An all-inclusive model for predicting invasive bacterial infection in febrile infants age 7-60 days

BACKGROUND

Invasive bacterial infections (IBIs) in febrile infants are rare but potentially devastating. We aimed to derive and validate a predictive model for IBI among febrile infants age 7-60 days.

METHODS

Data were abstracted retrospectively from electronic records of 37 emergency departments (EDs) for infants with a measured temperature >=100.4 F who underwent an ED evaluation with blood and urine cultures. Models to predict IBI were developed and validated respectively using a random 80/20 dataset split, including 10-fold cross-validation. We used precision recall curves as the classification metric.

RESULTS

Of 4411 eligible infants with a mean age of 37 days, 29% had characteristics that would likely have excluded them from existing risk stratification protocols. There were 196 patients with IBI (4.4%), including 43 (1.0%) with bacterial meningitis. Analytic approaches varied in performance characteristics (precision recall range 0.04-0.29, area under the curve range 0.5-0.84), with the XGBoost model demonstrating the best performance (0.29, 0.84). The five most important variables were serum white blood count, maximum temperature, absolute neutrophil count, absolute band count, and age in days.

CONCLUSION

A machine learning model (XGBoost) demonstrated the best performance in predicting a rare outcome among febrile infants, including those excluded from existing algorithms.

IMPACT

Several models for the risk stratification of febrile infants have been developed. There is a need for a preferred comprehensive model free from limitations and algorithm exclusions that accurately predicts IBIs. This is the first study to derive an all-inclusive predictive model for febrile infants aged 7-60 days in a community ED sample with IBI as a primary outcome. This machine learning model demonstrates potential for clinical utility in predicting IBI.

Epidemiology of Nontyphoidal Salmonella Bloodstream Infections in Children

BACKGROUND

Nontyphoidal Salmonella (NTS) infections are the most common culture-confirmed foodborne illness in the United States. Although extremes of age and chronic or immunosuppressing conditions are known risk factors for NTS bloodstream infection (BSI), further predictors of BSI and BSI with focal infection in children remain poorly understood.

METHODS

This was a retrospective review of NTS-positive blood cultures collected from 1999 to 2018 and stool studies collected from 2009 to 2018 in children. Incidence rates and risk factors for NTS BSI with and without focal infection were determined.

RESULTS

Incidence rates of NTS BSI have not decreased over the last 20 years. There were 211 cases of NTS BSI with an incidence rate of 1.4 per 100 000 children per year. Twenty-one (10%) had underlying comorbidities. S. heidelberg was the most common serotype occurring in 45 (21%) cases. Compared with children with uncomplicated NTS BSI, children with NTS BSI with focal infection were more likely to have an underlying comorbidity, less diarrhea, and higher absolute neutrophil count. On multivariable analysis, the only difference in having NTS BSI in children with NTS gastroenteritis who had blood cultures obtained was a longer duration of fever (4.4 vs 2.5 days), less bloody diarrhea, and S. heidelberg isolated from stool. Laboratory studies, group of NTS, and other symptoms were not significant.

CONCLUSIONS

Clinicians should remain vigilant for NTS BSI in children with prolonged fevers. S. heidelberg is the most common cause of NTS BSI in children and a predictor of BSI in children with NTS gastroenteritis.

CA FIRST (California Febrile Infant Risk Stratification Tool) Algorithm Development in a Learning Health System

Introduction There is considerable variation in the approach to infants presenting to the emergency department (ED) with fever. The authors' primary aim was to develop a robust set of algorithms using community ED data to inform modifications of broader clinical guidance. Methods The authors report the development of California Febrile Infant Risk Stratification Tool (CA FIRST) using key components of the Roseville Protocol (ROS) and American Academy of Pediatrics (AAP) Clinical Practice Guideline (CPG). Expanded guidance was derived using a retrospective analysis of a cohort of 3527 febrile infants aged 7-90 days presenting to any Kaiser Permanente Northern California ED between 2010 and 2019 who underwent a core febrile infant evaluation. Results Melding ROS and AAP CPG algorithms in infants 7-60 days old, CA FIRST Algorithms had comparable performance characteristics to ROS and AAP CPG. CA FIRST enhancements included guidance on febrile infants 61-90 days old, high-risk infants, infants with bronchiolitis, and infants who received immunizations within the prior 48 hours. This retrospective analysis revealed that of 235 febrile infants 22-90 days old with respiratory syncytial virus and 221 who had fever in the 48 hours following vaccination, there were no cases of invasive bacterial infection. Discussion CA FIRST is a set of 13 algorithms providing a thoughtful and flexible approach to the febrile infant while minimizing unnecessary interventions. Conclusions CA FIRST Algorithms empower clinicians to manage most febrile infants. Algorithms are being modified as new data become available, imparting useful and ever-current educational information within a learning health care system.

