Febrile young infants with abnormal urine dipstick at low risk of invasive bacterial infection

Role of urine Gram stain in young febrile infants with a suspected urinary tract infection: a cohort study

OBJECTIVE

To analyse the performance of the urine Gram stain for predicting a positive urine culture (UC) in young infants with fever without source (FWS) and pyuria.

DESIGN

Observational study; secondary analysis of a prospective registry-based cohort study.

SETTING

Paediatric emergency department; tertiary teaching hospital.

PATIENTS

Infants ≤90 days old with FWS, pyuria and urine Gram stain requested seen between 2010 and 2022.

MAIN OUTCOME MEASURE

Performance of the Gram stain, defined as positive if any bacteria were seen, for predicting urinary tract infection (UTI: UC by urethral catheterisation growing >10 000 CFU/mL of a single bacterial pathogen).

RESULTS

Among 367 febrile infants with pyuria, 281 (76.6%) had a positive Gram stain and 306 (83.3%) had a positive UC (277; 90.5% Escherichia coli).Rates of positive UC in patients with positive and negative Gram stains were 97.2% and 38.4%, respectively (p<0.01), showing a sensitivity of 89.2% (95% CI: 85.2% to 92.2%) and a specificity of 86.9% (95% CI: 76.2% to 93.2%). Sensitivity was lower for diagnosing UTIs caused by bacteria other than E. coli (69.0% vs 91.3% for UTIs caused by E. coli; p<0.01).Two (2.1%) of the 86 infants with negative Gram stains were diagnosed with bacteraemia unrelated to a UTI (Streptococcus pneumoniae and Staphylococcus aureus).

CONCLUSIONS

Around a third of infants with pyuria and a negative Gram stain will eventually be diagnosed with a UTI. These patients have a higher rate of UTIs caused by bacteria other than E. coli. Bacterial infections other than UTIs should also be considered in such cases.

Conundrums in the Management of Febrile Infants under Three Months of Age and Future Research

Febrile infants under three months of age pose a diagnostic challenge to clinicians. Unlike in older children, the rates of invasive bacterial infections (IBIs), such as bacteraemia or meningitis, are high. This greater risk of IBI combined with the practical challenges of assessing young infants results in a cautious approach with many febrile infants receiving parenteral antibiotics "just in case". However, there is a range of validated tailored care guidelines that support targeted investigation and management of febrile infants, with a cohort identified as lower risk suitable for fewer invasive procedures and observation without parenteral antibiotics. This manuscript outlines five common conundrums related to the safe application of tailored-care guidelines for the assessment and management of febrile infants under three months of age. It also explores future research which aims to further refine the management of febrile infants.

Multicentre Delphi study of physicians resulted in quality indicators for young infants with fever without source in emergency departments

AIM

Managing febrile infants has evolved without a generally accepted standard of care. We aimed to design quality indicators for managing infants ≤90 days old presenting to emergency departments (EDs) with fever without source.

METHODS

This multicentre Delphi study was carried out by the Febrile Infant Study Group of the Spanish Paediatric Emergency Research Network, from March 2021 to November 2021, and included paediatric emergency physicians from 24 Spanish EDs. A list of care standards was produced, following an extensive literature review and the involvement of all parties. Indicators were essential if they were voted by four panelists and also received a score of ≥4 from at least 95% of the 24 investigators.

RESULTS

We established 20 indicators, including one related to having a protocol, two to triage, nine to diagnostic processes, six to treatment and two to disposition. The following indicators were considered essential: having an ED management protocol, performing urinalysis on every infant, obtaining a blood culture from every infant and administering antibiotics in the ED to any febrile infant who did not appear well.

CONCLUSION

The Delphi method resulted in a comprehensive list of quality indicators for managing febrile young infants in Spanish EDs.

Febrile Urinary Tract Infection in Infants Less Than 3 Months of Age

INTRODUCTION

Urinary tract infection (UTI) is the leading cause of bacterial infection in infants younger than 3 months of age with fever without a source.

OBJECTIVE

The objective of the study was to analyze the characteristics of emergency department presentations of febrile infants younger than 3 months of age with a UTI and identify risk factors for invasive bacterial infection (IBI) secondary to UTI.

METHODS

This was a secondary analysis of a prospective observational registry that includes infants younger than 3 months with fever without a source managed at a pediatric emergency department between 2003 and 2019.

RESULTS

Of the 2850 patients included, 592 (20.8%) were diagnosed with a UTI (524, 88.5%, for Escherichia coli). Infants with UTIs showed significant clinical differences when compared with those not diagnosed with a bacterial infection: patients with a UTI were more likely to have a history of renal/urological problems (8.3% vs. 3.5%), temperature ≥39ºC (38.3% vs. 29%) and poor feeding (13% vs. 8.7%). Yet, nearly half (285 of the 592, 48.1%) of the infants with febrile UTIs had none of these 3 risk factors. Thirty-six infants (6.1%) had a secondary IBI. We identified the following independent risk factors for secondary IBI: infants younger than 1 month of age, parent-reported irritability, procalcitonin >0.5 ng/mL, and C-reactive protein >60 mg/L.

CONCLUSIONS

History and physical examination do not allow us to safely rule out a UTI among young febrile infants. Age, parent-reported irritability, and biomarkers are useful in identifying patients at increased risk of secondary IBI.

Outpatient and oral management is suitable for infants 60-90 days old with urinary tract infections at low risk of bacteremia

One previous study recommended oral and outpatient management for those infants aged 60-90 days with urinary tract infection (UTI) meeting the low-risk criteria identified: to be well-appearing and to have a procalcitonin value of < 0.7 ng/mL. A retrospective study was conducted, including infants aged 29 to 90 days with UTI from 2014 to 2019, to validate these low-risk criteria identified and determine the adherence to the new algorithm for managing these patients at the Emergency Department. Two hundred one patients were included; 105 (52.2%) were aged 60 to 90 days. Twelve (6%, 95% CI 3.4-10.1%) had bacteremia. One hundred thirty-six (67.7%) infants met low-risk criteria; none had a positive blood culture (0%, 95% CI 0-2.7%). Overall protocol adherence was 90.6%. One hundred and forty-four (71.6%) infants were admitted to the hospital; all patients meeting high-risk criteria were hospitalized. Among the 57 (28.4%) infants initially sent home, 4 (7.0%) required later hospital admission.Conclusions: A prediction rule including general appearance and procalcitonin is highly accurate in identifying young infants with UTI at low risk for bacteremia. Outpatient management with appropriate follow-up is safe for these infants. What is Known: • Patients under 2-3 months of age with a presumptive urinary tract infection (UTI) are commonly hospitalized because of concerns regarding concomitant bacteremia. What is New: • A prediction rule including general appearance and procalcitonin is highly accurate in identifying young infants with UTI at low risk for bacteremia. Outpatient management with appropriate follow-up is safe for these infants.