Abstract
BackgroundWhen urine infections are missed in febrile young infants with normal urinalysis, clinicians may worry about the risk – hitherto unverified – of concomitant invasion of blood and cerebrospinal fluid by uropathogens. In this study, we determine the extent of this risk.MethodsIn a retrospective cohort study of febrile 0–89 day old infants evaluated for sepsis in an urban academic pediatric emergency department (1993–1999), we estimated rates of bacteriuric sepsis (urinary tract infections complicated by sepsis) after stratifying infants by urine leukocyte counts higher, or lower than 10 cells/hpf. We compared the global accuracy of leukocytes in urine, leukocytes in peripheral blood, body temperature, and age for predicting bacteruric sepsis. The global accuracy of each test was estimated by calculating the area under its receiver operating characteristic curve (AUC). Chi-square and Fisher exact tests compared count data. Medians for data not normally distributed were compared by the Kruskal-Wallis test.ResultsTwo thousand two hundred forty-nine young infants had a normal screening dipstick. None of these developed bacteremia or meningitis despite positive urine culture in 41 (1.8%). Of 1516 additional urine specimens sent for formal urinalysis, 1279 had 0–9 leukocytes/hpf. Urine pathogens were isolated less commonly (6% vs. 76%) and at lower concentrations in infants with few, compared to many urine leukocytes. Urine leukocytes (AUC: 0.94) were the most accurate predictors of bacteruric sepsis. Infants with urinary leukocytes < 10 cells/hpf were significantly less likely (0%; CI:0–0.3%) than those with higher leukocyte counts (5%; CI:2.6–8.7%) to have urinary tract infections complicated by bacteremia (N = 11) or bacterial meningitis (N = 1) – relative risk, 0 (CI:0–0.06) [RR, 0 (CI: 0–0.02), when including infants with negative dipstick]. Bands in peripheral blood had modest value for detecting bacteriuric sepsis (AUC: 0.78). Cases of sepsis without concomitant bacteriuria were comparatively rare (0.8%) and equally common in febrile young infants with low and high concentrations of urine leukocytes.ConclusionIn young infants evaluated for fever, leukocytes in urine reflect the likelihood of bacteriuric sepsis. Infants with urinary tract infections missed because of few leukocytes in urine are at relatively low risk of invasive bacterial sepsis by pathogens isolated from urine.
Highlights
When urine infections are missed in febrile young infants with normal urinalysis, clinicians may worry about the risk – hitherto unverified – of concomitant invasion of blood and cerebrospinal fluid by uropathogens
The challenge to clinicians when utilizing screening urinalysis – heightened when relying on this test alone for decision-making – is to determine that the test is able to identify urinary tract infections, and that it independently reflects the risk, at the initial visit, of invasive bacterial infections due to the urinary tract pathogen if present
Screening urinalysis is only moderately sensitive and has been reported to miss approximately 20% of urinary tract infections in febrile young infants [3,5,6,7,8,10,15,16,17,18,19,20,21,22]. The worry, when this occurs, is that infants with missed urinary tract infections on account of normal screening urinalysis results will progress to septicemia or bacterial meningitis from concomitant bacteremia unrecognized at the initial visit
Summary
When urine infections are missed in febrile young infants with normal urinalysis, clinicians may worry about the risk – hitherto unverified – of concomitant invasion of blood and cerebrospinal fluid by uropathogens. The diagnosis is suspected when screening urinalysis reveals pyuria and confirmed when a uropathogen is isolated from urine culture When, this infection is missed on account of few leukocytes in urine (a recognized limitation), there is the concern – empirically unsubstantiated at present – that affected infants left untreated at the initial clinical encounter will return with invasive sepsis. This infection is missed on account of few leukocytes in urine (a recognized limitation), there is the concern – empirically unsubstantiated at present – that affected infants left untreated at the initial clinical encounter will return with invasive sepsis For this reason, the challenge to clinicians when utilizing screening urinalysis – heightened when relying on this test alone for decision-making (an option endorsed by clinical practice guidelines for the management of fever in young well-appearing infants [9]) – is to determine that the test is able to identify urinary tract infections, and that it independently reflects the risk, at the initial visit, of invasive bacterial infections due to the urinary tract pathogen if present. We tackle this question, hypothesizing an association in febrile young infants between the concentration of leukocytes in urine and the risk of bacteriuric sepsis
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call