Following Birth Hospitalization: Invasive Bacterial Infections in Preterm Infants Aged 7-90 Days

OBJECTIVE

To assess the incidence rate of invasive bacterial infections in preterm infants and compare invasive bacterial infection rates and pathogens between preterm and full-term infants at age 7-90 days.

STUDY DESIGN

This is a retrospective cohort study of the incidence rate of invasive bacterial infections among all infants born at Kaiser Permanente Northern California (KPNC), with blood and cerebrospinal fluid cultures collected between 7 and 90 days of chronological age from outpatient clinics, from emergency departments, and in the first 24 hours of hospitalization presenting for care between January 1, 2005, and December 31, 2017. Incidence rates of invasive bacterial infection by chronological age and postmenstrual age (PMA) and pathogens were compared between preterm and full-term infants.

RESULTS

Between January 1, 2005, and December 31, 2017, a total of 479 729 infants were born at KPNC, including 440 070 full-term infants and 39 659 preterm infants. There were 283 cases of bacteremia in 282 infants. The incidence rate of invasive bacterial infection was significantly higher for preterm infants compared with full-term infants. The highest incidence rates of invasive bacterial infection were in preterm infants at chronological age 7-28 days and/or 37-39 weeks PMA. There was a trend toward lower rates of invasive bacterial infection with increasing PMA in preterm infants aged 61-90 days. Preterm infants aged 29-60 days or at ≥40 weeks PMA and those aged 61-90 days or at ≥43 weeks PMA had a rate of invasive bacterial infection equivalent to the overall rate seen in full-term infants of the same chronological age group. The distribution of pathogens causing bacteremia and meningitis did not differ between preterm and full-term infants.

CONCLUSION

PMA and chronological age together were more useful than either alone in informing the incidence rate of invasive bacterial infection in preterm infants during the first 90 days of life.

Using AAP Guidelines for Managing Febrile Infants Without C-Reactive Protein and Procalcitonin

BACKGROUND AND OBJECTIVES

In 2021, the American Academy of Pediatrics (AAP) published the Clinical Practice Guideline (CPG) for management of well-appearing, febrile infants 8 to 60 days old. For older infants, the guideline relies on several inflammatory markers, including tests not rapidly available in many settings like C-reactive protein (CRP) and procalcitonin (PCT). This study describes the performance of the AAP CPG for detecting invasive bacterial infections (IBI) without using CRP and PCT.

METHODS

This retrospective cohort study included infants aged 8 to 60 days old presenting to Kaiser Permanente Northern California emergency departments between 2010 and 2019 with temperatures ≥38°C who met AAP CPG inclusion criteria and underwent complete blood counts, blood cultures, and urinalyses. Performance characteristics for detecting IBI were calculated for each age group.

RESULTS

Among 1433 eligible infants, there were 57 (4.0%) bacteremia and 9 (0.6%) bacterial meningitis cases. Using absolute neutrophil count >5200/mm3 and temperature >38.5°C as inflammatory markers, 3 (5%) infants with IBI were misidentified. Sensitivities and specificities for detecting infants with IBIs in each age group were: 8 to 21 days: 100% (95% confidence interval [CI] 83.9%-100%) and 0% (95% CI 0%-1.4%); 22 to 28 days: 88.9% (95% CI 51.8%-99.7%) and 40.4% (95% CI 33.2%- 48.1%); and 29 to 60 days: 93.3% (95% CI 77.9%-99.2%) and 32.1% (95% CI 29.1%- 35.3%). Invasive interventions were recommended for 100% of infants aged 8 to 21 days; 58% to 100% of infants aged 22 to 28 days; and 0% to 69% of infants aged 29 to 60 days.

CONCLUSIONS

When CRP and PCT are not available, the AAP CPG detected IBI in young, febrile infants with high sensitivity but low specificity.

Clinical management and outcomes for febrile infants 29–60 days evaluated in community emergency departments

Objective

Describe emergency department (ED) management and patient outcomes for febrile infants 29–60 days of age who received a lumbar puncture (LP), with focus on timing of antibiotics and type of physician performing LP.

Methods

Retrospective observational study of 35 California EDs from January 1, 2010 through December 31, 2019. Primary analysis was among patients with successful LP and primary outcome was hospital length of stay (LOS). Logistic regression analysis included variables associated with LOS of at least 2 days. Secondary outcomes were bacterial meningitis, hospital admission, length of antibiotics, and readmission.

