether a urinary isolate is truly pathogenic. This distinction is critical, as treatment decisions hinge on it. This pioneering study systematically applies a stepwise model to differentiate pathogenic from non-pathogenic urinary isolates-an approach not previously described.

AIM: To determine whether a urinary isolate is pathogenic (commensal, colonizer, or direct pathogen) or non-pathogenic (commensal, colonizer, or contaminant) using a structured, stepwise approach.

METHODS

This prospective, longitudinal, exploratory study was conducted over 24 months, starting in January 2022, at All India Institute of Medical Sciences Rishikesh, following approval from the Institutional Ethics Committee. A stepwise model developed by the investigators was applied to assess the nature of the isolates. Data recorded using REDCap, and analysis was performed using SPSS Version 25.

RESULTS

A total of 275 consecutive patients aged over 18 years with positive urine cultures-initially treated with antibiotics based on microbiological and clinical assessment-were included. The stepwise model classified 90.54% of cases as pathogenic (commensals: 61.81%, colonizers: 14.18%, and direct pathogens: 14.54%) and 9.45% as non-pathogenic. The model showed that there could be a significant reduction in average hospital stay by over 13 days, along with saving approximately Rs. 981 per patient in antibiotic costs in non-pathogenic cohort.

CONCLUSION

This novel model identified that approximately one in ten urinary isolates, initially considered pathogenic and treated with antibiotics, were in fact non-pathogenic. The model is safe, feasible, and potentially valuable in resource-limited settings, warranting broader validation and implementation.