Performance of the Modified Boston and Philadelphia Criteria for Invasive Bacterial Infections

Diagnostic test accuracy of procalcitonin and C-reactive protein for predicting invasive and serious bacterial infections in young febrile infants: a systematic review and meta-analysis

BACKGROUND

Febrile infants presenting in the first 90 days of life are at higher risk of invasive and serious bacterial infections than older children. Modern clinical practice guidelines, mostly using procalcitonin as a diagnostic biomarker, can identify infants who are at low risk and therefore suitable for tailored management. C-reactive protein, by comparison, is widely available, but whether C-reactive protein and procalcitonin have similar diagnostic accuracy is unclear. We aimed to compare the test accuracy of procalcitonin and C-reactive protein in the prediction of invasive or serious bacterial infections in febrile infants.

METHODS

For this systematic review and meta-analysis, we searched MEDLINE, EMBASE, Web of Science, and The Cochrane Library for diagnostic test accuracy studies up to June 19, 2023, using MeSH terms "procalcitonin", and "bacterial infection" or "fever" and keywords "invasive bacterial infection*" and "serious bacterial infection*", without language or date restrictions. Studies were selected by independent authors against eligibility criteria. Eligible studies included participants aged 90 days or younger presenting to hospital with a fever (≥38°C) or history of fever within the preceding 48 h. The primary index test was procalcitonin, and the secondary index test was C-reactive protein. Test kits had to be commercially available, and test samples had to be collected upon presentation to hospital. Invasive bacterial infection was defined as the presence of a bacterial pathogen in blood or cerebrospinal fluid, as detected by culture or quantitative PCR; authors' definitions of serious bacterial infection were used. Data were extracted from selected studies, and the detection of invasive or serious bacterial infections was analysed with two models for each biomarker. Diagnostic accuracy was determined against internationally recognised cutoff values (0·5 ng/mL for procalcitonin, 20 mg/L for C-reactive protein) and pooled to calculate partial area under the curve (pAUC) values for each biomarker. Optimum cutoff values were identified for each biomarker. This study is registered with PROSPERO, CRD42022293284.

FINDINGS

Of 734 studies derived from the literature search, 14 studies (n=7755) were included in the meta-analysis. For the detection of invasive bacterial infections, pAUC values were greater for procalcitonin (0·72, 95% CI 0·56-0·79) than C-reactive protein (0·28, 0·17-0·61; p=0·016). Optimal cutoffs for detecting invasive bacterial infections were 0·49 ng/mL for procalcitonin and 13·12 mg/L for C-reactive protein. For the detection of serious bacterial infections, procalcitonin and C-reactive protein had similar pAUC values (0·55, 0·44-0·69 vs 0·54, 0·40-0·61; p=0·92). For serious bacterial infections, the optimal cutoffs for procalcitonin and C-reactive protein were 0·17 ng/mL and 16·18 mg/L, respectively. Heterogeneity was low for studies investigating the test accuracy of procalcitonin in detecting invasive bacterial infection (I2=23·5%), high for studies investigating procalcitonin for serious bacterial infection (I2=75·5%), and moderate for studies investigating C-reactive protein for invasive bacterial infection (I2=49·5%) and serious bacterial infection (I2=28·3%). The absence of a single definition of serious bacterial infection across studies was the greatest source of interstudy variability and potential bias.

INTERPRETATION

Within a large cohort of febrile infants, a procalcitonin cutoff of 0·5 ng/mL had a superior pAUC value to a C-reactive protein cutoff of 20 mg/L for identifying invasive bacterial infections. In settings without access to procalcitonin, C-reactive protein should therefore be used cautiously for the identification of invasive bacterial infections, and a cutoff value below 20 mg/L should be considered. C-reactive protein and procalcitonin showed similar test accuracy for the identification of serious bacterial infection with internationally recognised cutoff values. This might reflect the challenges involved in confirming serious bacterial infection and the absence of a universally accepted definition of serious bacterial infection.

FUNDING

None.