Results

Among 2569 febrile infants (median age 39 days), 667 underwent successful LP and 633 received intravenous antibiotics. Most infants (n = 559, 88.3%) had their LP before intravenous antibiotic administration. Pediatricians performed 54% of LPs and emergency physicians 34%. Sixteen infants (0.6% of 2569) were diagnosed with bacterial meningitis, and none died. Five hundred and fifty‐eight (88%) infants receiving an LP were hospitalized. Among patients receiving an LP and antibiotics (n = 633), 6.5% were readmitted within 30 days. Patients receiving antibiotics before LP had a longer length of antibiotics (+ 7.9 hours, 95% confidence interval [CI] 3.8–13.4). Primary analysis found no association between timing of antibiotics and LOS (odds ratio [OR] 0.67, 95% CI 0.34–1.30), but shorter LOS when emergency physicians performed the LP (OR 0.66, 95% CI 0.45–0.97).

Conclusions

Febrile infants in the ED had no deaths and few cases of bacterial meningitis. In community EDs, where a pediatrician is often not available, successful LP by emergency physician was associated with reduced inpatient LOS.

Management and Outcomes in Children with Third-Generation Cephalosporin-Resistant Urinary Tract Infections

BACKGROUND

Third-generation cephalosporin-resistant urinary tract infections (UTIs) often have limited oral antibiotic options with some children receiving prolonged parenteral courses. Our objectives were to determine predictors of long parenteral therapy and the association between parenteral therapy duration and UTI relapse in children with third-generation cephalosporin-resistant UTIs.

METHODS

We conducted a multisite retrospective cohort study of children <18 years presenting to acute care at 5 children's hospitals and a large managed care organization from 2012 to 2017 with a third-generation cephalosporin-resistant UTI from Escherichia coli or Klebsiella spp. Long parenteral therapy was ≥3 days and short/no parenteral therapy was 0-2 days of concordant parenteral antibiotics. Discordant therapy was antibiotics to which the pathogen was non-susceptible. Relapse was a UTI from the same organism within 30 days.

RESULTS

Of the 482 children included, 81% were female and the median age was 3.3 years (interquartile range: 0.8-8). Fifty-four children (11.2%) received long parenteral therapy (median duration: 7 days). Predictors of long parenteral therapy included age <2 months (adjusted odds ratio [aOR] 67.3; 95% confidence interval [CI]: 16.4-275.7), limited oral antibiotic options (aOR 5.9; 95% CI: 2.8-12.3), and genitourinary abnormalities (aOR 5.4; 95% CI: 1.8-15.9). UTI relapse occurred in 1 of the 54 (1.9%) children treated with long parenteral therapy and in 6 of the 428 (1.5%) children treated with short/no parenteral therapy (P = .57). Of the 105 children treated exclusively with discordant antibiotics, 3 (2.9%, 95% CI: 0.6%-8.1%) experienced UTI relapse.

CONCLUSIONS

Long parenteral therapy was associated with age <2 months, limited oral antibiotic options, and genitourinary abnormalities. UTI relapse was rare and not associated with duration of parenteral therapy. For UTIs with limited oral options, further research is needed on the effectiveness of continued discordant therapy.

Roseville Protocol for the Management of Febrile Infants 7-60 Days

OBJECTIVES

The Roseville Protocol modifies the Rochester Protocol by adding a high-risk temperature criterion of >38.5°C for infants 7 to 28 days old and by allowing febrile infants 29 to 60 days old with abnormal urinalysis but reassuring complete blood cell counts to be discharged home on oral antibiotics without receiving a lumbar puncture (LP). In this study, we define the Roseville Protocol test characteristics to detect invasive bacterial infection (IBI) and retrospectively compare its performance to that of the Rochester, Philadelphia, and Boston protocols.

METHODS

In this retrospective study, we examine all cases of fever in infants aged 7 to 60 days presenting to a large health maintenance organization from 2007 to 2016 and having requisite laboratory tests for protocol analysis. The 4 protocols were retrospectively applied to this cohort to calculate each protocol's sensitivity and specificity to detect IBI. Protocols were compared regarding recommended LPs, admissions, and parenteral antibiotics.

RESULTS

In 627 infants 7 to 28 days old, the Roseville Protocol had a sensitivity of 96.7% and a negative predictive value of 99.5%. It identified 2 IBIs missed by the Rochester Protocol but recommended an absolute increase of 19% in LPs and admissions. In 1176 infants 29 to 60 days old, the Roseville Protocol had a sensitivity of 91.4% and a negative predictive value of 99.6%. There was an absolute reduction in LPs by 18% to 44% compared to the Rochester Protocol and by 74% to 100% compared to the Philadelphia and Boston protocols. There was an absolute reduction in admissions by 18% to 44% compared to the Rochester Protocol, by 25% to 51% compared to the Philadelphia Protocol, and by 10% to 36% compared to the Boston Protocol.

