Nonresponders: Prolonged Fever Among Infants With Urinary Tract Infections Richard Bachur, MD ABSTRACT. Background. The majority of young chil- dren with fever and urinary tract infections (UTIs) have evidence of pyelonephritis based on renal scans. Resolu- tion of fever during treatment is 1 clinical marker of adequate treatment. Theoretically, prolonged fever may be a clue to complications, such as urinary obstruction or renal abscess. Objective. Describe the pattern of fever in febrile children undergoing treatment of a UTI. Compare the clinical characteristics of those patients with prolonged fever to those who respond faster to therapy. Setting. An urban pediatric hospital. Design. Medical record review. Methods. All children <2 years old admitted to the pediatric service with a primary discharge diagnosis of pyelonephritis or UTI were reviewed for 65 consecutive months. Patients with previous UTI, known urologic problems, or immunodeficiency were excluded. Only pa- tients with an admitting temperature >38°C and those who met standard culture criteria were studied. Temper- atures are not recorded hourly on the inpatient unit; therefore, they were assigned to blocks of time. Nonre- sponders were defined as those above the 90th percentile for the time to defervesce. Nonresponders were then compared with the balance of the study patients, termed responders. Results. Of 288 patients studied, the median age was 5.6 months (interquartile range: 1.3–7.9 months old). Me- dian admission temperature was 39.3°C (interquartile range: 38.5°C– 40.1°C). Median time to defervesce ranged in the time block 13 to 16 hours. Sixty-eight percent were afebrile by 24 hours and 89% by 48 hours. Thirty-one patients had fever >48 hours (nonresponders). Nonre- sponders were older than responders (9.4 vs 4.1 months old) but had similar initial temperatures (39.8 vs 39.2°C), white blood cell counts (18.4 vs 17.1 1000/mm 3 ), and band counts (1.4 vs 1.2 1000/mm 3 ). Nonresponders had similar urinalyses with regard to leukocyte esterase pos- itive (23/29 vs 211/246), nitrite-positive (8/28 vs 88/221], and the number of patients with “too numerous to count” white blood cell counts per high power field (12/28 vs 77/220). Nonresponders were as likely as responders to have bacteremia (3/31 vs 21/256), hydronephrosis by renal ultrasound (1/31 vs 12/232), and significant vesicoureteral reflux (more than or equal to grade 3; 5/26 vs 30/219). Eschericia coli was the pathogen in cultures of 28 of 31 (nonresponders) and 225 of 257 (responders) cultures. The number of cultures with >100 colony-forming units/mL was similar (25/31 nonresponders vs 206/257 responders). Repeat urine cultures were performed in 93% of patients during the admission; all culture results were negative. No renal abscesses or pyo-hydronephrosis was diagnosed. Conclusions. Eighty-nine percent of young children with febrile UTIs were afebrile within 48 hours of initi- ating parenteral antibiotics. The patients who took longer than 48 hours to defervesce were clinically similar to those whose fevers responded faster to therapy. If antibiotic sensitivities are known, additional diagnostic studies or prolonged hospitalizations may not be justi- fied solely based on persistent fever beyond 48 hours of therapy. Pediatrics 2000;105(5). URL: http://www. pediatrics.org/cgi/content/full/105/5/e59; urinary tract in- fection, pyelonephritis, pediatric, antibiotic, fever. ABBREVIATIONS. UTI, urinary tract infection; IQR, interquartile range; CI, confidence interval; WBC, white blood cell. U rinary tract infections (UTIs) are present in 5% of infants with fever, including 17% of white female infants with a temperature of 39.0°C and no apparent source of fever by exami- nation. 1 The majority of febrile children with UTIs have evidence of pyelonephritis. 2,3 Resolution of the fever during treatment is 1 clinical marker of ade- quate treatment. For patients who are initially man- aged as outpatients, prolonged fever has been evoked as a reason to admit for parenteral antibiot- ics. Likewise, for those initially managed as inpa- tients, the absence of fever has been used as a dis- charge criterion. Theoretically, prolonged fever may be a clue to complications, such as urinary tract obstruction or renal abscess. The American Academy of Pediatrics recently published a practice parameter for young children with a first-time febrile UTI. 4 Contained within these guidelines, 2 recommendations refer to patients with prolonged fever: 1) infants and young children 2 months to 2 years of age with UTI who have not had the expected clinical response with 2 days of antimi- crobial therapy should be reevaluated and another urine specimen should be cultured; 2) infants and young children 2 months to 2 years of age with UTI who do not demonstrate the expected clinical re- sponse within 2 days of antimicrobial therapy should undergo ultrasound promptly. The strength of evi- dence for these 2 recommendations was rated as good and fair, respectively. From the Division of Emergency Medicine, Children’s Hospital, Boston, Massachusetts. This work was presented at the Ambulatory Pediatric Association/Society for Pediatric Research meeting; May 1– 4, 1999; San Francisco, CA. Received for publication Sep 13, 1999; accepted Nov 29, 1999. Reprint requests to (R.B.) Division of Emergency Medicine, Children’s Hospital, 300 Longwood Ave, Boston, MA 02115. E-mail: bachur@a1.tch. harvard.edu PEDIATRICS (ISSN 0031 4005). Copyright © by the American Academy of Pediatrics. http://www.pediatrics.org/cgi/content/full/105/5/e59 PEDIATRICS Vol. 105 No. 5 May 2000 1 of 4 by guest on July 14, 2016 Downloaded from