A comprehensive clinical and microbiological profile of culture-positive urinary episodes in children with acute lymphoblastic leukemiaurinary leukemia

Objective: This study aimed to assess the frequency, causative microorganisms, antimicrobial resistance patterns, and unusual clinical and laboratory findings of culture-positive urinary episodes throughout the entire chemotherapy course in pediatric patients with Acute Lymphoblastic Leukemia (ALL). Material and Methods: We reviewed the medical records of 93 pediatric ALL patients who completed BFM-based chemotherapy protocols between 2019 and 2025. A total of 1265 urine cultures were analyzed. Culture positivity was defined as ≥105 colony-forming units per milliliter (CFU/mL) of a single or two different pathogens. For retrospective analysis, contamination was defined by a negative control culture within 48–72 hours or clinical resolution without antibiotic treatment. Data on urinalysis, neutropenia status, and antibiotic resistance were collected. Results: Forty-eight patients (51.6%) experienced a median of two culture-positive episodes. Incidence was highest during intensive treatment phases (induction, reinduction). Escherichia coli was the most common agent (39.8%), followed closely by Klebsiella pneumoniae (36.7%). Overall ESBL positivity was 26.6%. A concerning 30.6% of K. pneumoniae isolates showed carbapenem resistance. Standard urinalysis was found to be unreliable, with 71.4% of positive cultures lacking typical findings; leukocyturia was only present when the absolute neutrophil count was relatively preserved. Three cases of urosepsis (3%) were identified, all involving highly resistant organisms. Conclusion: Pediatric ALL patients, particularly during intense chemotherapy, face a high burden of culture-positive urinary episodes and a notable shift towards multidrug-resistant non-E. coli pathogens like K. pneumoniae. The unreliability of standard urinalysis in this immunocompromised population necessitates the routine collection of urine cultures during febrile neutropenia workups, irrespective of symptoms, to ensure timely, targeted therapy guided by local resistance data. The observed extreme resistance profile appears to be a transient reflection of the intensive chemotherapy environment.