CONCLUSIONS

The Roseville Protocol has sensitivity and specificity comparable to that of existing protocols for IBI in febrile infants 7 to 60 days old, while allowing for fewer invasive procedures and hospitalizations in infants ≥29 days old.

Epidemiology and Risk Factors for Community Associated Clostridioides difficile in Children

OBJECTIVE

To assess which risk factors are associated with community-associated Clostridioides difficile infection (CDI) in children.

STUDY DESIGN

This case control study was a retrospective review of all children 1-17 years of age with stool specimens sent for C difficile testing from January 1, 2012, to December 31, 2016. Cases and controls were children who had C difficile testing performed in the community or first 48 hours of hospital admission and >12 weeks after hospital discharge, with no prior positive C difficile testing in last 8 weeks, without other identified causes of diarrhea, and with clinical symptoms. Cases had positive confirmatory testing for C difficile. Controls had negative testing for C difficile and were matched to cases 1:1 by age and year of specimen collection.

RESULTS

The overall incidence rate of community-acquired CDI in this cohort was 13.7 per 100 000 children per year. There was a substantial increase in community-acquired CDI from 9.6 per 100 000 children per year in 2012 to a peak of 16.9 per 100 000 children per year in 2015 (Cochran-Armitage test for trend P = .002). The risk factors for community-acquired CDI included non-Hispanic ethnicity; amoxicillin-clavulanate, cephalosporin, and clindamycin use within the previous 12 weeks; a previous positive C difficile test within 6 months; and increased health care visits in the last year.

CONCLUSIONS

As rates of community-acquired CDI are increasing, enhanced antibiotic stewardship and recognition of health care disparities may ease the burden of community-acquired CDI.

Fever Without a Source in an Infant Due to Severe Acute Respiratory Syndrome Coronavirus-2

A 5-week-old infant female admitted for fever without a source subsequently tested positive for severe acute respiratory syndrome coronavirus 2. She had a mild hospital course without respiratory distress. This unexpected presentation changed regional hospital screening for coronavirus disease 2019 and personal protective equipment use by medical providers who evaluate febrile infants.

Clinical Response to Discordant Therapy in Third-Generation Cephalosporin-Resistant UTIs

OBJECTIVES

To describe the initial clinical response and care escalation needs for children with urinary tract infections (UTIs) resistant to third-generation cephalosporins while on discordant antibiotics.

METHODS

We performed a retrospective study of children <18 years old presenting to an acute care setting of 5 children's hospitals and a large managed care organization from 2012 to 2017 with third-generation cephalosporin-resistant UTIs (defined as the growth of ≥50 000 colony-forming units per mL of Escherichia coli or Klebsiella spp. nonsusceptible to ceftriaxone with a positive urinalysis). We included children started on discordant antibiotics who had follow-up when culture susceptibilities resulted. Outcomes were escalation of care (emergency department visit, hospital admission, or ICU transfer while on discordant therapy) and clinical response at follow-up (classified as improved or not improved).

RESULTS

Of the 316 children included, 78% were girls and the median age was 2.4 years (interquartile range 0.6-6.5). Children were evaluated in the emergency department (56%) or clinic (43%), and 90% were started on a cephalosporin. A total of 7 of 316 children (2.2%; 95% confidence interval 0.8%-4.5%) experienced escalation of care. For the 230 children (73%) with clinical response recorded, 192 of 230 (83.5%; 95% confidence interval 78.0%-88.0%) experienced clinical improvement. In children with repeat urine testing while on discordant therapy, pyuria improved or resolved in 16 of 19 (84%) and urine cultures sterilized in 11 of 17 (65%).

CONCLUSIONS

Most children with third-generation cephalosporin-resistant UTIs started on discordant antibiotics experienced initial clinical improvement, and few required escalation of care. Our findings suggest that narrow-spectrum empiric therapy is appropriate while awaiting final urine culture results.

1526. Epidemiology of and Risk Factors for Nontyphoidal Salmonella Bacteremia in Children: A 20-Year Retrospective Cohort

Background

Nontyphoidal Salmonella (NTS) infections are the most common culture-confirmed foodborne illness in the United States. One to five percent of enteric infections due to NTS result in bloodstream infection (BSI). Host risk factors for NTS BSI include extremes of age and chronic or immunosuppressing conditions.