Improving Guideline-Concordant Care for Febrile Infants Through a Quality Improvement Initiative

OBJECTIVES

We aimed to examine the impact of a quality improvement (QI) collaborative on adherence to specific recommendations within the American Academy of Pediatrics' Clinical Practice Guideline (CPG) for well-appearing febrile infants aged 8 to 60 days.

METHODS

Concurrent with CPG release in August 2021, we initiated a QI collaborative involving 103 general and children's hospitals across the United States and Canada. We developed a multifaceted intervention bundle to improve adherence to CPG recommendations for 4 primary measures and 4 secondary measures, while tracking 5 balancing measures. Primary measures focused on guideline recommendations where deimplementation strategies were indicated. We analyzed data using statistical process control (SPC) with baseline and project enrollment from November 2020 to October 2021 and the intervention from November 2021 to October 2022.

RESULTS

Within the final analysis, there were 17 708 infants included. SPC demonstrated improvement across primary and secondary measures. Specifically, the primary measures of appropriately not obtaining cerebrospinal fluid in qualifying infants and appropriately not administering antibiotics had the highest adherence at the end of the collaborative (92.4% and 90.0% respectively). Secondary measures on parent engagement for emergency department discharge of infants 22 to 28 days and oral antibiotics for infants 29 to 60 days with positive urinalyses demonstrated the greatest changes with collaborative-wide improvements of 16.0% and 20.4% respectively. Balancing measures showed no change in missed invasive bacterial infections.

CONCLUSIONS

A QI collaborative with a multifaceted intervention bundle was associated with improvements in adherence to several recommendations from the AAP CPG for febrile infants.

Performance of Febrile Infant Decision Tools on Hypothermic Infants Evaluated for Infection

BACKGROUND

Given the lack of evidence-based guidelines for hypothermic infants, providers may be inclined to use febrile infant decision-making tools to guide management decisions. Our objective was to assess the diagnostic performance of febrile infant decision tools for identifying hypothermic infants at low risk of bacterial infection.

METHODS

We conducted a secondary analysis of a retrospective cohort study of hypothermic (≤36.0 C) infants ≤90 days of age presenting to the emergency department or inpatient unit among 9 participating sites between September 1, 2016 and May 5, 2021. Well-appearing infants evaluated for bacterial infections via laboratory testing were included. Infants with complex chronic conditions or premature birth were excluded. Performance characteristics for detecting serious bacterial infection (SBI; urinary tract infection, bacteremia, bacterial meningitis) and invasive bacterial infection (IBI; bacteremia, bacterial meningitis) were calculated for each tool.

RESULTS

Overall, 314 infants met the general inclusion criteria, including 14 cases of SBI (4.5%) and 7 cases of IBI (2.2%). The median age was 5 days, and 68.1% of the infants (214/314) underwent a full sepsis evaluation. The Philadelphia, Boston, IBI Score, and American Academy of Pediatrics Clinical Practice Guideline did not misclassify any SBI or IBI as low risk; however, they had low specificity and positive predictive value. Rochester and Pediatric Emergency Care Applied Research Network tools misclassified infants with bacterial infections.

CONCLUSIONS

Several febrile infant decision tools were highly sensitive, minimizing missed SBIs and IBIs in hypothermic infants. However, the low specificity of these decision tools may lead to unnecessary testing, antimicrobial exposure, and hospitalization.

La prise en charge des nourrissons de 90 jours ou moins, fiévreux mais dans un bon état général

On constate des pratiques très variées en matière d'évaluation et de prise en charge des jeunes nourrissons fiévreux. Bien que la plupart des jeunes nourrissons fiévreux mais dans un bon état général soient atteints d'une maladie virale, il est essentiel de détecter ceux qui sont à risque de présenter des infections bactériennes invasives, notamment une bactériémie et une méningite bactérienne. Le présent document de principes porte sur les nourrissons de 90 jours ou moins dont la température rectale est de 38,0 °C ou plus, mais qui semblent être dans un bon état général. Il est conseillé d'appliquer les récents critères de stratification du risque pour orienter la prise en charge, ainsi que d'intégrer la procalcitonine à l'évaluation diagnostique. Les décisions sur la prise en charge des nourrissons qui satisfont aux critères de faible risque devraient refléter la probabilité d'une maladie, tenir compte de l'équilibre entre les risques et les préjudices potentiels et faire participer les parents ou les proches aux décisions lorsque diverses options sont possibles. La prise en charge optimale peut également dépendre de considérations pragmatiques, telles que l'accès à des examens diagnostiques, à des unités d'observation, à des soins tertiaires et à un suivi. Des éléments particuliers, tels que la mesure de la température, le risque d'infection invasive à Herpes simplex et la fièvre postvaccinale, sont également abordés.