Methods

This was a retrospective review of the electronic health records (EHRs) of all blood cultures collected from January 1, 1999 to December 31, 2018 at Kaiser Permanente Northern California (KPNC) positive for Salmonella spp. The speciation and group of all Salmonella spp. were extracted from the microbiology records. Using KPNC population data, the incidence rate of NTS BSI by age and year of infection was calculated. Using a test for trend, the trend in rates of NTS BSI was determined. Risk factors for complicated NTS BSI using clinical and laboratory data were calculated.

Results

From 1999 to 2018, there were 212 cases of NTS BSI and 104 cases of Salmonella typhi and paratyphi BSI. The average number of cases per year was 10.6 (range 3–25). There were 14,952,802 evaluable children over the 20 years, with an average of 747,640 per year. The incident rate of NTS bacteremia was 1.4 per 100,000 children per year. The trend to increasing cases was not statistically significant (Figure 1). The distribution of NTS BSI cases were 114 (54%) Group B, 33 (15.5%) Group C, 31 (14.5%) Group D, 19 (9%) Groups E or G and 15 (7%) other/nonspecified. The predominant NTS pathogen was Salmonella heidelberg occurring in 37 (17.5%) cases. Forty-five percent of children were female. (Table 1) Forty-two percent of children were less than 3 years old with a steady rate after age 3. Two (0.9%) children had an underlying immunodeficiency, three (1.4%) additional with a malignancy and 16 (7.5%) with underlying non-immunosuppressing comorbidities.

Conclusion

Despite improvements in food safety, the rates of NTS bacteremia have not decreased over the last two decades. The rate of NTS was 1.4 per 100,000 children per year with the highest proportion in children less than 3 years. Two percent had underlying immunosuppressing comorbidities. Although only 10% had underlying comorbidities, this was substantially higher than the population at KPNC.

Disclosures

All authors: No reported disclosures.

The Prevalence of Bacterial Meningitis in Febrile Infants 29-60 Days With Positive Urinalysis

OBJECTIVES

This study evaluates whether bacterial meningitis prevalence differs by urinalysis result and whether antibiotic treatment of presumed urinary tract infection without cerebrospinal fluid (CSF) culture produces adverse sequelae in febrile infants 29 to 60 days old.

METHODS

This retrospective cohort study identified febrile infants 29 to 60 days old presenting to Kaiser Permanente Northern California sites from 2007 to 2015 who underwent urinalysis and blood, urine, and CSF cultures, comparing the prevalence of meningitis among infants with positive versus negative urinalysis results using a two 1-sided test for equivalence. Additionally, febrile infants treated with antibiotics for positive urinalysis results without CSF culture were identified and their charts were reviewed for adverse sequelae.

RESULTS

Full evaluation was performed in 833 febrile infants (835 episodes). Three of 337 infants with positive urinalysis (0.9%; 95% confidence interval [CI]: 0.0%-1.9%) and 5 of 498 infants with negative urinalysis (1%; 95% CI: 0.1%-1.9%) had meningitis. These proportions were statistically equivalent within 1%, using two 1-sided test with a P value of .04. There were 341 febrile infants (345 episodes) with positive urinalysis treated with antibiotics without lumbar puncture. Zero cases of missed bacterial meningitis were identified (95% CI: 0%-1.1%). Zero cases of severe sequelae (sepsis, seizure, neurologic deficit, intubation, PICU admission, death) were identified (95% CI: 0%-1.1%).

CONCLUSIONS

The prevalence of bacterial meningitis does not differ by urinalysis in febrile infants 29 to 60 days old. Antibiotic treatment of infants with positive results for urinalysis without lumbar puncture may be safe in selected cases.

Bacteremia in Children 3 to 36 Months Old After Introduction of Conjugated Pneumococcal Vaccines

BACKGROUND AND OBJECTIVES

In June 2010, Kaiser Permanente Northern California replaced all 7-valent pneumococcal conjugate vaccine (PCV7) vaccines with the 13-valent pneumococcal conjugate vaccine (PCV13). Our objectives were to compare the incidence of bacteremia in children 3 to 36 months old by 3 time periods: pre-PCV7, post-PCV7/pre-PCV13, and post-PCV13.

METHODS

We designed a retrospective review of the electronic medical records of all blood cultures collected on children 3 to 36 months old at Kaiser Permanente Northern California from September 1, 1998 to August 31, 2014 in outpatient clinics, in emergency departments, and in the first 24 hours of hospitalization.

RESULTS

During the study period, 57 733 blood cultures were collected in the population of children 3 to 36 months old. Implementation of routine immunization with the pneumococcal conjugate vaccine resulted in a 95.3% reduction of Streptococcus pneumoniae bacteremia, decreasing from 74.5 to 10 to 3.5 per 100 000 children per year by the post-PCV13 period. As pneumococcal rates decreased, Escherichia coli, Salmonella spp, and Staphylococcus aureus caused 77% of bacteremia. Seventy-six percent of all bacteremia in the post-PCV13 period occurred with a source.

CONCLUSIONS

In the United States, routine immunizations have made bacteremia in the previously healthy toddler a rare event. As the incidence of pneumococcal bacteremia has decreased, E coli, Salmonella spp, and S aureus have increased in relative importance. New guidelines are needed to approach the previously healthy febrile toddler in the outpatient setting.

Management and Outcomes of Previously Healthy, Full-Term, Febrile Infants Ages 7 to 90 Days

BACKGROUND

There is considerable variation in the approach to infants presenting to the emergency department and outpatient clinics with fever without a source. We set out to describe the current clinical practice regarding culture acquisition on febrile young infants and review the outcomes of infants with and without cultures obtained.

METHODS

This study analyzed Kaiser Permanente Northern California's electronic medical record to identify all febrile, full term, previously healthy infants born between July 1, 2010, and June 30, 2013, presenting for care between 7 and 90 days of age.

RESULTS

During this 3-year study, 96 156 full-term infants were born at Kaiser Permanente Northern California. A total of 1380 infants presented for care with a fever with an incidence rate of 14.4 (95% confidence interval: 13.6-15.1) per 1000 full term births. Fifty-nine percent of infants 7 to 28 days old had a full evaluation compared with 25% of infants 29 to 60 days old and 5% of infants 61 to 90 days old. Older infants with lower febrile temperatures presenting to an office setting were less likely to have a culture. In the 30 days after fevers, 1% of infants returned with a urinary tract infection. No infants returned with bacteremia or meningitis.

CONCLUSIONS

Fever in a medical setting occurred in 1.4% of infants in this large cohort. Forty-one percent of febrile infants did not have any cultures including 24% less than 28 days. One percent returned in the following month with a urinary tract infection. There was no delayed identification of bacteremia or meningitis.

Urinary Imaging Findings in Young Infants With Bacteremic Urinary Tract Infection

OBJECTIVES

To describe renal ultrasound (RUS) and voiding cystourethrogram (VCUG) findings and determine predictors of abnormal imaging in young infants with bacteremic urinary tract infection (UTI).

METHODS

We used retrospective data from a multicenter sample of infants younger than 3 months with bacteremic UTI, defined as the same pathogenic organism in blood and urine. Infants were excluded if they had any major comorbidities, known urologic abnormalities at time of presentation, required intensive unit care, or had no imaging performed. Imaging results as stated in the radiology reports were categorized by a pediatric urologist.

RESULTS

Of the 276 infants, 19 were excluded. Of the remaining 257 infants, 254 underwent a RUS and 224 underwent a VCUG. Fifty-five percent had ≥1 RUS abnormalities. Thirty-four percent had ≥1 VCUG abnormalities, including vesicoureteral reflux (VUR, 27%), duplication (1.3%), and infravesicular abnormality (0.9%). Age <1 month, male sex, and non-Escherichia coli organism predicted an abnormal RUS, but only non-E coli organism predicted an abnormal VCUG. Seventeen of 96 infants (17.7%) with a normal RUS had an abnormal VCUG: 15 with VUR (Grade I-III = 13, Grade IV = 2), 2 with elevated postvoid residual, and 1 with infravesical abnormality.

CONCLUSIONS

Although RUS and VCUG abnormalities were common in this cohort, the frequency and severity were similar to previous studies of infants with UTIs in general. Our findings do not support special consideration of bacteremia in imaging decisions for otherwise well-appearing young infants with UTI.

Bacteraemic urinary tract infection: management and outcomes in young infants

OBJECTIVES

To determine predictors of parenteral antibiotic duration and the association between parenteral treatment duration and relapses in infants <3 months with bacteraemic urinary tract infection (UTI).

DESIGN

Multicentre retrospective cohort study.

SETTING

Eleven healthcare institutions across the USA.

PATIENTS

Infants <3 months of age with bacteraemic UTI, defined as the same pathogenic organism isolated from blood and urine.

MAIN OUTCOME MEASURES

Duration of parenteral antibiotic therapy, relapsed UTI within 30 days.