Management of well-appearing febrile young infants aged ≤90 days

The evaluation and management of young infants presenting with fever remains an area of significant practice variation. While most well-appearing febrile young infants have a viral illness, identifying those at risk for invasive bacterial infections, specifically bacteremia and bacterial meningitis, is critical. This statement considers infants aged ≤90 days who present with a rectal temperature ≥38.0°C but appear well otherwise. Applying recent risk-stratification criteria to guide management and incorporating diagnostic testing with procalcitonin are advised. Management decisions for infants meeting low-risk criteria should reflect the probability of disease, consider the balance of risks and potential harm, and include parents/caregivers in shared decision-making when options exist. Optimal management may also be influenced by pragmatic considerations, such as access to diagnostic investigations, observation units, tertiary care, and follow-up. Special considerations such as temperature measurement, risk for invasive herpes simplex infection, and post-immunization fever are also discussed.

Prevalence of Invasive Bacterial Infection in Hypothermic Young Infants: A Multisite Study

OBJECTIVE

To determine the prevalence of bacteremia and meningitis (invasive bacterial infection [IBI]) in hypothermic young infants, and also to determine the prevalence of serious bacterial infections (SBI) and neonatal herpes simplex virus and to identify characteristics associated with IBI.

STUDY DESIGN

We conducted a retrospective cohort study of infants ≤90 days of age who presented to 1 of 9 hospitals with historical or documented hypothermia (temperature ≤36.0°C) from September 1, 2017, to May 5, 2021. Infants were identified by billing codes or electronic medical record search of hypothermic temperatures. All charts were manually reviewed. Infants with hypothermia during birth hospitalization, and febrile infants were excluded. IBI was defined as positive blood culture and/or cerebrospinal fluid culture treated as a pathogenic organism, whereas SBI also included urinary tract infection. We used multivariable mixed-effects logistic regression to identify associations between exposure variables and IBI.

RESULTS

Overall, 1098 young infants met the inclusion criteria. IBI prevalence was 2.1% (95% CI, 1.3-2.9) (bacteremia 1.8%; bacterial meningitis 0.5%). SBI prevalence was 4.4% (95% CI, 3.2-5.6), and neonatal herpes simplex virus prevalence was 1.3% (95% CI, 0.6-1.9). Significant associations were found between IBI and repeated temperature instability (OR, 4.9; 95% CI, 1.3-18.1), white blood cell count abnormalities (OR, 4.8; 95% CI, 1.8-13.1), and thrombocytopenia (OR, 5.0; 95% CI, 1.4-17.0).

CONCLUSIONS

IBI prevalence in hypothermic young infants is 2.1%. Further understanding of characteristics associated with IBI can guide the development decision tools for management of hypothermic young infants.

The Incidence of Serious/Invasive Bacterial Diseases in Infants 90 Days Old or Younger at an Emergency Hospital in Japan