RESULTS

The mean (±SD) duration of parenteral antibiotics for the 251 included infants was 7.8 days (±4 days), with considerable variability between institutions (mean range 5.5-12 days). Independent predictors of the duration of parenteral antibiotic therapy included (coefficient, 95% CI): age (-0.2 days, -0.3 days to -0.08 days, for each week older), year treated (-0.2 days, -0.4 to -0.03 days for each subsequent calendar year), male gender (0.9 days, 0.01 to 1.8 days), a positive repeat blood culture during acute treatment (3.5 days, 1.2-5.9 days) and a non-Escherichia coli organism (2.2 days, 0.8-3.6 days). No infants had a relapsed bacteraemic UTI. Six infants (2.4%) had a relapsed UTI (without bacteraemia). The duration of parenteral antibiotics did not differ between infants with and without a relapse (8.2 vs 7.8 days, p=0.81).

CONCLUSIONS

Parenteral antibiotic treatment duration in young infants with bacteraemic UTI was variable and only minimally explained by measurable patient factors. Relapses were rare and were not associated with treatment duration. Shorter parenteral courses may be appropriate in some infants.

Diagnostic accuracy of the urinalysis for urinary tract infection in infants <3 months of age

BACKGROUND

The 2011 American Academy of Pediatrics urinary tract infection (UTI) guideline suggests incorporation of a positive urinalysis (UA) into the definition of UTI. However, concerns linger over UA sensitivity in young infants. Infants with the same pathogenic organism in the blood and urine (bacteremic UTI) have true infections and represent a desirable population for examination of UA sensitivity.

METHODS

We collected UA results on a cross-sectional sample of 276 infants <3 months of age with bacteremic UTI from 11 hospital systems. Sensitivity was calculated on infants who had at least a partial UA performed and had ≥50 000 colony-forming units per milliliter from the urine culture. Specificity was determined by using a random sample of infants from the central study site with negative urine cultures.

RESULTS

The final sample included 245 infants with bacteremic UTI and 115 infants with negative urine cultures. The sensitivity of leukocyte esterase was 97.6% (95% confidence interval [CI] 94.5%-99.2%) and of pyuria (>3 white blood cells/high-power field) was 96% (95% CI 92.5%-98.1%). Only 1 infant with bacteremic UTI (Group B Streptococcus) and a complete UA had an entirely negative UA. In infants with negative urine cultures, leukocyte esterase specificity was 93.9% (95% CI 87.9 - 97.5) and of pyuria was 91.3% (84.6%-95.6%).

CONCLUSIONS

In young infants with bacteremic UTI, UA sensitivity is higher than previous reports in infants with UTI in general. This finding can be explained by spectrum bias or by inclusion of faulty gold standards (contaminants or asymptomatic bacteriuria) in previous studies.

Changing epidemiology of bacteremia in infants aged 1 week to 3 months

BACKGROUND

Bacteremia in young infants has remained an important ongoing concern for decades. Despite changes in prenatal screening and infant immunizations, the current epidemiology of this problem has received little attention.

METHODS

We conducted a retrospective analysis of all blood cultures collected at Kaiser Permanente Northern California on full-term, previously healthy infants presenting for care between 1 week to 3 months of age for whom a blood culture was drawn from January 1, 2005, through December 31, 2009.

RESULTS

During the study period, 4255 blood cultures were collected from 160 818 full-term infants. Only 2% of all blood cultures were positive for pathogens (93/4255), whereas 247 positive cultures were due to contaminants. The incidence rate of true bacteremia was 0.57 in 1000 full-term births. The most common pathogen was Escherichia coli (56%). Ninety-eight percent of infants with E coli bacteremia had a urinary tract infection. Group B Streptococcus and Staphylococcus aureus were the second and third most common pathogens, respectively. There were no cases of Listeria monocytogenes bacteremia or meningococcemia and only 1 case of enterococcal bacteremia. Ampicillin resistant pathogens accounted for 36% of organisms.

CONCLUSIONS

Our study indicates bacteremia in young infants occurs infrequently and in only 2.2% of those who had a blood culture drawn. On the basis of the epidemiology of pathogens found in this large cohort, these data suggest a change in currently recommended presumptive antibiotic coverage in 1-week to 3-month-old infants with suspected bacteremia.

Utility of DNA microarrays for detection of viruses in acute respiratory tract infections in children

OBJECTIVE

To assess the utility of a panviral DNA microarray platform (Virochip) in the detection of viruses associated with pediatric respiratory tract infections (RTIs).

STUDY DESIGN

The Virochip was compared with conventional direct fluorescent antibody (DFA)- and polymerase chain reaction (PCR)-based testing for the detection of respiratory viruses in 278 consecutive nasopharyngeal aspirate samples from 222 children.

RESULTS

The Virochip was superior in performance to DFA, showing a 19% increase in the detection of 7 respiratory viruses included in standard DFA panels, and was similar to virus-specific PCR (sensitivity, 85% to 90%; specificity, >/=99%; positive predictive value, 94% to 96%; negative predictive value, 97% to 98%) in the detection of respiratory syncytial virus, influenza A, and rhinoviruses/enteroviruses. The Virochip also detected viruses not routinely tested for or missed by DFA and PCR, as well as double infections and infections in critically ill patients that DFA failed to detect.

CONCLUSIONS

Given its favorable sensitivity and specificity profile and expanded spectrum for detection, microarray-based viral testing holds promise for clinical diagnosis of pediatric RTIs.

Utility of direct fluorescent antibody testing of nasopharyngeal washes in children with and without respiratory tract illness

BACKGROUND

Direct fluorescent antibody (DFA) testing of nasopharyngeal wash specimens is a rapid and reliable means of diagnosing respiratory viral infection. The utility of DFA testing in the evaluation of febrile children without respiratory symptoms has not been critically evaluated. It is not known whether clinical or demographic factors apart from respiratory symptoms are associated with a positive DFA or whether a positive DFA is more likely to be associated with lower or upper respiratory tract symptoms (RTS).

METHODS

This is a retrospective case-series of 756 consecutive nasopharyngeal specimens with respiratory DFA testing performed at the University of California San Francisco from November 1, 2002 through October 31, 2003.

RESULTS

No RTS was a statistically significant predictor of negative DFA [odds ratio (OR), 0.03; 95% confidence interval (CI), 0.004-0.2; P = 0.001] compared with lower RTS. Male subjects were more likely than female subjects to have a positive DFA (OR 1.8; 95% CI 1.1-2.8; P = 0.02). Specimens collected from April to October were less likely to have a positive DFA (OR 0.4; 95% CI 0.2-0.7; P = 0.001). Specimens collected at the time of hospital admission and during a hospitalization were less likely to have a positive DFA (OR 0.5; 95% CI 0.3-0.9; P = 0.01 and OR, 0.07; 95% CI 0.02-0.2; P = 0.001, respectively) compared with specimens collected in the outpatient setting.

CONCLUSION

The yield of testing children without respiratory tract illness is extremely low.

Changing epidemiology of outpatient bacteremia in 3- to 36-month-old children after the introduction of the heptavalent-conjugated pneumococcal vaccine

BACKGROUND

The introduction of routine vaccination with heptavalent conjugated pneumococcal vaccine has changed the overall incidence of bacteremia in children 3 months-3 years old.

OBJECTIVE

To describe the changing incidence and etiology of bacteremia in previously healthy toddlers presenting to outpatient clinical settings.

METHODS

Retrospective case series of all blood cultures obtained between September 1998 and August 2003 in Kaiser Permanente Northern California outpatient clinics and emergency departments from previously healthy children 3 months-3 years old.

RESULTS

Implementation of routine vaccination with the conjugated pneumococcal vaccine resulted in an 84% reduction of Streptococcus pneumoniae bacteremia (1.3-0.2%) and a 67% reduction in overall bacteremia (1.6-0.7%) in the study population. The rate of blood culture isolation of contaminating organisms remained unchanged at 1.8%; therefore, by the end of the study, >70% of organisms identified in blood cultures were contaminants. During the 5 study years, total blood cultures drawn decreased by 35% in outpatient pediatric clinics but remained unchanged in emergency departments. By 2003, one-third of all pathogenic organisms isolated from blood cultures were Escherichia coli, one-third were non-vaccine serotype S. pneumoniae, the majority of the remaining one-third were Staphylococcus aureus, Salmonella spp., Neisseria meningitidis and Streptococcus pyogenes. In our population of children routinely immunized with the conjugated pneumococcal vaccine, a white blood cell count >15,000 by itself is a poor predictor of bacteremia in the febrile toddler (sensitivity, 74.0%; specificity, 54.5%; positive predictive value, 1.5%; negative predictive value, 99.5%).

CONCLUSION

In the United States, routine vaccinations with Haemophilus influenzae type b and S. pneumoniae vaccines have made bacteremia in the previously healthy toddler a rare event. As the incidence of pneumococcal bacteremia has decreased, E. coli, Salmonella spp. and Staphylococcus aureus have increased in relative importance. The use of the white blood cell count alone to guide the empiric use of antibiotics is not indicated. New guidelines are needed to approach the previously healthy febrile toddler in the outpatient setting.