Background The incidence of severe bacterial infections (SBIs) in infants aged ≤90 days is thought to have decreased because of widespread vaccination programs. However, relevant epidemiological data in Japan are scarce. Materials and methods This observational, single-center study investigated the epidemiology of fever in infants aged ≤90 days. SBI was defined as the presence of meningitis, urinary tract infections (UTIs), or bacteremia. Invasive bacterial infection (IBI) was defined as the presence of meningitis, bacteremic UTI, or bacteremia. We determined the incidence of UTIs, bacteremia, meningitis, SBIs, and IBIs in the following three age groups: 0-28, 29-60, and 61-90 days. We subsequently calculated the relative incidence for the groups aged 29-60 and 61-90 days, using the group aged 0-28 days as the reference group.  Results Herein, 58, 124, and 166 infants were included in the 0-28 days, 29-60 days, and 61-90 days age groups, respectively. Of the total number of patients, 15.5%, 8.9%, and 16.9% in the 0-28 days, 29-60 days, and 61-90 days age groups, respectively, were diagnosed with SBI. The relative incidences were 1 for the 0-28 days group (reference group), 0.67 for the 29-60 days group (95% confidence interval [CI], 0.39-1.15), and 1.08 for the 61-90 days group (95% CI, 0.58-2.00). Of the total number of patients, 10.3%, 3.2%, and 0.6% in the 0-28 days, 29-60 days, and 61-90 days age groups, respectively, were diagnosed with IBI. Relative incidences were 1 (reference group), 0.50 (95% CI, 0.29-0.88), and 0.28 (95% CI, 0.19-0.41) for the 0-28 days, 29-60 days, and 61-90 days age groups, respectively. All cases of IBI were caused by Group B streptococcus (GBS), except for two cases of bacteremia, which were caused by Haemophilus influenzae.  Conclusion The incidence of SBI was similar in the 0-28 days and 61-90 days age groups. However, the incidence of IBI decreased with increasing age. The incidence of UTIs was highest in the 61-90 days age group, and that of meningitis and bacteremia decreased with increasing age.

Management and Outcome of Febrile Infants ≤60 days, With Emphasis on Infants ≤21 Days Old, in Swedish Pediatric Emergency Departments

BACKGROUND

Management of febrile infants ≤60 days of age varies, and the age for routine investigations and antibiotic-treatment is debated. The American Academy of Pediatrics recommended age threshold for lumbar puncture (LP) is 21 days and for blood culture 60 days. We describe management and adverse outcome of febrile infants ≤60 days old, in Sweden.

METHODS

Retrospective cross-sectional study of infants ≤60 days of age with fever without source evaluated in 4 University pediatric emergency departments, between 2014 and 2017. Adverse outcome was defined as delayed-treated invasive bacterial infection (IBI: meningitis or bacteremia).

RESULTS

We included 1701 infants. In infants ≤21 days old, LP was performed in 16% (95% CI: 12-20) and blood culture in 43% (95% CI: 38-48). Meningitis was diagnosed in 5 (1.3%; 95% CI: 0.4-3.0) and bacteremia in 12 (4.5%; 95% CI: 2.6-7.0) infants. Broad-spectrum antibiotics were not administered to 66% (95% CI: 61-71), of which 2 (0.8%; 95% CI: 0.1-2.8) diagnosed with IBI (1 meningitis and 1 bacteremia). In the 29-60 days age group, blood culture was performed in 21% (95% CI: 19-24), and broad-spectrum antibiotics were not administered to 84% (95% CI: 82-86), with no case of delayed-treated bacteremia.

CONCLUSIONS

The rates of LP, blood culture and broad-spectrum antibiotics were low. Despite that, there were few delayed-treated IBIs, but 2 of the 17 infants ≤21 days of age with IBI were not timely treated, which prompts the need for a safer approach for this age group. Also, the utility of routine blood culture for all febrile infants 29-60 days old could be questioned.

Rochester Criteria and Yale Observation Scale Score to Evaluate Febrile Neonates with Invasive Bacterial Infection

BACKGROUND

Febrile neonates undergo lumbar puncture (LP), empiric antibiotic administration, and admission for increased risk of invasive bacterial infection (IBI), defined as bacteremia and meningitis.

OBJECTIVE

Measure IBI prevalence in febrile neonates, and operating characteristics of Rochester Criteria (RC), Yale Observation Scale (YOS) score, and demographics as a low-risk screening tool.

METHODS

Secondary analysis of healthy febrile infants < 60 days old presenting to any of 26 emergency departments in the Pediatric Emergency Care Applied Research Network between December 2008 and May 2013. Of 7334 infants, 1524 met our inclusion criteria of age ≤ 28 days. All had fevers and underwent evaluation for IBI. Receiver operator characteristic (ROC) curve and transparent decision tree analysis were used to determine the applicability of reassuring RC, YOS, and age parameters as an IBI low-risk screening tool.

RESULTS

Of 1524 neonates, 2.9% had bacteremia and 1.5% had meningitis. After applying RC and YOS, 15 neonates were incorrectly identified as low risk for IBI (10 bacteremia, 4 meningitis, 1 bacteremia, and meningitis). Age ≤ 18 days was a statistically significant variable ROC (area under curve 0.63, p < 0.05). Incorporating age > 18 days as low-risk criteria with reassuring RC and YOS misclassified 7 IBI patients (6 bacteremia, 1 meningitis).

CONCLUSION

Thirty percent of febrile neonates met low-risk criteria, age > 18 days, reassuring RC and YOS, and could avoid LP and empiric antibiotics. Our low-risk guidelines may improve patient safety and reduce health care costs by decreasing lab testing for cerebrospinal fluid, empiric antibiotic administration, and prolonged hospitalization. These results are hypothesis-generating and should be verified with a randomized prospective study.

A Novel Algorithm With Paired Predictive Indexes to Stratify the Risk Levels of Neonates With Invasive Bacterial Infections: A Multicenter Cohort Study

BACKGROUND

Our aim was to develop a predictive model comprising clinical and laboratory parameters for early identification of full-term neonates with different risks of invasive bacterial infections (IBIs).

METHODS

We conducted a retrospective study including 1053 neonates presenting in 9 tertiary hospitals in China from January 2010 to August 2019. An algorithm with paired predictive indexes (PPIs) for risk stratification of neonatal IBIs was developed. Predictive performance was validated using k-fold cross-validation.

RESULTS

Overall, 166 neonates were diagnosed with IBIs (15.8%). White blood cell count, C-reactive protein level, procalcitonin level, neutrophil percentage, age at admission, neurologic signs, and ill-appearances showed independent associations with IBIs from stepwise regression analysis and combined into 23 PPIs. Using 10-fold cross-validation, a combination of 7 PPIs with the highest predictive performance was picked out to construct an algorithm. Finally, 58.1% (612/1053) patients were classified as low-risk cases. The sensitivity and negative predictive value of the algorithm were 95.3% (95% confidence interval: 91.7-98.3) and 98.7% (95% confidence interval: 97.8-99.6), respectively. An online calculator based on this algorithm was developed for clinical use.

CONCLUSIONS

The new algorithm constructed for this study was a valuable tool to screen neonates with suspected infection. It stratified risk levels of IBIs and had an excellent predictive performance.

Prevalence of Invasive Bacterial Infections in Well-Appearing, Febrile Infants

BACKGROUND AND OBJECTIVES

Data on invasive bacterial infection (IBI), defined as bacteremia and/or bacterial meningitis, in febrile infants aged <60 days old primarily derive from smaller, dated studies conducted at large, university-affiliated medical centers. Our objective with the current study was to determine current prevalence and epidemiology of IBI from a contemporary, national cohort of well-appearing, febrile infants at university-affiliated and community-based hospitals.

PATIENTS AND METHODS

Retrospective review of well-appearing, febrile infants aged 7 to 60 days was performed across 31 community-based and 44 university-affiliated centers from September 2015 to December 2017. Blood and cerebrospinal fluid bacterial culture results were reviewed and categorized by using a priori criteria for pathogenic organisms. Prevalence estimates and subgroup comparisons were made by using descriptive statistics.

RESULTS

A total of 10 618 febrile infants met inclusion criteria; cerebrospinal fluid and blood cultures were tested from 6747 and 10 581 infants, respectively. Overall, meningitis prevalence was 0.4% (95% confidence interval [CI]: 0.2-0.5); bacteremia prevalence was 2.4% (95% CI: 2.1-2.7). Neonates aged 7 to 30 days had significantly higher prevalence of bacteremia, as compared with infants in the second month of life. IBI prevalence did not differ between community-based and university-affiliated hospitals (2.7% [95% CI: 2.3-3.1] vs 2.1% [95% CI: 1.7-2.6]). Escherichia coli and Streptococcus agalactiae were the most commonly identified organisms.

CONCLUSIONS

This contemporary study of well-appearing, febrile infants supports previous epidemiological estimates of IBI prevalence and suggests that the prevalence of IBI may be similar among community-based and university-affiliated hospitals. These results can be used to aid future clinical guidelines and prediction tool development.

Evaluation and Management of Well-Appearing Febrile Infants 8 to 60 Days Old

This guideline addresses the evaluation and management of well-appearing, term infants, 8 to 60 days of age, with fever ≥38.0°C. Exclusions are noted. After a commissioned evidence-based review by the Agency for Healthcare Research and Quality, an additional extensive and ongoing review of the literature, and supplemental data from published, peer-reviewed studies provided by active investigators, 21 key action statements were derived. For each key action statement, the quality of evidence and benefit-harm relationship were assessed and graded to determine the strength of recommendations. When appropriate, parents' values and preferences should be incorporated as part of shared decision-making. For diagnostic testing, the committee has attempted to develop numbers needed to test, and for antimicrobial administration, the committee provided numbers needed to treat. Three algorithms summarize the recommendations for infants 8 to 21 days of age, 22 to 28 days of age, and 29 to 60 days of age. The recommendations in this guideline do not indicate an exclusive course of treatment or serve as a standard of medical care. Variations, taking into account individual circumstances, may be appropriate.

Evaluation and Management of the Febrile Young Infant (<90 days old) in the Absence of Universally Accepted Criteria for the Risk of Serious Bacterial Infection (SBI)

Fever (≥38°C) in young infants (<90 days of age) represents a common clinical challenge for pediatricians in both outpatient and inpatient settings. While the majority of febrile infants will ultimately be determined to have no serious infection, serious infections when present can cause significant morbidity and mortality in affected patients. Since the evaluation and empiric treatment of presumptive serious infection has associated risks (e.g. medication side effects, stress/disruption of hospitalization, nosocomial infection, etc.) as well as substantial costs, attempts have been made to clearly define an accurate method that enables clinicians to correctly stratify which infants are at relatively low risk for serious bacterial infection (SBI) and may therefore be safely managed less aggressively. Although this topic has been extensively studied and discussed, no single protocol has been universally adopted and clinical practices continue to vary. This paper discusses multiple distinct protocols currently in use, as well as the evidence upon which they are based and the points on which the evidence is not yet definitive.

External Validation of an Invasive Bacterial Infection Score for Young Febrile Infants

OBJECTIVES

The Aronson rule is a point-based clinical decision rule for the identification of febrile infants ≤60 days of age at low risk of invasive bacterial infection (IBI) in the emergency department. This rule uses variables of temperature, age, urinalysis, and absolute neutrophil count. We sought to externally validate this decision rule.

METHODS

We conducted a secondary analysis of a multicenter prospective cohort of febrile infants ≤60 days old presenting to the emergency department between December 2008 and May 2013. Infants were excluded if they had clinical sepsis or chronic conditions or were missing any laboratory components of the Aronson score. Our outcome was IBI (bacteremia and/or bacterial meningitis). We assessed the accuracy of the Aronson rule by reporting metrics of diagnostic accuracy with 95% confidence intervals (CIs) at different point thresholds.

RESULTS

Of 4130 included patients (780 <21 days of age; 2362 boys), 87 (2.1%) had an IBI, including 65 with isolated bacteremia and 22 with meningitis. Using an Aronson cutoff score of 2 resulted in a sensitivity of 93.1% (95% CI 85.6%-97.4%), specificity of 26.6% (95% CI 25.3%-28.0%), and negative predictive value of 99.4% (95% CI 98.8%-99.8%). Six patients with IBI (3 with bacterial meningitis) were misclassified as low risk when using a threshold of 2.

CONCLUSIONS

The Aronson rule demonstrates metrics of diagnostic accuracy that are comparable to the derivation study. Our findings suggest that the rule may be generalizable for the risk stratification of well-appearing febrile infants.